Tropicalisation and kelp loss shift trophic composition and lead to more winners than losers in fish communities

Climate-mediated species redistributions are causing novel interactions and leading to profound regime shifts globally.  For species that expand their distribution in response to warming, survival depends not only on their physiological capacity, but also on the ability to coexist or be competitive within the established community. In temperate marine reefs from around the world, the range expansion of tropical species, known as ‘tropicalisation’, has been linked to the disappearance of temperate habitat-forming kelps and shifts to dominance by low-biomass turfing algae. The consequences of these range expansions and habitat changes on resident fish communities are, however, unclear. Here, we use data derived from baited remote underwater video (BRUV) surveys to analyse changes in diversity and abundance of marine fishes over a 17-year period in warming reefs that have experienced kelp loss (occurring c. 2009). Despite the loss of kelp, we found that species richness and overall abundan...气候驱动的物种重新分布正催生全新的物种互作关系，并在全球范围内引发深刻的生态系统状态转变。对于因气候变暖而扩张分布范围的物种而言，其存活不仅取决于自身的生理耐受能力，还取决于在已构建的群落中实现共存或占据竞争优势的能力。在全球各地的温带海洋礁生境中，被称为「热带化（tropicalisation）」的热带物种分布扩张现象，已被证实与温带建群种大型褐藻（海带林）的消失，以及群落优势种被低生物量铺展型藻类取代的转变密切相关。然而，这类分布扩张与生境改变对栖息鱼类群落造成的影响仍不明晰。本研究利用诱饵式远程水下视频（baited remote underwater video, BRUV）调查获取的数据，对一处自约2009年起发生海带林退化的变暖海域礁体，开展了为期17年的海洋鱼类多样性与丰度变化分析。尽管海带林已发生退化，我们仍发现物种丰富度与总丰度……