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以西澳大利亞鯊灣極端鹽度梯度中的魚類群落為研究對象
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
環(huán)境條件的差異驅(qū)動著水生生態(tài)系統(tǒng)及其棲息者的變化，鹽度與溫度則影響著生物群落的時空分布格局。在澳大利亞西部鯊灣東灣聯(lián)合國教科文組織世界遺產(chǎn)區(qū)，存在極端的鹽度梯度，漢梅林池海洋自然保護區(qū)內(nèi)的鹽度甚至低于91.5 psu。我們在此鹽度梯度下，于四種生境（沙地、海草、低起伏疊層石和高起伏疊層石）及三個區(qū)域（東灣、福爾和漢梅林池）布設了288套誘餌式遠程水下立體視頻系統(tǒng)（立體-BRUVs），以探究魚類群落隨鹽度變化的差異。共記錄魚類20,533條，分屬90種（44科），其中86%為肉食性魚類，僅發(fā)現(xiàn)1種草食性物種。兩種魚類占觀察到的魚類的50%（八線魚（30%）和五足魚（20%））。組合的變化是由鹽度和棲息地的變化驅(qū)動的。物種數(shù)量隨著鹽度的增加而減少，而海草棲息地的物種豐度和數(shù)量始終最高。然而，海草附屬魚類群落的組成因地點而異。鯊魚灣內(nèi)的休閑漁民以觀察到的七種物種為目標。哈梅林池中的金斑魚明顯更大，石斑魚和寬尾石斑魚更豐富，這是一種潛在的海洋保護區(qū)效應。盡管鹽度發(fā)生了極端變化，但這里的魚類群落是多樣化的，哈梅林池可能有助于補充海洋自然保護區(qū)以外捕撈的物種。在當前氣候變化的影響下，世界各地的高鹽環(huán)境可能會看到鹽度水平進一步上升，魚類群落的多樣性可能會減少。
Keywords: Stereo-BRUVs; Seagrass; Habitats; Marine nature reserve; Stromatolites.
