Functional reorganization of marine fish nurseries under climate warming

Abstract

While climate change is rapidly impacting marine species and ecosystems worldwide, the effects of climate warming on coastal fish nurseries have received little attention despite nurseries’ fundamental roles in recruitment and population replenishment. Here, we used a 26‐year time series (1987–2012) of fish monitoring in the Bay of Somme, a nursery in the Eastern English Channel (EEC), to examine the impacts of environmental and human drivers on the spatial and temporal dynamics of fish functional structure during a warming phase of the Atlantic Multidecadal Oscillation (AMO). We found that the nursery was initially dominated by fishes with r‐selected life‐history traits such as low trophic level, low age and size at maturity, and small offspring, which are highly sensitive to warming. The AMO, likely superimposed on climate change, induced rapid warming in the late 1990s (over 1°C from 1998 to 2003), leading to functional reorganization of fish communities, with a roughly 80% decline in overall fish abundance and increased dominance by K‐selected fishes. Additionally, historical overfishing likely rendered the bay more vulnerable to climatic changes due to increased dominance by fishing‐tolerant, yet climatically sensitive species. The drop in fish abundance not only altered fish functional structure within the Bay of Somme, but the EEC was likely impacted, as the EEC has been unable to recover from a regime shift in the late 1990s potentially, in part, due to failed replenishment from the bay. Given the collapse of r‐selected fishes, we discuss how the combination of climate cycles and global warming could threaten marine fish nurseries worldwide, as nurseries are often dominated by r‐selected species.

Fish communities diverge in species but converge in traits over three decades of warming

“…As a global warming hotspot (Hobday & Pecl, ), the North Sea has been heavily impacted by temperature rise over the last few decades, with documented increases in fishes with small body sizes and fast life history strategies, particularly pelagic species (Beukhof et al, ; McLean, Mouillot, Lindegren, et al, ; Pecuchet et al, ; Simpson et al, ). Previous studies have suggested that such species can rapidly track environmental changes due to short generation times, fast population turnover, and by producing small, pelagic larvae with high dispersal rates (McLean, Mouillot, Goascoz, Schlaich, & Auber, ; Rijnsdorp et al, ). These species are further believed to have greater long‐term adaptive and evolutionary capacity given their quick population turnover and greater potential for rapid natural selection (Rijnsdorp et al, ).…”

“…Panels (b) and (d) show temporal changes in taxonomic (Bray-Curtis) and trait-based (modified Rao's Quadratic Entropy) beta diversity for the entire North Sea. Dotted lines indicate best fits from linear regressions and R 2 values are indicated in the upper left corner of each plot such species can rapidly track environmental changes due to short generation times, fast population turnover, and by producing small, pelagic larvae with high dispersal rates (McLean, Mouillot, Goascoz, Schlaich, & Auber, 2019;Rijnsdorp et al, 2009). These species are further believed to have greater long-term adaptive and evolutionary capacity given their quick population turnover and greater potential for rapid natural selection (Rijnsdorp et al, 2009).…”

Assessing Knowledge Gaps and Management Needs to Cope With Barriers for Environmental, Economic, and Social Sustainability of Marine Recreational Fisheries: The Case of Spain

“…Global warming exerts considerable effects on the marine ecosystems (Hoegh-Guldberg and Bruno, 2010;Kersting, 2016), which are affecting fish assemblages (e.g., Anacleto et al, 2018;Carozza et al, 2019;McLean et al, 2019), and the global fisheries that exploit them (Phillips and Pérez-Ramírez, 2017;Barange et al, 2018). It is plausible that recreational fisheries will be affected in a similar way to commercial fisheries (especially SSF), so response to global warming may be comparable in some cases (Townhill et al, 2019).…”

Climate‐driven shift in coral morphological structure predicts decline of juvenile reef fishes

“…Given that more than a half of small fish individuals tend to remain in a vulnerable size during their entire lives (Goatley & Bellwood, ), changes in shelter availability due to a functional reorganization of coral assemblages can potentially impact adult populations of these vulnerable and dominant small‐bodied fishes. Recently, marine fish communities underwent a climate‐driven functional switch from fast to slow life‐history species dominance (McLean, Mouillot, Goascoz, Schlaich, & Auber, ). In coral reefs, shifts from species with small body size and fast lifespan to large‐bodied and slow life‐history dominance can disrupt food chains (Hempson, Graham, MacNeil, Hoey, & Almany, ) and severely decrease ecosystem productivity (Brandl et al, ).…”