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Marine Organisms and Niches
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Estuaries
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Definition A partially enclosed area of coastal water where sea water mixes with freshwater.
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Salt Marshes The ground here is saturated with water and there is little oxygen, so decay takes place slowly. It has a surface inlet and outlet, and contains many invertebrates. It is also the breeding ground for many ocean animals. Ex. crabs and shellfish.
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Mangrove Forests These are along warm, tropical coasts where there is too much silt for coral reefs to grow. It is dominated by salt-tolerant trees called mangroves (55 different species exist). It also helps to protect the coastline from erosion and provides a breeding nursery for some 2000 species of fish, invertebrates, and plants.
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Importance of Estuaries Just one acre of estuary provides $75,000 worth of free waste treatment, and has a value of about $83,000 when recreation and fish for food are included. Prime Kansas farmland has a top value of $1,200 and an annual production value of $600.
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The Everglades Southern Florida to the Keys
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Case Study: Restoring the Florida Everglades The world’s largest ecological restoration project involves trying to undo some of the damage inflicted on the Everglades by human activities. o 90% of park’s wading birds have vanished. o Other vertebrate populations down 75-95%. o Large volumes of water that once flowed through the park have been diverted for crops and cities. o Runoff has caused noxious algal blooms.
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Problems As Miami develops, it encroaches on everglades. Plus, it prompts people vs. wildlife. It is freshwater and local areas are draining it.
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Restoring the Florida Everglades The project has been attempting to restore the Everglades and Florida water supplies. Figure 12-10
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Restoration Build huge aqueduct, or find other sources of fresh water an protect it federally under endangered species act, etc.
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SALTWATER LIFE ZONES The oceans that occupy most of the earth’s surface provide many ecological and economic services. Figure 6-4
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Marine Ecosystems Scientists estimate that marine systems provide $21 trillion in goods and services per year – 70% more than terrestrial ecosystems. Figure 6-4
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Marine Biomes Aquatic systems contain floating, drifting, swimming, bottom-dwelling, and decomposer organisms. o Plankton: important group of weakly swimming, free-floating biota. Phytoplankton (plant)- Producers that support most aquatic food chains o Algae, cyanobacteria, Zooplankton (animal)- herbivores that feed on phytoplankton or other zooplankton o Krill, small crustaceans o Necton: fish, turtles, whales top consumers in the aquatic ecosystem o Benthos: bottom dwellers (barnacles, oysters). primary consumers, decomposers
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Phytoplankton Description – small drifting plants Niche – they are producers that support most aquatic food chains Example – cyanobacteria & many types of algae
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Zooplankton Description – herbivores that feed on phytoplankton or other zooplankton Niche – food stock for larger consumers Example – krill; small crustaceans
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Nekton Description – larger, strong- swimming consumers Niche – top consumers in the aquatic ecosystem Example – fish, turtles, and whales
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Benthos Description – bottom-dwelling creatures Niche – primary consumers, decomposers Example – barnacles, oysters, and lobsters
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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. o Provides numerous ecological and economic services. o Subject to human disturbance.
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Biological Zones in the Open Sea: Light Rules Euphotic zone: brightly lit surface layer. o Nutrient levels low, dissolved O 2 high, photosynthetic activity. Bathyal zone: dimly lit middle layer. o No photosynthetic activity, zooplankton and fish live there and migrate to euphotic zone to feed at night. Abyssal zone: dark bottom layer. o Very cold, little dissolved O 2.
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Rocky and Sandy Shores: Living with the Tides Organisms in intertidal zone develop specialized niches to deal with daily changes in: o Temperature o Salinity o Wave action Figure 6-9
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Threats to Coral Reefs: Increasing Stresses Biologically diverse and productive coral reefs are being stressed by human activities. Figure 6-11
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Core Case Study: Why Should We Care About Coral Reefs? Coral reefs form in clear, warm coastal waters of the tropics and subtropics. o Formed by massive colonies of polyps. Figure 6-1
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Core Case Study: Why Should We Care About Coral Reefs? Help moderate atmospheric temperature by removing CO 2 from the atmosphere. Act as natural barriers that help protect 14% of the world’s coastlines from erosion by battering waves and storms. Provide habitats for a variety of marine organisms.
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We Have Much to Learn about Aquatic Biodiversity Greatest marine biodiversity o Coral reefs o Estuaries o Deep-ocean floor Biodiversity is higher o Near the coast than in the open sea o In the bottom region of the ocean than the surface region
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Human Activities Are Destroying and Degrading Aquatic Habitats Habitat loss and degradation o Marine Coastal Ocean floor: effect of trawlers o Freshwater Dams Excessive water withdrawal
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Invasive Species Are Degrading Aquatic Biodiversity Invasive species o Threaten native species o Disrupt and degrade whole ecosystems Three examples o Water hyacinth: Lake Victoria (East Africa) o Asian swamp eel: waterways of south Florida o Purple loosestrife: indigenous to Europe Treating with natural predators—a weevil species and a leaf-eating beetle—Will it work?
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Science Focus: How Carp Have Muddied Some Waters Lake Wingra, Wisconsin (U.S.): eutrophic o Contains invasive species Purple loosestrife and the common carp Dr. Richard Lathrop o Removed carp from an area of the lake This area appeared to recover
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Population Growth and Pollution Can Reduce Aquatic Biodiversity Nitrates and phosphates mainly from fertilizers enter water o Leads to eutrophication Toxic pollutants from industrial and urban areas
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