1. estuary upwelling salt marsh wetlan d benthos B a r r i e r I s l a n d plankton swamps nekton lake benthic zone saltwater littoral zone eutrophication freshwater algal bloom coral reef ocean salinity river AQUATIC ECOSYSTEMS CHAPTER 7

2. Freshwater Ecosystems

3. ...determine where Org lives in the water. Temp Sunlight O 2 Nutrients

4. TYPES of ORGS Plankton (phyto - & zoo -) –Float near surface –Principal food source in aquatic ecosystems Nekton –Free-swimming orgs: fish, turtles, whales... Benthos –Bottom-dwellers: mussels, worms, barnacles...

5. TYPES of FW Ecosystems Lakes Ponds Wetlands Rivers Streams

6. LIFE in a LAKE... LITTORAL ZONE –Near shore –Nutrient-rich –Abundant/diverse life due to sunlight (photosynthesis) BENTHIC ZONE –Lake bottom – no light for photosynthesis –Dead & decaying orgs –Decomposers, insect larvae, clams...carp....depends on the amount of sunlight available!

7. Eutrophication “Increase in amount of nutrients in aquatic ecosystem.” Nutrients cause plants & algae to increase... Bacteria increase as dead plant matter grows...bacteria use up dissolved O 2... O 2 - loving organisms die off. Lakes naturally become eutrophic over time....

8. ...but the process can be accelerated by sewer system or agricultural runoff that places fertilizer (and I use the term loosely!) into lakes & ponds.

9. FW WETLANDS “Areas of land periodically covered with water.” MARSHES: contain non-woody plants (cattails, reeds, rushes) SWAMPS: woody plants (trees, shrubs)

10. Marshes Characterized by low, flat land...little water movement...some “brackish,” some saltier. Flat-billed fowl (ducks, grebes) adapted for skimming insects off surface; those with spear-like beaks (herons) suited to grasping small fish & digging for buried frogs. Florida Everglades: largest freshwater wetland in U.S.

11. Swamps Flat, poorly drained land; woody shrubs or water-loving trees. Snakes...bullfrogs...alligators!

12. Freshwater WETLANDS provide important environmental functions: Act as filters or sponges to absorb & remove pollutants from groundwater; improve water quality of lakes/reservoirs downstream. Control flooding by absorbing extra water from rivers & hurricane storm surges...saving urban/residential areas from damage. Habitat for migratory waterfowl...spawning grounds for game fish...cranberries! Buffer zones to protect against shoreline erosion.

13. ...they used to be wastelands... For decades, it was believed they were just breeding grounds for mosquitoes... Millions of acres were “recovered” via drainage, filling in, clearing... Now (thanks to envi sci!) they are protected by government...their destruction is prohibited.

14. Rivers Rivers have been long used as free water sources for industry (and dumping grounds...) Toxins have killed off much river life and made river fish inedible...city & farm runoff put pesticides & other poisons in rivers. Dams alter ecosystems in and around rivers.

15. Marine Ecosystems

16. Estuaries “Freshwater source (river) mixes with saltwater source (ocean).” Currents cause nutrient trap to form @ bottom. Sunlight penetrates shallow waters. Rich nutrients/photosynthesis make estuaries some of the most biologically productive ecosystems on the planet. Protected from waves by peninsula/barrier islands.

17. Estuary Life Plants & plankton fishdolphins, manatees, seals et al...abundant food web. Oysters, barnacles, clams (filter feeders) Orgs are able to tolerate varying salinity Humans love estuaries too...

18. Threats to Estuaries Of the 10 largest urban areas on the planet, 6 are built on estuaries: –Tokyo –New York City –Shanghai –Buenos Aires –Rio de Janeiro –Bombay

19. Threats to Estuaries California: estuaries filled in with waste & used as building sites. Rivers carry pollutants downstream to estuary (sewage, ag waste, pesticides, toxic chemicals)

26. Chesapeake Bay

27. Barrier Islands Formed by rising sea levels (over the past 15,000 years) Long, narrow sand ridges parallel to coastline, 3 to 30 km out. Protect mainland & coastal wetlands from storms & waves....don’t spend a lot of $ buying a home on ‘em...

30. Sanibel Island

32. Southern Rhode Island

33. Coral Reefs Limestone ridges built by photosynthetic algae & skeletons of coral polyps. Found only in clear, warm, shallow saltwater. Among the most diverse ecosystems on planet (thousands of species). Convoluted shape provides habitats for fish, snails, clams, sponges...

34. Coral Reefs 27% of world’s coral reefs in danger... Oil spills...sewage...pesticides...silt runoff...overfishing... –If water gets too warm/too cold... –If fresh water drains onto reef... –If water gets too muddy/polluted... Reefs are fragile, they grow too slowly to repair themselves in time...

35. Great Barrier Reef

39. Oceans “Usable” sunlight penetrates to only 100 m depth......most ocean life thus located in shallow coastal areas, not in open oceans. –Seaweed, algae, plankton...inverts & fish that feed on them are concentrated near-shore. Many different “minisystems” exist... Open oceans are possibly the least productive of all ecosystems.

40. UPWELLING @ coastlines: surface currents carry water away from shore... Deeper, nutrient rich bottom water “wells up”to fill in... Phytoplankton love it...fish come for phytoplankton...humans come for fish...it’s all good?

42. Threats to Oceans Fertilizer runoff from shore causes algal bloom...some are poisonous! Industrial waste & sewage = coastal pollution. Overfishing is destroying some fish populations... Stupid fishing methods are murdering innocent creatures...