Aquatic Biomes, Continued

Transcription

1 Aquatic Biomes, Continued Introduction Extent of Marine biomes Issues & challenges Factors influencing distribution Dynamics in time & space Depth Tour of marine biomes Issues (by biome) Freshwater biomes Factors Issues Biome tour Molles & Cahill 2008 Readings: Today Chapter 3 Friday see links posted on Website:

2 Distribution of Water in the Biosphere <3% Mackenzie 2003

3 Temperature salinity, and nutrients (affected by currents) influence the distribution of marine organisms. Light penetration (depth) are also important. pelagic benthic = bottom abyssal Fig. 3.6 Molles & Cahill, 2008

4 Coastal Biomes Kelp forests and coral reefs Fig. 3.14, Molles & Cahill 2008

5 Coral reef tropics Kelp forests - Colder latitudes Figs 3.11 & 3.16 Molles & Cahill 2008

6 Intertidal region zone between low and high tide Fig Molles & Cahill, 2008

7 Intertidal organisms are adapted to extremes (physical forces, temperature extremes, dessication) Molles 2008

8 Sea stars, mussels and anemones in the rocky intertidal The rocky intertidal has been the subject of many classical studies in community ecology (e.g. work of Paine and colleagues on keystone species ). Fig. 3.18, Molles & Cahill 2008

9 Coastal biomes salt marshes and mangrove forests Note the distribution by latitude Fig. 3.24, Molles & Cahill 2008

10 Coastal Biomes Represent Transition Zones (between freshwater & saltwater) Fig Molles & Cahill

11 Salt marshes dominate coastlines in cool regions Molles 2008 Molles & Cahill 2008

12 Aerial view of a salt marsh note the gradual transition between land and sea Fig. 3.25, Molles & Cahill 2008

13 Mangroves dominate coastlines in warm (tropical) regions Fig Fig Molles & Cahill2008

14 The importance of Coastal Zones: Buffering by kelp forests, coral reefs, salt marshes, mangrove forests, and other near-shore ecosystems protect coastal communities. Human alteration of coastal zones disrupts these buffering processes. (Alterations include development, destruction, pollution, altered runoff ) Heywood, Global Biodiversity Strategy

15 Alteration of coastal habitat 60% of human population lives within 100 km of the coast (Vitousek et al. 1997)

16 Dredging and filling of salt marshes Fig. 3.29, Molles & Cahill

17 Jan. 3, 2003 Earthquake Spawns Tsunami High-resolution images: Khao Lak, Thailand Dec. 29, 2004 Wave ~ 10m IKONOS Coastal areas with healthy mangrove forests had significantly less loss of life than areas where mangrove forests had been removed.

18 Stroeve et al Arctic sea ice a shrinking marine biome The extent of permanent ice is changing rapidly.

19 sometimes leaving marine mammals stranded.

20 Freshwater biomes (Rivers, Lakes, & Wetlands)

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22 Human changes to freshwater biomes: Humans now divert 50% of the planet s freshwater supply (70% of this is used for agriculture) - Vitousek et al. 1986, 1994, 1997 Altered structure and flow regimes alter aquatic communities. China s Three Gorges Dam -

23 Factors affecting productivity and distribution of organisms in freshwater biomes: Temperature Nutrient levels (N, P, ) Remember Schindler s Lake Experiments: Oligotrophic Eutrophic Oxygen (O 2 ) Salinity (esp. desert water bodies) ph (e.g. bogs) Fig. 1.5, Molles & Cahill 2008

24 Distribution of major lakes Fig. 3.39, Molles & Cahill 2008

25 Lake Structure photic zone (epilimnion) Benthic region

26 Temperature stratification & periodic lake mixing Many temperate lakes have two periods of mixing (spring & fall) Lake mixing brings nutrients to the photic zone, causing periodic bursts of productivity. Fig. 3.41, Molles & Cahill 2008

27 Rivers & Streams Fig. 3.31, Molles & Cahill 2008

28 Stream order a system of classification (Strahler 1952)

29 Variation in biological communities along the river continuum Course Particulate Organic Matter (CPOM) Fine Particulate Organic Matter (FPOM) Fig. 3.37, Molles & Cahill 2008

30 Many streams are dynamic, and many organisms are adapted to disturbance Streams influence surrounding communities ( riparian zone ) Fig. 3.32, Molles & Cahill

31 Note differing flow regimes in streams from wet and dry climates Fig Flow regimes are further affected by human alteration (dams, irrigation, etc.) Fig. 3.35, Molles & Cahill 2008

32 Wetlands (including bogs & fens) Fig. 3.45, Molles & Cahill 2008

33 J. Gamon Arctic Tundra (Alaska s North Slope) Satellite image of Northern Alaska C. Tweedie Note how many northern (boreal and tundra) regions are filled with wetlands.

34 Bogs & Fens two common wetlands in Canada Bog stagnant water Cold, low ph, nutrient-poor ( low decomposition rates) Fen has some water flow Fig. 3.46, Molles & Cahill 2008

35 Note how soil carbon patterns match global wetland distribution Northern warming releases soil carbon stored over millenia will this affect the climate?