Comparative analysis of the epibiotic diatom assemblage on loggerhead sea turtles in pre-and post-hospitalization period

摘要: The loggerhead sea turtle is the most common species of marine turtle in the Adriatic Sea. Here, the neritic habitats represent important feeding pasture for these omnivorous reptiles. Currently, despite the extensive conservation effort, what can be called the anthropogenic disturbance remains the greatest threat to these animals. Due to various mechanical injuries caused by fishing gear, boat propellers, plastic pollution or “cold stunning” Adriatic loggerheads are frequently found stranded or floating near the shores. Many of them are recovered and transferred to rescue centers where they are given medical help and undergo rehabilitation. The aim of this study was to identify compositional changes in epibiotic diatom assemblage growing on the Adriatic loggerheads during prolonged captivity. We investigated ten turtles found and brought to the Turtle Rescue Centre in Pula, Croatia. Sampling took place upon the animal’s admission and after a period of rehabilitation. We used the biofilm formed on the walls of the sea turtle enclosure as a reference of the housing environment. In total, we identified 71 diatom taxa present on turtles’ skin and carapace, and detected changes in diatom assemblages after some time in captivity. Upon admission, we observed abundant populations of the presumably truly epizoic taxa Poulinea sp., Achnanthes elongata, and Medlinella amphoroidea, on the majority of turtles. As expected, after some time in captivity, the assemblage shifted and other taxa, common in the enclosure biofilm (Diploneis sp., Tabularia sp., Nitzschia sp.), gained dominance. However, although less abundant and contributing significantly less …