Correlation Between Microbial Community and Hatching Failure in Loggerhead Sea Turtle Caretta caretta

Abstract

Microbial communities provide essential information about host ecology and could be helpful as a tool to improve species conservation efforts. However, microbes can also infect and compromise the host development process and viability. Caretta caretta is the most widespread marine turtle species in the Mediterranean basin and is the only species of sea turtle nesting along the Italian coasts. Little is known about the microbiota composition of the nest of sea turtles and its correlation with hatching failures. In this study, the microbial composition of two nests of C. caretta featuring different rates of hatching success from a nesting beach in Lampedusa (Italy) was analyzed and compared. The bacterial community was determined using culture-dependent methods and next-generation sequencing based on 16S rRNA gene metabarcoding analysis. Our results showed five dominant bacterial phyla (Proteobacteria, Bacteroidetes, Actinobacteria, Verrucomicrobia, and Firmicutes) and indicated different bacterial families (Pseudomonadaceae and Brucellaceae) as likely causes of hatching failures. Besides, our findings demonstrated the nests’ active role in modulating the sand’s bacterial communities. This study suggests microbiological analysis could be a valuable tool in monitoring nests to take preventive actions and reduce hatching failures.

Potential impacts of environmental bacteria on the microbiota of loggerhead (Caretta caretta) and green (Chelonia mydas) sea turtle eggs and their hatching success

“…Our study found that 44%–49% of unhatched eggs and 61%–90% of hatched egg microbiota derived from the nest sand microbiota, suggesting that the nest sand environment played a stronger role in shaping both egg microbiota than the cloaca, which was estimated to contribute less than 1% to both hatched and unhatched egg microbiota (Figure 6). Our results support the findings of Capri et al (2023), who suggest that nest sand microbiota play a crucial role in shaping egg microbiota, with the different bacterial phyla present at each nest potentially being responsible for egg hatching failure. Due to the timing of egg sample collections (after incubation), we cannot dismiss maternal transfer as a critical component of sea turtle egg bacteria acquisition.…”

“…Pseudomonas spp. have been suggested to play a strong role in sea turtle egg hatching failure (Capri et al, 2023) and have been previously isolated and identified in unhatched sea turtle eggs from other studies (Awong-Taylor et al, 2008;Craven et al, 2007;Keene, 2012;Wyneken et al, 1988). The genus Pseudomonas contains over 200 known taxa (Girard et al, 2021) that have high metabolic diversity, simple nutritional requirements, and wide temperature growth ranges (4°C-42°C) allowing them to inhabit a variety of environments (e.g., soil, water, plants, and association with larger organisms) as commensals and opportunistic pathogens (Chakravarty & Anderson, 2015).…”

“…Their results suggested that egg microbiota are shaped by maternal and environmental influences alongside a protective role of eggshells, but their study lacked microbial sampling from the nesting females to validate this claim (Vecchioni et al, 2022). Capri et al (2023) used HTS and culture‐dependent methods to determine the bacteria and fungi responsible for hatching failure in two green sea turtle nests with different hatching success rates (0% and 59%). Their results found that differences in bacterial abundance may have a more predominant role in hatching success than fungi.…”

“…Additionally, their results found that Pseudomonas and Brucella were the main bacteria affecting hatching success. Capri et al (2023) also hypothesized that Pseudomonas derived from the sand while Brucella from the nesting female, however, their study lacks bacterial analysis from the nesting female to support this claim.…”

Antifouling Systems Based on a Polyhedral Oligomeric Silsesquioxane-Based Hexyl Imidazolium Salt Adsorbed on Copper Nanoparticles Supported on Titania

“…Thus, it is crucial to combat biofilm development at the very beginning of its formation, for instance, by using antifouling compounds. Moreover, Pseudomonas species are of extreme concern for such a matter since they are proficient biofilm producers, opportunistic pathogens for immunocompromised humans, as well as the cause of spoilage in aquatic environments [ 43 , 45 , 46 ]. Since POSS materials do not feature antimicrobial action per se , their functionalization with QASs can lead to efficient antifouling agents.…”