Within the SENHAR project, a three-day ecological survey of marine benthic and pelagic communities within the Hofra z-Zghira embayment was embarked upon by the Oceanography Marine Research Group within the Department of Geosciences of the Faculty of Science earlier this month. Academic and supporting staff from the University’s oceanography team who participated within this survey included Dr. Adam Gauci, Mr. Johann Galdies, Mr. Edward Sultana and Mr. Alessio Marrone, whilst Prof. Alan Deidun is the Principal Investigator at the University of Malta on the SENHAR project. The UM team was joined by colleagues from two different CNR Institutes in Italy – the CNR-IAMC one based in Sicily and the CNR Institute in Genoa.
The Hofra z-Zghira embayment was selected given that it is influenced by an operational discharge – a thermal effluent releasing seawater taken in by the Delimara power station to cool its turbines. Given that this effluent can warmer than 8 degrees Centigrade than the ambient seawater, it represents a case of thermal pollution, which can be deleterious to marine life in a number of ways. For instance, the dissolved oxygen content of seawater plummets with higher temperatures whilst the higher water temperatures can promote the growth of epiphytes on seagrass shoots, competing with the ecologically important seagrass for light, as well as the spread of pathogenic (disease-causing) organisms.
In order to assess the ecological impact of the thermal effluent on natural communities within the embayment, within the SENHAR project, the University’s Oceanography team conducted a multi-faceted sampling strategy, consisting of the in situ measurement of a number of Posidonia oceanica (Neptune seagrass) metrics, the sampling of infaunal (within-sediment) biota. The latter was achieved through a custom-built sampling device (known in Italian as ‘sorbona’) which makes use of negative pressure generated through a connected SCUBA diving cylinder to strain out biota from the surrounding sediment through a filtering mesh. A visual census of fish assemblages within the embayment was also conducted, whilst an array of water descriptors (salinity, temperature, chlorophyll, microplastic content, nutrients, pH) were measured at different distances from the outfall. The survey in question will be repeated in autumn so as to factor in seasonal variability.