School of BioSciences, University of Melbourne, Parkville, Victoria, 3010, Australia.
Ecol Appl. 2019 Oct;29(7):e01956. doi: 10.1002/eap.1956. Epub 2019 Jul 16.
Animals that select the best available habitats are most likely to succeed in degraded environments, but ecological change can create evolutionarily unfamiliar habitats that may be under- or over-utilized by native fauna. In temperate coastal waters, eutrophication and grazing have driven a global decline in native seaweeds and facilitated the establishment of nonnative seaweeds that provide novel macrophyte habitat. We tested whether a nonnative kelp canopy (wakame Undaria pinnatifida) functions as a viable habitat or ecological trap for several endemic reef fishes on urchin-grazed reefs in southern Australia. We assessed the willingness of fish to utilize native vs. wakame kelp canopy via a laboratory habitat choice experiment and by recording natural recruitment to specially constructed boulder reefs with manipulated kelp canopy. We also compared fish communities on natural reefs using a before-after-control-impact survey of wakame patches, and to assess the quality of wakame habitat for resident fish, compared fitness metrics for fish collected from habitats with native vs. wakame kelp canopy. Endemic fishes did not distinguish between the native or wakame canopy but preferred both to barren reef habitats. On urchin-grazed natural reefs, fish occurred in higher abundance and diversity where seasonal wakame canopy was present. Fitness metrics in fish collected from wakame patches were comparable to those in fish from adjacent native kelp patches. These findings indicate that the nonnative canopy provides a viable habitat for endemic fish and may play a role in sustaining native fauna populations in this degraded ecosystem. More broadly, we recommend that managers consider the role of nonnative habitats within the context of environmental change, as endemic fauna may benefit from nonnative habitat-formers in areas where their native counterparts cannot persist.
选择最佳可用栖息地的动物最有可能在退化的环境中取得成功，但生态变化会创造出进化上不熟悉的栖息地，这些栖息地可能被本地动物过度或未充分利用。在温带沿海水域，富营养化和放牧导致了本地海藻的全球减少，并促进了非本地海藻的建立，这些海藻提供了新的大型植物栖息地。我们在澳大利亚南部受海胆放牧的珊瑚礁上测试了一种非本地海带冠层（裙带菜 Undaria pinnatifida）是否可以作为几种特有礁鱼的可行栖息地或生态陷阱。我们通过实验室栖息地选择实验和记录特别建造的带有操纵海带冠层的大圆石礁的自然招募情况，评估了鱼类利用本地海带冠层与裙带菜海带冠层的意愿。我们还通过在裙带菜斑块上进行前后对照影响调查，对自然珊瑚礁上的鱼类群落进行了比较，并且为了评估本地和裙带菜海带冠层栖息地对定居鱼类的质量，比较了从有本地和裙带菜海带冠层的栖息地采集的鱼类的适应度指标。特有鱼类无法区分本地或裙带菜冠层，但更喜欢这两种冠层，而不是光秃秃的珊瑚礁栖息地。在受海胆放牧的自然珊瑚礁上，季节性裙带菜冠层存在的地方，鱼类的数量和多样性更高。从裙带菜斑块中采集的鱼类的适应度指标与从相邻的本地海带斑块中采集的鱼类相当。这些发现表明，非本地冠层为特有鱼类提供了可行的栖息地，并可能在这个退化的生态系统中维持本地动物种群的作用。更广泛地说，我们建议管理者在环境变化的背景下考虑非本地栖息地的作用，因为在其本地对应物无法持续存在的地区，特有动物可能会受益于非本地栖息地形成者。
