Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175, CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE, Montpellier, France and FitzPatrick Institute, DST-NRF Centre of Excellence at the University of Cape Town, Rondebosch 7701, South Africa.
Centre for Geometric Biology, School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia.
Curr Biol. 2017 Dec 4;27(23):R1263-R1264. doi: 10.1016/j.cub.2017.09.027.
Overfishing and ocean warming are drastically altering the community composition and size structure of marine ecosystems, eliminating large bodied species [1]. Against a backdrop of such environmental change, the heaviest of all bony fish, the ocean sunfish (Mola mola), seems an improbable survivor. Indeed this indolent giant is killed globally as bycatch, and is listed as 'Vulnerable'[2]. We undertook the most extensive aerial surveys of sunfish ever conducted and found surprisingly high abundances off the Atlantic and Mediterranean coasts of Western Europe. With up to 475 individuals per 100 km, these figures are one order of magnitude higher than abundance estimates for other areas [3-5]. Using bioenergetic modelling, we estimate that each sunfish requires 71 kg day of jellyfish, a biomass intake more than an order of magnitude greater than predicted for a similarly sized teleost. Scaled up to the population level, this equates to a remarkable 20,774 tonnes day of predated jellyfish across our study area in summer. Sunfish abundance may be facilitated by overfishing and ocean warming, which together cause reduced predation of sunfish by sharks and elevated jellyfish biomass. Our combined survey and bioenergetic data provide the first-ever estimate of spatialized ocean sunfish daily food requirements, and stress the importance of this species as a global indicator for the 'rise of slime'. This hypothesis posits that, in an overfished world ocean exposed to global warming, gelatinous zooplankton should flourish, to the detriment of other mesotrophic species such as small pelagic fish, causing irreversible trophic cascades as well as a series of other environmental and economic issues.
过度捕捞和海洋变暖正在极大地改变海洋生态系统的群落组成和大小结构，消灭了大型物种[1]。在这种环境变化的背景下，所有硬骨鱼类中最重的，翻车鱼（Mola mola），似乎是一个不太可能的幸存者。事实上，这种懒惰的巨型鱼类在全球范围内作为副渔获物被杀死，被列为“易危”[2]。我们进行了有史以来最广泛的翻车鱼空中调查，发现在西欧的大西洋和地中海沿岸海域数量惊人地高。每 100 公里有多达 475 条，这些数字比其他地区的估计数量高出一个数量级[3-5]。使用生物能量模型，我们估计每条翻车鱼每天需要 71 公斤水母，这一生物量摄入量比类似大小的硬骨鱼预测的要高出一个数量级以上。按种群水平计算，这相当于在我们的研究区域夏季，每天有 20774 吨被捕食的水母。过度捕捞和海洋变暖可能会促进翻车鱼的数量增加，这两者共同导致鲨鱼对翻车鱼的捕食减少，以及水母生物量的增加。我们的综合调查和生物能量数据提供了有史以来首次对空间化翻车鱼每日食物需求的估计，并强调了该物种作为全球指示物种的重要性，表明“黏液的兴起”。这个假设认为，在一个过度捕捞的海洋世界中，暴露在全球变暖下，凝胶状浮游动物应该会繁荣，从而损害其他中营养物种，如小型远洋鱼类，导致不可逆转的营养级联以及一系列其他环境和经济问题。
