BIOL 181 Study Guide Questions (ver 2020) (for BIOL 181: Life in the Oceans – Lecture Notes)
Use these Study Guide questions (and not your e-textbook’s Review questions found at the end of each chapter) for your weekly discussions. They represent the most important concepts in our course. These questions also serve as the Study Guide for your final exam. For weeks when we do not use them in our Discussions, I recommend you answer the questions on your own. Consider downloading the file into your computer for easy access while you are drafting your submissions.
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Week 1
Chapter 1: Introduction to Marine Biology
1. What percentage of the earth is covered with oceans? When did interest in the marine environment significantly increase and what powered that interest? Who was the scientist on board the HMS Beagle in 1831 and what theories did this scientist develop?
2. In the early 19th century who proposed that no life could live in the deep ocean? What was the basis for this proposal?
3. Describe the HMS Challenger voyage. Who was the chief scientist on board the HMS Challenger in 1872-76? What theories did Alexander Agassiz develop?
4. Explain why we should study marine biology? Provide a minimum of four definitive and numbered reasons.
5. Explain the process of the scientific method (SM). Be sure to include your SM tutorial’s information found at Course Resources > The Science Learning Center.
6. List (by number) and explain at least four direct and indirect ways in which the oceans influence the lives of humans.
7. Differentiate between the following terms: Oceanography, Physical Oceanography, Chemical Oceanography, Geological Oceanography, Biological Oceanography, and Marine Biology.
Chapter 2: Fundamentals of Ecology
8. Compare and contrast ecology and ecosystems. Compare and contrast habitat and niche.
9. Explain and provide two examples of abiotic factors affecting marine organisms. Explain and provide two examples of biotic factors affecting marine organisms.
10. Describe at least three roles that sunlight plays in the marine environment.
11. How does temperature and salinity play a role in the marine environment? What is a typical salinity value in the open ocean? In estuaries?
12. How does pressure and metabolic requirements play a role in the marine environment?
13. Describe and differentiate between an ectotherm and an endotherm. Describe and differentiate between an osmoregulator, and an osmoconformer.
14. What is the difference between a population and a biological community? Compare and contrast these three population density dispersion patterns: clumped, uniform, and random. Use a drawing (your own or insert an image) to clearly define each pattern.
15. Describe and differentiate the difference in temperature range between small bodies of water (e.g. a small, shallow bay) and open ocean areas. What adaptations or temperature tolerance do you expect to see in the animals living in either body of water?
16. Define the term homeostasis? What does it mean if an organism is anaerobic? What is osmosis?
17. Compare and contrast interspecific and intraspecific competition. Define a keystone species and give an example of one.
18. Osmoconforming animals, such as the spider crab, that live in the open ocean show little ability to withstand large variations in salinity, while coastal animals, such as the closely related fiddler crab, show great ability to withstand large salinity changes. Explain why this is the case, considering the relevant abiotic features of both habitats.
19. Name and describe the three types of symbiotic relationships. Provide a marine example of each.
20. Explain the term population. What is the carrying capacity of a population? Explain the terms: neritic, plankton, benthic, and pelagic.
21. What is the difference between epifauna and infauna? What do detritivores feed on?
22. Differentiate between an autotroph and a heterotroph. What is the primary energy source for autotrophs? How do chemosynthetic organisms generate energy?
23. Compare and contrast a food web and a food chain. What is the average percent of energy passed from one trophic level to another in a food chain? What is the rest used for? Explain the relative positions of primary producers, primary consumers, and top consumers in a food pyramid.
24. Explain eutrophication in detail. Explain two ways that oxygen is diminished due to eutrophication.
Last revised July 28, 2014
BIOL 181: Life in the Oceans – Lecture Notes
The text of these lecture notes for the Sea|mester courses Introduction to Marine Biology (v. 3.1),
by Chantale Bégin, Jessica Wurzbacher, Michael Cucknell, and Introduction to Oceanography
(v. 2.1), by Chantale Bégin and Jessica Wurzbacher, are used with the kind permission of the
authors. Images were researched and selected by UMUC BIOL and NSCI faculty.
Table of Contents
1. Introduction: Science and Marine Biology 2. Fundamentals of Ecology 3. Marine Provinces 4. Seawater 5. Tides 6. Biological Concepts 7. Marine Microorganisms 8. Multicellular Primary Producers 9. Sponges, Cnidarians, and Comb Jellies 10. Worms, Bryozoans, and Mollusks 11. Arthropods, Echinoderms, and Invertebrate Chordates 12. Marine Fish 13. Marine Reptiles and Birds 14. Marine Mammals 15. Intertidal Ecology 16. Estuaries 17. Coral Reef Communities 18. Continental Shelves and Neritic Zone 19. The Open Ocean 20. Life in the Ocean’s Depths 21. Marine Birds and Mammals in Polar Seas 22. Artificial Reefs 23. Marine Protected Areas 24. Impact of Tourism on the Marine Environment 25. The Global Trade of Marine Ornamental Species
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1. Introduction: Science and Marine Biology (The majority of the text below originally appeared as chapter 1 of Introduction to Marine Biology)
1.1. Science and Marine Biology
Oceans cover 71 percent of the earth, and affect climate and weather patterns that in turn impact
the terrestrial environments. They are very important for transportation and as a source of food,
yet are largely unexplored; it is commonly said that we know more about the surface of the moon
than we do about the deepest parts of the oceans!
Oceanography is the study of the oceans and their phenomena, and involves sciences such as
biology, chemistry, physics, geology, and meteorology. Marine biology is the study of the
organisms that inhabit the seas and their interactions with each other and their environment.
1.2. Brief History of Marine Biology
Marine biology is a younger science than terrestrial biology, as early scientists were limited in
their study of aquatic organisms by lack of technology to observe and sample them. The Greek
philosopher Aristotle was one of the firsts to design a classification scheme for living organisms,
which he called ―the ladder of life‖ and in which he described 500 species, several of which were
marine. He also studied fish gills and cuttlefish. The Roman naturalist Pliny the Elder published
a 37-volume work called Natural History, which contained several marine species.
Little work on natural history was conducted during the middle ages, and it wasn’t until the late
eighteenth century and early nineteenth century that interest in the marine environment was
renewed, fueled by explorations now made possible by better ships and improved navigation
techniques. In 1831, Darwin set sail for a five-year circumnavigation on the HMS Beagle, and
his observations of organisms during this voyage later led to his elaboration of the theory of
evolution by natural selection. Darwin also developed theories on the formation of atolls, which
turned out to be correct. In the early nineteenth century, the English naturalist Edward Forbes
suggested that no life could survive in the cold, dark ocean depths. There was little basis for this
statement, and he was proven wrong when telegraph cables were retrieved from depths
exceeding 1.7 km deep, with unknown life-forms growing on them. In 1877, Alexander Agassiz
collected and catalogued marine animals as deep as 4,240 m. He studied their coloration patterns
and theorized the absorption of different wavelengths at depth. He also noted similarities
between deepwater organisms on the east and west coast of Central America and suggested that
the Pacific and Caribbean were once connected.
Modern marine science is generally considered to have started with the HMS Challenger
expedition, led by the British Admiralty between 1872 and 1876. During a circumnavigation that
lasted 3.5 years, the Challenger sailed on the world’s oceans, taking samples in various
locations. The information collected was enough to fill 50 volumes that took 20 years to write.
The samples taken during the Challenger expedition led to the identification of over 4,700 new
species, many from great depths, and the chief scientist, Charles Wyville Thomson, collected
plankton samples for the first time.
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The Challenger expedition was the start of modern marine biology and oceanography, and is still
to date the longest oceanography expedition ever undertaken. However, modern technology has
allowed us to sample organisms more easily and more effectively and to quantify things more
accurately. Scuba diving and submersibles are used to directly observe and sample marine life;
remote sampling can be done with nets, bottles, and grabs from research vessels, and satellites
are used extensively for remote sensing.
1.3. Why Study Marine Biology?
1.3.1. To Dispel Misunderstandings about Marine Life
Though many people fear sharks, in reality 80 percent of shark species grow to less than 1.6 m
and are unable to hurt humans. Only three species have been identified repeatedly in attacks
(great white, tiger and bull sharks). There are typically only about eight to 12 shark attack
fatalities every year, which is far less than the number of people killed each year by elephants,
bees, crocodiles, or lightning.
1.3.2. To Preserve Our Fisheries and Food Source
Fish supply the greatest percentage of the world’s protein consumed by humans, yet about 70
percent of the world’s fisheries are currently overfished and not harvested in a sustainable way.
Fisheries biologists work to estimate a maximum sustainable yield, the theoretical maximum
quantity of fish that can be continuously harvested each year from a stock under existing
(average) environmental conditions, without significantly interfering with the regeneration of
fishing stocks (i.e., fishing sustainably).
1.3.3. To Conserve Marine Biodiversity
Life began in the sea (roughly 3-3.5 billion years ago), and about 80 percent of life on earth is
found in the oceans. A mouthful of seawater may contain millions of bacterial cells, hundreds of
thousands of phytoplankton, and tens of thousands of zooplankton. The Great Barrier Reef alone
is made of 400 species of coral and supports over 2,000 species of fish and thousands of
invertebrates.
1.3.4. To Conserve the Marine Environment
Each year, three times as much trash is dumped into the world’s oceans as the weight of the fish
caught. There are areas in the North Pacific where plastic pellets are six times more abundant
than zooplankton. Plastic is not biodegradable and can kill organisms that ingest it. Many
industrial chemicals biomagnify up the food chain and kill top predators. Some chemicals can
bind with hormone receptors and cause sex changes or infertility in fish. Understanding these
links allow us to better regulate harmful activities.
1.3.5. To Conserve the Terrestrial Environment
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Phytoplankton and algae use CO2 dissolved in seawater in the process of photosynthesis, and
together are much more important than land plants in global photosynthetic rates. Marine
photosynthesizers therefore have the ability to reduce the amount of CO2 dissolved in the oceans
and consequently in the atmosphere, which has important implications for the entire biosphere.
Many marine habitats, such as coral reefs and mangroves, also serve to directly protect coastlines
by acting as a buffer zone, reducing the impact of storm surges and tsunamis that may threaten
human settlements.
1.3.6. For Medical Purposes
Because the architecture and chemistry of coral is very similar to human bone, it has been used
in bone grafting, helping bones to heal quickly and cleanly. Echinoderms and many other
invertebrates are used in research on regeneration. Chemicals found in sponges and many other
invertebrates are used to produce several pharmaceutical products. New compounds are found
regularly in marine species.
1.3.7. For Human Health
Several species of plankton are toxic and responsible for shellfish poisoning or ciguatera.
Understanding the biology of those species allows biologists to control outbreaks and reduce
their impact on human health.
1.3.8. Because Marine Organisms Are Really Cool
Many fish are hermaphrodites and can change sex during their lives. Others, including several
deep-sea species, are simultaneous hermaphrodites and have both male and female sex organs at
the same time.
The blue whale is the largest animal to have ever live on earth, and has a heart the size of a
Volkswagen Beetle.
An octopus recently discovered and as of yet unnamed has the ability to mimic the color and
behavior of sole fish, lionfish, and sea snakes, all toxic animals, which greatly reduces its
likelihood of encountering predators.
1.4. How Is Marine Biology Studied? Using the Scientific Method
1.4.1. Science
The word science comes from the Latin (scientia) and means ―knowledge.‖ Science is a
systematic enterprise that builds and organizes knowledge in the form of testable explanations
and predictions about the world.
1.4.2. The Scientific Method
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The scientific method is widely used in the process of conducting science. Its general steps are to
make observations, form a hypothesis to explain the patterns seen, perform experiments to test
the hypothesis, and then draw conclusions (Figure 1.1).
Diagram showing the steps of the scientific method
by Erik Ong is licensed under CC BY-SA 3.0
Figure 1.1. Scientific method. Steps of the scientific method.
1.5. Review Questions: Introduction to Marine Biology
http://commons.wikimedia.org/wiki/File%3AThe_Scientific_Method.png
http://creativecommons.org/licenses/by-sa/3.0/
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1. What percentage of the earth is covered with oceans? 2. What was the driving force behind the initial studies into oceanography? 3. Who was the scientist on board the HMS Beagle in 1831? 4. What theories did this scientist develop? 5. In the early nineteenth century, who proposed that no life could live in the deep ocean? 6. Who was the chief scientist on board the HMS Challenger from 1872 to 1876? 7. What theories did Alexander Agassiz develop? 8. Why study marine biology? Give three reasons. 9. Explain the process of the scientific method.
BIOL 181: Life in the Oceans – Lecture Notes
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2. Fundamentals of Ecology (The majority of the text below originally appeared as chapter 2 of Introduction to Marine Biology)
2.1. Study of Ecology
Ecology (from Greek oikos meaning home) is the study of interactions of organisms with each
other and with their environment.
Ecosystems are composed of living organisms and their nonliving environment, while the
biosphere includes all of the earth’s ecosystems taken together.
The environment is all the external factors that act on an organism:
physical (abiotic): temperature, salinity, pH, sunlight, currents, wave action, and sediment
biological (biotic): other living organisms and their interactions, e.g., competition and reproduction
The habitat is the specific place in the environment where the organism lives; e.g., rocky or
sandy shore, mangrove, coral reefs. Different habitats have different chemical and physical
properties that dictate which organisms can live there.
Niche: what an organism does in its environment—range of environmental and biological factors
that affect its ability to survive and reproduce
physical: force of waves, temperature, salinity, moisture (intertidal)
biological: predator/prey relationships, parasitism, competition, organisms as shelter
behavioral: feeding time, mating, social behavior, young bearing
2.2. Environmental Factors that Affect the Distribution of Marine Organisms
2.2.1. Maintaining Homeostasis
All organisms need to maintain a stable internal environment, even though their external
environment may be changing continuously. Factors such as internal temperature, salinity, waste
products, and water content all need to be regulated within a relatively narrow range if the
organism is to survive. This regulation of the internal environment by an organism is termed
homeostasis. The ability to maintain homeostasis limits the environments where an organism can
survive and reproduce. Each species has an optimal range of each environmental factor that
affects it. Outside of this optimum, zones of stress exist where the organism may fail to
reproduce. At even more extremes lie zones of intolerance, where the environment is too extreme
for the organism to survive at all.
2.2.2. Physical Environment
Sunlight
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Sunlight plays an essential role in the marine environment. Photosynthetic organisms are the
base of nearly every food web in the ocean and are dependent upon sunlight to provide energy to
produce organic molecules. Light is also necessary for vision, as many organisms rely on this to
capture prey, avoid predation, and communicate, and for species recognition in reproduction.
Excessive sunlight can, however, be detrimental to some life forms, as it may increase
desiccation in intertidal areas and induce photo-inhibition through pigment damage to
photosynthetic organisms in the very top of the water column.
Click the link to see a graph showing the ranges of environmental “comfort zone.” Where planets
are concerned, the central location is referred to as the “Goldilocks Zone”: not too hot, not too
cold range of conditions for organisms.
Temperature
Most marine organisms are ectotherms (meaning that they rely on environmental heat sources)
and as such are increasingly active in warmer temperatures. Marine mammals and birds, on the
other hand, are endotherms and obtain heat from their metabolism. To keep this heat, they often
have anatomical adaptations such as insulation. The temperature of shallow subtidal and
intertidal areas may be constantly changing, and organisms living in these environments need to
be able to adapt to these changes. Conversely, in the open oceans and deep seas, the temperatures
may remain relatively constant, so organisms do not need to be as adaptable.
Salinity
Salinity is the measure of the concentration of dissolved organic salts in the water column and is
measured in parts per thousand (‰). Organisms must maintain a proper balance of water and
salts within their tissue. Semipermeable membranes allow water but not solutes to move across
in a process called osmosis. If too much water is lost from body cells, organisms become
dehydrated and may die. Some organisms cannot regulate their internal salt balance and will
have the same salinity as their external environment; these are termed osmoconformers. These
organisms are most common in the open ocean, which has a relatively stable salinity. In coastal
areas where the salinity may change considerably, osmoregulators are more common.
Pressure
At sea level, pressure is 1 atm. Water is much denser than air, and for every 10 meters descent
below sea level, the pressure increases by 1 atm. Thus, the pressure at 4,000 m will be 401 atm,
and in the deepest part of the oceans at nearly 11,000 m, the pressure will be about 1,101 atm.
The pressure of the water may affect organisms that both live in or visit these depths. Organisms
found in the deep oceans require adaptations to allow them to survive at great pressures.
Metabolic Requirements
Organisms need a variety of organic and inorganic materials to metabolize, grow, and reproduce.
The chemical composition of saltwater provides several of the nutrients required by marine
organisms. Nitrogen and phosphorous are required by all photosynthesizing plants or plant-like
http://www.cffet.net/eco/2.1.JPG
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organisms. Other minerals such as calcium are essential for the synthesis of mollusk shells and
coral skeletons. Although nutrients are essential for life, excessively high levels of nutrients in
sea water can cause eutrophication. This process of nutrient enrichment can lead to vast algal
blooms that eventually die and start to decompose. The decomposition may deplete the available
dissolved oxygen in the water, killing fish and other organisms.
2.3. Populations and Ecology
Population: a group of organisms of the same species that occupies a specific area. Different
populations are separated from each other by barriers that prevent organisms from breeding.
Biological community: populations of different species that occupy one habitat at the same
time. The species that make up a community are linked in some way through competition,
predator/prey relationships and symbiosis.
2.3.1. Population Range and Size
Since biologists can’t count every single individual in a population, they must instead estimate
size by sampling. One common way to sample a population is to count all individuals within a
few representative areas, and then extrapolate to the total number of individuals that are likely to
be in the entire range. Of course, this method only works well if the samples are representative of
the overall density of the population; if you happen to sample areas of exceptionally high
density, you would overestimate population size. Another common method to estimate
population size is the mark-recapture method. In this process, a certain number of individuals are
captured and tagged, then released back and allowed to mingle with the rest of the population.
After a certain period, a second sample is taken. As long as the marked individuals are dispersed
well within the population and haven’t suffered mortality from the first capture, the ratio of
marked: unmarked individuals in the second capture should reflect the ratio of marked: unmarked
individuals in the entire population. (Click the link to see a graphic demonstrating a simple mark
and recapture model for determining population density and distribution.) Therefore, we can
estimate population size with the following formula:
M m
—– = —–
N R
where:
N = Population size
M = Number of animals captured and marked in first sample
R = Number of animals captured in resampling event
m = Number of “R” that were already marked
2.3.2. Distribution of Organisms in a Population
Population density refers to the number of individuals per unit area or volume. In many
populations, individuals are not distributed evenly, and the dispersion (pattern of spacing among
http://cascadiaresearch.org/SPLASH/SPLASH-Education/images/markandrecapture.jpg
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BIOL 181: Life in the Oceans – Lecture Notes
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individuals) can tell a lot about the spacing of resources and interactions between individuals. A
clumped dispersion pattern may reflect variations in the physical environment, or a clumped food
source; a uniform distribution is often the result of strong intraspecific competition; random
dispersion reflects weak interactions among individuals.
2.3.3. Changes in Population Size
Populations change in size over time. They acquire new individuals through immigration and
births, and lose individuals through emigration and deaths. Different species can have varying
reproductive outputs, life span and generation times, all of which can affect how quickly
populations of that species can grow. Collectively, these traits and others that impact births,
deaths and reproduction are referred to as life history traits. On each extreme of a continuum of
life history, strategies are r-selected species (those that have short generation times, high
reproductive potential) and K-selected species (those that have much longer generation time and
are long-lived, but have low reproductive outputs and low population growth potential. The
typical traits of r- and K-selected species are outlined in table 2.1.
Table 2.1. Characteristics of Organisms that Are Extreme r or K Strategists
r
Unstable Environment; Density-
Independent
K
Stable Environment; Density-Dependent
Interactions
organism is small organism is large
energy used to make each individual is low energy used to make each individual is high
many offspring are produced few offspring are produced
organisms have early maturity organisms have late maturity, often after a
prolonged period of parental care
organisms have a short life expectancy organisms have a long life expectancy
each individual reproduces only once individuals can reproduce more than once in a
lifetime
organisms have a type III survivorship pattern,
in which most die within a short time, but a
few live much longer
organisms have a type I or II survivorship
pattern, in which most live to near the
maximum life span
Source: Adapted from University of Miami Department of Biology. Accessed July 15, 2014, from
http://www.bio.miami.edu/tom/courses/bil160/bil160goods/16_rKselection.html
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Populations change in size due to births, deaths, immigration, and emigration. Click here for a
graphic showing various factors that influence population size.
2.3.4. Population Growth
There are many ways in which a population can increase in size, including reproduction and
immigration. When a population has sufficient food or nutrients and is not greatly affected by
predation, it can grow rapidly in an exponential curve. However, no population can maintain this
growth forever—at some point resources become limited and slow down population growth
(either through lower birth rate or increased death rate). That population growth model is called
logistic growth. Here, the population levels off at size which the environment can sustain, known
as the carrying capacity of the environment. The carrying capacity is a dynamic point which may
fluctuate with changes in resource availability and predator behavior. Predator abundance often
mirrors prey abundance with somewhat of a lag in time. Click here to see a graph of exponential
(geometric) and logistic growth curves.
2.4. Communities
A biological community comprises the various populations of different species that interact
together in the same place at the same time. Organisms in a community interact with one another
in a variety of ways.
2.4.1. Niche
The niche of an organism is often described as its role in the community. It refers to the
environmental conditions and resources that define the requirements of an organism. The
broadest niche that an organism can occupy (defined mostly by resource availability and
tolerance to abiotic factors, e.g., pH, salinity) is called its fundamental niche. In reality,
organisms often occupy a smaller subset of their fundamental niche because of biological
interactions with other species such as competition and predation. This subset is called the
realized niche. Click the link to see a graphic indicating the difference between realized and
fundamental niches in nature and how these zones are determined.
2.4.2. Biological Interactions
Competition—occurs when organisms require the same limiting resources such as food, space
or mates. Interspecific competition occurs between organisms of different species, whereas
intraspecific competition is between organisms of the same species. Interspecific competition for
resources prevents different species from occupying exactly the same niche; if two species have
the same requirements, one will outcompete the other with several possible results: local
extinction (also known as competitive exclusion), displacement of the less successful competitor,
or selection for speciation that would lessen the competition.
To efficiently take advantage of a common resource, organisms may have unique anatomical and
behavioral specializations. This is commonly seen on coral reefs. For example, fairy basslets,
brown chromis, and soldierfish are all plankton feeders, but they do not directly compete with
View post on imgur.com
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each other. Fairy basslets feed close to the reef, chromic feed in the water column, and
soldierfish feed mainly at night. Another strategy to lessen competition is to take advantage of a
resource not in demand by other species, e.g., angelfish are one of the only reef fish that eat
sponges.
Predator-prey relationship—may determine the abundance of different trophic levels. The
amount of vegetation in a given area may determine the number of herbivores, which in turn may
limit or be limited by the amount of primary consumers and so on and so forth up the trophic
ladder. In some situations, if the population of primary consumers becomes large and consumes
many of the herbivores, then the vegetation of the area may thrive in a process known as a
trophic cascade. This would be an example of a top-down process in which the abundance of
prey taxa is dependent upon the actions of consumers from higher trophic levels. Bottom-up
processes are functioning when the abundance or diversity of members of higher trophic levels is
dependent upon the availability or quality of resources from lower levels. For example, the
amount of algae produced determines the amount of herbivorous fish produced, and this in turn
determines the amount of piscivorous fish the ecosystem will support.
A keystone species is an organism whose effect on the biological diversity of an area is
disproportionate to its abundance. For instance, the ochre sea star (Pisaster ochraceus) in the
intertidal zone of western North America is a keystone predator and makes it possible for many
other organisms to live through its predation on the mussel. Without the ochre sea star, the
intertidal zone becomes dominated by mussels, which outcompete most other species.
Symbiosis—occurs where organisms develop close relationships to each other, to the extent that
one frequently depends on the other for survival. There are three types of symbioses:
(a) Mutualism: both organisms benefit from the relationship; e.g., corals and zooxanthellae; clown fish and sea anemones
(b) Commensalism: one organism benefits while the other is not harmed but doesn’t benefit; e.g., remoras and sharks
(c) Parasitism: parasites live off a host, which is harmed; e.g., worms in digestive tract
2.5. Ecosystems
Ecosystems include the biological communities and their physical environment. Examples of
ecosystems include coral reefs, mangroves, rocky shores, sandy beaches, estuaries, kelp forests,
or the open ocean. Since different ecosystems don’t exist in complete isolation from one another,
important interactions between different ecosystems often exist (e.g., many coral reef fish spend
their juvenile stages in nearby mangroves).
2.5.1. Producers (Autotrophs)
Most producers obtain their energy from the sun or some form of chemicals. The vast majority of
primary producers photosynthesizes using a pigment called chlorophyll, which absorbs the sun’s
energy and convert it into an organic molecule called glucose (C6H12O6). Other autotrophs may
be chemosynthetic, using the energy from chemical reactions to produce organic compounds.
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The glucose produced by autotrophs may be used by the organism for its own metabolic needs or
is available for higher trophic levels.
2.5.2. Consumers (Heterotrophs)
Organisms that rely on other organisms for food are collectively known as heterotrophs. Primary
consumers are herbivores, feeding on plants. Secondary consumers are carnivores feeding on the
herbivores. Tertiary consumers then feed on the secondary consumers and so on until the top
carnivores are at the top of the food chain. There are also omnivores, which feed on both
producers and heterotrophs, and then decomposers, which feed on all organic matter, breaking it
back down to simple molecules.
Click here for a graphic showing the difference between a terrestrial food chain and a marine
food chain.
2.5.3. Food Chains and Food Webs
Food chains are simple representations of the feeding relationships in an ecosystem. They show
one organism feeding on one prey while being devoured by one predator. In reality, these
interactions may be much more complex with one organism feeding on several prey at different
trophic levels while having several potential predators. This more complex relationship is called
a food web.
2.5.4. Other Energy Pathways
Not all energy pathways in the marine environment involve one organism feeding on another.
Through several inefficient feeding and metabolic mechanisms, organic matter is released into
the marine environment in the form of dissolved organic matter (DOM). These energy-rich
organic molecules can be incorporated by bacteria and other small plankton, which in turn are
eaten by larger organisms. In this way DOM, which would otherwise be lost to the environment,
is funneled back into the food web. Detritus from feces and decaying plants and animals is also
an extremely important food source for organisms in the marine environment. Detritivores, such
as bacteria and zooplankton in the pelagic zone or animals in the benthos, feed on this detritus,
returning energy back into the food chains.
2.5.5. Trophic Levels
Energy flows from the sun through producers to higher orders of consumers. Energy received
from photosynthesis, or from food, is temporarily stored until the organism is eaten or dies and is
decomposed. Thus energy storage in an organism can be portrayed as a trophic level. Primary
producers represent the first trophic level; primary consumers the second, secondary consumer
the third, and so on. Energy transfer between trophic levels is inefficient; primary producers
capture and store less than 1 percent of the sun’s energy. From there, an average of only 10
percent of the energy is passed on to successive higher trophic levels while the rest is used for
feeding, metabolism, reproduction, etc.
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2.6. The Biosphere
2.6.1. Distribution of Marine Communities
Marine communities and ecosystems can be designated by the regions of the oceans that they
inhabit (click here for a simple representation of the ecological energy pyramid, showing energy
loss at different trophic levels). In the water column, known as the pelagic zone, the area of water
overlying the continental shelf is known as the neritic zone, whereas the area above deep ocean
basins is known as the oceanic zone. The organisms that inhabit the pelagic division exhibit one
of two different lifestyles. Plankton drift with the currents, whereas nekton are active swimmers
that can move against the currents. The benthic realm can be divided into the intertidal area, the
continental shelf, and the deep. Organisms in the benthic division are either epifauna, organisms
that live on the sediment, or infauna, organisms that live within the sediment.
2.7. Review Questions: Fundamentals of Ecology
1. Define the term ecology. 2. Define the term ecosystems. 3. Give an example of abiotic factors affecting marine organisms. 4. Give an example of biotic factors affecting marine organisms. 5. Define the term habitat. 6. Define the term niche. 7. Define the term homeostasis. 8. What is an ectotherm? 9. What is an endotherm? 10. What does it mean if an organism is anaerobic? 11. What is eutrophication? 12. What is the difference between interspecific and intraspecific competition? 13. What is resource partitioning, and give an example on a coral reef? 14. Define a keystone predator and give an example of one. 15. Name and describe the three types of symbiotic relationships. 16. What is osmosis? 17. What are osmoconformers? 18. In which type of symbiotic relationship does one organism benefit and the other is not
harmed in any way but does not benefit?
19. Define the term population. 20. What is the carrying capacity of a population? 21. What does the term neritic refer to? 22. What is plankton? 23. What does benthic refer to? 24. What does pelagic refer to? 25. What is the difference between epifauna and infauna? 26. What is an autotroph? 27. What is the equation for photosynthesis? 28. What is the primary energy source for autotrophs? 29. What inorganic nutrients do photosynthetic organisms require?
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30. How do chemosynthetic organisms generate energy? 31. What do detritivores feed on? 32. What is the average percent of energy passed from one trophic level to another in a food
chain? What is the rest used for?
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3. Marine Provinces (The majority of the text below originally appeared as chapter 3 of Introduction to Oceanography)
3.1. Introduction
Why study the oceans? To understand “Life in the Oceans” (our course title), we need to
understand the ocean environments. They cover 71% of our planet (Figure 3.1), and play an
important role in regulating global climate through their interaction with the atmosphere.
Map data: Google, NASA
Figure 3.1. Pacific Ocean from space. Here is an image you probably have not seen before. This
is the Pacific Ocean, with California in the upper-right corner and New Zealand in the lower-left
corner. Perhaps our planet should be named “Water” instead of “Earth” because oceans cover
71% of the planet. The Pacific Ocean is the largest ocean.
Oceans have been present for about 4 billion years, and are thought to be where life originated.
Moreover, the majority of the human population lives by the sea, and modern societies use
biological and mineral resources from the sea. Understanding the oceans is critical for optimal
and sustainable harvest of these resources.
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Four major oceans have traditionally been recognized, with one additional ocean newly
recognized (Figure 3.2).
World map of oceans (English version) by Pinpin is licensed under CC BY-SA 3.0
Figure 3.2. The world’s oceans.
The average depth of all oceans is 3.5 km. Pacific means peaceful or tranquil, but is inaccurately
named as the Pacific Ocean has numerous earthquakes and volcanoes along its edge (the Ring of
Fire). The Pacific is the oldest ocean, about 200 million years old, and the deepest, with an
average depth of 4.2 km. It is the largest (13,000 km wide) and covers 1/3 of the earth’s surface.
The Atlantic Ocean is half as old as the Pacific, and much smaller (6,600 km wide). It is 3.6 km
deep on average. The Indian Ocean is 7,000 km wide and has an average depth of 3.7 km. It is
confined to the Southern hemisphere. The Arctic Ocean is frozen but does not have any land
masses. It has an average depth of 1.1 km. Most oceanographers now also recognize the
Southern Ocean as a separate ocean. Although it is physically connected to the Pacific, Atlantic,
and Indian Oceans, this body of water, south of about 50 degrees south, is defined by the distinct
circulation of the Antarctic convergence.
Seas are bodies of salt water that are smaller than oceans. They have a direct connection to an
ocean and are often indentations into continents, or delineated by an island arc. There are many
seas around the world, including the Caribbean, Mediterranean and Red Sea
3.2. Determining Ocean Bathymetry
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Bathymetry is the study of the depth and shape of the bottom of the ocean. Depth can be
measured in various ways. The earliest depth readings were done using soundings: lowering a
heavy weight on a line until it reached the bottom. In the early 1900s, the first echo sounders
measured ocean depth by sending a sound signal to the bottom and measuring how long it takes
for its echo to return to the surface. Modern echo sounders have tremendously increased the
precision of the measurements, but these measurements are severely limited by ship time and
resources. For this reason, satellite remote-sensing is increasingly used to infer bathymetry.
Features on the ocean floor create sea level abnormalities above them, which can be measured
accurately by satellites after correcting for waves, tides and other interferences (Figure 3.3).
Because satellites can obtain much more data than ships, bathymetric charts derived from
satellite data are more much detailed than those produced by acoustics alone (Figure 3.4).
The Jason-1 Measurement System by NASA
is in the public domain in the United States.
Figure 3.3. The Jason-1 measurement system.
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Global seafloor topographic map by NOAA
is in the public domain in the United States.
Figure 3.4. Global bathymetric chart derived from sea surface abnormalities, which reveals
continental shelves and other shallow areas in pink, mid-ocean ridges in yellow-green and the
deepest parts of the ocean in blue.
3.3. Features of the Continental Margins
The ocean floor can generally be divided in three regions: continental margins, the ocean basins,
and mid-ocean ridges (Figure 3.5). The submerged edges of continents and the steep slopes that
lead to the sea floor, both made of continental crust, are the continental margins. Continental
margins may be passive or active. Passive margins are found where continents have rifted apart
(e.g., the Atlantic). Passive margins show little seismic or volcanic activity, and the transition
from continental to oceanic crust occurs on the same plate. They are typically wide. Active
continental margins, on the other hand, are associated with convergent plate boundaries and
subduction of oceanic crust beneath continental crust (e.g., Pacific Ocean). Active continental
margins are associated with earthquakes and volcanoes, and are typically narrow.
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Diagram Representing Oceanic Basin by Chris_Huh
is in the public domain in the United States.
Figure 3.5. Oceanic basin features.
Continental margins are made up of several sections (Figure 3.6). The continental shelf lies right
at the edge of the continent and is nearly flat, with an average depth of 130 m. The width of the
continental shelf varies greatly, and is much greater in passive continental margins. Continental
shelves have been alternately submerged and uncovered through fluctuations in sea level during
glacial ages, and when inundated, they may accumulate sediment derived from land and carried
by rivers. The shelf break marks the abrupt change in slope from the nearly flat continental shelf
to the continental slope. The angle of the slope varies greatly. Continental slopes have submarine
canyons that were formed during periods of low sea level (Figure 3.7). These canyons are V-
shaped with steep walls and transport sediments from the shelves to the deep sea floor. Caused
by earthquakes or overloading of sediments on the shelf, turbidity currents are a fast moving
flows of sediments on the continental slope that may travel to speeds of 90 km/hr and carry
enormous quantities of sediments. At the base of the continental slope the accumulation of
sediment creates a gentle slope. This portion of the continental margin is known as the
continental rise, and is most prominent on passive continental margins. The continental rise
marks the beginning of true deep ocean basins.
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Continental Shelf by the Office of Naval Research,
U.S. Department of the Navy, is in the public domain in the United States.
Figure 3.6. Continental margin, with continental shelf, slope, and rise.
Los Angeles Margin: Perspective View Looking North
by USGS is in the public domain in the United States.
Figure 3.7. Perspective view looking north over the San Gabriel (A) and Newport (B) submarine
canyons. The distance across the bottom of the image is about 17 km with a vertical exaggeration
of 6x. Both canyons formed when the San Gabriel River and the Santa Ana River flowed out
across the Los Angeles Basin and offshore shelf when it was exposed during lower eustatic sea
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level. Newport Canyon begins less than 360 m from shore at the north end of Newport Harbor
and is composed of individual channels that braid down the slope over a width of about 9 km.
San Gabriel Canyon begins as a series of channels that join together midway down the slope and
then split into two channels at the base of the slope. The width of San Gabriel Canyon at “C” is
815 m and incises about 25 m into the slope. Lasuen Knoll can be seen in the foreground.
(Caption from USGS)
3.4. Features of Deep Ocean Basins
The deep sea floor covers a huge area of the oceans, and most of it consists of vast flat plains
known as the abyssal plains (Figure 3.8). Sediments carried from continental shelves are
eventually deposited on the deep sea floor, covering irregular topography and forming this flat
abyssal plain. Abyssal hills and seamounts are scattered throughout the sea floor. Abyssal hills
are short (less than 1,000 m high) and are a very common feature of the deep oceans. Most are
volcanic in origin. Seamounts are steep volcanoes that sometimes pierce the surface of the water
and become islands. Submerged seamounts that have a flat top are known as guyots, and were
formed by wave erosion when they were at the surface (Figure 3.8). Deep sea trenches occur
along convergent plate boundaries and typically have steep sides. The deepest part of the oceans,
known as the Challenger Deep, occurs in the Mariana trench off Japan and is 11,020 m deep.
Ocean trenches are associated with volcanic arcs, on the side of the overriding plate, as material
from the subducted plate melts and rises. These volcanoes can form island arcs such as the
eastern Caribbean or volcanic mountain ranges such as the Andes. The Pacific Ocean is lined
with such trenches, which create volcanoes and earthquakes around its perimeter, which has been
dubbed the Pacific Ring of Fire (Figure 3.9).
Image courtesy of Prof. Denny Whitford, UMUC.
Figure 3.8. Ocean floor features. Abyssal plains comprise about 40% of the total area in the
oceans.
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Pacific Ring of Fire by Gringer is in
the public domain in the United States.
Figure 3.9. Deep sea trenches are especially common around the perimeter of the Pacific Ocean,
but are also found in the Indian and Atlantic Oceans. The perimeter of the Pacific Ocean is
known as “The Ring of Fire” because of earthquake activity resulting from tectonic plate
movement.
3.5. Features of the Mid-Ocean Ridges
Mid-ocean ridges and rises are the longest continuous mountain chain on earth and are
approximately 75,000 km long. Mid-ocean ridges are typically 2–3 km high and have a central
rift valley along the axis of spreading (Figure 3.10). A prominent feature of the rift valley is
hydrothermal vents (Figure 3.11a and b). These unique features are created when water seeps
down in cracks in the crust, gains heat and dissolved substances and is released by through the
seafloor. Hydrothermal vents can reach temperatures of over 350 °C and contain energy-rich
inorganic compounds such as hydrogen sulfides which can be used as a source of energy by
specialized communities than inhabit the vents. Volcanic seamounts can also be associated with
mid-ocean ridges, as magma can escape through the oceanic crust by side chambers (Figure
3.12).
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Age of the Sea Floor with Shaded Vegetation by
NOAA is in the public domain in the United States.
Figure 3.10. Sea floor bathymetric features and tectonic plate names. Mid-ocean ridges are
shown in red with a black line. Red indicates youngest sea floor age.
New Model for Water Dynamics of Deep-Sea Hydrothermal Vents
by Zena Deretsky, NSF, is in the public domain in the United States.
Black Smoker at a Mid-Ocean
Ridge Hydrothermal Vent by P.
Rona, NOAA, is in the public
domain in the United States.
Figure 3.11a and b. Structure and image of a hydrothermal vent.
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A Map of Seamount in the Arctic Ocean by
NOAA/NOS is licensed under CC BY 2.0
Figure 3.12. Seamounts rising from the seafloor. Color code indicates depth, with red and yellow
being the shallowest depth, and purple representing the deepest depths.
Mid-ocean ridges are cut by a number of fracture zones, parallel series of linear valleys
perpendicular to the ridge. Transform faults are the region of the fracture zone where plates
move in opposite direction (Figure 3.13). Earthquakes are frequent along transform faults.
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Tectonic Plate Boundaries by Jose F. Vigil (USGS, Smithsonian Institution,
US Naval Research Laboratory) is in the public domain in the United States.
Figure 3.13. Mid-ocean ridge (or oceanic spreading ridge) with multiple plate boundary types.
Note the transform plate boundaries, resulting in fracture zones (or transform faults) seen as lines
perpendicular to the ridge axis.
3.6. Review Questions
1. Which type of continental margin (passive or active) typically has a wide continental shelf?
2. What does bathymetry mean? 3. Which ocean has passive margins? 4. Which ocean has a lot of volcanoes and earthquakes along its margins? 5. What is the approximate average depth of a continental margin? 6. What is the name of the boundary between the continental shelf and the continental
slope?
7. What are abyssal plains very flat? 8. Where are hydrothermal vents typically located? 9. Where are rift valleys located? 10. What is the difference between a transform fault and a fracture zone? 11. What size of sediments are typically found on the deep sea floor (fine or coarse)? 12. What is the continental rise? 13. What is a turbidity current?
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4. Seawater (The majority of the text below originally appeared as chapter 6 of Introduction to Oceanography)
4.1. Properties of Seawater
Salinity
Salinity refers to the amount of inorganic material dissolved in water. This excludes sediments
held in suspension since those particles are not dissolved. The polar nature of the water molecule
allows it to readily dissolve salts. As salts (e.g., NaCl) are added to water, they dissociate into
ions (e.g., Na +
and Cl ˗ ), and bond with water molecules. Water can hold a certain quantity of salt
in solution; this is called the saturation value. An increase in temperature increases the saturation
value of salts.
On average the ocean has a salinity of 35 ‰, (ppt, parts per thousand), which means that 1,000 g
of seawater is composed of 965 g of water and 35 g of dissolved solids (Figure 4.1). The most
abundant salts in water are referred to as major ions. Note that the six most abundant of the
major ions make up 99% of all salts in seawater. Minor constituents include more ions, as well as
some gases and nutrients. Trace elements are present in concentrations lower than 1 ppm, and
include aluminum, copper, cobalt, iron, mercury and silver, among others. Though trace
elements are present only in very small quantities, they may still play an important role
biologically (e.g., iron).
Proportion of salt to sea water and chemical composition of sea salt
by Hannes Grobe is licensed under CC BY-SA 2.5
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Figure 4.1. Major ions in seawater. Note that ‰ means “parts per thousand” and % indicates
“parts per hundred.” Therefore 3.5% equals 35 ‰.
Determining Salinity
The principle of constant proportions states that the ratio of one major ion to another remains the
same, regardless of variations in salinity. This applies to major conservative ions in open-ocean,
not where rivers bring dissolved substances or reduce salinities. The ratios of minor non-
conservative constituents (e.g., nutrients and gases) do not follow the principle of constant
composition as they vary because they are connected to life cycles of organisms.
The salinity of water can be measured in a variety of ways. It can be measured with a
salinometer, which measures the conductivity of water (the saltier the water, the more it conducts
electricity). CTDs (Conductivity-Temperature Devices) are modern instruments that also
measure salinity through conductivity. It is also possible to titrate the chlorine in the water,
which is directly proportional to the total salinity because of the principle of constant
proportions. A refractometer measures the bending of light as it passes from air to water; the
saltier the water, the more dense it is, and the more it refracts light.
Pure Water versus Seawater
Seawater has slightly different properties than pure water: it freezes at a lower temperature, boils
at a higher temperature, has higher density and higher pH.
4.2. Processes Affecting Salinity
In the open ocean, salinity varies slightly, from about 33 to 38‰. Salinity variations are much
more extreme in coastal areas, where freshwater input and evaporation can create brackish water
(between seawater and freshwater) or hypersaline water (e.g., up to about 42‰ in the Red Sea).
Salinity often varies seasonally based several factors that affect water input or removal (and to a
much lesser degree, salt input or removal).
Salts present in the oceans originally came from the crust and interior of the earth and were
released through volcanism and hydrothermal vents. Physical and chemical weathering of rocks
on land also adds salt to the oceans through river runoff.
It is estimated that the oceans have been present for about 3.5 billion years, and it appears that
salinity has remained stable for the last 1.5 billion years. If salts are continuously added through
the processes explained above, then they must also be removed by other processes for salinity to
be stable (See an illustration of these processes). Removal of salts occurs in various ways. Sea
spray leaves some salt on land, which is removed from water. Shallow seas that evaporate over a
long period of time leave salt deposits (evaporites). Biological organisms concentrate ions in
their feces and shells, which may then be transferred to sediments. Salts in sediments may be
returned to the interior of the earth as tectonic plates collide and one plate is subducted (pulled)
under the other, along with some of the sediment overlying it. Finally, ions can adhere on the
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surface of small particles, e.g., clay, in a process called adsorption. Salts are then incorporated in
sediments and do not return to seawater readily.
The residence time is the average time a substance remains in solution in the ocean. Conservative
constituents have long residence times (e.g., millions of years), because they tend to be non-
reactive with water and are not added or removed by biological processes. Conservative
constituents include major ions as well as some trace elements and some gases. Non-
conservative constituents, on the other hand, are typically tied to biological, seasonal or
geological cycles. They have a short residence time (25 m depth or fry and spat using cast nets. No anchoring of
boats.
Replenishment Zones (5,214 ha)—Line fishing and anchoring permitted so long as chain does not touch coral. No taking of conch or lobster.
Designated Grouper Spawning Sites—No fishing of grouper during winter spawning season (November 1—March 31).
Animal Sanctuaries (on land)—No hunting, no collection of any species, and no littering.
No Diving Zone—No diving.
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Dense Cover of Brittle Stars, by Peter Southwood, is available under a
Creative Commons Attribution-ShareAlike 3.0 Unported license.
Figure 23.1. Marine protected area.
Other regulations have also been enforced regarding species size limit, maximum take and closed
seasons. This includes Caribbean lobster (Panulirus argus), which has a closed season between
February 1 to July 31, and only three individuals larger than 6 inches can be taken per person.
In order to police Cayman waters, special law enforcement officers have been created. The Royal
Cayman Islands Police have two Marine Policy Officers while the Department of Environment
has four Marine Enforcement Officers. The penalties for breaking these regulations are harsh.
Violation of any Marine Conservation Law is subject to a fine of CI$ 5,000 (US$ 6,250), a
possibility of one year in jail, and the seizure of your boat and equipment.
23.6. Conclusion
In the past, many MPAs have been created by consumer groups, e.g., villagers, in a bottom-up
management style. While these areas may have strong control and regulation from the
population, they often lack strong legal and financial backing. On the other scale, governments
sometimes try to impose MPAs on populations in a top-down management type. While these
sometimes will have financial and legal backing, they often fail in their support by the local
consumer groups, with poaching and illegal activities occurring. What has become clear over
time is that a co-management of top-down/bottom-up approach is best with consumer group
support and regulation backed up by governmental legal and financial backing. Once established,
MPAs have the potential to finance themselves through park fees and user permits.
A considerable number of measures are available for the protection of coral reefs, including
fisheries controls, protected areas, and other schemes ranging from diver cleanups to consumer-
or market- driven controls on reef utilization. All of these measures are heavily dependent on
awareness, education, and the establishment of training programs.
Education needs to be aimed at all levels, including politicians and senior managers, artesian and
commercial fishers, recreational users of reefs, tourists, and aquarium hobbyists, but also the vast
number of people whose lifestyles and businesses may affect reefs through pollution or
sedimentation.
The concept of integrated coastal zone management (ICZM) has been widely accepted and
promoted in many countries. In essence, this involves developing a policy, not for particular
locations but for the entire coastal zone, including inland watersheds, and also offshore waters.
Such policies, if developed with active participation of local stakeholders, can be a highly
effective means. The development of such integrated measures is critical, but also challenging,
requiring considerable coordination of different groups of people and complex negotiations and
processes of conflict resolution. Provision of further information and research remain a further
priority. This includes establishing or expanding systems to monitor coral reefs around the world
in order to establish a clearer baseline and provide warning of change.
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23.7. Review Questions: Marine Protected Areas
1. Name three important values of the marine environment.
2. Name three natural threats to the marine environment.
3. How can MPAs help protect a reef from natural threats?
4. Give three anthropogenic threats to the reef.
5. What are the two broad main reasons for these anthropogenic threats?
6. What is the “tragedy of the commons”?
7. What are four benefits of MPA?
8. What is the Spill Over effect?
9. What is a “paper park”?
10. What are three possible aims of an MPA?
11. What are three questions to consider when planning an MPA?
12. List four potential stakeholders in an MPA.
13. Give three reasons why MPAs often fail.
14. Explain an effective way of financially supporting an MPA, and give an example of
somewhere this is used.
15. What are some traditional management systems, and why are they beginning to fail?
16. Why is the Great Barrier Reef MPA so effective?
17. Give an example of three fishing regulations in the Cayman Islands.
18. Why is it important that the management of MPAs takes a holistic approach using
integrated coastal zone management (ICZM)?
19. What is the difference between a top-down and a bottom-up approach to marine
management? And what is the most effective solution?
20. What is meant by the term ―shifting baselines‖?
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24. Impact of Tourism on the Marine Environment (The majority of the text below originally appeared as chapter 21 of Introduction to Marine Biology)
Tourism is the fastest growing industry worldwide. As more people travel around, their activities
directly and indirectly affect the environment. In this chapter, we explore how activities such as
scuba diving and boating negatively affect the marine environment.
24.1. Dive Tourism
24.1.1. History and Background
Scuba diving was developed by Jacques Cousteau and his team in the 1940s. It became a more
widely practiced sport in the 1970s with important technological advances (which included
nonreserve K-valves, single-hose regulators and BCDs) and the implementation of a certification
system. The scuba diving industry has seen incredible growth in the last few decades, and there
are now around 1 million new certified divers each year. People dive all around the world in
many different types of habitats, including lakes, quarries, and kelp forests. However, it is coral
reefs, with their impressive diversity of life and color, which are among the most dived
environments. Coral reef tourism generates revenues of $2 million/year in Saba and $682
million/year in Australia. This section will focus on the impact of divers on coral reef
ecosystems.
24.1.2. Pressure from Divers
The density of divers is astounding in some parts of the world. In heavily used dive sites of Eilat
(Red Sea), there are over 30,000 dives per site per year, which averages to over 82 divers per
day. Studies in this area have shown that on average, each diver causes one coral break per dive.
The Cayman Islands, in the Caribbean, see 350,000 divers who collectively conduct millions of
dives each year. The Great Barrier Reef receives over 2 million visitors annually, and 15 percent
of the divers are observed damaging coral. These numbers are constantly increasing with the
increase in the number of certified divers.
24.1.3. How Divers Can Affect the Coral
Most damage caused by divers is by direct breakage caused by their fins. Touching live tissue of
the coral without breaking the skeleton is also damaging: it induces stress which requires energy
to repair, and damaged corals may be more susceptible to pathogens, so they thus have a higher
mortality. Moreover, poor buoyancy and swimming too close to the bottom can raise sediment
clouds that can later settle and smother corals. The coral animals then need to divert energy from
growth and reproduction to get rid of this sediment.
Dive tourism also means that more boats come to the reefs, many of which can cause damage to
corals through anchoring where no moorings are available. The overall impact from divers
increases the stress on the coral animals and may reduce their ability to cope with hurricanes,
storms, disease and other natural threats.
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24.1.3. Actual Impact of Divers on Reefs
In Eilat (Red Sea), the proportion of broken and/or abraded coral can be up to 100 percent
around heavily used sites. In the Cayman Islands, increased number of divers has been correlated
with decreased coral cover and increased dead coral and rubble. In Bonaire, heavily dived sites
showed a higher abundance of branched corals, which tend to have a higher growth rate and are
usually the first to grow back after disturbances.
24.1.4. Which Divers Are Most Damaging to Reefs?
Student (uncertified) divers or certified divers with poor buoyancy skills are more likely to
inadvertently touch the bottom. All divers are more likely to touch the bottom in the first 10
minutes of a dive, while they are adjusting their buoyancy. Moreover, male divers have been
shown to damage the reef more than female divers. Women touch the reef more with their hands
but less with their fins, resulting in less damage. Underwater photographers also touch the reef
frequently, as they spend more time closer to the reef busy handing their cameras, and therefore
can lose focus on their buoyancy. Finally, night dives result in more damage to the reef than day
dives.
24.1.5. Which Sites Are Most Sensitive?
Shore dives tend to result in much higher contact than boat dives. Branching coral is usually
more susceptible to breakage than massive (mound-shaped) coral, but it also grows faster and
therefore recovers faster after damage.
24.1.6. What Can Be Done?
Regulating agencies could limit the number of dives per site per year by calculating a ―carrying
capacity.‖ Opinions vary on this carrying capacity, and it has been suggested to be around 5,000
dives/site/year in Bonaire and Eilat, yet as high as 10,000 to 15,000 dives/site/year in Egypt. It is
difficult to simply calculate a carrying capacity for a given site, as diver behavior is often more
important than simply the number of divers.
Some areas require that all dives be led by guides, and ideally guides should lead by example,
staying far from the reef and not touching it. Dive leaders can intervene when they observe
contact with the reef and encourage divers to stay even farther away from the reef at night. Dive
operators can increase environmental awareness with a mandatory short briefing before dives,
which can include reef biology, contacts caused by divers and the concept of protected area.
Governments could set up strict accreditation criteria for dive operators and remove the
accreditation and license to operate if they are not following the standards.
Governments can exclude uncertified or new divers from vulnerable reefs and forbid the use of
gloves; divers are less likely to touch the reef if they might hurt themselves. Dive moorings
reduce anchor damage, and the provision of entry points in nonsensitive areas allows for divers
to adjust their buoyancy at the beginning of the dive.
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It has even been suggested that in particularly vulnerable or damaged areas, divers should be
encouraged to dive on artificial reefs or wrecks, even on underwater theme parks. All of these
would take pressure away from the natural reefs.
Marine parks that provide much of the support for maintaining dive moorings and regulating the
diving can ask for a fee from divers, which can allow them to be self-funded.
24.1.7. Shark/Fish Feeding Dives
It is common practice in many areas to feed fish, turtles and sharks. This ensures that divers see
them, and yet it is highly debated whether this practice should continue. Feeding the organisms
(Figure 24.1) may have ecological and health impacts on the wildlife, and could increase the risk
of harm to divers.
Fish Feeding, by Philippe Bourjon, is available under a
Creative Commons Attribution-ShareAlike 3.0 Unported license.
Figure 24.1. Fish-feeding.
http://commons.wikimedia.org/wiki/File%3AFish_Feeding_Reunion.jpg
http://creativecommons.org/licenses/by-sa/3.0/
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Ecological impacts: Feeding marine organisms disrupts their natural behavior, alters their
distribution and feeding patterns, and attracts them to a certain dive site so that feeding becomes
an event associated with people and boats.
Health impacts: The fed marine life becomes dependent on foods they often cannot digest
properly, or which would not be a part of their natural diet otherwise.
Increased risk of harm to divers? Attacks and bites have been increasingly reported by those
conducting feeding activities and others in the vicinity because the marine life may mistake
diver’s actions for handouts and/or the marine life loses their natural wariness of humans
underwater.
It seems clear that feeding marine life has detrimental ecological consequences, but it is highly
debated whether shark feeding increases bites and attacks on humans. There is not enough
evidence to draw a definite conclusion. However, Florida and Hawaii have both outlawed shark
feeding dives in their waters.
24.2. Boating
There are 17 million recreational boats in the United States, from canoes to yachts. This number
has increased dramatically in the last decade. Their combined activities can have a significant
impact on the marine environment.
24.2.1 Environmental Impacts of Recreational Boats
Habitat damage: Coral reefs and seagrass beds are negatively affected by grounding, propellers
and anchors. The anchor chain can also cause damage by dragging around on the substrate with
the impacted area being quite large.
Propeller contact with marine mammals: Manatees are particularly vulnerable to propeller
injuries because they are slow and spend much time at the surface. Seventy to 100 manatees are
killed every year in Florida alone, and many more are injured.
Sewage: In the United States, boats equipped with a head are required to have holding tanks and
sewage cannot be released within 3 nm from shore. However, most areas outside US waters and
outside major ports do not strictly enforce the holding tank regulations, and many heads are
dumped directly overboard. This does not have a significant impact offshore and for small boats
near shore, as long as numbers are low. However, it may be a problem where there is a big
concentration of boats with limited water circulation (e.g., Tobago Cays in the spring).
Spilled fuel and oil: Many small boats lack a fuel gauge, and simply stop filling their tanks
when it overflows. Fuel in the water affects marine organisms in many ways. It blocks light and
reduces primary production; it is toxic and enters the food chain, where it bioaccumulates and
biomagnifies, becoming more concentrated at higher levels of the food chain. Eventually it kills
fish, and causes internal bleeding and death in birds and mammals.
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Food waste: Though food is clearly biodegradable, high levels of food dumped in a small area
diminishes water and sediment quality, and elevates nutrient levels. If large amounts are
regularly dumped at the same place, it would possibly result in ecological changes such as
changes in species behavior and alterations to community composition. However, the input from
the typical boat is small, especially if the boat is moving in various areas; this is more of a
concern for warships and cruise ships.
Products: Eighty-nine percent of the 10,500 ingredients that are used in personal care products
have not been evaluated for safety, and the impacts on marine life are unknown. Several UV
filters used in sunscreen are suspected to have endocrine disrupting effects, and products that
target hormone systems have been linked to feminization of fish and other aquatic life.
24.3. Impact of Cruise Ships
24.3.1. Numbers
In 2003, there were 250 cruise ships around the world, collectively carrying 12 million
passengers per year. Cruises are the fastest growing sector of the tourism industry, with an 8
percent increase yearly. The Caribbean and Mediterranean are the most important destinations,
but polar regions are increasing in popularity.
In one week, a typical cruise ship generates:
210,000 gallons of sewage
1,000,000 gallons of “gray water” from showers, sinks, dishwashers and washing machines
37,000 gallons of oily bilge water
More than eight tons of solid waste
Toxic wastes from onboard operations like dry cleaners and photo processing laboratories.
24.3.2. Problems
Illegal discharges of oil: Though this is very strictly regulated, many cruise ships have been
found to illegally discharge their oil. The Texas Treasure is accused of having illegally
discharged waste oil and deliberately bypassed its pollution prevention equipment. Ecstasy,
Fantasy, Imagination, Paradise, Sensatio, and Tropicale were found on numerous occasions
from 1996 through 2001 to have discharged oily waste from their bilges into the sea by
improperly using pollution prevention equipment. They also falsified the oil record books in
order to conceal those practices.
Anchoring on coral reefs: In 1988, the Wind Spirit dropped anchor on a coral reef in the US
Virgin Islands, destroying an area 128 m long and 2–3 m wide.
Running aground: In 1994, the Starward discharged 100 gallons of hydraulic oil on the reef
when the ship ran aground in St. John, US Virgin Islands.
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Waste: Big cruise ships generate as much waste as a small city. On average, they produce 3.5 kg
of trash per passenger per day. Many cruise ship destinations that have not signed MARPOL
(Convention for the Prevention of Marine Pollution), can refuse to accept the ship’s trash and
reduce pressure in their own landfills. Cruise ships are then more likely to dump at sea.
A large cruise ship generates 1 million liters of black water in one week. Some have treatment
facilities, but most do not. They must retain the black water until they are out to sea, but there is
some illegal dumping. The Norwegian Sun was found guilty of an illegal discharge of 16,000
gallons (40 tons) of raw sewage into the Strait of Juan de Fuca, known to be habitat for Orca
whales.
Tourism to remote destinations: Cruise ships bring tourists to remote destinations they could
not otherwise access. For example, they bring snorkelers and divers to remote reefs that would
otherwise be mostly untouched. Moreover, they bring a high number of tourists to polar
ecosystems that are quite vulnerable.
Cruise ships have been operating in Alaska and the Canadian Arctic for many years. Many are
now traveling to Antarctica, in what appears so far to be an environmentally sustainable industry.
The International Association of Antarctic Tour Operators sets up guidelines to minimize impact,
which has kept cruise ship and tourist numbers to a minimum. However, the mega cruise ship
Golden Princess (109,000 tons; 3,700 passengers) is now proposed to visit Antarctica (as of
September 2006)
24.4. Review Questions: Impact of Marine Tourism
1. Name three ways divers can directly damage coral while diving.
2. Name three additional ways the impact of divers negatively affects the reef.
3. How does raising sediment clouds hurt corals?
4. What are five ways to reduce the impact of divers on the reefs?
5. Which types of divers are more susceptible to damage reefs?
6. Which types of dive sites or corals are more susceptible to damage?
7. What are the potential negative impacts of feeding marine organisms, e.g., sharks?
8. Explain five ways in which recreational boats negatively affect the marine environment.
9. Explain four ways in which cruise ships negatively affect the marine environment.
10. Why are oil and fuel damaging to the marine environment?
11. How is sewage potentially damaging to the marine environment?
12. Define bioaccumulation and biomagnification.
13. Which marine mammal is particularly vulnerable to propeller damage in Florida?
14. Which countries can refuse the trash from cruise ships and other boats?
15. Why should we be concerned about an influx of tourists to remote areas?
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25. The Global Trade of Marine Ornamental Species (The majority of the text below originally appeared as chapter 22 of Introduction to Marine Biology)
Note: Statistical information for this chapter comes from UNEP-WCNC, From Ocean to
Aquarium: The Global Trade in Marine Ornamental Species (2003).
Between 1.5 million and 2 million people worldwide have marine aquaria, and the majority of
animals for these are collected on coral reefs. There are also aquaria in many public service
buildings such as dental offices, hospitals, restaurants, and night clubs, and there are many large
public aquaria, e.g., the Georgia Aquarium, which contains 8 million gallons of water, and more
aquatic life than any other aquarium. The aquarium trade has been heavily criticized in the past
for the use of unsustainable collection techniques and poor husbandry practices.
However, this industry provides a potential source of income for communities living close to
coral reefs and an incentive for coral reef conservation from the fishermen involved. In 2003, an
interesting report was published by UNEP World Conservation Monitoring Centre, “From Ocean
to Aquarium: The Global Trade in Marine Ornamental Species,” taking an objective look at this
international industry.
25.1. When Did This Industry Begin and How Has It Developed?
The collection and export of tropical marine fish for the aquarium trade started in Sri Lanka in
the 1930s, on a very small scale. Trade expanded during the 1950s, with an increasing number of
places (e.g., Hawaii and the Philippines) issuing permits for the collection of species destined for
the marine aquarium trade.
In general, the overall value of the marine fish trade has remained fairly stable in recent years.
However, the export of live coral has increased by 12–30 percent annually from 1990 to1999,
only stabilizing since 2000.
25.2. Where Do the Fish Come from?
Over 20 million wild fish are caught every year for the aquarium trade, mainly from tropical
coral reefs in Southeast Asia, particularly Indonesia, but increasingly from several island nations
in the Indian and Pacific oceans. To date, only 1–10 percent of marine fish and less than 1
percent of coral species can be bred in captivity. Even fewer species are bred in commercial
quantities. This is a large contrast to freshwater aquaria species, where 90 percent of species are
currently farmed. Perhaps advancements in aquaculture may enable the farming of marine
ornamental species in the future.
25.3. What Organisms Are Traded?
Very few of the species traded are exploited directly for other purposes, and aquarium animals
are the highest value-added product that can be harvested from a reef.
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A total of 1,471 species of fish are traded globally, and the annual trade is between 20 million–
24 million individuals. Damselfish (Pomacentridae) make up almost half of the trade, with
species of angelfish (Pomacanthidae), surgeonfish (Acanthuridae), wrasses (Labridae), gobies
(Gobiidae) and butterflyfish (Chaetodontidae) accounting for approximately another 25–30
percent. One of the most traded fish is the anemonefish (Figure 25.1), particularly after the
release of Disney’s movie Finding Nemo.
Clown Fish by Michael Johnson is available under a Creative Commons Attribution 2.0 Generic license.
Figure 25.1. Clown fish, Amphiprion ocellaris.
The bluestreak cleaner wrasse (Labroides dimidiatus) (Figure 25.2a) and the mandarin fish
(Synchiropus splendidus) (Figure 25.2b) are known to not acclimatize well to aquarium
conditions, mainly due to their restricted dietary requirements. However, according to trade data
collected for the Global Marine Aquarium Database (GMAD) (2000), they are very commonly
traded.
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Cleaner Wrasse with a Client, by Alexander Vasenin, is available under a
Creative Commons Attribution-ShareAlike 3.0 Unported license.
http://en.wikipedia.org/wiki/Bluestreak_cleaner_wrasse#mediaviewer/File:Cleaner_wrasse_with_a_client.JPG
http://creativecommons.org/licenses/by-sa/3.0/
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Mandarin Fish by Steve Childs is available under a Creative Commons Attribution 2.0 Generic license.
Figure 25.2a and b. The bluestreak cleaner wrasse, Labroides dimidiatus, servicing a larger fish
(a) and two mandarin fish (Synchiropus splendidus) (b).
A total of 140 species of scleractinian corals (reef-building corals) are traded worldwide, with
the annual global trade ranging from 11 to 12 million pieces. Sixty-one species of soft coral are
also traded, amounting to close to 390,000 pieces per year.
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Seashells, Coral, Shark Jaws and Dried Blowfish by Tom Oates (2008) is available
under a Creative Commons Attribution-ShareAlike 3.0 Unported license.
Figure 25.3. Coral collected for the aquarium trade.
Several species of soft corals are commonly traded due to their ability to heal wounds and
regenerate tissue rapidly. Sarcophyton spp. and Dendronephthya spp. (Figure 25.4a and b) are
two of the most commonly traded species of soft coral. The biology of Sarcophyton spp. makes it
a hardy, fast-growing and easily propagated species under aquarium conditions. Unfortunately,
Dendronephthya spp. usually die within a few weeks, mainly because they lack photosynthetic
symbionts and rely on filtering particles and nutrients in the water column for food.
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Sarcophyton glaucum at Shaab Angosh Reef, by Alexander Vasenin,
is available under a Creative Commons Attribution-ShareAlike 3.0 Unported license.
http://en.wikipedia.org/wiki/Sarcophyton_glaucum#mediaviewer/File:Sarcophyton_glaucum_at_Shaab_Angosh_reef.JPG
http://creativecommons.org/licenses/by-sa/3.0/
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Dendronephthya soft coral at Gilli Lawa Laut, by Alexander Vasenin,
is available under a Creative Commons Attribution-ShareAlike 3.0 Unported license.
Figure 25.4a and b. Sarcophyton sp (a) and Dendronephthya sp (b).
In addition to coral, a further 516 species of invertebrates are traded for aquaria. The annual
global trade ranges from 9–10 million animals, mostly mollusks, shrimps and anemones. Two
species of cleaner shrimp (Figure 25.5) and one genus of anemones accounts for 15 percent of all
invertebrates traded.
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Banded Coral Shrimp by Richard Ling available under a
Creative Commons Attribution-ShareAlike 2.0 Generic license.
Figure 25.5. Cleaner shrimp, Stenopus sp., one of the most commonly traded invertebrate
species.
Linckia laevigata (Figure 25.6) is the most commonly imported sea star in the aquarium trade,
and accounts for 3 percent of the total trade in invertebrates. However, they are very difficult to
maintain in aquarium conditions, due to their dietary needs of organically enriched detritus that
typically cover live rock, and they will refuse artificial aquarium food.
http://commons.wikimedia.org/wiki/File%3AStenopus_hispidus_1.jpg
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Linkia Laevigata by NOAA is in the public domain in the United States.
Figure 25.6. Linckia laevigata, the most commonly traded sea star.
In order to make more informed decisions on the suitability of marine organisms for the
aquarium trade, more information is need on the population dynamics and life history
characteristics of these targeted organisms.
25.4. What Is the Global Value of the Aquarium Trade?
Although the volume of organism traded is relatively low, the value is very high. The trade of
marine ornamental species is a global multimillion dollar industry, estimated to be worth
US$200 million–$330 million annually. This can potentially provide an incentive for fishermen
to conserve reef habitats and offers a livelihood to coastal communities often in low-income
areas.
In 2000, 1 kg of aquarium fish from the Maldives was valued at almost US$500, whereas the
same weight of fish harvested for food was worth only US$6. Similarly, the live coral trade is
estimated to be worth about US$7,000 per ton, whereas the use of harvested coral for the
production of limestone yields only about US$60 per ton. In the Pacific island of Palau, live rock
is exported for the aquarium trade at US$2.2–$4.4 per kilo whereas it is sold locally as
construction material for less than US$0.02 per kilo. In Sri Lanka, an estimated 50,000 people
are directly involved in the export of marine ornamentals.
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Live Rock, by Mrbrefast, is available under a Creative Commons Attribution-ShareAlike 3.0 Unported license.
Figure 25.7. Live rock.
25.5. What Are the Benefits?
The aquarium trade could potentially be a sustainable use for coral reefs, if correctly managed.
Anthropogenic impacts threaten 88 percent of all reefs, particularly in Southeast Asia, the major
source of animals for the marine ornamental trade. It is important that the collection of aquarium
species does not further compound these problems. Some collection techniques have minimal
impact on coral reefs, and well-managed shipping and husbandry practices can also minimize
mortality levels.
The trade of marine ornamentals can also provide a valuable source of foreign exchange for
national economies and a strong economic incentive for the sustainable management of reefs.
Aquarium animals are the highest value-added product that can be harvested sustainably from
coral reefs, so collecting and exporting marine ornamentals in developing countries creates jobs
in rural, low-income, coastal areas where resources and alternative options for generating income
can be limited.
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Domestic or public saltwater aquaria increase awareness and educate the public about coral reefs,
a mostly hidden ecosystem.
25.6. What Are the Associated Problems?
Destructive collection techniques, the introduction of alien species, possible overharvesting of
some species, high levels of mortality associated with inadequate handling and transport, the lack
of scientific information for many species collected and the threat of extinction of target species
continue to pose significant challenges to achieving sustainability.
25.6.1. Destructive Harvesting Techniques
Chemicals are often used to stun and catch fish. Sodium cyanide is squirted into crevices where
fish hide and stuns the fish, making them easier to catch. However, there are high mortality rates
post-capture due to their weakened state. Therefore, more fish are collected to allow for these
fatalities. Between 5–75 percent of fish collected using narcotics die within hours of collection,
and 20–50 percent die soon after. On average, another 30 percent die prior to export, and
importing countries register mortalities of 30 percent or more. Cyanide poisoning is nonselective
and may destroy coral reef habitat by poisoning and killing nontarget animals, including corals.
Reports have demonstrated that exposure of corals to cyanide causes bleaching.
The use of cyanide originated in Taiwan and/or the Philippines in the 1960s and in the mid-
1980s, more than 80 percent of all fish harvested in the Philippines for the aquarium trade were
collected using cyanide. Its use then spread to Indonesia, and in the mid-1990s it was estimated
that about 90 percent of vessels transporting live fish in the eastern islands of Indonesia had
cyanide on board. In the past 20 years, more than 1 million kg (1,100 tons) of sodium cyanide
has been used in reefs. This amount is enough to kill 500 million people.
Cyanide fishing is illegal in most countries. In Indonesia, for example, legislation since 1985
includes specific prohibition of the use of destructive fishing practices, such as the use of poison,
with penalties up to 10 years in prison and/or a fine equivalent to US$12,000. However, the high
premium paid, the ease with which a great number of fish can be caught in a short time period,
the often poor law enforcement capacities and high levels of corruption have allowed the use of
poison to spread rapidly throughout the Asia-Pacific region and have made the eradication of this
illegal and highly destructive fishing technique nearly impossible.
During collection of corals, many other colonies may be damaged or broken. In some cases,
coral is actually broken to allow access to fish sheltering in the reef. This tends to be more
common with branching species in which small fish, such as damselfish species, often find
refuge.
Collection of live rock is potentially destructive as it may lead to increased erosion and loss of
important fisheries habitat. The results of studies of the effects of collection of live rocks on reef
habitats have been inconclusive and this is a relatively new trade, so its impacts have not been
well studied. More research and monitoring is needed.
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There are also risks to the divers themselves, who often go to considerable depths for extended
periods of time and may suffer from decompression sickness, “the bends,” upon return to the
surface.
25.6.2. Overfishing of Target Organisms
There are fears that favored species of ornamental fish species have been reduced to levels that
are beyond recovery, and it is believed that collection restrictions must be implemented.
Although no marine species collected for the aquarium trade are known to have been driven to
global extinction, various studies in Sri Lanka, Kenya, the Philippines, Indonesia, and Hawaii all
reported localized depletion of a number of target aquarium species of fish (e.g., butterflyfish,
angelfish) due to heavy collecting pressure.
Corals are extremely slow growing, and mortality rates of coral pieces in home aquaria are fairly
high, although improved technology may one day increase longevity. It is important to bear in
mind that practices such as coral mining for the production of lime rock have a much more
significant impact on coral populations and community structure than the collection of corals for
the ornamental trade.
Due to their distinctive bright coloration, males of many coral reef fish species tend to be
preferred as they fetch a higher price. Selectively harvesting for males on a regular basis may
lead to reproductive failure and ultimately population collapse due to heavily biased sex ratios in
remaining schools.
25.6.3. Post-Harvesting Mortality
There are many factors that lead to post-harvesting mortality, such as physical damage and use of
chemicals during collection, poor handling practice and disease. Where organisms are collected,
stored and handled by adequately trained individuals, and transported in unsuitable conditions,
estimated levels of fish mortality have been as low as a few per cent. As a result of such
mortality, more fish must be collected to meet market demand.
25.6.4. Invasive Species
The introduction of species to an area where they do not naturally occur can be a serious
problem. Species are introduced through intentional and accidental stocking, release of bait fish,
release of unwanted aquarium fish, escape from aquarium facilities and discharge of ballast
water from ships. Lionfish (Pterois volitans) (Figure 25.8) are a commonly kept aquarium
species. Their dramatic invasion of the Caribbean was due to release from an aquarium in
Florida. Lionfish are now extremely abundant in the Bahamas and some parts of the Caribbean,
and they are thought to dramatically reduce the abundance of small reef fish through predation.
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Lionfish, by Altbert Kok, is in the public domain in the United States.
Figure 25.8. Lionfish (Pterois volitans). The lionfish is an invasive species in the southern
United States.
25.7. How Is the Trade of Marine Ornamentals Being Managed and How Can
Sustainability Be Improved?
Ornamental fisheries must be managed to be biologically sustainable, not conflict with other
resource uses and keep post-harvest mortalities to a minimum. In order to reach biological
sustainability, the species must replenish naturally at the same or a greater rate than they are
caught, and negative impacts on the environment must be minimized. Organisms unsuitable for
aquariums must not be collected.
25.7.1. Management
Protection can be achieved through the establishment of marine reserves, in which it is illegal to
collect marine ornamentals. Other methods to control collection pressures include setting quotas
and size limits, and restricting access through the use of permits.
http://commons.wikimedia.org/wiki/File%3ALionfish.JPG
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A number of countries (e.g., Australia, the Cook Islands, Palau) make effective use of a licensing
system to monitoring the industry and regulate collection effort by issuing a limited number of
permits each year. In Australia, there are also restrictions on net size to prevent a greater fishing
effort offsetting the limited number of permits. However, in countries such as Indonesia, permits
are issued but enforcement is difficult and so the permits are largely ineffective.
The number of fish exported from any source country can also be limited though quotas. Quotas
are relatively easy to enforce and they are only effective is based on rigorous scientific research.
They must also be implemented at a species-specific level, as general quotas may encourage
collectors to focus on the most valuable species.
Juveniles are favored in the aquarium industry due to their distinctive coloration, low transport
costs and optimal size for home aquariums. However, young fish are easily stressed and suffer
high mortality during holding and transporting. Minimal size limits help ensure stock is not
unnecessarily wasted. Maximum size limits are equally important to ensure sufficient numbers of
breeding adults remain. Maximum size restrictions for collection of coral ensures mature
colonies are not removed from the reef, and removing small colonies is less likely to damage the
habitat structure of the reef.
Marine reserves are often used to manage marine fisheries, usually food fisheries, and they have
been shown to increase fish abundance and protect ecosystems from habitat destruction.
Therefore, if managed correctly they could also be valuable in managing aquarium fisheries.
Temporary closures protect species during the reproductive phase to ensure sufficient
recruitment to sustain the population. These are only effective if implemented at the right time
and in the right location. At present, there are no closed seasons in operation specifically for the
aquarium trade.
It is important that management decisions, such as the location of reserves, involve the
participation of all stakeholders, including appropriate consultation with scientists and fishermen
at the local and national levels.
25.7.2. Certification
The government and industry can help support conservation initiatives; however, consumers can
also encourage and promote best practices. Certification empowers consumers to assist in
reducing the environmental impacts of the trade by selectively purchasing specimens produced in
an environmentally friendly manner. The Marine Aquarium Council (MAC) is developing a
certification scheme that aims to ensure market demand and support for quality products and
sustainable practices. The scheme covers practices (industry operators, facilities, and collection
areas) and products (organisms).
Industry operators can be certified through evaluation for compliance with MAC standards for
Certification of Practices. Participating companies initially have to pay fees to an independent
certification authority as well as MAC, although this is balanced against superior returns from
certified marine ornamentals from the industry as well as the consumers’ willingness to pay a
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premium for certified products. For certification systems to be effective, public awareness should
be raised as the purchasing power that hobbyists possess is undoubtedly the single most
important market force in the marine aquarium industry.
25.7.3. Mariculture
The pressure on wild populations could be relieved by supplying the industry with tank-bred
rather than wild-caught specimens.
Corals
The aquaculture of corals is achieved through fragmentation of a colony and attaching the
smaller fragments to a new substrate, which can either be left in a holding tank or placed back in
the ocean until they reach marketable size. An additional advantage is that cultured coral adapts
better to aquarium conditions than wild-caught coral. Seventy-five species of coral can be bred in
captivity, but only fast-growing species are economically profitable, e.g. Acropora and
Pocillipora. Unfortunately, most of the popular species in the trade are slow-growing and
difficult to propagate. Between 1997–2001, 99 percent of the total global trade in live corals
originated from “wild” sources and only 0.3 percent was captive-bred.
The economic viability of aquaculture must also be explored. In newly set-up operations, start-up
costs and operating costs are typically very high, with fairly low returns in comparison to wild-
caught products. However, these costs can be greatly reduced if established exporters set up
farming as a side industry. Governments and foreign aid may assist by providing initial funding.
Fish
To date, virtually all marine ornamentals fish are wild caught (breeding and rearing marine
species only accounts for 1–2 percent of the trade at present), and efforts to develop captive
cultivation have been limited.
Aquaculture can be an environmentally sound way to increase the supply of such organisms, by
helping reduce pressure on wild fish populations and producing juvenile and market-size fish of
a wide variety of species year-round. Furthermore, rearing aquarium fish in closed systems is
likely to lead to the production of hardier species, which fare better in captivity and survive
longer.
Blennies, gobies, and members of the Pomacentridae family are relatively easy to rear in
captivity as they attach or deposit their eggs on or in various substrates and, for species such as
the clown fish, can be conditioned to spawn voluntarily by manipulation of day length and water
temperature. Most other fish species such as angelfish and butterflyfish are known as broadcast
spawners, i.e., they spread their eggs freely in the water column and are therefore more difficult
to culture in captivity. They also usually require hormone treatment to induce spawning.
Invertebrates
BIOL 181: Life in the Oceans – Lecture Notes
345
There is considerable interest in giant clam mariculture (Figure 25.9) for several reasons; they
require no artificial feeding, rearing techniques are relatively simple, and the setting up of
facilities requires little capital investment and can involve local community members.
Furthermore, unlike many other forms of mariculture, it does not require broodstock to be
continuously captured from the wild, and hence the impact on wild stocks is minimal.
Giant Clam Mariculture, by JSLUCAS75, is available under a
Creative Commons Attribution-ShareAlike 3.0 Unported license.
Figure 25.9. Giant clam mariculture. Giant clams have been successfully grown in captivity.
25.8. What Is the Future?
Coral reefs are suffering from many threats, and it is important that the aquarium trade is
effectively managed in order to not further compound these problems. The United Nations
believes that if properly managed, the trade of marine ornamental species can help coastal
communities climb out of poverty.
The highly selective nature of this fishery increases the impact on populations of targeted
species. It may also, directly through the use of destructive fishing practices or indirectly through
the removal of key species (e.g., cleaner fish/shrimp), impact other species and ecological
processes in the habitats where fishing for the aquarium trade occurs.
http://commons.wikimedia.org/wiki/File%3AGiant_clam_mariculture.JPG
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BIOL 181: Life in the Oceans – Lecture Notes
346
25.9 Review Questions: Global Trade of Marine Ornamental Species
1. Is it just reef fish that are traded for aquaria?
2. True or false? The live coral trade for aquaria is significantly more valuable than sale to
the construction industry.
3. What is one of the main benefits of the aquarium trade for coral reef ecosystems?
4. How do they typically catch fish for the aquarium trade?
5. What are three problems associated with the aquarium trade?
6. What are two possible solutions to help alleviate problems associated with the aquarium
trade?
IntroductionScienceAndMarineBiology
FundamentalsOfEcology
MarineProvinces
Seawater
Tides
BiologicalConcepts
MarineMicroorganisms
MulticellularPrimaryProducers
SpongesCnidariansAndCombJellies
WormsBryozoansAndMollusks
ArthropodsEchinodermsAndInvertebrateC
MarineFish
MarineReptilesAndBirds
MarineMammals
IntertidalEcology
Estuaries
CoralReefCommunities
ContinentalShelvesAndNeriticZone
TheOpenOcean
LifeInTheOceansDepths
MarineBirdsAndMammalsInPolarSeas
ArtificialReefs
MarineProtectedAreas
ImpactOfTourismOnTheMarineEnvironment
TheGlobalTradeOfMarineOrnamentalSpecies
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