Ictiofauna do Ribeirão Limoeiro, Bacia do Rio Cachoeira, BA

Abstract

Abstract:The streams of the Eastern Basin are characterized by being small, somewhat complex and endemic fish fauna due to geographical isolation. In this context, a study of species distribution and community structure of stream fish Limoeiro, BA along a spatial gradient in one year, using electrofishing as the collection method. Twenty one fish species were collected totalizing 2264 specimens in four points: two points near the head (P1A and P1M), one in the middle course (P2) and another near the mouth (P3). Characiformes and Siluriformes were the orders more important among the four registered. Some species occurred exclusively at the head (Astyanax sp. and Trichomycterus cf. bahianus) and other near the mouth (Leporinus sp. and Callichthys callichthys). On the other hand, Characidium zebra, Parotocinclus cf. cristatus, Poecilia vivipara, Astyanax sp.1, Rhamdia sp. and Poecilia reticulata occurred all sampling points. Was collected one specie the "status" of vulnerable (Nematocharax venustus) and two exotics (Tilapia rendalli and Poecilia reticulata). About the community structure, the values of the index of richness of "Margalef" and of the index of diversity of "Shannon" were greater in this point P3, then this point were significantly lower value of "Berger-Parker" dominance index. The point with riparian vegetation preserved (P1M) showed a lower average water temperature and the points near the head (P1A and P1M) showed the highest values of dissolved oxygen and surface velocity. Conductivity, width and depth of the medium increased toward the mouth. Several results are in accordance with the current literature dealing with community ecology of neotropical stream fish.

Caracterização das assembléias de peixes de riachos de cabeceira no período chuvoso na bacia do rio Cachoeira (SE da Bahia, NE do Brasil)

“…Isto pode ser confirmado pelo gráfico da rarefação, que apresentou uma tendência a atingir a assíntota, levando a supor que um aumento no esforço, representado aqui em número de indivíduos, não levaria a um acréscimo na riqueza de espécies. Pode-se afirmar que esta situação indica a eficiência do método de coleta, como observado por Ferreira (2007), Carmassi (2008) e Trindade (2008), que encontraram estimativas de riqueza muito próximas daquelas existentes nas coletas.…”

Histopathology of Fish Liver to Assess the Water Quality of Limoeiro Stream, Floresta Azul, Ba, Brazil

“…The occurrence of high frequency of severe changes in samples collected from Limoeiro stream was probably due to the fact that the sampling points were environmentally compromised due to not having riparian vegetation, suffer with the dumping of sewage and the presence of waste from human activities (Trindade et al, 2010). This result is reinforced by fact that these places are influenced by stressors originated from urban areas, which compromise the water quality of these ecosystems.…”

“…According to Trindade et al (2010), Limoeiro is an over 11 km long small permanent stream located near the town of Floresta Azul; the stream flows into the Salgado river, which is one of those that eventually form the Cachoeira river. Sampling points were defined from the study of Trindade et al (2010), considering their position in the basin and accessibility to the stream (Fig. 1).…”

“…Based on the methodology proposed by Suzuki et al (1997) and Mazzoni et al (2000), fish were collected by electrofishing. Two operators dressed in insulating rubber jumpsuit equipped with electrodes connected to dip nets that combined back and forth movements over a 75-100 m stretch in the downstream/upstream direction and thus captured fish by immobilizing them with the use of electric currents (Trindade et al, 2010).…”

“…Color pattern and morphology exhibit a wide diversity, hindering the identification of species, particularly those with large geographic distribution (Rubert et al, 2008). In studying the fish fauna of Limoeiro stream, Trindade et al (2010) have observed a high presence of the species Hypostomus cf. unae (Steindachner, 1878) at the sampling point, which caused it to be chosen as object of the present study.…”