First report of Fusarium species occurrence in loggerhead sea turtle (Caretta caretta) nests and hatchling success in Iztuzu Beach, Turkey

Abstract

There are various biotic factors affecting the hatching success of loggerhead sea turtles (Caretta caretta) nesting on Mediterranean beaches. Eggs contaminated by fungi and bacteria are adversely affected in terms of hatching success. This study aims to identify Fusarium species that cause infection by sampling eggs and nest sands that failed to hatch during the 2015–2016 nesting season. Biospeedy fungal diversity kit was used to identify Fusarium species. Fungi were isolated from eggs and nest sands F. solani, F. oxysporum, F. falciforme and F. keratoplasticum were isolated from nest sand, and F. solani, F. oxysporum were isolated from egg contents. Fusarium species were determined for the first time using molecular methods for Turkey. Fusarium solani (54.55%) was observed to be dominant and F. oxysporum (40.91%) subdominant species. In addition to these dominant species, F. falciforme (1.82%) and F. keratoplasticum (2.73%) have been the other isolated species. The hatching success of the nests contaminated with Fusarium spp. was found to be 10.6% lower than in non-infected ones. Although there was no significant difference between the percentage of hatchling success in infected and non-infected nests in the 2015 season (n = 20) where the number of nests used in sampling was low, a significant difference was found between the success rates in the 2016 season (n = 41) where the number of nests used in sampling was higher (p = 0.676, p = 0.028, respectively). Nest temperature, depth and distance from the sea were higher infection rate, whereas relative humidity was lower in infected nests than in non-infected nests (p < 0.05 for all). Identifying the Fusarium species, which pose serious risks for sea turtle nests worldwide, and investigating their effects on hatching success became more of an issue. In this study, the determination of Fusarium species contaminating the eggs in Iztuzu Beach (Muğla, Turkey) and their sequence analysis was conducted for the first time. © 2020, Institute of Zoology, Slovak Academy of Sciences.