Major threats to aquatic biodiversity include habitat loss, invasive species, pollution, climate change, and overexploitation, which are exacerbated by human population growth. The greatest marine biodiversity is found at coral reefs, estuaries, and on the deep ocean floor. While protections for whales have led to recovery of some populations, others are still threatened by illegal hunting. Invasive species like the Asian swamp eel and lionfish degrade ecosystems, while activities such as agriculture, development, and waste dumping pollute waterways and oceans. Climate change poses a growing threat through sea level rise, warming, and acidification. Overfishing has driven many fish species toward extinction.

1. Sustaining Aquatic Biodiversity
Part 1—Major Threats
Sky
Harbor
Interna.onal
Airport
Built
on
Hohokam
Canals.
Archaeology
Magazine.
2014
April
1.

2. Fig.
11-­‐1,
p.
250
Cetaceans are
Whales
Toothed whales
Sperm
whale
with
squid
Killer whale
Narwhal
Bottlenose dolphin
0 2 4 6 8 10 1214 16 18 20 22 24 26 28 30
Meters
Baleen whales
Blue whale
Fin whale
Bowhead
whale
Right whale
Sei whale
Humpback
whale
Gray whale
Minke whale
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Meters

3. Is Protecting Whales a Success Story?
• Cetaceans are toothed whales and baleen whales
• 8 of 11 major species hunted to commercial extinction by 1975
• 1946 International Whaling Commission (IWC)
• Quotas based on insufficient data
• Quotas often ignored
• 1970 U.S.
• Stopped all commercial whaling
• Banned all imports of whale products
• 1986 IWC moratorium on commercial whaling
• Differences in kills—42,480 whales killed in 1970, 1500 killed in
2009
• Norway, Japan, and Iceland ignore moratorium

4. Major Threats to Aquatic
Biodiversity?
Aquatic species are threatened by habitat loss,
invasive species, pollution, climate change, and
overexploitation, all made worse by the growth of
the human population.

5. We Have Much to Learn about
Aquatic Biodiversity
• Greatest marine biodiversity at
• Coral reefs
• Estuaries
• Deep-ocean floor
• Biodiversity is higher
• Near the coast than in the open
sea
• In the bottom region of the
ocean than the surface region
• Vampyroteuthis infernalis
Cephalopod
of
the
Week.
2014
April
1.

6. Fig.
8-­‐15,
p.
181

7. Human Activities Destroy and Degrade
Aquatic Habitats
Fig.
11-­‐2,
p.
252

8. Invasive Species Are Degrading
Aquatic Biodiversity
• Invasive species
• Threaten native species
• Disrupt and degrade whole ecosystems
• Two examples
• Asian swamp eel in the waterways of south Florida
• Lionfish in the Atlantic

9. Fig.
11-­‐3,
p.
254
“An almost perfectly-designed invasive
species”

10. Loosestrife and Carp
• Lake Wingra, Wisconsin invasive species
• Purple loosestrife (Lythrum salicari)
• Invades wetlands
• Intentionally imported from Europe and Asia
• Still sold in most states as ornamental
• Common carp (Cyprinus carpio)
• Degrade aquatic vegetation on which birds
depend
• Intentionally imported from Europe and Asia
• Considered sport fish, eats natives

11. Invaders Have Ravaged Lake Victoria
• Nile perch deliberately introduced, fine food source
• Loss of biodiversity, for example cichlids
• Now frequent algal blooms in positive feedback loop
• Nutrient runoff
• Spills of untreated sewage
• Less algae-eating cichlids

12. Invaders Have Ravaged Lake Victoria
• Water hyacinth freed from insect predators
• Blocks sunlight and consumes oxygen
• Reduces biodiversity in the lake
• Scientists reduced the problem at strategic locations by
removing the hyacinth and by introducing two weevils (a type of
beetle) that feed on the invasive plant.

13. Population Growth and Pollution Can
Reduce Aquatic Biodiversity
• More noise and crowding from humans
• Nitrates and phosphates, mainly from fertilizers, enter water
• Toxic pollutants from industrial and urban areas
• Plastics
• The "plastisphere" is a term coined by marine biologist Erik Zettler to
describe the creatures who thrive on hard surfaces in water. Before human-
made hard surfaces were everywhere, they would have lived on rocks or
flotsam.
• The problem with the plastisphere is that it's radically changing the balance
of a sea ecosystem that was once mostly just open ocean creatures.
•

14. North Pacific Gyre
• Most pieces of garbage in the Pacific Gyre are "about the size of
your pinkie fingernail,” according to Scripps Institution marine
biologist Miriam Goldstein.
• Most are microscopic.
• What's alarming about them isn't their size, but the sheer amount of
plastic.
• Listen to Miriam—http://youtu.be/tFSv2eW7g6E

15. Climate Change is a
Growing Threat
• Sea levels rise
• Aquatic biodiversity threatened
• Coral reefs
• Low-lying islands
• Drown many highly productive coastal wetlands
• New Orleans, New York City, Maldives

16. Overfishing and Extinction
• Marine and freshwater fish are threatened with extinction by
human activities more than any other group of species.
• A fishprint is the area of ocean needed to sustain the fish
consumption of a person, country, or the world.
• Commercial extinction means a species is no longer
economically feasible to harvest.
• Collapse of the Atlantic cod fishery caused a domino effect
• Fewer larger fish
• More problems with invasive species
• Increase in algae and bacteria with fewer predators to eat them

17. Natural
Capital
Degrada.on:
Collapse
of
the
Cod
Fishery
Off
the
Canadian
Coast
Fig.
11-­‐7,
p.
257

18. Clashing Scientific Views Can Lead to
Cooperation and Progress
• Ray Hilborn and Boris Worm disagreed about the
long-term prognosis for the world’s fisheries
• Then the two agreed to work together
• Developed new research methods and standards
• Examined maximum sustained yield
• Reported findings and prognosis in 2009

19. From Their Paper
Marine ecologists and fisheries scientists often tend to favor contrasting
approaches, and we observe that these schools of thought have
polarized over time. We now recognize this situation as counterproductive
and propose to address this controversy where possible. In the proposed
Working Group we are trying to define common ground among marine
ecologists and fishery scientists by
(1) developing a unifying terminology and a common analytical framework for
assessing marine fisheries and ecosystem change
(2) applying this framework to a number of representative marine ecosystems
around the globe
(3) assessing management successes and failures in order to identify a set
of tools that have been proven to reverse trends of degradation in
marine fish stocks and ecosystems…
The central question we are trying to answer is: how can we merge
contrasting objectives, tools, and scientific criteria among marine ecology,
fisheries science, and management into a unifying framework. We envision
that this group will be acting as a catalyst for joining scientific forces in a
quest to sustain and restore valuable marine resources.

20. Major
Commercial
Fishing
Methods
Used
to
Harvest
Various
Marine
Species
Fig.
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