estuary

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

2. Freshwater Ecosystems

3. ...determine where Org livesin the water. • Temp • Sunlight • O2 • 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. 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. LIFE in a LAKE... ...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 O2... • O2 - 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 fish dolphins, 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...