Sustaining Aquatic Biodiversity Ecosystem Approach

1. Sustaining Aquatic Biodiversity Ecosystem Approach • The number, variety and variability of Earth’s organisms • Consists of four components: • Ecosystem Diversity • Species Diversity • Genetic Diversity • Functional Diversity

2. Chapter 6 Aquatic Biodiversity

3. Chapter Overview Questions • What are the basic types of aquatic life zones and what factors influence the kinds of life they contain? • What are the major types of saltwater life zones, and how do human activities affect them? • What are the major types of freshwater life zones, and how do human activities affect them?

4. Core Case Study:Why Should We Care About Coral Reefs? • Coral reefs form in clear, warm coastal waters of the tropics and subtropics. • Formed by massive colonies of polyps. Figure 6-1

5. Fig. 6-1a, p. 126

6. Fig. 6-1b, p. 126

7. Core Case Study:Why Should We Care About Coral Reefs? • Help moderate atmospheric temperature by removing CO2 from the atmosphere. • Act as natural barriers that help protect 14% of the world’s coastlines from erosion by battering waves and storms. • Provide habitats for a variety of marine organisms.

8. AQUATIC ENVIRONMENTS • Saltwater and freshwater aquatic life zones cover almost three-fourths of the earth’s surface Figure 6-2

9. AQUATIC ENVIRONMENTS Figure 6-3

10. Aquatic Environmental Factors • Temperature is less important in aquatic ecosystems • Most fundamental difference is between freshwater and saltwater – thus salinity is key. Salinity affects the kinds of organisms present • Dissolved oxygen • Light penetration is a key abiotic factor – photosynthesis.

11. Aquatic Environmental Factors • pH is another important abiotic factor • Presence or absence of currents and waves also impact the species of organisms present

12. Light Penetration • Water greatly affects the penetration of light. Thus, photosynthetic organisms remain near the surface of the water while rooted plants grow only in the shallows.

13. What Kinds of Organisms Live in Aquatic Life Zones? • Aquatic systems contain floating, drifting, swimming, bottom-dwelling, and decomposer organisms. • Plankton: important group of weakly swimming, free-floating biota. • Phytoplankton (plant), Zooplankton (animal), Ultraplankton (photosynthetic bacteria) • Necton: fish, turtles, whales. • Benthos: bottom dwellers (barnacles, oysters). • Decomposers: breakdown organic compounds (mostly bacteria).

14. Life in Layers • Life in most aquatic systems is found in surface, middle, and bottom layers. • Temperature, access to sunlight for photosynthesis, dissolved oxygen content, nutrient availability changes with depth. • Euphotic zone (upper layer in deep water habitats): sunlight can penetrate.

15. SALTWATER LIFE ZONES • The oceans that occupy most of the earth’s surface provide many ecological and economic services. Figure 6-4

16. The Coastal Zone: Where Most of the Action Is • The coastal zone: the warm, nutrient-rich, shallow water that extends from the high-tide mark on land to the gently sloping, shallow edge of the continental shelf. • The coastal zone makes up less than 10% of the world’s ocean area but contains 90% of all marine species. • Provides numerous ecological and economic services. • Subject to human disturbance.

17. The Coastal Zone Figure 6-5

18. Ecological Categories • Free-floating Plankton • Small organisms that are feeble swimmers • Carried about at the mercy of currents and waves • Strongly Swimming Nekton • Fishes, turtles and whales • Bottom-Dwelling Benthos • Fix themselves to one spot – sponges, oysters, barnacles – or burrow (worms, clams) or walk about

19. Plankton • Phytoplankton • Photosynthetic algae and cyanobacteria • Form the base of most aquatic food webs • Zooplankton • Nonphotosynthetic • Protozoa, shrimplike crustaceans • Immature larva of many animals

20. Freshwater Ecosystems • Rivers and Streams – Flowing-water ecosystem • Lakes and Ponds – standing-water ecosystem • Marshes and Swamps – freshwater wetlands

21. Rivers and Streams • Characteristics vary between its source (begins) and the its mouth (empties into another body) • Headwater streams – small tributaries that are clear, shallow and swiftly flowing and highly oxygenated

22. Rivers and Streams • Rivers downstream are slower, wider and deeper and cloudy with suspended particles. Because they are slower moving and warmer, are less oxygenated. • Organisms will vary greatly from one stream to another dependent on DO, turbidity and stream flowrate.

23. Rivers and Streams • Swift moving stream organisms may have abilities to attach themselves. Fish maybe able to swim the current. • Stream and rivers depend on the surrounding land to provide energy input (detritus). • Human activities adversely impact through damming, boating, point and nonpoint pollution

24. Lakes and Ponds • Zonation characterizes standing-water ecosystems • Littoral Zone • Limnetic Zone • Profundal Zone • Benthnic Zone • Littoral zone is most productive – receives and produces steady energy input. Fish visit to reproduce and feed. Shoreline; plants.

25. Lakes and Ponds • Limnetic Zone extends from the surface of open water to the limits of sunlight. • Phytoplankton and zooplankton • Fairly large fish live in this zone • Profundal Zone – the dead zone (for plants). Stuff dies and sinks. Mineral rich and anaerobic. No producers to absorb the nutrients. Low DO, cooler and dark

26. Lakes and Ponds • Benthnic Zone - again, like streams and rivers, this is where we find the bottom dwellers. • This is the bottom of the lake or pond and species diversity does vary as you move from shore to deeper regions • Many fish feed in this area feasting on plants, macroinverterbrates and smaller fry attempting to hide among the plants.

27. Lakes: Water-Filled Depressions • Lakes are large natural bodies of standing freshwater formed from precipitation, runoff, and groundwater seepage consisting of: • Littoral zone (near shore, shallow, with rooted plants). • Limnetic zone (open, offshore area, sunlit). • Profundal zone (deep, open water, too dark for photosynthesis). • Benthic zone (bottom of lake, nourished by dead matter).

28. Animation: Lake Zonation PLAY ANIMATION

29. Effects of Plant Nutrients on Lakes:Too Much of a Good Thing • Plant nutrients from a lake’s environment affect the types and numbers of organisms it can support. Figure 6-16

30. Effects of Plant Nutrients on Lakes:Too Much of a Good Thing • Plant nutrients from a lake’s environment affect the types and numbers of organisms it can support. • Oligotrophic (poorly nourished) lake: Usually newly formed lake with small supply of plant nutrient input. • Eutrophic (well nourished) lake: Over time, sediment, organic material, and inorganic nutrients wash into lakes causing excessive plant growth.

31. Effects of Plant Nutrients on Lakes:Too Much of a Good Thing • Cultural eutrophication: • Human inputs of nutrients from the atmosphere and urban and agricultural areas can accelerate the eutrophication process.

32. Freshwater Streams and Rivers:From the Mountains to the Oceans • Water flowing from mountains to the sea creates different aquatic conditions and habitats. Figure 6-17

33. Marshes and Swamps • Highly productive and species richness. • Swamps are characterized by trees and marshes by grasses. • Freshwater wetlands include hardwood bottomlands along rivers and streams; potholes and peat moss bogs.

34. Marshes and Swamps • Wetland soils are rich in accumulated nutrients; anaerobic conditions discourage decomposition. • Provide flood control as excess water holding areas. • Ecosystem service by trapping, holding and filtering out pollutants.

35. Freshwater Inland Wetlands: Vital Sponges • Filter and degrade pollutants. • Reduce flooding and erosion by absorbing slowly releasing overflows. • Help replenish stream flows during dry periods. • Help recharge ground aquifers. • Provide economic resources and recreation.

36. Threatened Wetlands • Wetlands provide habitat for many species • 1/2 of all endangered fish species • 1/3 of all endangered bird species • 1/6 of all endangered mammal species • Human activities threaten wetlands • Drainage for agriculture or mosquito control; dredging or channelization for navigation; construction of dams and dikes; filling in for devris disposal or building or road development; conversion for aquaculture……

37. Impacts of Human Activities on Freshwater Systems • Dams, cities, farmlands, and filled-in wetlands alter and degrade freshwater habitats. • Dams, diversions and canals have fragmented about 40% of the world’s 237 large rivers. • Flood control levees and dikes alter and destroy aquatic habitats. • Cities and farmlands add pollutants and excess plant nutrients to streams and rivers. • Many inland wetlands have been drained or filled for agriculture or (sub)urban development.

38. Threatened Wetlands • Legal policies in place to prevent further destruction and loss • Clean Water Act 1972 • Emergency Wetland Resources Act 1986

39. Case Study:Dams, Wetlands, Hurricanes, and New Orleans • Dams and levees have been built to control water flows in New Orleans. • Reduction in natural flow has destroyed natural wetlands. • Causes city to lie below sea-level (up to 3 meters). • Global sea levels have risen almost 0.3 meters since 1900.