2Aquatic EcosystemsThe major kinds of aquatic environments are streams and rivers, lakes, wetlands, estuaries, and oceans.Each of these can be subdivided further with respect to many factors.
3Aquatic EcosystemsIn aquatic ecosystems, depth, water temperature, flow rate, and oxygen and nutrient concentrations are the dominant physical factorMany of the producers in many aquatic ecosystems are single-celled algaeAquatic ecosystems have been classified by salinity, water movement, and depthUnlike terrestrial ecosystems, defining aquatic ecosystems according to vegetation would be impossible.
4Flowing Water: Streams and Rivers All aquatic ecosystems interact with the terrestrial biomes that surround themStreams receive runoff, groundwater, and organic matter from the surrounding landA variety of organisms live their lives in both aquatic and terrestrial environments
5Flowing Water: Streams and Rivers Could you name some other interactions between aquatic ecosystems and terrestrial biomes?Frogs and salamanders, for example, have aquatic larval stages and terrestrial adult stagesSome terrestrial animals feed on organisms that grow in streams and lakesMany organisms with aquatic larval stages, such as mosquitoes, feed on terrestrial organisms
6Flowing Water: Streams and Rivers Stream and river systems are referred to as lotic systemsFlowing water erodesRivers and streams are created by erosionMost streams and rivers are older than lakes – although they move around morelotic systems-applied to flowing water systems
7Flowing Water: Streams and Rivers Streams form wherever precipitation exceeds evaporationStreams grow with distance as they join together with rivers
8Flowing Water: Streams and Rivers River continuum concept-ecosystems are more complex and more productive downstream because water flows more slowly and becomes warmer and richer in nutrients.The River Continuum Concept describes the physical processes (geology, climate) outside of a river that effect the biological processes (vegetation) along a river, which effect the physical and biological processes within a river (temperature, nutrients).
9Flowing Water: Streams and Rivers Riffle areas are where water runs rapidly over a rocky substratumWater is well oxygenated in riffles
10Flowing Water: Streams and Rivers Pools are deeper stretches of more slowly moving watersPools tend to accumulate silt and organic matter
11Flowing Water: Streams and Rivers Are these two areas productive or unproductive?Both areas tend to be unproductive because the nutrients needed for life are washed away in riffles, whereas the oxygen and sunlight needed for life are lacking in pools.
12Flowing Water: Streams and Rivers Streams lack the richness and diversity of lifeToward the headwaters of rivers, the productivity of algae and other photosynthetic organisms tend to be lowRiparian zones are transitional areas between the aquatic system and adjacent landRiparian zones are influenced by seasonal flooding and elevated water tables
13Flowing Water: Streams and Rivers Much of the food web of headwater ecosystems depends on leaves and other organic matterOrganic material that enters the aquatic ecosystem the outside is termed allochthonousleaves and other organic matter fall or washes into streams from surrounding vegetationuh-lok-thuh-nuhs
14Flowing Water: Streams and Rivers The larger the river , the more its organic material is autochtonous, originating where it is found
15Flowing Water: Streams and Rivers As you move downstream, rivers become wider, slower moving, more nutrient laden, and more exposed to sunlightNutrients and sunlight support growth of algae and plants
16Flowing Water: Streams and Rivers Lotic systems are sensitive to any modification of their water flowRates of flow, water temperature, and sediment patterns are all alteredCould you name one major modification?
17Flowing Water: Streams and Rivers Dams are built for flood control, to provide water for irrigation, or to generate electricityWater behind dams becomes warmer, and bottom habitats become choked with silt, destroying habitat for fish and other aquatic organismsUsing dams for flood control changes the seasonal cycles of floodingDams disrupt the natural movement of aquatic organisms
18Standing Water: Lakes and Ponds Referred to as lentic systems, distinguished by non-flowing watersRange in size from small, temporary rainwater to lakes thatare about a mile in depthExample: Lake Baikal,in Russia, contains about1/5th of all the freshwater at the surface of theearth.
19Standing Water: Lakes and Ponds Many lakes and ponds areformed by theretreat of glaciersGlaciers leavebehind gouged-outbasins and blocksof ice buried inglacial depositsExample: TheGreat Lakes of NorthAmerica formed in glacialbasins
20Standing Water: Lakes and Ponds Lakes are also formed in geologically active regionsVertical shifting of blocks of the earth’s crust creates basins w/in water accumulates
21Standing Water: Lakes and Ponds Oxbow lakes are broad bends of the former river cut off by shifts in the main channel
22Standing Water: Lakes and Ponds Lakes are subdivided into several ecological zones, each of which has distinct physical conditionsLittoral zoneLimnetic zoneBenthic Zone
23Standing Water: Lakes and Ponds Littoral zone is the shallow zone around the edge of a lake or pond w/in which one finds rooted vegetationLimnetic zone is the open water where producers are floating single-celled algae, phytoplankton.
24Standing Water: Lakes and Ponds The sediments at the bottoms of lakes and ponds make up the benthic zoneThe benthic zone provides habitat for burrowing animals and microorganisms
25Standing Water: Lakes and Ponds Are lakes and ponds permanent?Most temporary ponds can dry out each yearMost small temperate lakes that formed when glaciers retreated will gradually refill in w/ sediment until there is no open waterWhat will happen to the former aquatic ecosystem?Small temporary ponds can dry out each year, often multiple times during a seasonMost small temperate lakes that when glaciers retreated will gradually fill in with sediment until there is no open waterThe formerly aquatic ecosystem will slowly change into a terrestrial ecosystem, first a wet meadow and later the natural terrestrial biome of the region
26WetlandsAreas of land consisting of soil that is saturated w/ water and supports vegetation specifically adapted to such conditions
27Wetlands What are some examples of wetlands? Swamps, marshes, and bogs Salt marshes and mangrove wetlands associated w/ marine envrionments
28WetlandsMost of the plants can tolerate low oxygen concentrations in the soil. Many are specialized for anoxic conditions and grow nowhere elseWetlands provide important habitat for a wide variety of animalsWetlands protect coastal areas from the ravages of hurricanes and other stormsWetland sediments immobilize potentially toxic or polluting substances dissolved in water
29Estuaries Estuaries are found at the mouths of rivers Are unique because of their mix of fresh and salt waterAre abundantly supplied w/ nutrients and sediments carried downstream by riversEstuaries tend to be areas of sediment depositionSupports high biological productivity
30Marine Aquatic Systems Oceans cover the largest portion of the earthVariation in marine environments comes from differences in temperature, salinity, depth, currents, substrata, and tidesWhat does depth influence?Depth influences light and pressure.
31Marine Aquatic Systems The littoral zone (also calledthe intertidal zone) extends between the highest and lowest tidal water levelsExposed periodically to airEcological conditions w/inthe littoral zone changerapidly as the tide flowsin or out
32Marine Aquatic Systems The neritic zone extends to depths of about 200m, which correspond to the edge of the continental shelfRegion of high productivityThe sunlit surface layers of water are close enough to the nutrients in the sediments below that strong waves can move them to the surface
33Marine Aquatic Systems The oceanic zone is beyond the neritic zone where the seafloor drops rapidly to great depthsIn the oceanic zone, nutrients are sparse and production is strictly limitedThe seafloor beneath the oceanic zone is the benthic zone.
34Marine Aquatic Systems Both the neritic and oceanic zones are subdivided vertically into a photic zoneIn the photic zone, there is sufficient light for photosynthesis
35Marine Aquatic Systems Organisms in the aphotic zone depend mostly on organic material raining down from above
36Marine Aquatic SytemsWhat other ecosystem could be compared to the open ocean?What other ecosystem could be compared to the tropical rainforest?
37Marine Aquatic SytemsCoral reefs are like tropical rainforests, both in the richness of their biological production and the diversity of their inhabitantsReef-building corals are found in shallow waters of warm oceansCoral reefs usually surround volcanic islands, where they are fed by nutrients eroding from the rich volcanic soil and by the deep water currents forced upward by the profile of the island
38Marine Aquatic SytemsCoral reefs are doubly productive because photosynthetic algae w/in their tissues generate carbon energy that fuels the coral’s rates of growth