Influence of Limnological Processes and Water Level Variation on the Biodiversity of Brazilian Amazon Lakes: An Ecological Approach
Assad J. Darwich
National Institute of Research in Amazonian, INPA - 69060-001, Amazonas, Brazil.
Fabio Aprile *
Western of Pará Federal University, UFOPA - 68040-070, Pará, Brazil.
*Author to whom correspondence should be addressed.
Abstract
This research makes a brief review of the limnology of lakes in wetlands in the Western Amazon, associating physical-chemical and morphological aspects to the biodiversity of black-waters lakes and whitewaters lakes. Lakes in these areas can show different patterns of vertical stratification, both in dissolved oxygen concentration and temperature. Furthermore, there are different mixing patterns. These events depend mainly on the way lakes connect to rivers, the time and extent of flooding, as well as the water levels variation. The availability of nutrients, particularly of phosphate, controls the biodiversity of the lakes and it is directly related with the thermal stratification and oxygen level in water column. In general, the most of the Amazon floodplain lakes can be classified as polymictic. Nevertheless, there are lakes of black-waters with trend to meromixy with permanent stratification. Under these conditions, stratification of other limnological variables also occurs, e.g., pH and electrical conductivity. Consequently, black-waters lakes systems with high species richness result in contrast to whitewaters lakes systems with lower species richness and high abundance of specimens.
Keywords: Black-waters, whitewaters, water level variation, Floods and Ebbs Cycles (FEC), richness of species, Amazon floodplain