Forecasting shifts in habitat suitability across the distribution range of a temperate small pelagic fish under different scenarios of climate change

André R.A Lima,Miguel Baltazar-Soares,Susana Garrido,Isabel Riveiro,Pablo Carrera,A Miguel Piecho-Santos,Myron A Peck,Gonçalo Silva

doi:10.1016/j.scitotenv.2021.150167

Abstract

Climate change often leads to shifts in the distribution of small pelagic fish, likely by changing the match-mismatch dynamics between these sensitive species within their environmental optima. Using present-day habitat suitability, we projected how different scenarios of climate change (IPCC Representative Concentration Pathways 2.6, 4.5 and 8.5) may alter the large scale distribution of European sardine Sardina pilchardus (a model species) by 2050 and 2100. We evaluated the variability of species-specific environmental optima allowing a comparison between present-day and future scenarios. Regardless of the scenario, sea surface temperature and salinity and the interaction between current velocity and distance to the nearest coast were the main descriptors responsible for the main effects on sardine's distribution. Present-day and future potential “hotspots” for sardine were neritic zones (<250 km) with water currents <0.4 m s−1, where SST was between 10 and 22 °C and SSS > 20 (PSU), on average. Most variability in projected shifts among climatic scenarios was in habitats with moderate to low suitability. By the end of this century, habitat suitability was projected to increase in the Canary Islands, Iberian Peninsula, central North Sea, northern Mediterranean, and eastern Black Sea and to decrease in the Atlantic African coast, southwest Mediterranean, English Channel, northern North Sea and Western U.K. A gradual poleward-eastward shift in sardine distribution was also projected among scenarios. This shift was most pronounced in 2100 under RCP 8.5. In that scenario, sardines had a 9.6% range expansion which included waters along the entire coast of Norway up and into the White Sea. As habitat suitability is mediated by the synergic effects of climate variability and change on species fitness, it is critical to apply models with robust underlying species-habitat data that integrate knowledge on the full range of processes shaping species productivity and distribution.

Highlights

Climatic fluctuations enhanced by anthropogenic activities are resulting in shifts in atmosphere-ocean physical forcing, leading to critical changes in biogeochemical processes that poses a major threat to global marine biodiversity in the long-term (Ramírez et al, 2017)
The final GAMs for the pooled dataset concerning the present-day condition and future scenarios included as main effects: sea surface temperature (SST), sea surface salinity (SSS) and the interaction of current velocity (CVEL) with distance to the nearest coast (DIST) [European sardine ~ s(SST) + s(SSS) + s(CVEL, DIST)] based in the lowest Akaike's Information Criterion (AIC) and higher deviance explained (Table 2)
A more pronounced decrease in suitability when the SSS is below ~20 (PSU) is expected to occur by 2100 under all Representative Concentration Pathways (RCPs) when compared to the previous scenarios

Summary

Introduction

Climatic fluctuations enhanced by anthropogenic activities are resulting in shifts in atmosphere-ocean physical forcing, leading to critical changes in biogeochemical processes that poses a major threat to global marine biodiversity in the long-term (Ramírez et al, 2017). The changes translate into O2 depletion (often causing coastal hypoxia), ocean acidification, sea level rise and shifts in upwelling intensity with multiple potential effects on ocean food webs at global and regional scales (Xiu et al, 2018; Claireaux and Chabot, 2019). Consequences of these “new” oceanic dynamic on the ecology of organisms have been extensively reported for a wide range of marine taxa (Brander et al, 2003; Doney et al, 2012; Poloczanska et al, 2013; Ramírez et al, 2017). The magnitude of such impacts is challenging to forecast in the marine environment since responses to climate change are species-specific, and plants and animals may adapt to/tolerate new conditions or shift their distribution to follow environmental optima (Melo-Merino et al, 2020)

Methods

Results

Conclusion