Abstract

JONCK, Célio Roberto  and  ARANHA, José Marcelo Rocha. Influence of a waterfall over richness and similarity in adjoining pools of an Atlantic Rainforest stream. Acta Limnol. Bras. (Online) [online]. 2010, vol.22, n.4, pp. 378-383. ISSN 2179-975X.  http://dx.doi.org/10.4322/actalb.2011.003.

AIM: The main goal of the study was to determine the effect of the Morato Fall in the richness and composition of the aquatic animal community; METHODS: We compared faunal richness and similarity in four substrate samples from two pools separated by a waterfall in the Morato River, southern Brazil; RESULTS: The richness was not significantly different, although the upstream pool had 72 taxa and the downstream one just 65. On the other hand, composition was poorly similar, just a 36.5% similarity between the two sites; CONCLUSIONS: That indicates a strong influence of the waterfall, mainly on organisms which spent its entire life cycle on the water, such as fish and small crustaceans. That allow aquatic insects, a group with airborne adult phase and, therefore, able to disperse up to the upstream pool, to evolve with less predatory pressure, becoming the top group in the food web of this environment.

Keywords : stream; waterfall; richness; similarity; Atlantic Forest.