Abstract
Satellite data show a steady increase, in the last decades, of the surface temperature (upper few millimetres of the water surface) of the Mediterranean Sea. Reports of mass mortalities of benthic marine invertebrates increased in the same period. Some local studies interpreted the two phenomena in a cause-effect fashion. However, a basin-wide picture of temperature changes combined with a systematic assessment on invertebrate mass mortalities was still lacking. Both the thermal structure of the water column in the Mediterranean Sea over the period 1945–2011 and all documented invertebrate mass mortality events in the basin are analysed to ascertain if: 1- documented mass mortalities occurred under conditions of positive temperature trends at basin scale, and 2- atypical thermal conditions were registered at the smaller spatial and temporal scale of mass mortality events. The thermal structure of the shallow water column over the last 67 years was reconstructed using data from three public sources: MEDAR-MEDATLAS, World Ocean Database, MFS-VOS programme. A review of the mass mortality events of benthic invertebrates at Mediterranean scale was also carried out. The analysis of in situ temperature profiles shows that the Mediterranean Sea changed in a non-homogeneous fashion. The frequency of mass mortalities is increasing. The areas subjected to these events correspond to positive thermal anomalies. Statistically significant temperature trends in the upper layers of the Mediterranean Sea show an increase of up to 0.07°C/yr for a large fraction of the basin. Mass mortalities are consistent with both the temperature increase at basin scale and the thermal changes at local scale, up to 5.2°C. Our research supports the existence of a causal link between positive thermal anomalies and observed invertebrate mass mortalities in the Mediterranean Sea, invoking focused mitigation initiatives in sensitive areas.
Highlights
Global environmental change is a major threat to marine ecosystems
An extended literature analysis yielded 35 publications that report on 19 mass mortality events involving 59 species across the Mediterranean Sea (S1 Table)
Our results show that positive temperature trends have been observed at most areas where mass mortalities have been reported
Summary
Changes in Sea Surface Temperature (SST) are acknowledged as an important component of global change [1] and have long been charged as one of the main physical drivers influencing both marine biodiversity and the services it provides. Experimental simulations of the effects of thermal anomalies along the water column on marine ecosystems can be complex [12,13,14] and hydrological measurements are seldom collected consistently in space and time with the specific goal of documenting the effects of warming on marine ecosystems [15]. Expanding present knowledge on the magnitude of changes of the SST to the upper water column (0–50 meters) combining data at wide temporal and spatial scale is critical to anticipate future changes, propose mitigation strategies, and set conservation priorities
Sign-in/Register to view highlights & summary 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 callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
