Novaes J L C, Moreira S I L, Freire C E C, Sousa M M O, Costa R S
Departamento de Ciências Animais, Universidade Federal Rural do Semi-Árido ? UFERSA, Mossoró, RN, Brazil.
Ciências e Tecnologia do Rio Grande do Norte ? IFRN, Natal, RN, Brazil.
Braz J Biol. 2014 May;74(2):290-301. doi: 10.1590/1519-6984.14712.
The aim of this study was to analyse the composition, structure and spatial and temporal patterns of diversity and abundance of the ichthyofauna of the Santa Cruz Reservoir in semi-arid Brazil. Data were collected quarterly at eight sampling locations on the reservoir between February 2010 and November 2011 using gillnets from 12- to 70-mm mesh that were left in the water for 12h00min during the night. We evaluated the composition, structure and assemblage descriptors (Shannon-Wiener diversity index and equitability, respectively) and catch per unit effort by the number (CPUEn) and biomass (CPUEb) of the ichthyofauna. The 6,047 individuals (399,211.6 g) captured represented three orders, ten families and 20 species, of which four belonged to introduced species. The family Characidae was the most abundant with a total of 2,772 (45.8%) individuals captured. The species-abundance curve fit the log-normal model. In the spatial analysis of diversity, there were significant differences between sampling sites in the lacustrine and fluvial regions, and the highest values were found in the lacustrine region. In the temporal analysis of diversity, significant differences were also observed between the rainy and dry seasons, and the higher values were found during the dry season. Equitability followed the same spatiotemporal pattern as diversity. The Spearman correlation was significantly negative between diversity and rainfall. A cluster analysis spatially separated the ichthyofauna into two groups: one group formed by sampling sites in the fluvial region and another group formed by the remainder of the points in the lacustrine region. Both the CPUEn and CPUEb values were higher at point 8 (fluvial region) and during the rainy season. A two-way ANOVA showed that the CPUEn and CPUEb values were spatially and temporally significant. We conclude that the spatial and temporal trends of diversity in the Santa Cruz reservoir differ from those of other Brazilian reservoirs but that the fish community composition and spatiotemporal patterns of abundance were similar.
本研究的目的是分析巴西半干旱地区圣克鲁斯水库鱼类区系的组成、结构以及多样性和丰度的时空格局。2010年2月至2011年11月期间，使用网目尺寸为12至70毫米的刺网，每季度在水库的八个采样点收集数据，刺网于夜间在水中放置12小时。我们评估了鱼类区系的组成、结构和集合描述符（分别为香农-维纳多样性指数和均匀度）以及单位努力捕捞量（以数量计为CPUEn，以生物量计为CPUEb）。捕获的6047个个体（399211.6克）代表三个目、十个科和20个物种，其中四个属于外来物种。脂鲤科是数量最多的科，共捕获2772个个体（占45.8%）。物种丰度曲线符合对数正态模型。在多样性的空间分析中，湖泊区和河流区的采样点之间存在显著差异，最高值出现在湖泊区。在多样性的时间分析中，雨季和旱季之间也观察到显著差异，旱季的值更高。均匀度与多样性遵循相同的时空模式。多样性与降雨量之间的斯皮尔曼相关性显著为负。聚类分析在空间上将鱼类区系分为两组：一组由河流区的采样点组成，另一组由湖泊区其余的点组成。CPUEn和CPUEb值在第8点（河流区）和雨季时较高。双向方差分析表明，CPUEn和CPUEb值在空间和时间上具有显著性。我们得出结论，圣克鲁斯水库多样性的时空趋势与巴西其他水库不同，但鱼类群落组成和丰度的时空模式相似。
