Different Test Forms and Numerous Apertures of Cibicidella variabilis (d’Orbigny) from The Turkish Coast of Eastern Aegean Sea

Abstract

In the last ten years, morphological abnormalities and colored tests have been observed in benthic foraminifera specimens collected from Aegean and Southwestern coasts of Turkey. Specific morphological abnormalities show distinct distribution patterns, suggesting the need for special environmental conditions facilitating the development of such abnormalities. Physical and chemical parameters have been proposed to be responsible for these morphological changes. The benthic foraminifera, Cibicidella variabilis (d’Orbigny) specimens have been collected from different locations on the East Aegean coast of Turkey. Some of them, especially those from Dikili Bay, were found to have variable number of apertures, ranging from one to five. These apertures not structurally, but positionally differ. The abundance of certain test forms in specific locations draws attention. The aim of this study is to determine the possible causes of this aberrant morphology observed in tests of Cibicidella variabilis (d’Orbigny).Cibicidella variabilis (d’Orbigny) shows a wide distribution range on the Aegean coast of Turkey, and has been found in Saros Bay, Gökçeada, Bozcaada, Çanakkale, Edremit Bay, Dikili Bay, Çandarlı Bay, Karaburun Peninsula, Kuşadası, Güllük Bay, Gulf of Gökova, Gulf of Datça, and Marmaris Bay. But, the individuals collected from Gulf of Edremit, Dikili Bay, Çandarlı Bay, Gulf of Gökova, and Gulf of Datça were morphologically different than those collected from the rest of the regions. The variation in the number of apertures, as well as their positions were typical in these samples. Besides, the variations in the shape of the tests observed in adult individuals, but not in juveniles indicates that some environmental factors, which were specific to these regions, might have been involved in this unusual test development. The submarine springs caused by the tectonic activities are typical of the Aegean Sea. It is well documented that these kinds of springs change the characteristics of the surrounding habitat and its fauna. Therefore, it is possible that some of the trace elements, which are abundant in hot spring waters, may be related with the abnormal test morphology observed in our samples. On the other hand, it is also possible that, not only the chemical and physical conditions of the surrounding water, but also its biological properties may affect the test development.