Variations and Factors Affecting the Benthic Foraminifer Assemblages Around the Submarine Springs Which are Known/Suggested to Be Present on the Eastern Aegean Coasts of Turkey Doğu Ege Denizi Türkiye Kiyilarinda Varliği Bilinen veya Düşünülen Deniz İçi Termal Çiktilar Çevresinde Gözlenen Bentik Foraminifer Topluluklarinda Belirlenen Değişimler ve Etkenler

Abstract

© 2019, Hacettepe Universitesi Yerbilmler. All rights reserved.Benthic foraminifer assemblages have been known to include individuals with colored tests and morphological abnormalities on the coasts of Eastern Aegean Sea (Turkey) and Lesbos Island (Greece). For same reasons, surroundings of the thermal springs that are known to be present or suggested to be present were studied. Great qualitative and quantitative differences were observed in the distributions of the alien species, such as Coscinospira hemprichii, Euthomonacha polita, Peneroplis pertusus, P. planatus, Amphisorus hemprichii, Sorites orbiculus, S. variabilis, Cymbaloporetta plana, C. squammosa and Amphistegina lessonii, A. lobifera. The foraminifer assemblages around the thermal spring in Kuşadasi Bay were found to be rich in alien species, wheras, an exact opposite case was observed in Doğanbey Bay. The assemblages in Karaburun Peninsula and Ilica Cove also showed differences. The alien foraminifer Amphistegina lobifera, which is typical for the Aegean Sea, was not found in Ilica, but it was abundant in the recent sediment samples collected from northwest of Karaburun Peninsula. On the north, two thermal springs, with 40oC and 51oC temperatures, are closely located on the coast of Ilica Cape, near Aliağa (İzmir). Except Amphistegina lobifera, the alien species, such as, Peneroplis pertusus, P. planatus Amphisorus hemprichii and Sorites orbiculus, which are typical for Aegean Sea were not observed in the 13 samples collected from the region. Differences were found when the findings of the present study are compared with previous studies conducted in Kuşadasi, Doğanbey and northwest of Karaburun Peninsula, which worths attention. Peneroplis pertusus, P. planatus, Coscinospira hemprichii, Sorites orbiculus and Amphistegina lobifera individuals have been observed in the above mentioned localities, but none of them were found in Aliağa samples. These findings can be explained by the differences in environmental factors. For example, except Amphistegina lobifera, the above mentioned benthic foraminifer species have been observed around the thermal spring in Çeşme Ilica Cove, which had a temperature of 28.4oC. Southern Pacific and Red Sea originated Euthomonacha polita and Coscinospira acicularis individuals have been abundantly found in Kuşadasi Bay, Ilica Cove and northwest of Karaburun Peninsula. The absence of the mentioned five benthic foraminifers and any other alien foraminifer around the two thermal springs with 51oC and 40oC temperatures on Aliağa Ilica Cape, suggests that certain temperatures are required for these genera and species to live and the temperature values of the springs on Ilica Cape are too high. According to these findings, different genera and species are affected by the environmental conditions and they can, or not, continue to survive. Besides, numerous gypsum crystals were observed in sample A11 from samples of Ilica Cape, suggesting a thermal spring has been present in the past. In contrasts to high biodiversity of the foraminifer fauna, ostracod and mollusc fauna were very poor, which might be the result of sulphate found in the thermal water. Sulphate might have a negative effect on ostracod and molluscs, but not on foraminifers. It is evident that these alien foraminifer species are affected by the physical or chemical environmental conditions, can proliferate and expand in suitable regions, but cannot survive in certain locations. In addition, alien benthic foraminifers were also observed on the northwestern and western Aegean Sea (Greece), which did not show a diverse genera and species composition. However, detailed studies which should be conducted in the future will probably show the presence of a diverse alien foraminiferal fauna on these coasts.