Sustaining Aquatic Biodiversity Chapters 6 & 12

Key Concepts Important aquatic resources: economic and ecological importance Effects of human activities and the power of choice Solutions to protecting and sustaining aquatic diversity: for example, wetland restoration in estuarine habitats

AQUATIC ENVIRONMENTS Saltwater and freshwater aquatic life zones cover almost three-fourths of the earth’s surface

AQUATIC ENVIRONMENTS

What Kinds of Organisms Live in Aquatic Life Zones? Aquatic systems contain floating, drifting, swimming, bottom-dwelling, and decomposer organisms. – Plankton: important group of weakly swimming, free-floating biota. Phytoplankton (plant), Zooplankton (animal), Ultraplankton (photosynthetic bacteria) – Necton: fish, turtles, whales. – Benthos: bottom dwellers (barnacles, oysters). – Decomposers: breakdown organic compounds (mostly bacteria).

Life in Layers Life in most aquatic systems is found in surface, middle, and bottom layers. Temperature, access to sunlight for photosynthesis, dissolved oxygen content, nutrient availability changes with depth. – Euphotic zone: brightly lit surface layer, low nutrients, high DO, area of photosynthetic activity – Bathyl zone: dimly lit middle layer, no PA, organisms migrate to EZ to feed at night – Abyssal zone: dark bottom layer, very cold, little DO

Marine Ecosystems  Scientists estimate that marine systems provide $21 trillion in goods and services per year – 70% more than terrestrial ecosystems.

The Coastal Zone: Where Most of the Action Is The coastal zone: the warm, nutrient-rich, shallow water that extends from the high-tide mark on land to the gently sloping, shallow edge of the continental shelf. The coastal zone makes up less than 10% of the world’s ocean area but contains 90% of all marine species. – Provides numerous ecological and economic services. – Subject to human disturbance.

The Coastal Zone

Centers of Aquatic Biodiversity ~ spp of fish – 63% marine + 37% freshwater Centers of aquatic diversity: - coral reefs - deep sea - coastal & estuaries Food and chemicals

Human Impacts on Aquatic Biodiversity Greatest threats: - habitat loss & degradation - overfishing - non-native spp - pollution - global warming Habitat loss: -50% of wetlands lost in US and globally -> 25% of coral reefs damaged -> 33% of mangroves lost -Ocean bottom degraded by trawling

HUMAN IMPACTS ON AQUATIC BIODIVERSITY  Area of ocean before and after a trawler net, acting like a giant plow, scraped it.

Fish farming in cage Trawler fishing Spotter airplane Sonar Purse-seine fishing Trawl flap Trawl lines Trawl bag Fish school Drift-net fishing FloatBuoy Fish caught by gills Deep sea aquaculture cage Long line fishing Lines with hooks

Commercial Whaling After many of the world’s whale species were overharvested, commercial whaling was banned in 1960, but the ban may be overturned Despite ban, Japan, Norway, and Iceland kill about 1,300 whales of certain species for scientific purposes. Although meat is still sold commercially.

FRESHWATER LIFE ZONES Freshwater life zones include: – Standing (lentic) water such as lakes, ponds, and inland wetlands. – Flowing (lotic) systems such as streams and rivers

Lakes: Water-Filled Depressions

Freshwater Streams and Rivers: From the Mountains to the Oceans Water flowing from mountains to the sea creates different aquatic conditions and habitats.

Human Impacts on Aquatic Biodiversity Invasive species threaten marine and freshwater biodiversity. – Bioinvaders are blamed for about 2/3 of fish extinctions in the U.S. between ~50% world world’s people live on or near a coastal zone 80% of ocean water pollution comes from land land-based human activities.

Ocean Pollution

Freshwater Pollution

Eutrophication Plant nutrients from a lake’s environment affect the types and numbers of organisms it can support. – Oligotrophic (poorly nourished) lake: Usually newly formed lake with small supply of plant nutrient input. – Eutrophic (well nourished) lake: Over time, sediment, organic material, and inorganic nutrients wash into lakes causing excessive plant growth. Cultural eutrophication : – Human inputs of nutrients from the atmosphere and urban and agricultural areas can accelerate the eutrophication process.

Too Much of a Good Thing Plant nutrients from a lake’s environment affect the types and numbers of organisms it can support.

Why is it difficult to protect aquatic biodiversity? Rapidly increasing human impacts Invisibility of problems People are just unaware Lack of legal jurisdiction hinders protection Many people incorrectly view the oceans as an inexhaustible resource

Commercial Extinction and Tragedy of the Commons Overfishing leads to commercial extinction Estimated sustainable yield - catch rate at which spp renews itself Tragedy of the Commons as one cause Large open ocean fish and bottom dwellers have declined 90% since the early 1950s

Protecting and Restoring Rivers to help salmon and other riverine spp. Pollution Disruption of water flow Loss of biodiversity Invasive species

PROTECTING, SUSTAINING, AND RESTORING LAKES AND RIVERS Dams can provide many human benefits but also disrupt ecological services rivers provide. 119 dams on Columbia River have sharply reduced (94% drop) populations of wild salmon. U.S. government has spent $3 billion in unsuccessful efforts to save the salmon. Removing hydroelectric dams will restore native spawning grounds.

Protecting and Sustaining Marine Biodiversity Legally protect rare species Sustainable management of marine fisheries Establish protected areas (marine reserves make up <0.3% of world ocean area) Integrated coastal management Regulate and prevent ocean pollution

Managing and Sustaining the World’s Marine FisheriesManaging Fisheries Economic approaches By-catch reduction Control nonnative species Consumer information

PROTECTING, SUSTAINING, AND RESTORING WETLANDS 50% lost in US US--90% in CA! Permits for filling or destroying U.S. wetlands has slowed their loss (Clean Water Act) Attempts to weaken this protection continue

Restoration is underway! Returning the natural, indigenous ecosystem Includes species and natural processes Wetland restoration projects across the country …. Florida Everglades South Bay San FranSilver Sands Milford

Restoring the Florida Everglades The project has been attempting to restore the Everglades and Florida water supplies. 90% of park90% park’s wading birds have vanished. Other vertebrates down %. Large volumes of water diverted for crops and cities. Runoff has caused noxious algal blooms. The Everglades needs its water regime and quality

South Bay Salt Pond Restoration: Wildlife Island in an Urban Sea Why restore estuarine habitats like the San Francisco Bay? Immense natural capital and value to society Flood protection Fisheries support: no wetlands, no fish! Water quality protection Incredible productivity and biodiversity Carbon sequestration

Moving Forward with Restoration Use the best existing data Collect more data during planning Implement the most scientifically -sound plan Use adaptive management to learn & improve

How might these projects effect you? Flood protection is a central goal More recreation More plants and animals Healthier coastal ecosystems Improved water quality Opportunities for volunteering & research