©2010 Elsevier, Inc. Chapter 24 Freshwater Ecosystems Dodds & Whiles

©2010 Elsevier, Inc. FIGURE 24.1 Graphic representation of one of the first accountings of energy flux through an ecosystem. Flux rates in g-cal cm 22 y 21. The data are for Cedar Bog Lake. (Lindeman, 1942).

©2010 Elsevier, Inc. FIGURE 24.2 Biomass (A), production (B), and production per unit biomass (C) of Silver Springs, Florida. Note that production is divided into respiration and growth. (Data from Odum and Odum, 1959).

©2010 Elsevier, Inc. FIGURE 24.3 An Allen curve showing changes in density and individual weights of a cohort of animals over time. N is number and W is individual weight; subscript t and t 1 1 indicate points in time. Over time, the number of individuals declines (moving down the y axis; difference between N t and N t11 5 mortality) and individuals grow (moving left to right on the x axis). The sum of the new biomass created by survivors (represented by the light gray rectangle) and the biomass produced in the interval but lost to mortality (darker grey triangle) represent production for the time interval depicted. Total production for the cohort is the area under the curve; note that the area under the dashed line at the top would represent total production for the cohort if no mortality occurred.

©2010 Elsevier, Inc. FIGURE 24.4 Diagram of nitrogen fluxes in a cold water spring (Mare’s Egg Spring) dominated by Nostoc, a nitrogen-fixing cyanobacterium. Fluxes are given in moles N year 21. Note: Fluxes are measured so where the budget does not balance there are measurement errors. (Redrawn from Dodds and Castenholz, 1988).

©2010 Elsevier, Inc. FIGURE 24.5 Benthic macroinvertebrates that burrow into layered sediments and accelerate nutrient cycling and movement of materials into the water column. Burrowing bivalve, crayfish, tubificid worms, and aquatic insect larvae mix O 2 into the sediments through their activities. Surface-dwelling invertebrates increase turnover of microbial communities and increase sediment suspension. (Reproduced with permission from Covich et al., 1999).

©2010 Elsevier, Inc. FIGURE 24.6 Ranges of documented respiration rates from various types of sediments. (Data from Kieft and Phelps, 1997).

©2010 Elsevier, Inc. FIGURE 24.7 A diagram of nutrient spiraling in streams. S is the total spiral length, S p is the time spent in particulate form in water column or the benthic zone and S w is the average time spent in the water. Average velocity is greater in the riffle on the left, so spiral length is greater than in the pool at the right.

©2010 Elsevier, Inc. FIGURE 24.8 Diagram of the river continuum concept. See text and Table 24.3 for explanation. (Modified from Vannote et al., 1980).

©2010 Elsevier, Inc. FIGURE 24.9 A simple diagram of nutrient flux through a lake ecosystem. The system is represented as a two-compartment bioreactor with a pelagic zone and the benthic zone. (Modified from Covich et al., 1999).

©2010 Elsevier, Inc. FIGURE Diagram of carbon flux in Lawrence Lake, Michigan. (Data from Wetzel, 1983).

©2010 Elsevier, Inc. FIGURE Ranges and means of production by various ecosystems. (Data from Whittaker, 1975).

©2010 Elsevier, Inc. FIGURE Sediment deposition rates for wetlands. (Data from Schlesinger, 1997).

©2010 Elsevier, Inc. FIGURE Carbon biomass and flux rates for the Creeping Swamp ecosystem. Biomass values in g cm 2 are listed in the compartment boxes, and flux rates in g C m 22 y 21 are in parentheses. (Data from Mullholland, 1981).

©2010 Elsevier, Inc. FIGURE Freshwater habitats aligned across gradients that drive ecosystem properties.

©2010 Elsevier, Inc. FIGURE Comparison of carbon flow pathways and trophic complexity of groundwater, wetland, lake, and stream habitats.