有人喜咸—
以西澳大利亚鲨湾极端盐度梯度中的鱼类群落为研究对象
Abstract
Variation in environmental conditions drive changes within aquatic ecosystems and their associated inhabitants, with salinity and temperature influencing the spatial and temporal patterns of biological communities. An extreme salinity gradient exists within the Eastern Gulf of Shark Bay UNESCO World Heritage Area, Western Australia, reaching <91.5 psu within Hamelin Pool Marine Nature Reserve. We deployed 288 baited remote underwater stereo-video systems (stereo-BRUVs) across four habitats (sand, seagrass, low relief stromatolites, and high relief stromatolites) and three locations (Eastern Gulf, Faure Sill, and Hamelin Pool) to examine variation in fish assemblages across this salinity gradient. A total of 20,533 fish from 90 species (44 Families) were identified, 86 % of which were carnivores, with only one herbivorous species recorded. Two species accounted for 50 % of fish observed (Helotes octolineatus (30 %) and Pentapodus vitta (20 %)). Variations in assemblages were driven by changes in salinity and habitat. The number of species decreased with increasing salinity, while seagrass habitats consistently had the highest abundance and number of species. However, the composition of seagrass affiliated fish assemblages differed among locations. Seven species observed are targeted by recreational fishers within Shark Bay. Chrysophrys auratus were significantly larger, and Epinephelus coioides and Lethrinus laticaudis more abundant in Hamelin Pool, a potential marine reserve effect. Despite extreme changes in salinity, fish assemblages here are diverse, with Hamelin Pool potentially facilitating the replenishment of species that are fished outside of the Marine Nature Reserve. Under the current effects of climate change, hypersaline environments around the world are likely to see salinity levels increase further, with a potential decrease in the diversity of their fish assemblages.
摘要
环境条件的差异驱动着水生生态系统及其栖息者的变化，盐度与温度则影响着生物群落的时空分布格局。在澳大利亚西部鲨湾东湾联合国教科文组织世界遗产区，存在极端的盐度梯度，汉梅林池海洋自然保护区内的盐度甚至低于91.5 psu。我们在此盐度梯度下，于四种生境（沙地、海草、低起伏叠层石和高起伏叠层石）及三个区域（东湾、福尔和汉梅林池）布设了288套诱饵式远程水下立体视频系统（立体-BRUVs），以探究鱼类群落随盐度变化的差异。共记录鱼类20,533条，分属90种（44科），其中86%为肉食性鱼类，仅发现1种草食性物种。两种鱼类占观察到的鱼类的50%（八线鱼（30%）和五足鱼（20%））。组合的变化是由盐度和栖息地的变化驱动的。物种数量随着盐度的增加而减少，而海草栖息地的物种丰度和数量始终最高。然而，海草附属鱼类群落的组成因地点而异。鲨鱼湾内的休闲渔民以观察到的七种物种为目标。哈梅林池中的金斑鱼明显更大，石斑鱼和宽尾石斑鱼更丰富，这是一种潜在的海洋保护区效应。尽管盐度发生了极端变化，但这里的鱼类群落是多样化的，哈梅林池可能有助于补充海洋自然保护区以外捕捞的物种。在当前气候变化的影响下，世界各地的高盐环境可能会看到盐度水平进一步上升，鱼类群落的多样性可能会减少。
Keywords: Stereo-BRUVs; Seagrass; Habitats; Marine nature reserve; Stromatolites.
