The Effect of Thermal Pollution on Benthic Foraminiferal Assemblages, in the Mediterranean Shore Face Adjacent to Hadera Power Plant (Israël)

Over the past several decades public and scientific awareness to global warming has increased significantly. As a result, many studies have examined the affects of global warming. However, the consequences of global warming on marine living organisms at the Levantine basin of the East Mediterranean has not yet been explored. In this study, we have used the thermal pollution of a power plant at the Mediterranean coast of Israel as an analog for the expected future trend of sea surface temperature (SST) rise. We have performed a sequence of 11 sampling campaigns at 5 stations located along a temperature gradient of approximately 10°C, from the discharge site of the heated cooling seawater to a few kilometers south, where temper39 atures are normal. The large natural variations in seawater temperature (16- 30°C) enable us to examine the seasonal impact at relatively extreme conditions, which are intensified during summer, when the temperature anomaly becomes a threat to the environment. Thus, the main objectives of this study were to examine the response of the benthic foraminifera, known as sensitive indicators of environmental changes, to the locally elevated SST and compare it with the response of other groups such as crustaceans, ostracods and mollusks. The SST varied between winter, 27°/18°C and summer, 35°/29°C along the transect. The preliminary results show that the maximal abundance of foraminifera, ostracodes and crustaceans occur in winter while that of the mollusks in summer. The total standing stocks (TSS) of foraminifera are negatively correlated with the SST anomaly. The numerical abundance (per g dry sediment) of the common species is negatively correlated to the temperature gradient in both winter and summer. The species diversity increases as the temperature anomaly decreases and during the winter it is significantly higher than during summer. The assemblage is more even and of lower dominance during winter compared to summer, during which ~80% of the assemblage consisted of only two species. Species richness, in the control station, representing normal sea temperature, varied from 8 to 17, whereas in the warmest station it varied from 3 to 10 species. The variation in species diversity between the five stations indicates that some species have adapted to the elevated temperatures better than others. The preliminary results of this study point towards the conclusion that global warming has a primary negative affect on foraminifera populations and thereby on other marine microorganisms as well.