Transcript Ch. 14
CH. 14 Marine Ecosystems What is ecology? • It is the science that studies how organisms relate to • • • • each other and their environment. Considers both biotic (living) and abiotic (nonliving) aspects. Examples of abiotic factors: temperature, wind, pH, currents, minerals, and sunlight Examples of biotic factors: quantity and type of organisms in an environment Studies the relationships and interactions of the abiotic and biotic aspects of the environment Ecology Terminology • Ecosystem: a distinct entity usually with clearly defined • • • • • physical boundaries, distinct abiotic conditions, an energy source, and a community of interacting organisms Community: collection of different organisms living and interacting in an ecosystem Population: a group of the same species living and interacting within a community Habitat: includes the area and conditions in which you find an organism; organism’s address Microhabitat: exists on a very small scale; Niche: an organisms role in the habitat; it’s job Energy Flow and Nutrient Cycles • Energy flow through a food web affects an ecosystem by • • • • determining how much energy is available for organisms at higher trophic levels Carbon Cycle is the basis for most ecosystems Nitrogen Cycle thought to be more limited in marine ecosystems than on land ecosystems Temperate ecosystems get less sunlight but get far more nutrients Most productive marine ecosystem found in cold temperate regions ECOSYSTEMS IN THE OPEN SEA Neuston Ecosystems • Neuston: plankton that live afloat on the surface; only few millimeters thick • Thin ecosystem, but makes up a major ecosystem that receives the max amount of sunlight and covers 71% of Earth’s surface • In some areas, photosynthesis and primary productivity may be higher below this ecosystem; this is due to 2 factors 1) Photoinhibition: UV light may account for this; ozone depletion could make this worse; too much light overwhelms an autotroph to photosynthesize 2) Pollutants: may be reducing global warming by absorbing carbon dioxide; but oil-based pollutants stop this carbon dioxide from being absorbed at the surface • The Sargasso Sea is the world’s largest floating ecosystem Upwellings • Important to open-ocean ecosystems • HOW?? • Bring nutrients from deep colder waters to surface • High upwelling activity= high nutrient activity COASTAL ECOSYSTEMS Estuaries • Exist where tides meet rivers; • • • • • common where tidal range is high Can be large complex deltas or simple wide stretches of river entering the sea Rich with nutrients and biologically productive Contain halophytes: saltwater plants which also support a large community of primary and secondary consumers Organisms must tolerate wide salinity ranges Provide shallow sheltered water so larvae and juveniles of other species can avoid predation and grow until they venture out to sea Salt Marshes • Can exist in estuaries and along the • • • • coasts Grow where its relatively flat land with nutrient rich sediment washed by the tides Conditions vary within a salt marsh: upper marsh: rarely flooded by the tides lower marsh: areas flooded by salt water as a regular part of the tidal cycle Halophytes in lower marsh deal with constant osmotic stress; Spartina: contain stomata- pores in the leaves through which it breathes (adaptation for survival) Plants in upper marsh have a reduced osmotic stress; Pickleweed handles excess salt accumulation by storing it in the leaves; once reaches a certain point, leaf drops off Mangrove Swamps • Contain mangrove trees that have a very • • • • • similar niche as halophytes in salt marshes Mangroves have adaptations that allow them to live in salt water and anaerobic mud For example: red mangroves grow above the water line allowing oxygen to reach the roots Use reverse osmosis (process of transporting water through a semipermeable membrane against the natural osmotic gradient) to obtain fresh water by filtering seawater through its roots Other mangroves grow below the waterline; aerate their roots with tubes called pneumatophores which carry air from above the surface to roots Mangroves in this ecosystem: have strong, tangled roots that provide habitats for juvenile fish and invertebrates; they also trap nutrients that help to protect coral reefs Seagrass Ecosystem • Similar to the other ecosystems in • • • • that they stabilize sediments and provide shelter and habitats for other organisms Seagrasses (plants that inhabit this ecosystem) live entirely under water except during unusually low low tides They do not need a freshwater source These ecosystems do not need a freshwater source and can exist in deep water These ecosystems are heavily grazed by microbes, invertebrates, fish, turtles, and manatees Beaches • Rich and productive ecosystems • Organisms live on the organic • • • • material in the sand mix Worms, mollusks etc. live submerged in the sand Meiofauna- benthic organisms that live in the spaces between sand grains- also very diverse in this ecosystem Algae also live among the sand grains The physical and organic processes that occur here aid in making the beach a giant filter; provides organic and inorganic material for certain organisms; run-off and material that has been washed up Kelp and Seaweed Ecosystems • One organism that eats kelp is the sea urchin. • The sea urchin is also one of the primary foods of a sea • • • • otter Killing the sea otters disrupts the kelp’s ecological balance by removing the sea urchin’s main predator. With no sea otter’s to feed on sea urchins, the sea urchin population will rise, which means more grazing on kelp Eventually sea urchin eats the kelp faster than it can grow. Example of the interdependence that exists within an ecosystem. Coral Reefs • Most diverse ecosystems in the ocean; however, also • • • • • very fragile Located in clear waters which make photosynthesis easier Also require water that is relatively free of nutrients WHY?? Pass on and preserve organic material; lack of nutrients protects coral from competitive organisms Eutrophication (nutrient build up) and global warming (increase temp) both pose threats to coral ecosystems Loss of coral will have a major affect on the global ecosystem POLAR ECOSYSTEMS The Arctic • Marine ecosystems in the arctic face challenges such as • • • • reduced sunlight under the ice and water; life is scarce under these ice caps Animals that do live here have special adaptations: antifreezing compounds in blood, low metabolisms However, when ice melts during warmer months, productivity increases; occurs mainly from April to August along the North Pacific and North Atlantic This supports massive fisheries, marine mammals, and other organisms Ecosystem flourishes from nutrients churned up from bottom The Antarctic • More extreme climate than Arctic • During winter: sea ice doubles the area around the continent; adds area about the size of NA • Antarctic Divergence: largest nutrient rich area on Earth; supports massive phytoplankton blooms, copepod populations, and krill populations • Organisms have special adaptations (as in Arctic): some fish have anti freezing characteristics, slowed metabolisms • Most species here are specialized and found only here DEEP SEA ECOSYSTEMS The Abyssal Zone and Whale Falls • No sunlight; no photosynthesis; No • • • • primary productivity in most of the deep ocean Gets nutrients from marine snow: fall of sediment, dead organisms, fecal pellets and other nutrients from waters above Most of deep ocean= abyssal zone. Covers about 30% of Earths surface; smoothest and flattest area; lacks dense life concentrations, but diverse species live here Organisms that survive here: echinoderms, sea cucumbers, sea lilies, brittle stars, etc. Whale fall: a place where a dead whale comes to rest on the deep-ocean floor; carcass brings massive concentration of nutrients Hydrothermal Vents and Cold Seeps • Hydrothermal vents: source of primary productivity; bacteria at these vents are the base of this productivity • Cold Seeps: sulfide-rich fluids seep from rock on the ocean floor; called “cold” seeps because they are cold compared to hydrothermal vents • Cold seeps also contain the sulfide consuming bacteria found in hydrothermal vents Hadal Zone- Ocean Trenches • Scientists know little about ecosystems within the hadal zone….. • WHY?? • Limits in technology: extreme pressure makes it expensive and difficult to make instruments capable of observing these depths • There have been brief observations made that found organisms in the Mariana Trench (deepest place on Earth); however, character and extent of these ecosystems remain largely unknown