Callisto M, Goulart M, Barbosa F A R, Rocha O
Federal University of Minas Gerais, Dept. General Biology, C.P. 486, CEP 30.161-970, Belo Horizonte, Minas Gerais, Brazil.
Braz J Biol. 2005 May;65(2):229-40. doi: 10.1590/s1519-69842005000200006.
In order to verify the cascade-system effect in benthic macroinvertebrate communities, and the implications for policy making and proposals for conservation and sustainable use of the lower portion of São Francisco river basin (Bahia State, Brazil), a three-reservoir cascade system including two stretches downstream were studied during dry (June, 1997) and rainy (March, 1998) periods. The dominant groups found were Mollusca (Melanoides tuberculata), Oligochaeta, and Chironomidae larvae. Low Shannon-Wiener and Pielou index values were found, but with no significant difference between the sampling periods. However, density and taxonomic richness were significantly different (t(0.05: 31)) = -2.1945; p < 0.05; e t(0.05; 31) = -3.0600; p < 0.01) between the sampling periods, with a reduction in the number of taxa and macroinvertebrate abundance during the rainy period. An increasing gradient in benthic macroinvertebrate community structures was noted along the reservoir cascade from the first reservoir (Apolônio Sales), followed by a decrease downstream from the third reservoir of the system (Xing6). Despite the negative consequences of rapid proliferation of dams, which have caused widespread loss of freshwater habitats, the reservoir cascade system promoted an increase in benthic macroinvertebrate diversity, due to water-quality improvement along the system.
为了验证底栖大型无脊椎动物群落中的梯级系统效应，以及其对巴西巴伊亚州圣弗朗西斯科河流域下游部分的政策制定、保护及可持续利用建议的影响，在旱季（1997年6月）和雨季（1998年3月）对一个包括下游两段的三水库梯级系统进行了研究。发现的优势类群为软体动物（瘤拟黑螺）、寡毛纲和摇蚊科幼虫。香农-维纳指数和皮洛指数值较低，但采样期之间无显著差异。然而，采样期之间的密度和分类丰富度存在显著差异（t(0.05: 31)）= -2.1945；p < 0.05；以及t(0.05; 31) = -3.0600；p < 0.01），雨季期间分类单元数量和大型无脊椎动物丰度减少。沿水库梯级从第一个水库（阿波洛尼奥·萨莱斯）到系统第三个水库（兴6）下游，底栖大型无脊椎动物群落结构呈现出递增梯度，随后递减。尽管水坝快速增殖造成淡水生境广泛丧失等负面后果，但梯级水库系统因水质沿系统得到改善，促进了底栖大型无脊椎动物多样性的增加。
