Aquatic Biodiversity and Life Zones: Exploring the Depths

1. Chapter 6 Aquatic Biodiversity

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

3. AQUATIC ENVIRONMENTS Figure 6-3

4. 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).

5. 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.

6. FRESHWATER LIFE ZONES • Freshwater life zones include: • Standing (lentic) water such as lakes, ponds, and inland wetlands. • Flowing (lotic) systems such as streams and rivers. Figure 6-14

7. 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).

8. Lakes: Water-Filled Depressions • During summer and winter in deep temperate zone lakes the become stratified into temperature layers and will overturn. • This equalizes the temperature at all depths. • Oxygen is brought from the surface to the lake bottom and nutrients from the bottom are brought to the top. • What causes this overturning?

9. Lakes: Water-Filled Depressions Figure 6-15

10. 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

11. 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.

12. 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.

13. 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

14. Drainage Basins • Surface water or runoff is the basis for a watershed or drainage basin • Source zone: source of the runoff from precipitation, snow and ice; narrow • Shallow, cold, clear, fast moving water • Not very biodiverse • Transition zone: headwater streams merge to form wider, deeper, warmer streams • Slower moving, warm, more diversity • Floodplain zone: form deltas, channels • Very warm, low D.O., large population of producers

15. Watershed • Watershed is the area of land where all of the water that is under it or drains off of it goes into the same place. John Wesley Powell, scientist geographer, put it best when he said that a watershed is: • "that area of land, a bounded hydrologic system, within which all living things are inextricably linked by their common water course and where, as humans settled, simple logic demanded that they become part of a community." • Watersheds cross county, state, and national boundaries. • In the continental US, there are 2,110 watersheds; • In Hawaii Alaska, and Puerto Rico, there are 2,267 watersheds.

17. Why watersheds? • A watershed approach is the most effective framework to address today's water resource challenges. Watersheds supply drinking water, provide recreation and respite, and sustain life. More than $450 billion in food and fiber, manufactured goods, and tourism depends on clean water and healthy watersheds.

18. What exactly is a watershed important? • Is hydrologically defined • geographically focused • includes all stressors (air and water) • Involves all stakeholders • includes public (federal, state, local) and private sector • is community based • includes a coordinating framework • Strategically addresses priority water resource goals (e.g. water quality, habitat) • integrates multiple programs (regulatory and voluntary) • based on sound science • aided by strategic watershed plans • uses adaptive management

19. Wetlands • Generally, wetlands are lands where saturation with water is the dominant factor determining the nature of soil development and the types of plant and animal communities living in the soil and on its surface. • Wetlands vary widely because of regional and local differences in soils, topography, climate, hydrology, water chemistry, vegetation, and other factors, including human disturbance. Indeed, wetlands are found from the tundra to the tropics and on every continent except Antarctica.

20. EPA Definition • Wetlands are areas where water covers the soil, or is present either at or near the surface of the soil all year or for varying periods of time during the year, including during the growing season. Water saturation (hydrology) largely determines how the soil develops and the types of plant and animal communities living in and on the soil. Wetlands may support both aquatic and terrestrial species. The prolonged presence of water creates conditions that favor the growth of specially adapted plants (hydrophytes) and promote the development of characteristic wetland (hydric) soils.

21. What is a Wetland? (in English) • Wetlands are a transition zone between the land and water. • Marsh: soft stemmed vegetation • Swamps: mostly woody plants • Bogs: freshwater wetlands formed from old glacial lakes; spongy peat deposits, evergreen trees and shrubs, moss • Fens: freshwater peat-forming wetlands covered with grasses, reeds and wildflowers

22. Coastal (Tidal) Wetlands • Coastal wetlands are found along the Atlantic, Pacific, Alaskan, and Gulf coasts. They are closely linked to our nation's estuaries, where sea water mixes with fresh water to form an environment of varying salinities. The salt water and the fluctuating water levels (due to tidal action) combine to create a rather difficult environment for most plants. Consequently, many shallow coastal areas are unvegetated mud flats or sand flats. Some plants, however, have successfully adapted to this environment. Certain grasses and grasslike plants that adapt to the saline conditions form the tidal salt marshes that are found along the Atlantic, Gulf, and Pacific coasts. Mangrove swamps, with salt-loving shrubs or trees, are common in tropical climates, such as in southern Florida and Puerto Rico. Some tidal freshwater wetlands form beyond the upper edges of tidal salt marshes where the influence of salt water ends.

23. Inland Wetlands • Inland wetlands are most common on floodplains along rivers and streams (riparian wetlands), in isolated depressions surrounded by dry land (for example, playas, basins, and "potholes"), along the margins of lakes and ponds, and in other low-lying areas where the groundwater intercepts the soil surface or where precipitation sufficiently saturates the soil (vernal pools and bogs). Inland wetlands include marshes and wet meadows dominated by herbaceous plants, swamps dominated by shrubs, and wooded swamps dominated by trees.

24. Seasonal Inlands Wetlands • Many of these wetlands are seasonal (they are dry one or more seasons every year), and, particularly in the arid and semiarid West, may be wet only periodically. The quantity of water present and the timing of its presence in part determine the functions of a wetland and its role in the environment. Even wetlands that appear dry at times for significant parts of the year -- such as vernal pools-- often provide critical habitat for wildlife adapted to breeding exclusively in these areas.

25. Function of Wetlands • Habitat for birds and other wildlife • Clean Water (the kidney’s of the land by trapping sediment, solids, nutrients, etc. before they reach the ocean) • Flood prevention by storing storm water • Fisheries • Jobs • Tourism

26. Freshwater Inland Wetlands: Vital Sponges • Inland wetlands act like natural sponges that absorb and store excess water from storms and provide a variety of wildlife habitats. Figure 6-18

27. 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.

29. Legislation • Clean Water Act • There are several sections of this Act which pertain to regulating impacts to wetlands. • Section 101 specifies the objectives of this Act which are implemented largely through Title III (Standards and Enforcement), Section 301 (Prohibitions). The discharge of dredged or fill material into waters of the United States is subject to permitting specified under Title IV (Permits and Licenses) of this Act and specifically under Section • 404 (Discharges of Dredge or Fill Material) of the Act . • Section 401 (Certification) specifies additional requirements for permit review particularly at the state level.

30. Section 404 • Section 404 of the SWA establishes a program to regulate the discharge of dredged or fill material into water, including wetlands. • Requires a permit prior to discharge of dredge or fill material

31. VA Legislation • Tidal Wetlands Act of 1972: permits for discharge into tidal wetlands areas

32. US Army Corps of Engineers • Administers the daily program including permit decisions • Conducts inspections • Develops policy guidelines • Enforces Section 404 provisions

33. US EPA • Develops and interprets policy, guidance and environmental criteria to evaluate permit applications • Determines geographic jurisdiction • Approves state and tribal assumptions • Can prohibit, deny or restrict the use of any defined area as a disposal site • Can elevate a case • Enforces section 404 provisions

34. US Fish and Wildlife Services • Evaluates the ecological impact on fish and wildlife • Elevates specific cases or policy issues

35. Restoration (Mitigation) • Restoration is the return of a degraded wetland or former wetland to its preexisting naturally functioning condition, or as close as possible. • EPA has grants available, 5-star restoration projects • How would you restore a wetland?

36. 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.

37. Katrina • Was what happened in New Orleans from Katrina a natural disaster or did human impact magnify the effects of the hurricane? • Wetlands and Flooding in New Orleans : NPR • How New Orleans Flooded

38. 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.

39. Impacts of Human Activities on Freshwater Systems • These wetlands have been ditched and drained for cropland conversion. Figure 6-19

40. SALTWATER LIFE ZONES • The oceans that occupy most of the earth’s surface provide many ecological and economic services. • Scientists estimate that marine systems provide $21 trillion in goods and services per year – 70% more than terrestrial ecosystems. Figure 6-4

41. 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.

42. The Coastal Zone Figure 6-5

43. Biological Zones in the Open Sea:Light Rules • Euphotic zone: brightly lit surface layer. • Nutrient levels low, dissolved O2 high, photosynthetic activity. • Bathyal zone: dimly lit middle layer. • No photosynthetic activity, zooplankton and fish live there and migrate to euphotic zone to feed at night. • Abyssal zone: dark bottom layer. • Very cold, little dissolved O2.

44. Fig. 6-6, p. 130

45. Estuaries and Coastal Wetlands: Centers of Productivity • Estuaries include river mouths, inlets, bays, sounds, salt marshes in temperate zones and mangrove forests in tropical zones. Figure 6-7

46. Mangrove Forests • Are found along about 70% of gently sloping sandy and silty coastlines in tropical and subtropical regions. Figure 6-8

47. Estuaries and Coastal Wetlands: Centers of Productivity • Estuaries and coastal marshes provide ecological and economic services. • Filter toxic pollutants, excess plant nutrients, sediments, and other pollutants. • Reduce storm damage by absorbing waves and storing excess water produced by storms and tsunamis. • Provide food, habitats and nursery sites for many aquatic species.

48. Rocky and Sandy Shores: Living with the Tides • Organisms experiencing daily low and high tides have evolved a number of ways to survive under harsh and changing conditions. • Gravitational pull by moon and sun causes tides. • Intertidal Zone: area of shoreline between low and high tides.

49. Rocky and Sandy Shores: Living with the Tides • Organisms in intertidal zone develop specialized niches to deal with daily changes in: • Temperature • Salinity • Wave action Figure 6-9

50. Barrier Islands • Low, narrow, sandy islands that form offshore from a coastline. • Primary and secondary dunes on gently sloping sandy barrier beaches protect land from erosion by the sea. Figure 6-10