Santiago Pascual

Anisakis infestation in marine fish and cephalopods from Galician waters: an updated perspective

Abstract. A total of 2,673 fresh specimens of cephalopod and fish representing 35 species were obtained from commercial local fisheries in Galician waters (NW Spain). They were examined for anisakid nematodes by digestion of the muscle and elution of the viscera and whole body cavity. All larval nematodes recovered were identified by light microscopy and multilocus electrophoresis as belonging to the species Anisakis simplex sensu stricto and A. pegreffii. Encysted larvae mostly occurred in the viscera but were also found in the flesh of squid and fish. Demographic values for larval nematodes are discussed in relation to host preferences and the ecological niche of both anisakid species at the sampling area. Primary recommendations are also expressed concerning the effects of current fishing and aquaculture practices on the Anisakis problem.

Parasites in commercially-exploited cephalopods (Mollusca, Cephalopoda) in Spain: an updated perspective

Abstract This paper represents an updated review of the published and unpublished records of parasites collected from cephalopod molluscs (teuthoid squids, cuttlefish and octopods) in waters off Spain, with special mention for those inhabiting coastal and shelf waters off Galicia (NW Spain). The examination of about 1600 cephalopods in the southeastern North Atlantic Ocean revealed a new parasite species Stellicola hochbergi , 37 new host records for Atlanto-Iberian waters, and 18 new host records for the world Ocean (three for coccidian Aggregatidae; three and one for cestodes Phyllobothriidae and Tentaculariidae; five and one for nematodes Anisakidae and Cystidicolidae; one and four for copepods Lichomolgidae and Pennellidae). Results suggests the important role of cephalopods as intermediate or final hosts in the life cycles of ten systematic groups of parasites.

The mussel Xenostrobus securis: a well-established alien invader in the Ria de Vigo (Spain, NE Atlantic)

Biological and habitat characterization of the non-indigenous invasive species Xenostrobus securis was undertaken in the Ria de Vigo. This study included genetic identification of mussel samples collected from introduced and endemic areas, and the assessment of mussel size, population abundance, geographic distribution, pathological condition, and sediment composition of substrata type. The mussel had a marked patchy distribution, being more abundant in brackish sites with fine sediments and high organic matter content. Pathological analysis revealed that X. securis does not play any role as vector for introducing allochthonous pathogens in the Ria de Vigo. Nevertheless, depending on its invasiveness potential, the mussel could be a key host favouring spreading and epizootic outbreaks of marteliosis which is known to be harmful for local bivalve populations. Phylogenetic analyses of the COI gene placed all the resulting sequences in a clade within the genus Xenostrobus and its phylogeny congruent with an Australian/Pacific origin. The COI tree suggests two historical introductions in European waters. One of these invasions seems to have started in Galicia, moving from there towards Italy and France, while the geographical spread of the second invasion cannot be deciphered, although the Australian/Pacific origin of this invasion seems very possible. The 18S network is congruent with one invasion starting in Galicia or in Italy, as the Australian haplotype is closely related to the haplotype found in these areas. Several hypotheses accounting for the colonization history of this species in Galician waters are discussed.

Optimization of the pepsin digestion method for anisakids inspection in the fishing industry.

During the last 50 years human anisakiasis has been rising while parasites have increased their prevalence at determined fisheries becoming an emergent major public health problem. Although artificial enzymatic digestion procedure by CODEX (STAN 244-2004: standard for salted Atlantic herring and salted sprat) is the recommended protocol for anisakids inspection, no international agreement has been achieved in veterinary and scientific digestion protocols to regulate this growing source of biological hazard in fish products. The aim of this work was to optimize the current artificial digestion protocol by CODEX with the purpose of offering a faster, more useful and safer procedure for factories workers, than the current one for anisakids detection. To achieve these objectives, the existing pepsin chemicals and the conditions of the digestion method were evaluated and assayed in fresh and frozen samples, both in lean and fatty fish species. Results showed that the new digestion procedure considerably reduces the assay time, and it is more handy and efficient (the quantity of the resulting residue was considerably lower after less time) than the widely used CODEX procedure. In conclusion, the new digestion method herein proposed based on liquid pepsin format is an accurate reproducible and user-friendly off-site tool, that can be useful in the implementation of screening programs for the prevention of human anisakiasis (and associated gastroallergic disorders) due to the consumption of raw or undercooked contaminated seafood products.

Xenostrobus securis (Lamarck, 1819) (Mollusca: Bivalvia): first report of an introduced species in Galician waters

The presence of the non-indigenous species, the black-pygmy mussel Xenostrobus securis, is reported here for the first time in an intense shellfish farming area off Galicia (NW Spain). Very high concentrations of this mytilid bivalve have colonized estuarine waters located at the inner part of the Ria de Vigo. The invasive role of X. securis is discussed in the context of the wide ecological tolerance of the species and the recent finding of settlements of this species on numerous colonies of the economically-important blue mussel Mytilus galloprovincialis. The mode of introduction of the black-pygmy mussel is also discussed in relation to human management activities.

Biotic relationships of Illex coindetii and Todaropsis eblanae (Cephalopoda, Ommastrephidae) in the Northeast Atlantic: Evidence from parasites

Abstract Parasites were collected from 1,200 short-finned squid (Illex coindetii, Todaropsis eblanae) caught as bycatch in a multispecies trawling fishery in the northwest Spanish Atlantic waters in 1992-1993. Parasites found included six species of helminths, threetetraphyllidean cestodes (Phyllobothrium sp., Pelichnibothrium speeiosum, Dinohothrium sp.), two trypanorhynchidean cestodes (Nybelinia yamagutii, Nybelinia lingualis), and one ascaridoid nematode (Anisakis simplex B). Two of these parasites (Phyllobothrium sp., A. simplex B), which could be recognised as component species, were used in analyses of host-parasite relationships. Levels of infection varied significantly with host size or stage of maturation for both squid species. Regional variation in infection level seems attributable to geographical variation in availability of prey, discreteness and movements of host populations and to size or age-related changes in the prey selection oftheir host. Parasite evidences suggest that both ommastre...

What makes a cephalopod a suitable host for parasite? The case of Galician waters

Abstract We analyse the cephalopod–parasite systems taking into account the abiotic and biotic factors that may affect the host risk of infection (contact) with parasites. On the basis of 2000 individuals comprising 10 cephalopod species collected at a microgeographic area (Galician waters, NW Spain), an attempt is made to find associations between parasite relative species diversity (RSD) and cephalopod life cycle characteristics. Additionally, an index of similarity and the ratios of adult/immature (A/I) and specialist/generalist (S/G) regarding the parasite condition were used to define cephalopod ecological groupings at those species with similar risk of becoming infected with a given parasite fauna. Results show the existence of three ecological groupings (coastal, intermediate, and nerito-oceanic), which suggest that the ecological niche of a cephalopod species is more important in determining its risk of parasitic infection than is phylogeny.

Squid as trophic bridges for parasite flow within marine ecosystems: the case of Anisakis simplex (Nematoda: Anisakidae), or when the wrong way can be right

Long-term (1991–1997) information on parasitic infection by anisakid nematodes in cephalopods and top predators (marine mammals) of the south-eastern area of the North Atlantic underlines the important role of small cetaceans as final hosts for A. simplex. The ommastrephid squid Illex couidetii, Todaropsis eblanae and Todarodes sagittatus are the most important cephalopod paratenic hosts in the life cycle of the parasite. Information on parasite flow and parasite-caused diseases could be of use for stock assessment purposes. Moreover, it largely agrees with what is known about interactions between prey (squid) and predator (cetacean) in the same area. Parasitic castration and stomach wall ulceration were the most important parasite-caused effects recorded in infected cephalopods and cetaceans respectively.

Assessing the risk of an emerging zoonosis of worldwide concern: anisakiasis

Anisakiasis is an emerging zoonosis caused by the fish parasitic nematode Anisakis. Spain appears to have the highest reported incidence in Europe and marinated anchovies are recognised as the main food vehicle. Using data on fishery landings, fish infection rates and consumption habits of the Spanish population from questionnaires, we developed a quantitative risk assessment (QRA) model for the anchovy value chain. Spaniards were estimated to consume on average 0.66 Anisakis per untreated (non-frozen) raw or marinated anchovy meal. A dose-response relationship was generated and the probability of anisakiasis was calculated to be 9.56 × 10−5 per meal, and the number of annual anisakiasis cases requiring medical attention was predicted between 7,700 and 8,320. Monte Carlo simulations estimated post-mortem migration of Anisakis from viscera to flesh increases the disease burden by >1000% whilst an education campaign to freeze anchovy before consumption may reduce cases by 80%. However, most of the questionnaire respondents who ate untreated meals knew how to prevent Anisakis infection. The QRA suggests that previously reported figures of 500 anisakiasis per year in Europe is a considerable underestimate. The QRA tool can be used by policy makers and informs industry, health professionals and consumers about this underdiagnosed zoonosis.

Nyctiphanes couchii as intermediate host for the acanthocephalan Bolbosoma balaenae in temperate waters of the NE Atlantic

Cystacanths of the acanthocephalan Bolbosoma balaenae (Gmelin, 1790) were found encapsulated in the cephalothorax of the euphausiid Nyctiphanes couchii (Bell, 1853) from temperate waters in the NE Atlantic Ocean. Euphausiids were caught in locations outside the Ría de Vigo in Galicia, NW Spain, and prevalence of infection was up to 0.1%. The parasite was identified by morphological characters. Cystacanths were 8.09 ± 2.25 mm total length (mean ± SD) and had proboscises that consisted of 22 to 24 longitudinal rows of hooks, each of which had 8 or 9 hooks per row including 2 or 3 rootless ones in the proboscis base and 1 field of small hooks in the prebulbar part. Phylogenetic analyses of 18S rDNA and cytocrome c oxidase subunit I revealed a close relationship with other taxa of the family Polymorphidae (Meyer, 1931). The results extend northwards ot the known distribution of B. balaenae. Taxonomic affiliation of parasites and trophic ecology in the sampling area suggest that N. couchii is the intermediate host for B. balenae, and we suggest that the whales Balaenoptera physalus (Linnaeus, 1758) and B. acutorostrata (Lacepède, 1804) are its definitive hosts. This life cycle is probably completed with or without paratenic hosts.