Thus, biotic interactions underlie much of the within-lake variation in the zoobenthos. Likewise, the density and kind of macrophytes, which are important in providing surfaces for attachment, shelter from predation, and food for benthic animals, change markedly with water depth, and can drive major changes in the zoobenthos. The numbers and kinds of fish change from the littoral to the profundal zone indeed, anoxic profundal sediments may be free from fish predation. Fish predation can have very large effects on the number, size, and species composition of benthic animals (Figure 9). Reduced zoobenthic density and diversity near the water's edge, particularly in large lakes and reservoirs.įinally, many of the biotic interactions that affect the zoobenthos are depth-dependent. Hypolimnetic depositional Hypolimnetic nondepositionalįigure 8 Mean (☑SE) biomass (wet mass) of macrobenthic animals at various sites in Lake Memphremagog, Quebec, as a function of thermal and depositional regime. The dashed horizontal line shows the depth at which oxygen at the sediment surface falls below 1 mg l_1 by late summer. Adapted from Jonasson (2004).įigure 7 Species richness, abundance, and biomass of benthic animals (including all metazoans) as a function of water depth in Mirror Lake, a small unproductive lake in New Hampshire. Figure 1 Reported density of zoobenthos as a function of sieve mesh size in a series of lakes from the northern temperate zone (r2 = 0.72, p 101g dry mass) are more Table 1 Estimates of species richness of the zoobenthos (excluding parasitic forms) in Mirror Lake, a small, unproductive lake in New Hampshire (USA), and typical densities of major phyla in lakesįigure 6 Distribution of benthic animals with water depth in eutrophic Lake Esrom, Denmark.
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