The influence of trophic status and seasonal environmental variability on morpho-functional traits in tropical man-made shallow lakes.

In the tropics, seasons are delimitated by the extent of rainfall resulting in seasonal differences in water parameters shaping phytoplankton community dynamics. Dry periods can intensify eutrophication and often result in seasonal or even perennial cyanobacterial dominance. This study was developed to evaluate phytoplankton response to trophic state and seasonal differences of environmental filters (dry and rainy periods) using the morphology-based functional groups (MBFG) approach.

Selective Grazing by a Tropical Copepod () Facilitates Dominance.

Top-down grazer control of cyanobacteria is a controversial topic due to conflicting reports of success and failure as well as a bias toward studies in temperate climates with large generalist grazers like . In the tropical lowland lakes of Brazil, calanoid copepods of the complex dominate zooplankton and co-exist in high abundance with permanent blooms of toxic cyanobacteria, raising questions for grazer effects on bloom dynamics (i.e.

Mutagenic potential assessment associated with human exposure to natural radioactivity.

Lucrécia city, known to harbor a high cancer rate, is located in a semiarid region characterized by the presence of mineral reservoirs, facing a high exposure to metal and natural radioactivity. The present study aimed to assess the environmental scenario at a semiarid region located in Northeastern Brazil. Metal concentration, alpha and beta radiation, and cyanobacteria content in tap water along with indoor radon and gamma emitters (U, K and Th) concentrations were measured.

Effects of the cyanobacterium Cylindrospermopsis raciborskii on feeding and life-history characteristics of the grazer Daphnia magna.

Laboratory experiments were used to test the hypothesis that feeding and growth of the zooplankton grazer Daphnia magna will decrease with increasing proportions of the cyanobacterium Cylindrospermopsis raciborskii in the diet (mixed feeds with the green alga Scenedesmus obliquus). A strain of C. raciborskii, which does not produce cylindrospermopsin but contains saxitoxins and gonyautoxins, was not acutely toxic to Daphnia, as the daphnids survived slightly longer in suspensions with the cyanobacterium as the sole feed than in medium without food.