First multicenter coprological survey on helminth parasite communities of free-living loggerhead sea turtles Caretta caretta (Linnaeus, 1758) from the Adriatic Sea and Northern Ionian Sea

Parasitological investigation and potential effects of parasitism on hematological, genotoxic and immune parameters in free ranging sea turtles rescued along the Southern Adriatic coast (Eastern Mediterranean Sea)

Sea turtles can host a wide range of parasitic taxa, some of which may lead to severe diseases, weakening and endangering their health. Assessing free-ranging sea turtles' responses to these potential pathogens using biomarkers can provide valuable insights into the cellular and molecular impacts of parasites. This information can serve as a crucial tool for conservation efforts. During rehabilitation, hematological, genotoxic and innate immune parameters were evaluated in 70 free-ranging sea turtles rescued along the Southern Adriatic coast (Eastern Mediterranean Sea) from 2021 to 2023, 24 of which were found to have parasitic infections. Hapalotrema mistroides, Sulcascaris sulcata and Neospirorchis sp. were identified by coprological and molecular techniques. Some significant differences for biomarkers were associated with these parasites. These findings highlight the importance of considering the infection status of free-ranging sea turtles when evaluating biomarker results, as major pathogens like parasites can influence certain parameters.

Dolphins and sea turtles may host zoonotic parasites and pathogenic bacteria as indicators of anthropic pressure in the Gulf of Taranto (Northern Ionian Sea, Central-Eastern Mediterranean Sea)

The occurrence of protozoan parasites Giardia duodenalis and Cryptosporidium spp. such as the pathogenic bacteria Salmonella spp. and Escherichia coli was molecularly investigated in the following free ranging species of striped dolphins (Stenella coeruleoalba), Risso's dolphins (Grampus griseus) as well as loggerhead (Caretta caretta) and green (Chelonia mydas) sea turtles living in the Gulf of Taranto (Mediterranean Sea). Out of forty-one investigated individuals belonging to the 4 species, 13 (31.7%) were positive to one or more pathogens and zoonotic G. duodenalis assemblage A, Cryptosporidium parvum and S. enterica were identified in striped dolphins, loggerhead and green sea turtles. In this work, the presence of these opportunistic pathogens has been investigated in fecal samples of free ranging dolphin and sea turtle species for the first time. Moreover, this is the first record of C. parvum in loggerhead sea turtles. These results may provide baseline data for the potential role of cetaceans and sea turtles as potential sentinel species for zoonotic and terrestrial pathogens in the marine environment.

Helminth Infection of the Loggerhead Sea Turtle Caretta caretta along the Coasts of Sicily and the North West Adriatic Sea

Simple Summary

We report new data on the presence of trematode and nematode parasites species in stranded specimens of loggerhead sea turtles (Caretta caretta). These parasites can potentially cause severe damage to internal organs, endangering the lives of the animals. The results showed a greater presence of digeneans.

Abstract

We provide new data on the presence of helminth parasites in 64 individual loggerhead sea turtles Caretta caretta stranded along the coasts of Sicily and the northwest Adriatic Sea between June 2014 and August 2016. The necropsy examination revealed 31 individuals (48.4%) positive for endoparasites, showing a greater prevalence of trematodes than nematodes. In particular, seven species and a single genus of Trematoda (Hapalotrema) and a single species and genus of Nematoda (Kathlania) were identified. Among the Digenea flukes the species with the highest prevalence of infection were Rhytidodes gelatinosus (34.6%) and Hapalotrema sp. (33.3%), while among the Nematoda they were Kathlania sp. (33.3%) and Sulcascaris sulcata (33.3%). Analysis of variance (ANOVA) was applied among the recovery sites of the stranded loggerhead sea turtles and prevalence of endoparasites was used to highlight any relationship between the parasites and the origin of the hosts. ANOVA showed significant differences (p < 0.001) among the data used.

Wild whale faecal samples as a proxy of anthropogenic impact

The occurrence of protozoan parasite, bacterial communities, organic pollutants and heavy metals was investigated in free-ranging species of fin (Balaenoptera physalus, n. 2) and sperm (Physeter macrocephalus, n. 2) whales from the Pelagos Sanctuary, Corsican-Ligurian Provencal Basin (Northern-Western Mediterranean Sea). Out of four faecal samples investigated, two from fin whales and one from sperm whale were found positive to Blastocystis sp. A higher number of sequences related to Synergistetes and Spirochaetae were found in sperm whales if compared with fin whales. Moreover, As, Co and Hg were found exclusively in sperm whale faecal samples, while Pb was found only in fin whale faecal samples. The concentration of both PAH and PCB was always below the limit of detection. This is the first report in which the presence of these opportunistic pathogens, bacteria and chemical pollutants have been investigated in faecal samples of free-ranging whale species and the first record of Blastocystis in fin and sperm whales. Thus, this study may provide baseline data on new anthropozoonotic parasite, bacterial records and heavy metals in free-ranging fin and sperm whales, probably as a result of an increasing anthropogenic activity. This survey calls for more integrated research to perform regular monitoring programs supported by national and/or international authorities responsible for preservation of these still vulnerable and threatened whale species in the Mediterranean Sea.