Fish and Invertebrate Assemblages in Seagrass, Mangrove, Saltmarsh, and Nonvegetated Habitats

Many studies compare utilization of different marine habitats by fish and decapod crustaceans; few compare multiple vegetated habitats, especially using the same sampling equipment. Fish and invertebrates in seagrass, mangrove, saltmarsh, and nonvegetated habitats were sampled during May–August (Austral winter) and December–January (Austral summer) in the Barker Inlet-Port River estuary, South Australia. Sampling was undertaken using pop nets in all habitats and seine nets in seagrass and nonvegetated areas. A total of 7,895 fish and invertebrates spanning 3 classes, 9 orders, and at least 23 families were collected. Only one fish species, Atherinosoma microstoma, was collected in all 4 habitats, 11 species were found in 3 habitats (mangroves, seagrass, and nonvegetated), and 13 species were only caught in seagrass and nonvegetated habitats. Seagrass generally supported the highest numbers of fish and invertebrates and had the greatest species richness. Saltmarsh was at the other extreme with 29 individuals caught from two species. Mangroves and nonvegetated habitats generally had more fish, invertebrates, and species than saltmarsh, but less than seagrass. Analyses of abundances of individual species generally showed an interaction between habitat and month indicating that the same patterns were not found through time in all habitats. All habitats supported distinct assemblages although seagrass and nonvegetated assemblages were similar in some months. The generality of these patterns requires further investigation at other estuaries. Loss of vegetated habitats, particularly seagrass, could result in loss of species richness and abundance, especially for organisms that were not found in other habitats. Although low abundances were found in saltmarsh and mangroves, species may use these habitats for varying reasons, such as spawning, and such use should not be ignored.

诸多研究已针对鱼类与十足目甲壳类（decapod crustaceans）对不同海洋生境的利用模式开展对比，但鲜有研究对多种植被型海洋生境进行同类对比，且其中多数未采用统一的采样装备。本研究于澳大利亚南部的巴克湾-波特河河口，在5月至8月（南半球冬季）与12月至次年1月（南半球夏季）期间，对海草（seagrass）生境、红树林（mangrove）生境、盐沼（saltmarsh）生境以及无植被生境中的鱼类和无脊椎动物开展采样。所有生境均采用弹出式网（pop nets）进行采样，海草与无植被生境则额外使用围网（seine nets）开展采样。本次采样共收集到7895尾（只）鱼类与无脊椎动物，隶属于3纲、9目，至少23个科。仅有一种鱼类（Atherinosoma microstoma）在全部4类生境中均被采集到；另有11个物种分布于3类生境（红树林、海草与无植被生境）；还有13个物种仅在海草与无植被生境中被捕获。海草生境通常承载着最高丰度的鱼类与无脊椎动物，同时拥有最高的物种丰富度。盐沼生境则处于物种丰度与丰富度的最低水平，仅采集到29个个体，隶属于2个物种。红树林生境与无植被生境的鱼类、无脊椎动物丰度及物种丰富度整体上均高于盐沼生境，但低于海草生境。针对单个物种丰度的分析整体上显示，生境类型与采样月份之间存在交互效应，表明不同生境的物种分布模式并非随时间保持一致。所有生境均拥有独特的生物群落组成，尽管海草生境与无植被生境的生物群落在部分月份中表现出相似性。上述模式的普适性仍需在其他河口开展进一步研究加以验证。植被型海洋生境的丧失（尤其是海草生境）可能会导致物种丰富度与个体丰度的下降，对于那些仅分布于此类生境的生物而言尤为如此。尽管盐沼与红树林生境中的生物丰度较低，但部分物种可能会基于产卵等不同原因利用此类生境，此类生境利用模式不应被忽视。