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Marine and Coastal Systems:
Resources, Impacts, and
Conservation
Chapter Objectives
This chapter will help students:
Identify physical, geographical, chemical, and biological aspects of the
marine environment
Describe major types of marine ecosystems
Outline historic and current human uses of marine resources
Assess human impacts on marine environments
Review the current state of ocean fisheries and reasons for their decline
Evaluate marine protected areas and reserves as innovative solutions
Lecture Outline
I. Central Case: Collapse of the Cod Fisheries
A. No fish had more impact on human civilization than the Atlantic cod.
B. This abundant groundfish (fish that feed on the bottom of the ocean)
was a dietary staple in cultures on both sides of the Atlantic.
C. Cod provided the economic engine for many communities along
coastal New England and Canada.
D. After decades of technologically advanced fishing techniques
harvested many mature breeding adults, the cod populations in the
Atlantic “crashed.”
E. Government officials in Canada, followed by U.S. officials, closed
fishing areas to all commercial fishing. In most of the areas, the cod
have not rebounded.
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1. It is believed that cod remain limited because the former prey of
adult cod are now competing for food with and even eating young
cod before they can mature.
2. A bright spot in the story is that areas of the Georges Bank are
recovering due to elimination of destructive practices such as
trawling. Some other species are recovering such as Ocean
Scallops. There is evidence that young cod are beginning to
appear as well.
II. The Oceans
1. The study of the physics, chemistry, and geology of the oceans is
called oceanography.
2. Oceans influence global climate, teem with biodiversity, facilitate
transportation and commerce, and provide us resources.
A. Oceans cover most of Earth’s surface.
B. The oceans contain more than water.
1. Ocean water is salty because the ocean basins are the final
repositories for water that runs off the land.
2. The salinity of ocean water generally ranges from 33 to 37 parts
per thousand (ppt), varying from place to place because of
differences in evaporation, precipitation, and freshwater runoff
from land and glaciers.
3. Seawater also contains nutrients such as nitrogen and phosphorus
that play essential roles in nutrient cycling.
4. Another aspect of ocean chemistry is dissolved gas content,
particularly the dissolved oxygen upon which gill-breathing
marine animals depend.
C. Ocean water is vertically structured.
1. Water density increases as salinity rises and as temperature falls,
giving rise to different layers of water.
2. The waters of the surface zone are heated by sunlight each day
and are stirred by wind.
3. The pycnocline is the region below the surface zone in which
density increases rapidly with depth.
4. The deep zone of the ocean lies beneath the pycnocline and is not
affected by wind and sunlight.
5. Oceans help regulate Earth’s climate by absorbing and releasing
heat to the atmosphere.
D. Ocean water flows horizontally in currents.
1. The ocean surface is composed of currents—vast, riverlike flows
driven by density differences, heating and cooling, gravity, and
wind.
2. Currents transport heat, nutrients, pollution, and the larvae of
many marine species.
E. Vertical movement of water affects marine ecosystems.
1. Upwelling is the vertical flow of cold, deep water toward the
surface, bringing nutrients from the bottom.
2. Downwelling transports warm water rich in dissolved gases
downward, providing oxygen for deep-water life.
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F. Seafloor topography can be rugged and complex.
1. Parts of the ocean floor are just as complex as the terrestrial
portion of the lithosphere.
2. In the bathymetric profile, gently sloping continental shelves
underlie the shallow waters bordering continents.
3. Most of the seafloor is flat, but there are volcanic peaks, reefs, and
deep trenches.
4. Oceanic zones differ greatly, and some support more life than
others.
a. The well-lit top 10 meters, called the photic zone, contains
nearly all of the oceans’ primary productivity.
b. Between the ocean’s surface and the floor are the pelagic
habitats.
c. On the ocean floor is the benthic area.
III. Marine Ecosystems
A. Open-ocean ecosystems vary in their biological diversity.
1. Much of the ocean’s life is concentrated near the surface in areas
of nutrient-rich upwelling. These areas include a variety of
photosynthetic species and many free-swimming animals.
2. In the deep ocean, animals are adapted to deal with extreme water
pressures and to live in the dark.
3. Some extremely deep ecosystems cluster around hydrothermal
vents.
B. Kelp forests harbor many organisms in temperate waters.
1. Kelp is a large, brown algae, with some types reaching 200 feet in
length.
C. Coral reefs are treasure troves of biodiversity.
1. A coral reef is a mass of calcium carbonate composed of the
skeletons of tiny colonial marine organisms called corals.
2. Corals are tiny invertebrate animals related to sea anemones and
jellyfish.
3. Coral animals capture food with stinging tentacles and also derive
nourishment from symbiotic algae, known as zooxanthellae,
which inhabit their bodies and produce food through
photosynthesis.
4. Coral reefs host an incredible diversity of life, and they protect
shores from damage by waves and storms.
5. Coral reefs are experiencing worldwide declines, probably due to
increased sea surface temperatures and the influx of pollutants.
D. Intertidal zones undergo constant change.
1. The intertidal or littoral zone lies along shorelines between low
tide and high tide.
2. Tides are the periodic rising and falling of the ocean’s height at a
given location, caused by the gravitational pull of the moon and
sun.
3. The intertidal zone is a tough place to make a living, but is home
to a remarkable diversity of organisms.
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4. The rocky intertidal zone is so diverse because environmental
conditions change dramatically from the low part of the intertidal
zone to the high part.
E. Salt marshes cover large areas of coastline in temperate areas where
tides wash over gently sloping sandy or silty substrates.
1. Salt marshes filter pollution, buffer the coastal regions from storm
surges and are prime sites for development worldwide.
2. Destruction of the salt marsh community near New Orleans,
caused impact from Hurricane Katrina to be more severe.
F. Mangrove forests line coastlines throughout the tropics and
subtropics.
1. Mangroves are trees with unique types of roots that curve upward
like snorkels to obtain oxygen.
2. Mangrove forests serve as nurseries for fish and shellfish,
providing economic benefit to residents.
3. In south Florida and elsewhere, mangrove forests have been
removed as people have converted coastal areas to residential,
recreational, and commercial uses.
G. Freshwater meets salt water in estuaries.
1. Estuaries are areas where rivers flow into the ocean, mixing
freshwater with salt water.
2. Estuaries provide critical habitat for many organisms.
3. Estuaries around the world have been affected by urban and
coastal development.
IV. Human Use and Impact
A. The oceans provide transportation routes.
B. We extract energy and minerals.
1. By the 1980s, about 30% of our production of crude oil and nearly
half of our natural gas came from exploitation of ocean deposits.
2. Methane hydrate is an icelike solid consisting of molecules of
methane (CH4, the main component of natural gas) embedded in a
crystal lattice of water molecules.
a. The U.S. Geological Survey estimates that the world’s
deposits of methane hydrates may hold twice as much carbon
as all known deposits of oil, coal, and natural gas combined.
b. Destabilizing a methane hydrate deposit could lead to a
catastrophic release of gas, which could cause a massive
landslide and tsunami. This event would also release huge
amounts of methane, a potent greenhouse gas, into the
atmosphere, exacerbating global climate change.
3. We extract minerals from the seafloor.
C. Marine pollution threatens resources.
D. Nets and plastic debris endanger marine life.
1. Because most plastic is not biodegradable, it can drift for decades
before washing up on beaches, and may be mistaken for food by
marine mammals, seabirds, fish, and sea turtles, which may die as
a result of ingesting it.
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2. Lost or discarded fishing nets frequently continue snaring animals
for decades.
3. In December 2006, the U.S. Congress responded to these threats
and sent the Marine Debris Research, Prevention, and Reduction
Act to President George Bush for his signature.
E. Oil pollution comes from spills of all sizes.
1. The majority of oil pollution comes not from large spills, but from
the accumulation of innumerable widely spread small sources.
2. Minimizing the amount of oil we release is important because
petroleum pollution is detrimental to the marine environment and
the human economies that draw sustenance from that
environment.
3. Over the past three decades, the amount of oil spilled in U.S.
waters and worldwide has decreased, in part because of an
increased emphasis on spill prevention and response.
F. Toxic pollutants can contaminate seafood.
1. Mercury is a central nervous system toxin and can have severe
neurological impact on a developing fetus.
2. Mercury is emitted from combustion of coal in power plants.
G. Excess nutrients can cause algal blooms.
1. The release of excess nutrients into surface waters can spur
unusually high growth rates of algae, called harmful algal
blooms. Some algal species produce reddish pigments, and
blooms of these species are nicknamed red tides.
2. Harmful algal blooms can cause illness and death among
zooplankton, birds, fish, marine mammals, and humans as their
toxins are passed up the food chain.
V. Emptying the Oceans
A. We have long overfished.
1. A recent synthesis of historical evidence revealed that ancient
overfishing likely affected ecosystems in astounding ways that we
only partially understand today.
2. Florida Bay is suffering today from the overhunting of green sea
turtles in past centuries.
3. If current trends continue, a comprehensive 2006 study in the
journal Science predicts that all fish species humans harvest from
the oceans will collapse by 2048.
B. Fishing has industrialized.
1. Modern commercial fishing fleets use fossil fuel, huge boats, and
advanced technologies to harvest unimaginable amounts of ocean
life.
2. Many vessels today are able to capture, process, and freeze their
catch in a vertically integrated operation. This technique is called
factory fishing.
C. Fishing practices kill nontarget animals and damage ecosystems.
1. By-catch refers to the accidental capture of animals, and it
accounts for the deaths of many thousands of fish, sharks, marine
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mammals, and birds each year.
Driftnetting, longlining, and bottom-trawling are all techniques
that are responsible for huge fish catches but also for massive
catches of nontarget animals.
Modern fishing fleets deplete marine life rapidly.
1. The percentage of oceanic fish stocks that are overfished
increased tenfold from 1950 to 1994.
2. A prime example of fishery collapse took place in the 1990s with
groundfish fisheries in the North Atlantic off the Canadian and
U.S. coasts.
3. Removing top trophic level feeders from marine ecoystems causes
their prey species to proliferate. Many scientists conclude marine
ecosystems were probably very different ecosystems prior to
commercial fishing.
Several factors mask declines.
1. Despite the fact that fish stocks have been depleted in region after
region as industrialized fishing has intensified, the amount of
overall global fish production has remained stable for 15 years.
2. Fishing fleets travel longer distances, fish in deeper waters, spend
more time fishing, and set out more nets and lines.
3. Improved technology, including sonar mapping, satellite
navigation, and thermal sensing systems, also helps to explain
high catches.
We are “fishing down the food chain.”
1. Fisheries data reveal that as fishing increases, the size and age of
fish caught decline.
2. We are also shifting from large, desirable species that have
become rare to smaller, less desirable ones.
Some fishing practices kill nontarget animals and damage ecosystems.
1. Many fishing practices catch more than target species. By-catch
refers to the capture of unintended animals including fish, sharks,
marine mammals, and birds.
a. Boats that drag driftnets through the water capture substantial
numbers of large nontarget species. This method has been
banned or restricted by many nations.
b. Longline fishing involves dragging extremely long lines with
baited hooks spaced along their lengths, resulting in a large
by-catch.
c. Bottom-trawling involves dragging weighted nets over the
floor of the continental shelf to catch benthic organisms,
resulting in damage to entire benthic ecosystems. Trawling
crushes many organisms and leaves long swaths of damaged
sea bottoms.
Consumer choice can influence fishing practices.
1. Purchasing ecolabeled seafood products exercises consumer
choice, and thus influences the fishing industry.
2. Several nonprofit organizations have devised guides to help
consumers make ecologically sound choices
Marine biodiversity loss erodes ecosystem services.
2.
D.
E.
F.
G.
H.
I.
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VI. Marine Conservation
A. Fisheries management has been based on maximum sustainable yield.
1. The goal of this strategy is to allow for maximal harvests of
particular populations while keeping fish available for the future.
2. Despite such efforts, many fish stocks have plummeted.
3. A suggested key change is to shift the focus from individual fish
species toward viewing the larger ecological system, considering
the effects of fishing practices on habitat quality, and other
factors.
B. We can protect areas in the ocean.
1. Large numbers of marine protected areas (MPAs) have been
established, mostly along coastlines of developed countries.
Nearly all MPAs allow fishing and other extractive activities.
2. The United States is now inventorying areas for inclusion in a
national network of MPAs.
3. Because of the lack of refuges from fishing pressure, many
scientists have urged the establishment of areas where no fishing
is allowed. These areas are called marine reserves and are
designed to preserve entire ecosystems intact and to improve
fisheries.
C. Reserves can work for both fish and fishers.
1. Data indicate that marine reserves do work, boosting fish biomass
and total catch while decreasing habitat destruction.
D. How should reserves be designed?
1. How large do reserves need to be, how many should there be, and
where should they be placed?
2. Involving fishers directly in the planning process is crucial.
3. Studies have estimated that from 10% to 65% of the ocean should
be protected in no-take reserves. Most estimates range between
20% and 50%.
4. Other studies are modeling how to optimize the size and spacing
of individual reserves so that ecosystems are protected, fisheries
are sustained, and people are not overly excluded from marine
areas.
VII. Conclusion
A. In the Florida Keys and hundreds of other areas around the country,
scientists are gradually demonstrating that setting aside protected
areas can serve to maintain natural systems and enhance fisheries.
B. As historical studies reveal more information on how much
biodiversity our oceans formerly contained and have lost, we may
increasingly consider restoring the ecological systems that used to
flourish.
Key Terms
benthic
by-catch
continental shelf
coral reef
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current
downwelling
estuary
factory fishing
groundfish
harmful algal bloom
intertidal
kelp
littoral
mangrove
marine protected areas (MPAs)
marine reserve
methane hydrate
oceanography
pelagic
pycnocline
red tide
salt marsh
tide
upwelling
Teaching Tips
1. Provide students with information about a marine sanctuary found in or near
your region. There are a growing number of sanctuaries in the United States,
and information about them can be found at www.sanctuaries.nos.noaa.gov.
2. This chapter introduces several ocean habitats, such as mangroves and
seagrass beds, kelp forests and coral reefs, and tidepools and salt marshes. It is
important to emphasize that these ecosystems serve as nurseries for many
juvenile fish and invertebrates. Assign groups of students to study various
ocean habitats (e.g., all of the above, plus barrier islands and barrier reefs,
polar ice caps, pelagic and deep-water habitats, and ocean vents) and have
each group create a poster or presentation on the locations around the world,
the food webs, major threats to the area posed by humans, and the area’s
importance to our way of life.
3. Use tide tables to teach the concept of tides. Tide tables that show predicted
high and low tides at sites across the country can be accessed from NOAA at
http://tidesandcurrents.noaa.gov. The site has both tables and graphs that can
be displayed in a variety of ways.
One suggestion is to create a tidal graph for the period from August 24
through September 10, 2005, for the East Bank 1, Norco—the measuring
station at the southwestern edge of Lake Ponchartrain, Lousiana. This includes
the time period before, during, and after Hurricane Katrina.
For further information about Hurricane Katrina’s effects on the Gulf Coast,
read the levee research at http://soundwaves.usgs.gov/2006/01/ and the
offshore research at http://soundwaves.usgs.gov/2006/01/fieldwork3.html.
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4. The text discusses overfishing and by-catch in the world’s oceans, as well as
some of the issues with fish farms. Show students the Monterey Bay
Aquarium’s Seafood Watch web page
(www.mbayaq.org/cr/seafoodwatch.asp), which helps consumers make
choices for healthy oceans. The website explains the aquarium’s seafood
guides and lists fish and shellfish—domestic, foreign, domestic farmed, and
foreign farmed—with recommendations for or against purchase, based on the
sustainability of the methods used to catch or to raise the organisms. There is
no information on mercury contamination, other than in a pocket guide that
shows a red asterisk next to those species listed in a mercury advisory from
the United States Food and Drug Administration and the Environmental
Protection Agency. For more information about mercury in ocean-caught fish,
see the USDA’s Food Safety Research Information Office fact sheet Mercury
Levels in Commercial Fish and Shellfish (www.cfsan.fda.gov/~frf/seamehg.html).
5. Questions are an important tool for instructors, both in classroom interactions
and in written materials such as labs, quizzes, and exams. Benjamin Bloom
created a Taxonomy of Educational Objectives, which organizes questions into
six basic categories based on the level of thinking involved.
The first two categories, Knowledge and Comprehension, are very basic
informational categories. When you ask for a definition or give a set of
matching questions on an exam, you are having students recall knowledge,
possibly verbatim. You have no way of gauging whether they understand the
information; you only discover whether they have memorized it.
The next two categories, Application and Analysis, involve asking students to
apply information to solve a problem or use what they have learned to analyze
a new situation. Application may still be at the level of rote memorization
(when given a problem of type x, use method y to solve it). Analysis, however,
is the beginning of what are considered to be the higher-order thinking skills
that we would like to foster in our students.
The final two categories, Synthesis and Evaluation, require students to use
multiple resources to create new information, develop new ways of looking at
current information, or generate appropriate criteria to assess a situation.
In an entry-level course, many of the questions will necessarily be at the levels
of Knowledge and Comprehension as students learn the terminology and basic
concepts. However, it is very important to move beyond those levels, and to
require students to analyze, synthesize, and evaluate both in class discussions
and in written work. This is where the course truly begins to be relevant and
applicable to the students’ lives, as they become capable of using the concepts
to understand current events and the issues that affect their own communities
and families.
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Bloom’s Taxonomy is also useful as you plan a course. You will want to
ensure that some of your course objectives are drawn from the higher levels of
thinking. Some excellent websites that provide useful information, including
sample lists of verbs that will help you write exams, are
www.coun.uvic.ca/learn/program/hndouts/bloom.html and
http://faculty.washington.edu/krumme/guides/bloom.html.
Two sites that use a taxonomy wheel to illustrate the ways to use the various
levels of thinking are www.stedwards.edu/cte/resources/bwheel.htm and
www.in2edu.com/downloads/thinking/blooms_taxonomy_chart.pdf.
Additional Resources
Websites
1. CoRIS: Coral Reef Information System, National Oceanic and Atmospheric
Administration, United States Department of Commerce
(www.coris.noaa.gov)
This website gives users access to coral reef data and maps as well as detailed
information about coral reef biology.
2. National Marine Sanctuaries, National Oceanic and Atmospheric
Administration, United States Department of Commerce
(www.sanctuaries.nos.noaa.gov)
This is the official home page for the National Marine Sanctuaries Program
with information about the history and current management of our nation’s
marine sanctuaries.
3. Oceans Alive, The Museum of Science (www.mos.org/oceans)
This web resource has information about ocean formation, physical
characteristics of oceans, water cycle, tides, currents, ocean life, and how
marine scientists conduct their research.
4. Secrets of the Ocean Realm, PBS Online (www.pbs.org/oceanrealm)
This website provides information and classroom activities about unique and
fascinating creatures that inhabit the ocean’s depths.
5. Wetlands, Oceans and Watersheds, United States U.S. Environmental
Protection Agency.(EPA) (www.epa.gov/OWOW)
This website provides information and classroom activities abou unique and
fascinating creatures that inhabit the ocean’s depths.
6. Ocean Conservancy promotes healthy and diverse ocean ecosystems and
opposes practices that threaten ocean life and human life. Through research,
education, and science-based advocacy, Ocean Conservancy informs, inspires,
and empowers people to speak and act on behalf of the oceans. In all its work,
Ocean Conservancy strives to be the world’s foremost advocate for the
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oceans. Projects include: restoring sustainable North American fisheries,
protecting wildlife from human impact, conserving special ocean places, and
reforming government for better ocean stewardship.
(www.oceanconservancy.org)
Audiovisual Materials
1. Canary of the Ocean: America’s Troubled Reef, 1997, produced and
distributed by Miranda Productions (www.mirandaproductions.com/canary)
This video, narrated by Andie MacDowell, is a documentary of the past and
present condition of the coral reefs of the Florida Keys. It also describes the
Florida Everglades and its connection to Florida Bay and the Keys.
2. Ocean Fisheries Case Study Series, 1998, produced by David Conovor,
Compass Light Documentary, Mainewatch Institute, and Island Institute, and
distributed by The Video Project (www.videoproject.com)
This three-video set examines Maine fisheries that illustrate worldwide
resource management issues. The set includes Underwater Out of Sight: An
Ecosystem Case Study; A Tale of Two Fisheries; and Managing for the
Future: Tragedy of the Commons Revisited.
3. Coral Reef Adventure, 2003, video produced and distributed by MacGillivray
Freeman Films (www.coralfilm.com)
This IMAX film follows two divers as they explore reefs of the South Pacific,
documenting problems with overfishing, sedimentation, and coral bleaching.
4. Secrets of the Ocean Realm, 1998, produced by PBS Video and available from
Amazon.com (www.amazon.com)
This five-tape set explores the behavior of deep-sea creatures and includes
Cathedral in the Sea; Survival in the Sea; Venom; Creatures of the Darkness;
The Great Whales; Sharks; City in the Sea; Star Gardens; Mountain in the
Sea; and Filming Secrets.
5. Ocean Wilds, 2001, produced by Feodor Pitcairn and available from PBS
(www.shoppbs.com)
This five-tape set explores the behavior of sea creatures and includes Realm of
the Killer Whales; Creatures of Coral; Sperm Whale Oasis; Gathering of
Giants; and Oases in the Sea.
Weighing the Issues: Facts to Consider
Why Understand Ocean Currents?
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Facts to consider: Knowing where ocean currents flow helps scientists and
other planners determine optimal locations and boundaries for marine
reserves. If reserve boundaries take advantage of currents, then it is more
likely the reserves will receive significant numbers of larvae from diverse
species, allowing the young of important species to settle and grow. A healthy
reserve supports increasing population density and diversity both within the
reserve and in surrounding areas, benefiting not only the ecosystems
themselves but also the fishing industry in that region. Ocean currents carry
larvae of marine organisms as well as food supplies for these creatures, from
biologically based detritus to plankton and marine plants. Currents also may
carry undesirable material, including spilled oil, toxins, invasive species, and
debris such as plastics. Thus, understanding ocean currents can help people
control, treat, and prevent marine damage from such sources. It can also help
fishing fleets locate fish populations, and guide these fleets as well as other
oceangoing vessels to travel most efficiently on the ocean by working with the
natural routes of surface currents. Knowledge of currents also helps people
investigate marine ecosystems, plan and protect coastline areas, and enjoy
ocean-based recreation.
The Coral Crisis
Facts to consider: New technologies may enhance coral growth and reefinhabiting organisms. But the rate of coral destruction may be too fast for such
methods to halt the decline of coral reefs overall, particularly because the
damage is occurring now while these methods are in their early stages of
development. Also, to the extent that coral reef problems have been
exacerbated by the warming of the oceans through global climate change, new
technologies may not be able to compensate adequately for the scope of the
effect of the warming. Taking certain actions that are currently available
would have a much greater impact at a much faster rate. Avoiding trawling in
coral reef areas would prevent the reefs’ destruction at rates much greater than
they
can regrow, though such a restriction would face opposition from some fishing
interests. Reducing the amount of artificial pollutants in ocean waters may
reduce coral loss, but the connection between pollutants and damage to coral
has not yet been definitively proven, with the sources of such pollutants being
difficult to identify. Efforts that retard global climate change could help coral
reefs, but such changes are large in scale, controversial, and slow to take
effect. Forbidding the use of cyanide to catch fish would also help, though
collectors, communities engaged in this method of fishing, and representatives
from developing nations might argue against the economic burden imposed on
those who currently use this method.
Preservation on Land and at Sea
Facts to consider: This question requires an individual response. As land
animals, humans are more likely to notice changes in land ecosystems than in
marine ecosystems because we can actually see the land systems, while it is
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more challenging for us to observe the oceans, especially deep-water
ecosystems. For most of human existence, people’s sense of marine ecosystem
health has been gauged in terms of the abundance of food resources—as long
as human beings have found new ways to harvest from the sea, the general
sense has been that such resources are boundless. In addition, the oceans seem
to absorb maltreatment without apparent harm, such as when untreated
garbage and wastewater are dumped into offshore areas. Interestingly, our
response to garbage and other waste being washed up on shorelines has been
to dump the waste farther offshore, regardless of what may happen to deepwater ecosystems and of wherever the waste may travel when it encounters
deep-water currents.
The Science behind the Stories: Thinking Like
a Scientist
China’s Fisheries Data
Observation: China’s marine fisheries catch increased dramatically in the
1990s while fisheries catch in many other countries declined. Given the
overexploitation of its oceanic fisheries, China’s reported catch appeared
suspiciously high.
Hypothesis: China was systematically overreporting its total catch to the
United Nations Food and Agricultural Organization, thus contributing to an
overly optimistic view of the health of the world’s fisheries.
Experiment: Reg Watson and Daniel Pauly, fisheries scientists at the
University of British Columbia, developed a statistical model to predict
catches based on oceanographic factors, species distributions, and fishing
access. They then compared the predicted catch to each country’s reported
catch.
Results: For most regions, the reported catch was similar to the predicted
catch. In China, however, the reported catch (10.1 million metric tons in 1999)
was almost twice as large as the predicted catch (5.5 million metric tons). The
finding suggests that the total global catch, rather than remaining stable
through the 1990s, actually began to decline in the 1980s.
Do Marine Reserves Work?
Question: What effect do marine reserves have on fish populations in nearby
areas?
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Study: Callum Roberts and Julie Hawkins of York University conducted a 5year study of the Soufrière Marine Management Area (SMMA) and the
surrounding areas on the island of St. Lucia. They conducted visual fish
surveys and interviewed local fishermen. In addition, Roberts’s team, along
with Darlene Johnson and James Bohnsack of NOAA, investigated fish
migrations into and out of Merritt Island National Wildlife Refuge (MINWR)
off Cape Canaveral, Florida, based on earlier findings from a fish population
survey of the reserve by Johnson and Bohnsack. Fish migration was studied by
analyzing trophy fish records from the International Game Fish Association.
Results: In St. Lucia, Roberts’s team found that the biomass of five
commercially important fish species had increased threefold inside the reserve
and twofold outside the reserve within 3 years of establishment of the SMMA.
The catch in fishers’ traps increased from 46% to 90%, depending on trap
size. These data revealed that the reserve seemed to improve surrounding
fisheries despite the expansion of the fishing grounds. Johnson and
Bohnsack’s study of the MINWR obtained similar findings and included the
supposition that the reserve’s fish appeared to be migrating to nearby
commercial and recreational fishing areas. Analysis of trophy fish records
showed that the number of trophy-sized fish caught in the Merritt Island area
increased significantly after the establishment of the MINWR in 1962.
Roberts’s team hypothesized that game fish grew to a larger size within the
protection of the reserve and then migrated to nearby areas where they were
caught by recreational fishers. While there is some criticism of the methods
and conclusions of the study, Roberts, Hawkins, Johnson, Bohnsack, and their
colleagues clearly showed that well-managed reserves are an effective tool in
the establishment of sustainable fisheries.
Causes and Consequences
The following answers for the Causes and Consequences features are examples,
and are not intended to represent a comprehensive list. In addition, the sequence
of items is not meant to connote relative importance.
Issue: Marine Pollution
Causes:
plastic debris, discarded nets, other trash
oil spills
runoff from land
nutrient pollution
Consequences:
animals become entangled and die
animals ingest plastic and die
organisms become coated in oil and die
red tides
dead zones
Solutions:
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prevent dumping and littering; pick up trash from beaches
properly dispose of oil and other pollutants to reduce runoff
better farm practices and other measures to reduce nutrient runoff
Unintended consequences:
Picking up trash in itself has no effect on others' behavior.
…and New solutions:
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InvestigateIt Case Studies and Videos
Case Studies
Plan Would Expand
Ocean Fish Farming
Tracking the Imperiled
Bluefin From Ocean to
Sushi Platter
A Modern Peril: Living
Near the Jaws of the
Sea
Scientists Warn Fewer
Kinds of Fish Are
Swimming the Oceans
British Scientists Say
Carbon Dioxide Is
Turning the Oceans
Acidic
Lobster Boom And Bust
In Europe, High-Tech
Flood Control, With
Nature's Help
Saving a Reef for the
Fish, And the People
In Sri Lanka, Suffering
and Hope
2 Recent Storms Show
Forests Help Blunt
Hurricanes' Force
“Bringing the Ocean to
the World,” in High-Def
In Beach Enclave,
Affluent Are Split Over
Effluent
Saving Coral Reefs
Becomes a Tourism
Priority
Saving Coral Reefs
Becomes a Tourism
Priority
Saving Coral Reefs
Location
Puerto Rico
Topic
Region
Environmental
Policy
Global
Commons
Environmental
Policy
Bangladesh
Land Use
Global
Commons
Oceans
Scotland
Rhode Island
Toxic Waste
Oceans
Netherlands
Land Use
Belize
Conservation
Sri Lanka
Land Use
Honduras
Oceans
Honduras
Washington
Oceans
Washington
Rincon Point,
CA
Oceans
California
Mesoamerican
Reef
Oceans
Mexico
Great Barrier
Reef
Coral Triangle
Oceans
Oceans
Australia
Indonesia
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Becomes a Tourism
Priority
Videos
Saving the Oceans:
Pollution Hurting the
Seas
Obesity in America
Location
Pacific Ocean
Topic
Marine
Resources
Region
Atlanta, GA
Urbanization
Georgia
Answers to End-of-Chapter Questions
Testing Your Comprehension
1. Approximately 71% of Earth’s surface is covered by ocean waters containing,
on average, about 3.5% salt. Water temperature declines with depth, and
density increases slightly at lower temperatures and higher salinities.
Therefore, deep water tends to be colder, saltier, and denser than the surface
water.
2. Ocean currents are driven by the prevailing wind currents at the surface, by
gradients in water temperature, by gravity, and by the Coriolis effect. Surface
currents move horizontally in large circulation patterns. Vertical currents
(upwellings and downwellings) slowly mix the deep waters with the surface
waters, affecting the distribution of nutrients and primary productivity.
3. Biologically productive areas are concentrated in areas of upwelling, in the
shallower waters along continental margins, and at hydrothermal vents of the
deep mid-ocean ridges.
4. Along the coasts there are kelp forests that shelter invertebrates, smaller
fishes, seals, and top carnivores such as great white sharks. Coral reef
communities, which include zooxanthellae, anemones, sponges, hydroids,
tubeworms, molluscs, flatworms, starfish, urchins, and thousands of fish
species, are among the most diverse and productive ecosystems on Earth.
Intertidal ecosystems include rocky and sandy beaches, salt marshes, estuaries,
and mangrove forests, which serve to buffer the land from the effects of storm
surges and act as nursery areas for many marine organisms of economic
importance, such as shrimp.
5. Coral reefs absorb wave energy and protect shorelines from damage, as well
as providing essential habitat for many species. Increased water temperatures
from global climate change, turbidity, nutrient influx (as from agricultural
fertilizers in runoff), and toxic pollutants can all damage coral reef
communities. Salt marshes and mangrove forests are often drained and
converted to residential, commercial, recreational, or agricultural uses.
6. Examples include government policy regulating the shipping industry to cut
down on oil spills; volunteer beach cleanups to pick up plastic trash and other
non-biodegradable debris that can choke or injure organisms that ingest or
become entangled in it; and policy and approaches to reduce overuse and
runoff of excess nutrients that cause eutrophication, as with the Gulf of
Mexico’s dead zone (Chapter 7).
7. Overfishing can remove the larger and fully mature fish faster than they are
replaced by the population, thereby resulting in a decline in catch size and
quality, and a decrease in the fish population because the death and export of
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individuals exceeds birth and import. Some fishing techniques (bottom
trawling, for instance) physically damage or destroy certain marine
ecosystems. The collapse of North Atlantic cod fisheries is a prime example of
overexploitation through trawling damage and direct fishing pressure.
8. Myers and Worm concluded that the oceans today contain only one-tenth of
the large-bodied animals they once did, and that the loss (from industrialized
fishing) happened so quickly in most places that scientists never knew the
original abundance of these animals.
9. Commercial driftnetting catches and kills (by drowning) marine mammals and
turtles, as well as many non-target fish species that die from exposure to air on
ships’ decks. Similar by-catch problems exist with longline fishing, which
hooks unwanted species as well as those desired, and even catches and kills
marine birds. Bottom-trawling disturbs the seafloor and reefs, destroying
habitat inhabited by many species.
10. Nearly all marine protected areas allow fishing or other extractive activities,
whereas marine reserves do not permit such activities. Such marine reserves
can serve as production areas for fish larvae that then disperse outside the
reserve and stock other parts of the ocean.
Interpreting Graphs and Data
1. Before the management plan, swordfish biomass was declining fairly rapidly.
Beginning immediately after the plan, biomass rebounded. The opposite trends
are apparent for fishing mortality: it rose before the plan and decreased after
the plan. Overall, there is an inverse correlation between fishing mortality and
biomass of the stock.
2. If trends continue, the swordfish stock should continue to increase.
3. The establishment of marine reserves (i.e., protected habitat) is vital for many
species, although this is not always the case with large open-ocean fish such as
swordfish unless the reserve is very large. For a species hunted for its meat
like the swordfish, consumer seafood preferences may make at least as much
difference; if people show concern for the species’ decline and reduce their
consumption of swordfish, these purchasing choices will drive down the price
of the fish and fishers will have less economic incentive to fish for them.
Calculating Ecological Footprints
Consumer group
North America
(21.6 kg per
Annual consumption
China
(27.7 kg per
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World
(16.2 kg per
You
Your Class
Your State
The United
States
The World
capita)
capita)
21.6 kg
Answers will vary
Answers will vary
6.48 × 109 kg
27.7 kg
Answers will vary
Answers will vary
8.31 × 109 kg
16.2 kg
Answers will vary
Answers will vary
4.86 × 109 kg
1.77 × 1011 kg
1.04 × 1011 kg
1.38 × 1011 kg
capita)
1. North American versus world fish consumption: 21.6 kg/16.2 kg = 1.33. North
American vs. world ecological footprints: 3-nation average of 6.6 hectares/2.2
hectares = 3.00. With regards to fish consumption, North America is not as far
above the world average as compared to our ecological footprint as a whole.
This may be because of a greater popularity of seafood in many other cuisines
around the world. We are, however, still 33% above the world average.
2. China’s large population already has an ecological footprint that exceeds the
land area of its country. In order to feed that population, they must either
import food from other countries, or harvest food from a common area that is
part of no country (i.e., Earth’s oceans).
3. Answers will vary, but globally, fisheries are already suffering from
overexploitation. The total human impact on those fisheries is the product of
our population size and our per capita consumption rates, so if both are
increasing, their product will increase even more quickly. The ecological
consequences of such overexploitation may not be reversible, and numerous
marine species could be driven to extinction.
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