Zerlin R A, Henry R
Department of Zoology, Institute of Biosciences, State University of São Paulo ? UNESP, Botucatu, SP, Brazil.
Braz J Biol. 2014 May;74(2):408-19. doi: 10.1590/1519-6984.26812.
Benthic macro-invertebrates are important components of freshwater ecosystems which are involved in ecological processes such as energy transfer between detritus and consumers and organic matter recycling. The aim of this work was to investigate the variation in organism richness, diversity and density of benthic fauna during the annual cycle in Camargo Lake, a lake marginal to Paranapanema River, southeast Brazil. The correlation of environmental factors with community attributes of the macro-benthic fauna was assessed. Since Camargo Lake is connected to the river, we tested the hypothesis that water level variation is the main regulating factor of environmental variables and of the composition and abundance of benthic macro-invertebrates. The results indicated that lake depth varied with rainfall, being the highest at the end of the rising water period and the lowest at the beginning of this period. The sediment granulometry was more heterogeneous at the bottom of the lake by the end of the high water period. The benthic macro-invertebrate fauna was composed by 15 taxa. The Diptera order was represented by seven taxa and had greater richness in relation to other taxa. This group was responsible for 60% of the total abundance of organisms, followed by Ephemeroptera (22%) and Anellida (16%). Significant differences were observed over time in total richness and, in density of Narapa bonettoi, Chaoborus, Ablabesmyia gr. annulata, Chironomus gigas, Larsia fittkau, and Procladius sp. 2. Total taxa richness correlated negatively with water pH, transparency, conductivity, and bottom water oxygen. Higher positive correlations were found between the densities of some taxa and bottom water oxygen, conductivity and very fine sand, silt + clay of sediment, while negative correlations were recorded with organic matter, and fine, medium and coarse sand, bottom water temperature, mean temperature and rainfall. The significant temporal difference in water level was associated with changes in abiotic factors and macro-invertebrate community attributes.
底栖大型无脊椎动物是淡水生态系统的重要组成部分，参与碎屑与消费者之间的能量传递以及有机物质循环等生态过程。本研究旨在调查巴西东南部帕拉纳潘ema河边缘的卡马戈湖底栖动物在年度周期内的物种丰富度、多样性和密度变化。评估了环境因素与大型底栖动物群落属性之间的相关性。由于卡马戈湖与河流相连，我们检验了水位变化是环境变量以及底栖大型无脊椎动物组成和丰度的主要调节因素这一假设。结果表明，湖泊深度随降雨而变化，在涨水期结束时最高，在该时期开始时最低。在高水位期结束时，湖底的沉积物粒度更为不均匀。底栖大型无脊椎动物群落由15个分类单元组成。双翅目由7个分类单元代表，相对于其他分类单元具有更高的丰富度。该类群占生物总数的60%，其次是蜉蝣目（22%）和环节动物门（16%）。在总丰富度以及纳拉帕·博内托伊、摇蚊、环纹阿布拉贝丝摇蚊、大摇蚊、菲氏拉西亚摇蚊和原摇蚊属2的密度随时间存在显著差异。总分类单元丰富度与水体pH值、透明度、电导率和底层水氧气呈负相关。一些分类单元的密度与底层水氧气、电导率以及沉积物的极细砂、粉砂+黏土呈较高的正相关，而与有机质、细砂、中砂和粗砂、底层水温度、平均温度和降雨量呈负相关。水位的显著时间差异与非生物因素和大型无脊椎动物群落属性的变化有关。
