Sustaining Aquatic Biodiversity Part 1—Major Threats

Sky  Harbor  Interna.onal  Airport  Built  on  Hohokam  Canals.  Archaeology  Magazine.  2014  April  1.  

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 12 14 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

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

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.

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.  

Fig.  8-­‐15,  p.  181  

Human Activities Destroy and Degrade Aquatic Habitats

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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

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“An almost perfectly-designed invasive species”

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

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

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.

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.

•   

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

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

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

Natural  Capital  Degrada.on:  Collapse  of  the  Cod  Fishery  Off  the  Canadian  Coast  

Fig.  11-­‐7,  p.  257  

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

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.

Major  Commercial  Fishing  Methods  Used  to  Harvest  Various  Marine  Species  

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