Importance of Aquatic Ecosystems

Why is preserving these ecosystems important?

What services do they provide to other ecosystems, organisms, or humans?

What are ways that humans are threatening these ecosystems? (specific ways)

Threats to Aquatic Ecosystems

Chapter 11

Human Impacts on BiodiversitySpecific threats to Aquatic Biodiversity

Pollution (non-point and point source)

Degradation of coastal/inland wetlands and estuaries

Overfishing

Invasive species

Altering lake/river flow—dams and irrigation

Climate change

Ocean Habitat destruction (ocean bottom and coral reefs)

Threats to Aquatic Biodiversity…and biodiversity in general

HIPPCOH-Habitat Loss and Degradation

I- Invasive Species

P- Human Population Growth

P- Pollution

C- Climate Change

O- Overexploitation

HIPPCOHabitat Loss and Degradation

little is understood about the ocean and its organisms 90% of all fish species spawn on coral reefs, coastal

wetlands and marshes, in mangrove forests, and rivers. these are among the most threatened aquatic

ecosystems Sea grass beds (which act as nurseries) are being lost or

degraded Rising sea levels (due to climate change) will destroy

reefs and swamp coastal wetlands Sea bottom habitats destroyed due to harmful fishing

practices (trawling/dredging)

In freshwater ecosystems... dams alter river flows irrigation for agriculture provides enormous stress on

water resources

HIPPCOInvasive Species

introduced deliberately or accidentally

displace or cause the extinction of native species and disrupt ecosystem functioning

most have arrived in ship ballast water (globalization)

HIPPCOHuman Population Growth

majority of the worlds population lives in coastal areas, this increase has added additional pressure to these ecosystems

oceans becoming more crowded (collisions with whales and ships)

oceans becoming noisier (disrupt communication and migration patterns)

HIPPCOPollution

most comes from land-based activities

run-off of nitrogen and phosphorus fertilizers increase eutrophication and cause algal blooms

toxic chemicals (DDT, PCBs, mercury)from industry can kill aquatic species or alter their physiology

Plastic. Mimic food sources and are accidentally ingested. Release toxic compounds to the water.

HIPPCOClimate Change

Rising sea levels destroy reefs,

wetlands, and other ecosystems

displace humans to other areas

Warmer and more acidic water. increases dissolved

CO2, breaks down shells of organisms

HIPPCO Overexploitation

Overfishing. Industrial fishing fleets

include ~4 million boats currently harvesting 57%

more than the sustainable yield

“Commercial Extinction”--no longer profitable to continue harvesting the species

If given time, fisheries can recover quickly, but if continued to be exploited then less likely to bounce back.

larger fish species (tuna, cod, marlin, swordfish) are increasingly scarce...so begin to fish “down the food chain” which provides less food for larger species

Too many boats, chasing Too many boats, chasing too few fish….too few fish….

Fishery: concentration of a particular wild aquatic species suitable for commercial harvesting

Fishprint: defined area of ocean needed to sustain the fish consumption of an average person, nation, or world.

Bycatch: unwanted, accidentally caught organisms that are thrown back (33% of total catch)20 million metric tons are destroyed a year80,000 whales, dolphins, seals, and turtles are

among the animalsShrimp trawlers throw back 5.2 pounds of marine life

that will eventually die for every pound of shrimp caught

As fisheries continue to be exploited their recovery time increases

Commercially valuable wild species (cod, tuna, marlin, swordfish, mackerel, even sharks) will be driven to extinction if continued to be harvested at current rates.Some estimate as soon as 2050!Aquatic species are disappearing 5 times faster than

terrestrial ones

Example: Atlantic Cod off the coast of Newfoundland Species was hunted to brink of extinction. Ban on fishing was implemented in early 1990s.

Populations have still not recovered. (Tragedy of the Commons!)

Industrial Fishing PracticesModern fishing boats are

very sophisticated using GPS, sonar, spotter planes, large nets and long fishing lines to find the fish.Essentially the fish have

no chance to hide…Cause tremendous

ecosystem damage and reduce biodiversity

A large portion of the fishing vessels come from less-developed countries (especially Asia)Many which don’t abide by

international fishing quotas

TrawlingUsed to catch cod, flounder,

shrimp and scallops

Drag a funnel shaped net along the ocean bottom, weighted with chains and platesSome nets large enough to hold

12 747s!!

VERY destructive. Destroys everything in its pathSame as clear cutting a forest

Purse-SeineUsed to catch surface

dwelling species (tuna, mackerel, anchovies , salmon and herring), schooling species

A large net encloses the school, tightens around it then brings fish to the boat

Long-LineLines up to 60 miles

long with thousands of baited hooks

Depth of line adjusted to catch open-ocean species (swordfish, tuna, shark) or ocean-bottom species (halibut and cod)

Accidently catch sea turtles, birds, and dolphins on hooks

Driftnet (gill net)Drifting nets go as deep as

50 feet and 40 miles long

Leads to unwanted fish caught as well as overfishing of certain species

Accidentally catch mammals, turtles ,and bird

Lines longer than 1.2 miles banned by the UN in 1992 in international watersCompliance is voluntary!

Whaling IndustryDuring the height of the whaling industry 1.5 million

whales were killed (1950-1975)Drove 8 of the 11 major species to commercial

extinction Right, bowhead, blue, fin, sei, humpback, minke and sperm

whalesBlue whale numbers (largest mammal) are less than

5000

1946 International Whaling Commission was established to regulate industry1986 set moratorium on whaling (banned) including

the sale of whale products Iceland (minke, fin) Japan (minke, sei and fin), and Norway

(minke) ignore ban

Fisheries ManagementDifficult to estimate fish numbers due to size of ecosystem

and migration Aim for harvesting “optimum sustained yield”

Set quotas and fishing allotment (fishing seasons)

Decrease government subsidies on fish

Consumer vote (buy sustainably harvested fish) Marine Stewardship Council Labels Ask where fish came from

Protect predator species (eat lower on food chain)

Aquaculture “farming fish” Presents a new set of problems…

Protecting and Sustaining Aquatic Biodiversity

Difficult to protect aquatic ecosystems due to rapidly growing human population and expanding ecological footprint

Damage isn’t always visible

Historically have believed ocean is an inexhaustible resource

Ocean lies outside the legal jurisdiction of any country—or have rivers/lakes that span multiple countriesLeads to overexploitation (Tragedy of the

Commons)

Challenges…

Laws and Treaties1975- Convention on the International Trade in

Endangered SpeciesEnsures trade of organisms doesn’t harm their survival

(endangered and threatened species)

1979 Global Treaty on Migratory SpeciesProtects migration routes and habitat for terrestrial,

aquatic and avian species (UN)

1972 Marine Mammal Protection ActListed organisms may not be “taken” in US waters or

high seas or their products imported

1973- US Endangered Species ActLists and protects endangered species and their

habitats

1976- US Whale Conservation and Protection ActProtects whales along US coasts including Mexico and

Canada; prohibits sale of whale products (including imports)

1995- International Convention on Biological DiversityDevelop strategies to sustain and protect biodiversity on

a global level

1986- International Moratorium on WhalingGlobally prohibits the hunting of whales and selling of

whale products

**All of these are difficult to enforce international compliance

Marine EcosystemsEconomic Incentives to Protect Species (ecotourism)

Animals worth more alive than dead

Marine Sanctuaries Countries allocate offshore fishing zones (it regulates up to 200

nautical miles from shoreline) Boats may only fish here with permission “high seas”- ocean area beyond any legal jurisdiction (difficult to

monitor and enforce)

“Law of the Sea Treaty” Outlines who can fish where

Need to switch focus to protecting ecosystems, not just individual species Less than 1% of the ocean currently protected in marine reserves,

recommended to protect 30-50%

Freshwater EcosystemsWetlands

Develop land areas away from them Permit required to fill in more than 3 acres Only 6% of remaining wetlands protected “mitigation banking”—may destroy wetlands as long as

recreate the same size in another area (not always effective)

Lakes and Rivers 1968 Wild and Scenic Rivers Act—protects only 3% of US rivers

Preserve rivers in their natural “free-flowing” state Minimize exposure to invasive species, or work to remove those

already present Protect watersheds

Identify pollutant sources Damming rivers causes ecosystem disruption

Prevent fish species from spawning