The Mediterranean Mussel (Mytilus galloprovincialis) as Intermediate Host for the Anisakid Sulcascaris sulcata (Nematoda), a Pathogen Parasite of the Mediterranean Loggerhead Turtle (Caretta caretta)

Abstract

Sulcascaris sulcata (Anisakidae), a pathogenic nematode of sea turtles, may cause ulcerous gastritis with different degrees of severity. Previous studies demonstrated a high prevalence of infection in the Mediterranean loggerhead turtle (Caretta caretta), although no data on the potential intermediate hosts of this nematode has been published thus far from the Mediterranean basin. Here, using molecular analyses, we demonstrated that the cross sections of nematode larvae observed histologically in Mediterranean mussels (Mytilus galloprovincialis) collected from a farm along the Tyrrhenian coast of southern Italy belong to S. sulcata. The BLAST analysis of sequences at the ITS2 region of rDNA and mtDNA cox2 gene loci here obtained from samples of two Mediterranean mussels containing nematode larvae showed 100% homology with those at the same gene loci from the adults of S. sulcata collected from the Mediterranean Sea and deposited in GenBank. To our knowledge, this study is the first to present data on a potential intermediate host of S. sulcata in the Mediterranean basin and to report a nematode parasite from the Mediterranean mussel.

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

“…In fact, the presence of S. sulcata had been described in clams and scallops in Pretto et al [ 40 ] and Marcer et al [ 39 ] and according to Lazar et al [ 35 ] they represent the most frequent ingested bivalve molluscs for the Adriatic C. caretta . Conversely to Santoro et al [ 33 ] who examined some specimens of loggerhead sea turtle from the Sicilian coasts, in our samples we did not find any individual with these parasites. This apparent contrast could be explained by the scarcity of these molluscs (scallops, clams and mussels) in Sicily.…”

“…According to Gracan et al [ 21 ] and Valente et al [ 30 ] this difference could be attributed to the feeding ecology or habitat preferences of C. caretta ; in fact, authors found [ 21 , 30 ] a different composition of the helminthic fauna during necropsies of individuals of C. caretta from different parts of the Mediterranean Sea and the Atlantic Ocean. This difference is also evidenced by the exclusive presence of the nematode S. sulcata in the individuals from the Adriatic Sea, previously reported by Manfredi [ 31 ], Scaravelli [ 32 ], Gracan [ 21 ], Santoro [ 33 ] and by the presence of the eggs of digenean Spirorchiidae, Hapalotrema sp. [ 4 ].…”

“…The most important aspect of these results is the evidence of Spirorchiidae and nematode infections in C. caretta in the Mediterranean Sea [ 33 , 34 ] with particular reference to the Sicilian coasts where reports on the latter parasites are very few. According to Santoro et al [ 3 , 33 ], who studied the infection prevalence of Spirorchiidae flukes Hapalotrema mistroides and the Nematoda S. sulcata in loggerhead sea turtles from different areas of the Mediterranean Sea, the prevalence of these highly pathogenic parasites could be linked to the different habitats frequented by the hosts. In fact, during their life cycle C. caretta frequent different habitats showing differences in the diet composition depending on the area where they feed [ 35 ].…”

“…The natural presence in the Adriatic Sea of bivalve molluscs such as mussels, is increased by the various mussel farm ropes present in the northernmost part of the Adriatic Sea. Santoro et al [ 3 , 32 ] have recently shown that the high prevalence of S. sulcata in the Gulf of Naples [ 3 ] and in the Adriatic Sea [ 33 ] in loggerhead sea turtles is related to the consumption of mussels or other species of bivalves. In fact, while for the Caretta caretta samples from the Gulf of Naples they found a correlation between the consumption of mussels, including farmed ones, and the presence of S. sulcata , this close correlation was not highlighted in the C. caretta samples analyzed from the Adriatic Sea although this does not mean that S sulcata is not present.…”

An update and ecological perspective on certain sentinel helminth endoparasites within the Mediterranean Sea

“…However, knowledge concerning the first intermediate hosts of Anisakis and Hysterothylacium in Mediterranean waters is currently lacking. For Sulcascaris, bivalve molluscs and gasteropods serve as intermediate hosts in Mediterranean (Marcer et al, 2020;Santoro et al, 2020aSantoro et al, , 2022a. In particular, the Mediterranean scallop Pecten jacobeus and the queen scallop Aequipecten opercularis were recognized as intermediate hosts in the Adriatic Sea (Marcer et al, 2020).…”