Majority of the alien foraminifer species observed on the southwestern coast of Turkey are Indo-Pacific originated and suggested to be introduced from Red Sea. The most abundant species is Amphistegina lobifera Larsen. Other than Amphistegina, some other large Indo-Pacific foraminifer species, such as Amphisorus hemprichii Ehrenberg, Sorites orbiculus Ehrenberg and Heterostegina depressa d'Orbigny were found in this area. Peneroplis arietinus (Batsch) was abundantly observed in only this region and not reported from elsewhere in the Mediterranean. The abundance of alien foraminifer species along the southwestern coasts of Turkey is very interesting. Most of these alien benthic foraminifer species prefer warm, saline, tropical seas world-wide. Langer and Hottinger (2000) indicate that Amphisorus hemprichii Ehrenberg prefers 16-34 °C, Sorites orbiculus Ehrenberg 14-34 °C, Amphistegina spp. 14-34 °C and Heterostegina depressa d'Orbigny 19-34 °C. But the conditions in the Mediterranean and Aegean coasts of Turkey are remarkably different. The presence of Mesozoic and Cenozoic limestones with karstic characteristics in the Taurus Mountains combined with numerous cold water springs along the coastline cause salinity and temperature variations in these regions. 23 submarine springs have been located along the coastline between Kalkan and Kekova Island (Oztan et al., 2004). The differences in distribution patterns and abundances of alien species suggest the diversity of ecological characteristics in the region. It is still under debate whether such a large number of Erythrean species will exert a competitive pressure on the local biota resulting in the disappearence of native species. However there is an obvious ongoing process of destruction of the coastal ecosystem along the southwestern coasts of Turkey, where the damage is directly caused by the increased population of the Erythraen foraminifer Amphistegina lobifera Larsen.
It has been known that some of the alien species showed unusual population explosions in a very short time, soon after they were first recorded in the Mediterranean (Golani, 2004). A similar situation is seen in the Amphistegina lobifera at first glance, but the analysis of the core samples showed that the A. lobifera population has been stable for a while, before a rapid expansion has occured. The cause of this expansion might be a change in environmental conditions; such as nutrients, temperature or a change in the chemical composition of sea water. Further analysis of the tests for age determination and mineral composition will probably reveal the reasons of this unique event and figure out the environmental history of the research area as well as the fate of the native biota.
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