Abstract
Estuaries are threatened by intense and continuously increasing human activities. Here we estimated the sensitivity of fish assemblages in a set of estuaries distributed worldwide (based on species vulnerability and resilience), and the exposure to cumulative stressors and coverage by protected areas in and around those estuaries (from marine, estuarine and freshwater ecosystems, due to their connectivity). Vulnerability and resilience of estuarine fish assemblages were not evenly distributed globally and were driven by environmental features. Exposure to pressures and extent of protection were also not evenly distributed worldwide. Assemblages with more vulnerable and less resilient species were associated with estuaries in higher latitudes (in particular Europe), and with higher connectivity with the marine ecosystem, moreover such estuaries were generally under high intensity of pressures but with no concomitant increase in protection. Current conservation schemes pay little attention to species traits, despite their role in maintaining ecosystem functioning and stability. Results emphasize that conservation is weakly related with the global distribution of sensitive fish species in sampled estuaries, and this shortcoming is aggravated by their association with highly pressured locations, which appeals for changes in the global conservation strategy (namely towards estuaries in temperate regions and highly connected with marine ecosystems).
Highlights
Estuaries are highly productive and valuable ecosystems[1], albeit not especially diverse
Estuarine communities are potentially impacted by human activities in and around estuaries which affect species that colonize estuaries and their environmental conditions[8, 9]
This study shows that the vulnerability and resilience traits of fish from the sampled estuarine assemblages worldwide are associated with geography and certain environmental gradients (Fig. 2; Table 2)
Summary
This study shows that the vulnerability and resilience traits of fish from the sampled estuarine assemblages worldwide are associated with geography and certain environmental gradients (Fig. 2; Table 2). Intensity of human pressures in and around sampled estuaries shows a clear geographical pattern (higher in Europe and Asia, intermediate in Africa, North America and South America, and lower in Oceania), regardless of the variable considered (Hmarine, Hestuary, Hfreshwater, Hmean or Hweighted-mean) (Fig. 3) This pattern reflects the mean human population density of continents (http://data.worldbank.org). Our approach revealed that intense anthropogenic pressures in and around sampled estuaries overlap many estuarine fish assemblages with higher sensitivity traits, and this occurs in: estuaries in particular regions (high latitude, especially Europe) and estuaries with certain environmental features (high connectivity with the marine ecosystem - open and with wide tidal amplitude), as modelled (Fig. 2; Table 2).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
