Combining projected changes in species richness and composition reveals climate change impacts on coastal Mediterranean fish assemblages

Abstract

Species Temporal Turnover (STT) is one of the most familiar metrics to assess changes in assemblage composition as a consequence of climate change. However, STT mixes two components in one metric, changes in assemblage composition caused by a process of species loss or gain (i.e. the nestedness component) and changes in assemblage composition caused by a process of species replacement (i.e. the species replacement component). Drawing on previous studies investigating spatial patterns of beta diversity, we propose measures of STT that allow analysing each component (species replacement vs. nestedness), separately. We also present a mapping strategy to simultaneously visualize changes in species richness and assemblage composition. To illustrate our approach, we used the Mediterranean coastal fish fauna as a case study. Using Bioclimatic Envelope Models (BEMs) we first projected the potential future climatic niches of 288 coastal Mediterranean fish species based on a global warming scenario. We then aggregated geographically the species-level projections to analyse the projected changes in species richness and composition. Our results show that projected changes in assemblage composition are caused by different processes (species replacement vs. nestedness) in several areas of the Mediterranean Sea. In addition, our mapping strategy highlights that the coastal fish fauna in several regions of the Mediterranean Sea could experience a 'cul-de-sac' effect if exposed to climate warming. Overall, the joint exploration of changes in species richness and composition coupled with the distinction between species replacement and nestedness bears important information for understanding the nature of climate change impacts on biodiversity. These methodological advances should help decision-makers in prioritizing action in the areas facing the greatest vulnerability to climate.

The Influence of the Spatial Scale on the Fishery Landings-SST Relationship

“…Studies in the Mediterranean Sea confirmed this pattern, both in terms of observations (Galil, 2008;Zenetos et al, 2012) and future projections (Ben Rais Lasram et al, 2010;Albouy et al, 2012).…”

Modeling species invasions using thermal and trophic niche dynamics under climate change

“…Poleward shifts in distributional areas were predicted (Albouy et al, 2012) and already recorded (Parmesan, 2006;Cheung et al, 2013), all around the world. According to the shifting scheme just reported, every species can simultaneously act as native loser and non-indigenous winner, depending on the perspective (original or new ecosystem, respectively), and the phenomenon of native species substitution with thermophilic non-indigenous invaders (eulerian view) can be seen as a simple species shifts (lagrangian view point).…”

The relative roles of the environment, human activities and spatial factors in the spatial distribution of marine biodiversity in the Western Mediterranean Sea

“…Thus, the simultaneous analysis of the relative effects of ecologically important predictor sets is essential to preventing misinterpretations of the ecological mechanisms that explain spatial distribution of marine biodiversity. With these results, we contribute to the current knowledge on the spatial distribution of marine biodiversity in the Mediterranean Sea (i.e., Albouy et al, 2012;Coll et al, 2010Coll et al, , 2012Lasram et al, 2010), advancing progress towards the development of more complex spatial analyses (Pennino et al, 2013;Steenbeek et al, 2013).…”