saltwater/marine (estuaries,coastlines, coral reeds, coastal marshes, mangrove swamps, oceans) 2. freshwater (lakes, ponds, streams, rivers, inland wetlands) cover about 71% of the earth’s surface;giant circulatory system transporting water from one place to another as part of the earth’s water cycle play vital roles in biological productivity, climate, biogeochemical cycles, biodiversity
Four Major types of Organisms
1. Plankton: free-floating; 3 types-phtyoplankton/plant plankton: producers that support aquatic food chains/webs-zooplanktion/animal plankton: primary consumers that feed on phytoplankton and seconday consumers that feed on other zooplankton -ultraplankton: much smaller; photosynthetic bacteria responsible for 70% of primary productivity near ocean surface 2.
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nekton: strongly swimming consumers (fish turtles whales) 3. benthos: dwell at bottom (oysters, worms, lobsters) 4. decomposers: bacteia that break down waster into sumple nutrient compounds
Aquatic vs. Terrestrial Systems
. -have less pronounced and fixed boundaries-have more complex/longer food chains/webs-more difficult to monitor and study
Depths of Aquatic Life Zones
*temp, access to sunlight, dissolved oxygen, nutrients are factors that determine the types/#s of organims found in layers 1. Upper/Euphotic Zone: sunlight can penetrate through; more photosynthesis; dissolved O2 is higher; low levels of CO2 2.
Deeper zones: Oxygen levels fall ans carbon dioxide levels rise due to aerobic respiration by animals and oxygen gas dissolves less in deep cold water
warm nutrient-rish, shallow water that extends from the high-tide mark on land to the gently-sloping, shallow edge of the continental shelf; contains 90% of all marine species; high net primary productivity per unit of area due to ample sunlight and plant nutrients estuaries, coastal wetland, mangrove swamps
estuaries/coastal wetlands/mangrove swamps
estuary: partially enclosed area of coastal water where seawater mixes with freshwater and nutrients from rivers, streams and runoff from land Temperature and salinity levels vary widely in estuaries and coastal wetlands due to tides/seasonal variations in the flow of freshwater into the estuary / unpredictable flows of freshwater after heavy rains and salt water after storms/hurricanes constant water movement stirs up nutient-rich silt; filter toxic pollutants, excess plant nutrients, sediments and other pollutants Mangrove forest swamps: dominant organisms: trees that can grow in salt water; extensive roots that extend about water to get O2 and for support; nutrient rich forests in sheltered regions along tropical coasts
area of shoreline between low and high tides its organisms must be able to deal with tides and varying salinity; either hold on, dig in or hide in shells
low, narrow, sandy islands that form offshore from coastline; help protect mainland, estuaries, and coastal wetlands from storm waves have one or more rows of natural sand dunes held in place my grass roots which serve as first line of defense against waves
form on clear, warm coastal waters; ecologically complex interactions among diverse organisms vulnerable to damage because they grow slowly & disrupted easily; thrive only in clear warm fairly shallow water of constant high salinity sediment runoff and human activities are biggest threats
sharp increase in water depth at the edge of the continental shelf separates coastal zone from vast volume of the ocean divided into three vertical zones 1. euphotic zone:lighted upper zone where phytoplanktion photosynthesize; high oxygen low nutrients 2. bathyal zone: dimly lit middle zone; zooplankton and smaller fish 3. abyssal zone: dark, cold and little O2; enough nutrients on the ocean floor to support 98% of species living in the ocean deposit feeders: take mud in and extract nutrients filter feeders: pass water through/over bodies and extract nutrients average primary productivity and NPP per unit are low except at an occasional equatorial upwelling
Freshwater Life Zones
water with a dissolved salt concentration of less than 1% -standing (lentic) bodies (lakes, ponds, inland wetlands) -flowing (lotic) bodies (streams, rivers) less than 1% of earth’s surface
large natural bodies of standing fresh water formed when precipitaion,;runoff or groundwater seepage fill depressions in the earth’s surface depression can be caused by glaciation, crustal displacement, and volcanic activity four distinct zones 1.
littoral zone: shallow sunlit waters near shore to the depth at which rooted plants stop growing, high biological diversity; adequate nutrients from bottom sediments 2. limnetic zone: open sunlit water surface away from the shore that extensd to the depth penetrated by sunlight; main photosynthetic body of the lake 3. profundal zone: deep, open water where it is too dark for photosynthesis; low oxygen levels 4.benthic zone: bottom of the lake; decomposers, detritus feeders -during the summer and winter the water in deep temperate zone lakes become stratified into different temperature layers which do not mix -fall and spring the waters mix in overturns that equalize the temp
types of lakes
-oligotropic lake: newly formed; small supply of plant nutrients; deep, steep banks; clear water; low net primary productivity – eutropic lake: large or excessive supply of nutrients; murky water; high net primary productivity; bottom layer is depleted of dissolved oxygen in warm months cultural eutrophication mesotropic lakes: between two extremes
freshwater streams and rivers
surface water: precipitation that dusnt sink/evaporate runoff: flows into streams watershed/drainage basin: land area that delivers runoff, sediment to a stream downward flow of surface water to sea has three dif zones 1. source zone:headwaters rush downwards dissolving oxygen; not productive due to lack of nutrients 2. transition zone: wider, deeper streams that flow down gentler slopes; more producers(phytoplankton) and fish 3.
floodplain zone: wider deeper rivers over flat valleys; higher temperature and less oxygen than first two zones; large amount of producers; muddy and lots of silt
lands covered with fresh water and located away from coastal area (marshes, swamps, prairie potholes, floodplains)
human impacts on freshwater systems
1. dams, diversions, canals fragment 60% of worlds largest rivers 2. floor control levees alter and destroy habitats 3. cities and farmlands add pollutants and exess plant nutrients to streams/rivers 4. many inland wetlands have been drained