Port Curtis portwide macrobenthos study

Spatial patterns in benthic infaunal community structure of Port Curtis estuary (north-eastern Australia) were determined from quantitative grab samples and examined in relation to environmental variables. A total of 149 riverine, estuarine and open coastal stations were sampled during the survey, and 5744 individuals and 466 species dentified. Filter-feeding organisms (primarily polychaetes, molluscs and crustaceans) dominated the bedforms, and accounted for 50% of the total species abundance and 30% of the total species richness. Most taxa were uncommon, and 98% of species individually represented less than 2% of the total abundance. Distributional patterns in total species richness and abundance were highly correlated, and both parameters varied significantly with sediment structure. Numbers of species and individuals were typically highest in coarse-sand and gravel sediments, and lowest in fine, well-sorted, sands. Cluster analysis of species abundance data revealed nine community groupings characterised by small species subsets with restricted distributions. These groupings were found to be primarily related to measures of depth, salinity, dissolved oxygen and sediment structure. Not all variation in community structure was explained by these environmental variables, and it is likely that other unmeasured factors play an important role in determining benthic faunal composition in the estuary.本研究以澳大利亚东北部波特柯蒂斯河口（Port Curtis estuary）为研究区域，通过定量采泥样品（quantitative grab samples）获取数据，解析其底栖内生动物群落（benthic infaunal community）结构的空间分布模式，并探讨该模式与环境变量的关联。本次调查共布设149个河流、河口及开放海岸采样站位，共采集并鉴定出5744个个体，隶属466个物种。滤食性生物（filter-feeding organisms，主要包括多毛类（polychaetes）、软体动物（molluscs）与甲壳类（crustaceans））为该区域底栖生境的优势类群，其个体丰度占总丰度的50%，物种丰富度占总丰富度的30%。绝大多数分类单元较为稀有，98%的物种其个体丰度占总个体丰度的比例均低于2%。总物种丰富度与个体丰度的空间分布模式高度相关，且两类参数均随沉积物结构（sediment structure）呈现显著差异。物种数量与个体数量通常在粗砂与砾石沉积物中达到峰值，而在细粒、分选良好的砂质沉积物中最低。对物种丰度数据开展聚类分析（cluster analysis）后，共识别出9个群落类群，每一类群均以分布范围受限的小型物种子集为典型特征。进一步分析表明，此类群落类群主要与水深、盐度、溶解氧及沉积物结构等环境指标密切相关。但并非所有群落结构的变异均可由上述环境变量解释，推测仍有其他未被测定的因子在该河口底栖动物群落组成的塑造过程中发挥重要作用。