<p>Colonization by bacteria and fungi has been shown to reduce hatching success of sea turtle nests. Presence of microbial pathogens is commonly associated with egg failure, and in some species, it has even been shown to cause up to 90% nest mortality. Developing sea turtle embryos can only rely on non-specific defenses, such as the eggshell and the proteins present in the egg albumen. For a long time, it has been suggested that the fluid in which the eggs are coated during oviposition may contain antimicrobial properties that might protect eggs against potential pathogens that are found in the egg chamber. This study aimed to evaluate the antimicrobial properties of the cloacal fluid of loggerhead sea turtles. Cloacal fluid samples were collected at the Wassaw National Wildlife Refuge, Georgia during the 2021 nesting season (June-July). Protein fractionation of the samples was carried out using commercially available ultracentrifugation devices of 3K, 10K and 30K molecular cut-off weights. A microplate-based turbidimetric growth inhibition assay recorded the antimicrobial activity of the peptide fractions and the crude extract. We found that the cloacal fluid of loggerheads has antimicrobial properties against <i>Serratia marcescens</i> and <i>Morganella morganii</i>, and some mild action against <i>Pseudomonas aeruginosa</i>. Results obtained from the microplate-based turbidimetric assay were confirmed by assessing viability of cells upon 24 hours of exposure to the fluid. Furthermore, this study found that the cloacal fluid contains proteins with molecular weight ranging from approximately 5 to 250 kDa, and that proteins with higher molecular weights (MW>30kDa) are found in greater abundance. Further studies are needed to understand the mechanism of action of the proteins and peptides present in the cloacal fluid to potentially develop antimicrobial compounds that can be used to increase hatching success globally.</p>

A variety of anthropomorphic and environmental stresses are threatening the existence of all seven species of sea turtles. There is growing evidence that alterations in surface waters and sediment temperatures are negatively impacting reproductive success of loggerhead sea turtles (Caretta caretta). Fluctuations in water temperature associated with localized climate oscillations heavily alter the food web dynamics of the ocean. Feeding conditions are expected to be a critical factor in determining body mass and productivity for breeding seasons. An increase in regional temperatures could lead to prolonged reduction in food sources, as well as reduced nesting and recruitment. Loggerhead sea turtle nesting data from 1995-2011 werre compared with the average yearly North Atlantic Oscillation (NAO) and Atlantic Multidecadal Oscillation (AMO) which are important climatic events impacting the SST in the Atlantic Ocean. Because El Niño Southern Oscillation (ENSO) is a global event, it was proposed that turtles in the Atlantic may follow a similar trend. ENSO was quantified using Oceanic Nino Index (ONI). Analysis of loggerhead sea turtle nest frequencies from the years 1995-2011 in comparison to seasonal climate changes showed a significant inverse relationship between the detrended loggerhead nests and average yearly NAO when lagged two years, suggesting loggerheads may spend years prior breeding obtaining optimum body mass to increase successful reproduction. The detrended nesting data showed a tendency toward higher occurrence of nests during La Niña years while nest frequencies decreased during El Niño year; when the yearly detrended loggerhead nesting data was compared with the average yearly ONI; showing a significant inverse relationship without a lag. This may also suggest a relationship between changes of productivity of the ocean influenced by smaller scale climate changes and loggerhead nest frequencies.