Embryonic Mortality in Loggerhead Turtle (Caretta caretta) Nests: A Comparative Study on Fethiye and Göksu Delta Beaches

Authors: ADEM ÖZDEMİR, OĞUZ TÜRKOZAN, ÖZGÜR GÜÇLÜ

Abstract: In total, 66 loggerhead turtle nests were examined and compared in terms of embryonic mortality during the 2004 and 2005 breeding seasons on Fethiye and Göksu Delta beaches. In all, 5012 eggs were counted, 2751 (54.90%) of which hatched successfully. Of the 2261 unhatched eggs, 68 (1.35%) were classified as unidentified eggs and 2193 (43.75%) were classified as containing dead embryos. Of these dead embryos, a high percentage were in the early stage (n = 1177, 23.48%) and late stage (n = 814, 16.24%,) of development. The lowest percentage of the eggs with dead embryos (n = 202, 4.03%) were in the mid-stage of development. The embryonic mortality rate was higher at Göksu Delta than at Fethiye Beach. Of the examined ecological variables, none accounted for the early stage embryonic mortality. Embryonic mortality in the middle and late stages of development increased with decreasing slope and dry sand depth of the nests; however, embryonic mortality during these stages decreased with declining moisture and wet sand depth of the nests.

Keywords: Embryonic mortality, Caretta caretta, Fethiye, Göksu, Abiotic factors

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