First data on microflora of loggerhead sea turtle (Caretta caretta) nests from the coastlines of Sicily

Abstract

Caretta caretta is threatened by many dangers in the Mediterranean basin, but most are human-related. The purposes of this research were: (i) to investigate microflora in samples from six loggerhead sea turtle nests located on the Sicilian coast and (ii) to understand microbial diversity associated with nests, with particular attention to bacteria and fungi involved in failed hatchings. During the 2016 and 2018 summers, 456 eggs and seven dead hatchling from six nests were collected. We performed bacteriological and mycological analyses on 88 egg samples and seven dead hatchlings, allowing us to isolate: Fusarium spp. (80.6%), Aeromonas hydrophila (55.6%), Aspergillus spp. (27.2%) and Citrobacter freundii (9%). Two Fusarium species were identified by microscopy and were confirmed by PCR and internal transcribed spacer sequencing. Statistical analyses showed significant differences between nests and the presence/absence of microflora, whereas no significant differences were observed between eggs and nests. This is the first report that catalogues microflora from C . caretta nests/eggs in the Mediterranean Sea and provides key information on potential pathogens that may affect hatching success. Moreover, our results suggest the need for wider investigations over extensive areas to identify other microflora, and to better understand hatching failures and mortality related to microbial contamination in this important turtle species.

Keywords: Caretta caretta; Fusarium; Mediterranean Sea; Microflora; Sea turtle eggs.

Fig. 1.

Microscopic appearance of Fusarium spp. stained with Lactophenol Blue or Giemsa. (A) Lactophenol Blue, (B) Giemsa. Magnification of 40×.

Fig. 2.

Bayesian phylogram based on a 491-bp-long fragment of the ITS gene. Node support is reported as ‘BI nodal posterior probabilities’/‘ML bootstrap support’. The accession numbers of the sequences derived from GenBank are shown in brackets. ‘Haplotype 1’ was observed in two nests (nests 3 and 6) and corresponds to F. oxysporum. ‘Haplotype 2’ was observed in four nests (nests 1, 2, 5 and 6) and corresponds to F. solani. See Table 1 for details on the occurrence of the two species in the studied sites and samples.