Aberrant otoliths in four marine fishes from the Aegean Sea, Black Sea, and Sea of Marmara (Turkey)

Abstract

Saccular otoliths are hearing and balance structures in teleosts and normally consist of aragonite, but in some cases may become aberrant vaterite. Environmental factors, nutritional problems, pollution, stress, and changes in water parameters, as well as a combination of these, may cause abnormal saccular otoliths. The aberrant otoliths may cause several problems such as discriminating hyaline and opaque rings, validating and tracing otolith rings, and measuring radii in the fisheries studies. In the present study, the aberrant and normal saccular otoliths morphologies were examined and described in Pagellus acarne, Trachurus mediterraneus, Diplodus puntazzo, and Merlangius merlangus from the Aegean Sea, Black Sea, and Sea of Marmara. The saccular otolith morphologies of the four fish species were classified from normal to completely crystalline as ”Type 0”, ”Type 1”, ”Type 2”, ”Type 4”, and ”Type 5”. ”Type 3” was not detected in the current study. The current study presents for the first time anomalous otolith morphology on the saccular otoliths in the D puntazzo, P. acarne, and T. mediterraneus. The data obtained from this study provide a comparison between populations and habitats for the researchers working in this field. The present study revealed that different fish species represented distinctive and similar morphological otolith characteristics in terms of abnormal otolith morphology.