Composition, biomass aquatic species

In this chapter we discuss the distribution and the development of plant communities in floodplain areas, mainly of the big whitewater rivers, focusing on factors such as diversity, species composition, biomass and primary production. Based upon these factors, we also discuss the annual dynamics of bioelements stocks and their turnover through herbaceous and floodplain forest communities. Finally, we examine the implications of such nutrient dynamics and turnover for the aquatic biota. We do not address carbon and nutrient budgets, as these are thoroughly discussed in chapter 14. 

Decomposition rates of some organic substrates are reduced. Substantial changes in the species composition of primary producers occur. The richness of phytoplankton species is reduced, while biomass and productivity of phytoplankton are not reduced by acidification. The biomass of herbivorous and predaceous zooplankton is probably reduced because of reductions in numbers of organisms and/or reduction in their average size. Many benthic invertebrates such as species of snails, clams, crayfish, amphipods, and various aquatic insects are intolerant of low pH and are seldom found in acidic lakes. However, certain large aquatic insects such as water boatmen and gyrinids are very acid tolerant and may become the top predators in some acidified lakes. Acidification of aquatic systems has major effects on fish population. 

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