This document summarizes a college course paper on ecological extinction in marine ecosystems. It examines factors like overexploitation, pollution, habitat destruction, and climate change across different marine systems including estuaries, coastal seas, continental shelves, the open ocean, and coral reefs. Through data review and case studies, it finds evidence that overfishing and human pollution have degraded these ecosystems, causing population declines and extinctions. The document concludes by recommending more sustainable fisheries, improved coastal pollution controls, and actions to mitigate climate change in order to reduce threats of ecological extinction in oceans.

1. University of Puerto Rico
Río Piedras Campus
College of Natural Sciences
Department of Environmental Sciences
By: Wilmer O. Rivera
Course: Coastal Environments
Prof. Loretta Roberson, Ph.D.
September 6, 2012

2. Introduction
 There truly ecological extinction in
marine ecosystems?
 Which factors should be considered
in order to discuss a possible
ecological extinction in marine
systems?
 Great discussion about the main
causes of ecological extinction. NRC-
focus in overfishing.

3. Objectives
 Evaluation of diverse marine systems:
a) Estuaries and Coastal Seas
b) Continental Shelves
c) The Open Ocean Pelagic Realm
d) Coral Reefs
• Data review of previous studies of different
factors that may be conduct ecological
extinction:
1) Exploitation
2) Biological and Chemical Pollution
3) Habitat destruction
4) Climate change
5) Loose of biodiversity (Top-Down, Bottom-
Top effects)
• Recommendations for better practices in order to
reduce the effects of ecological extinction.

4. Estuaries and Coastal Seas
I. Fundy Bay-Case of exploitation
A. People have congregated along the coast that
produce cumulative effects.
1. Pollution
2. Exploitation
3. Habitat degradation
B. Fundy Bay-good example of ecological
degradation caused by the effects of exploitation.
1. Hunting and whaling of sea whales, other
marine mammals, birds and code
2. Extinction of 3sp. of sea mink.
3. Significant Reductions:
a. 7Sp. of Atlantic gray whale
b. Salmons, code and other marine
groundfish.
c. 40% of birds decline severely
(3/83sp. hunted to extinction)
4. Regulations don’t increase
the number of individuals.

5. Estuaries and Coastal Seas
II. Global patterns-exploitation
A. Evaluation of 12 coastal seas-Worst scenarios of
overfishing.
B. 80Sp. was examined and the results show:
1. Average global degradation range between
39%-(crustaceans) and 91% (oysters-extreme
depletion).
2. Mammals, birds and reptiles were severely
depleted by 1900 and had declined even
further by 1950.
3. Of the 80sp. 7% are extinct.
4. One-half to two-thirds
of global wetlands and seagrass beds also have
been lost.

6. Estuaries and Coastal Seas
III. Biological and Chemical pollution
A. Biological effects- Introduction of exotic species.
1. In 5 study areas (estuaries)- Average of 117
exotics sp. found.
2. Commonly displaced native animals and plants
to become the dominant species.
B. Chemical pollution-Water quality due the excess
of nutrients from land areas.
1. Eutrophication due to deforestation and
agriculture.
2.Runnoff of sediments and inputs of nitrogen
fertilizers.
3. Estuaries experience massive
nutrient inputs, extended eutrophication,
hypoxia and population explosions of
microbes.

7. Continental Shelves
I. Patterns-Exploitation
A. Longline fishing and trawling removed 89% of
the pristine abundance.
1. Degradation on the structure of sea floor
2. Effects on Biodiversity
3. Effects on large predatory fisches like: cod
and haddock (North Atlantic Region).
4. Between 1986-2000 large sharks in the
northwest Atlantic were reduced by 40–89%.
B. Trophic cascade by the removal of predatory fishes.
1. Increase in the abundance of organism in
other trophic level and the decrease of other
organisms in low trophic levels by
consumption.
2.Example: <cod >shrimp  <zooplankton  >plankton
3.Top and down control affects ecosystem structure.
4. Trophic cascades is closely linked to the phenomenon
of fishing down the food web-(Exploitation of specific
species population).

8. Continental Shelves
II. Eutrophication and dead zones
A. Major river systems-Ej. (Amazon and
Mississippi-Missouri ), discharge vast amounts
of nutrients, into relatively small areas of open
coast.
B. Formation of vast eutrophic and hypoxic regions
comparable with the worst conditions in
estuaries.
1. Mississippi delta-Hypoxic zone has
doubled in the past 20 years to 20,000km2,
and the rate of increase in area.
2. This regions increase in function of
nitrogen loading from the Mississippi
drainage (Fig.1).
3. Increase the mortality of some species
(Shrimps).

9. Open Ocean Pelagic Realm
I. Exploitation
A. Ward & Myers (2005), evaluated 19 oceanic fisheries.
1. 12sp. like sharks and tunas decrease.
2. Large predator showed significant decrease.
3. Trophic cascades are present in this systems.
II. Climate Change
A. Warming- Increase in sea surface temperature
1.Increase the stratification of water.
2. Inhibit upwelling of cooler and denser nutrient rich
water from below.
a. Drops productivity of oceans-(Ej.Nothern-Pacific)
b. Effects on phytoplankton communities.
3.Models predict permanent “El Niño” conditions
on sea water.
B. Acidification-Increase in solution CO2
1. Effects on all calcareous marine organisms.
2. Measurements have already demonstrated a
drop of 0.1 pH units in the oceans.

10. Coral Reef
I. Demise of reef fauna
A. Caribbean- Decrease in live coral cover from
an average of 55% in 1977 to 5% in 2001.
B. Indo-West Pacific- live coral cover still averages
22%, which is about one-half of that in 1980.
C. Reef fishes decreases throughout the more than
one-half between 1977 and 2003.
II. Indirect effects of exploitation
A. Overfishing increase macroalgal abundance
1. Effects on water quality
2. Decrease of coral reef and survival
a. Increase in dissolved organic matter
b. Destabilizes microbial communities on corals
and promotes coral disease.
III. Ocean warming and acidification
A. Warming cause mass mortality of corals-Bleaching
B. Low pH can decrease skeletal density and may stop
calcification (Low production of colonies).

11. Conclusions
I. Overview
A. The three ecosystems discussed are degraded
1. Overexploitation
2.Nutrient and toxic pollution
3. Climate change
B. Some humans activity contribute to this
degradation
1. Fisheries
2. Agriculture
3. Ways to obtain energy

12. Recommendations
I. Sustainable fisheries-Alternatives
A. Industrial scale aquaculture of Sp.-low in
food webs.
B. Improve new regulations to prevent ecosystems
degradation (mangrove, estuaries, shrimp farms)
II. Coastal Pollution-Alternatives
A. Evaluated soil management practices
B. Regulations of animal production systems
C. Removal of subsidies on fertilizers products
III. Climate change and acidification
A. Moderation of fossil fuels and improve new alternatives
energy sources.
B. Local protections form overexploitation and pollution
C. Local conservation efforts on marine resources.

13. Questions???