Nest microbiota and pathogen abundance impact hatching success in sea turtle conservation

Abstract

Hatchery practices are pivotal to conservation success. In sea turtle hatchery, reusing the same sand has been a norm but remains unclear whether such approach increases the risk of Fusarium solani species complex (FSSC) infection causing huge mortality in sea turtle eggs worldwide. We employed 16S and ITS amplicon sequencing in 123 sand samples and isolated fungal strains from diseased eggs across seven hatcheries and neighboring beaches in Malaysia. FSSC was isolated from all sampled hatcheries where F. solani/falciforme was the predominant species. A distinct microbial composition and higher abundance of FSSC (mean = 5.2 %) was found in all but one hatchery when compared to nesting beaches (mean = 1.3 %). Specifically, an ascomycetous fungus Pseudallescheria boydii consistently appeared in higher abundance (mean = 11.4 %) in FSSC-infected nests and was significantly associated with lower hatching success. The hatchery that maintained the most stringent practice by changing sand every nesting season had a microbiota resembling nesting beaches as well as lowest FSSC and P. boydii abundance. The results of current study imply the need to avoid reusing sand in sea turtle hatchery.