Francisco E. Montero

Effects of the gill parasite Zeuxapta seriolae (Monogenea: Heteraxinidae) on the amberjack Seriola dumerili Risso (Teleostei: Carangidae)

Zeuxapta seriolae (Monogenea: Heteraxinidae) infection was associated with important mortalities of amberjacks (Seriola dumerili) reared in tanks in the experimental facilities of the Spanish Institute of Oceanography (Western Mediterranean) during the period 1998–2000. Fish infested by this parasite presented characteristics similar to those described for Seriola quinqueradiata parasitized by Heteraxine heterocerca in Japan. All dead amberjacks had high parasite abundance (mean abundanceFS.D.=686.7F125.4) and egg strings entangled in gills. The parasitological analysis of 17 live amberjacks collected from the infested tanks showed that 41.2% of fish harboured Z. seriolae with intensities ranging between 5 and 731 parasites per fish. No apparent relationship was observed between the abundance of the parasite and the condition factor (rS=0.175, n=17, p>0.5). However, the haematocrit values were significantly lower in the fish infested with monogeneans. The relationship between parasite abundance and haematocrit values was negative and statistically significant (rS=0.625, n=17, p<0.01). The light and scanning electron microscope studies of affected gills revealed that the parasites attached to the host grasping one or two lamellae with each clamp of the haptor, which led to lamellar synechiae, lamellar clubbing and disruption of epithelial and vascular structures. A mild to moderate epitheliocystis infection was also

Composition and structure of the parasite faunas of cod, Gadus morhua L. (Teleostei: Gadidae), in the North East Atlantic

BackgroundAlthough numerous studies on parasites of the Atlantic cod, Gadus morhua L. have been conducted in the North Atlantic, comparative analyses on local cod parasite faunas are virtually lacking. The present study is based on examination of large samples of cod from six geographical areas of the North East Atlantic which yielded abundant baseline data on parasite distribution and abundance.Materials and MethodsA total of 826 fish was sampled in the Baltic, Celtic, Irish and North seas, Icelandic waters and Trondheimsfjord (Norway) in 2002 (spring and autumn) and 2003 (spring). The gills and internal organs (oesophagus, stomach, intestine, pyloric caeca, liver, heart, spleen, gall bladder and gonads) were examined for macroparasites following a standardised protocol. The taxonomic consistency of the identification was ensured thorough the entire study.ResultsWe discuss some problems in parasite identification, outline the composition of the parasite faunas in cod in the six North East Atlantic regions, provide novel data on parasite prevalence and abundance and a comparative assessment of the structure of the regional parasite faunas with respect to the higher-level taxonomic groupings, host specificity and zoogeographical distribution of the parasites. Altogether 57 different parasite forms were found including seven new host records (Diclidophora merlangi, Rhipidocotyle sp., Fellodistomum sp., Steringotrema sp., Cucullanus sp., Spinitectus sp., and Chondracanthus ornatus). The predominant groups of cod parasites were trematodes (19 species) and nematodes (13 species) including larval anisakids which comprised 58.2% of the total number of individuals.ConclusionOur study reveals relatively rich regional parasite faunas in cod from the North East Atlantic which are dominated by generalist parasites with Arcto-Boreal distribution. Further, it provides more detailed data on the distribution in the North East Atlantic of the majority of cod parasites which may serve as baselines for future studies on the effect of climate change. Based on the faunal comparisons, predictions can be made in relation to the structure and diversity of the parasite communities in the North East Atlantic regions studied.

Cardicola aurata sp. n. (Digenea : Sanguinicolidae) from Mediterranean Sparus aurata L. (Teleostei : Sparidae) and its unexpected phylogenetic relationship with Paradeontacylix McIntosh, 1934

A new sanguinicolid trematode, Cardicola aurata sp. n., is described from gilthead seabream Sparus aurata L., from off the Spanish Mediterranean coast. The morphology of C. aurata sp. n. generally agrees with the diagnosis of the genus, however, in contrast to all other reported Cardicola spp. the male pore is located sub-medially at the posterior end of the body instead of sinistrally before the posterior end of the body. Based on a comparison of the morphology as well as partial 28S and ITS2 rDNA sequence data from the present species with that from closely related species, it was decided to emend the diagnosis of Cardicola rather than create a new genus, as the aberrant position of the male pore is likely to be an autapomorphy. The phylogenetic analyses revealed a close relationship between Cardicola and Paradeontacylix, two genera with considerable morphological differences; C. aurata sp. n. occupies a position intermediate to these genera. Thus, a morphological comparison of Cardicola, Paradeontacylix and Braya, a genus which is morphologically similar to Cardicola but clusters basal to the Cardicola/Paradeontacylix clade, was conducted. The results of this comparison showed that despite large differences with regard to body shape, the organisation of the internal organs is very similar in species of Cardicola and Paradeontacylix. The synopsis of morphological data and molecular phylogeny allows for interpretations regarding the importance of different morphological features for the phylogenetic inference of the Sanguinicolidae.

Speciation of the Paradeontacylix spp. (Sanguinicolidae) of Seriola dumerili. Two new species of the genus Paradeontacylix from the Mediterranean

Two new species of teleost blood fluke belonging to the sanguinicolid genus Paradeontacylix are described from the greater amberjack, Seriola dumerili, i.e. Paradeontacylix ibericus n. sp. from the Iberian Peninsula and Paradeontacylix balearicus n. sp. from the Balearic Islands. P. ibericus n. sp. and P. balearicus n. sp. show morphological similarities with Paradeontacylix kampachi and Paradeontacylix grandispinus respectively, which occur in mixed infection in S. dumerili from Japan. Multivariate analysis of morphometrical data provided statistical evidence for the separation of four species. However, component by component analysis did not show statistically significant differences between P. balearicus and P. grandispinus. Molecular data based on rITS2 and mCO1 gene sequences also supported the separation into four species. Morphological and molecular data were used to examine phylogenetic relationships between Paradeontacylix species from S. dumerili and other species in the genus. The results coincided in revealing two main branches with P. kampachi+P. ibericus and (((P. grandispinus+P. balearicus) Paradeontacylix sanguinicoloides) Paradeontacylix godfreyi). Paradeontacylix odhneri, for which little data are available, was located basal in a separate branch. This is the only species of Paradeontacylix which parasitizes a non-carangid host which might probably explain the separation from the other species. Paired similarities between the Japanese and the Mediterranean species, despite the large geographic distance, could be explained by the speciation of parasite geminate lines before host separation by tectonic events. Consequently, geographic and historical isolation support the morphological and genetic differences leading to the evolution of the new species described here.

Skoulekia meningialis n. gen., n. sp. (Digenea: Aporocotylidae Odhner, 1912) a parasite surrounding the brain of the Mediterranean common two-banded seabream Diplodus vulgaris (Geoffroy Saint-Hilaire, 1817) (Teleostei: Sparidae): description, molecular phylogeny, habitat and pathology.

This study describes a new aporocotylid genus and species, Skoulekia meningialis n. gen., n. sp. which was detected in the ectomeningeal veins surrounding the optic lobes of the brain of the common two-banded seabream Diplodus vulgaris (Geoffroy Saint-Hilaire, 1817) from the Gulf of Valencia (Mediterranean Sea). A detailed morphological description of S. meningialis is provided, including drawings, measurements and scanning electron microscopy images as well as a phylogenetic study of S. meningialis and closely related taxa using DNA sequence data obtained from whole ITS2 and partial 18S and 28S rDNA regions. Morphology as well as molecular phylogeny strongly support the erection of a new genus and demonstrate its close relationship with the genera Psettarium (Goto & Ozaki, 1930) and Pearsonellum Overstreet & Køie, 1989. Skoulekia is the second aporocotylid genus described in the Sparidae, a family including economical important fishes. In contrast to the majority of the aporocotylids, which inhabit the heart or the blood vessels of the gills, S. meningialis inhabits the ectomeningeal veins surrounding the optic lobes. Eggs were found trapped within the gill vessels. Normally, blood fluke pathology is almost exclusively related to the eggs. However, in the case of S. meningialis, main histopathological alterations were related to the adult blood flukes which were found to cause mild localised meningitis.

Fish Health and Fisheries, Implications for Stock Assessment and Management: The Mediterranean Example

Although fish health may influence key population-level processes, particularly those dealing with natural mortality, reproduction, and growth, which, in turn, affect stock productivity, little emphasis has been placed on the links between fish health and the management of marine fisheries. This article addresses this gap and illustrates how knowledge of fish health could provide insight for marine fisheries biologists, stock assessment modelers, and managers. The study proposes ways in which the consideration of condition indicators (energy reserves) and parasitism improves stock assessment and fisheries management, especially in situations of data shortage when standard methods cannot be applied, as is the case in many Mediterranean fish stocks. This article focuses on seven case studies of different fish species from the Mediterranean and Black Seas. Overall, and although the relationship between fish health and productivity cannot always be found or quantified, the article emphasizes the importance of the physical health of exploited stocks, particularly during critical life periods of the fish (e.g., prior to spawning, migration, or in the early life stages), as an essential element of sustainable and profitable fisheries. On the basis of these results, stock assessment and fisheries management implications are discussed.

Morphological characterisation and identification of four species of Cardicola Short, 1953 (Trematoda: Aporocotylidae) infecting the Atlantic bluefin tuna Thunnus thynnus (L.) in the Mediterranean Sea.

Blood flukes of the genus Cardicola Short, 1953 are considered the most potentially pathogenic parasites in bluefin tuna cultures. Morphological study and genetic analyses of the ribosomal internal transcribed spacer ITS-2 and the mitochondrial cytochrome c oxidase 1 (cox1) gene fragments revealed the occurrence of four aporocotylid species (C. forsteri Cribb, Daintith & Munday, 2000, C. orientalis Ogawa, Tanaka, Sugihara & Takami, 2010, C. opisthorchis Ogawa, Ishimaru, Shirakashi, Takami & Grabner, 2011 and Cardicola sp.) in 421 Thunnus thynnus (L.) from the Western Mediterranean (274 fished from the wild and 147 from sea-cages). Cardicola opisthorchis was the most abundant species, with higher prevalence in the cage-reared fish than in those fished in the wild (21 vs 6%, p < 0.05). Adults of three species were recovered: C. forsteri from both gills and heart, C. opisthorchis from heart and C. orientalis from gills. The secondary gill lamellae were profusely infected by eggs of C. orientalis. A fourth species was found in four tunas, based on the molecular analyses of eggs apparently indistinguishable in size and shape from the eggs of C. orientalis. The findings provided evidence that infections with Cardicola spp. differed in relation to locality, host origin (wild vs cage-reared) and site of infection. It is necessary to estimate the possible different pathogenic effects of each species of Cardicola in order to take appropriate control measures.

Intestinal helminth fauna of the South American sea lion Otaria flavescens and fur seal Arctocephalus australis from northern Patagonia, Argentina.

We report on the intestinal helminth fauna of 56 South American sea lions, Otaria flavescens, and 5 South American fur seals, Arctocephalus australis, from northern Patagonia, Argentina. A total of 97,325 helminth specimens were collected from sea lions. Gravid individuals were represented by 6 species of parasites: 1 digenean (Ascocotyle (Ascocotyle) patagoniensis), 1 cestode (Diphyllobothrium spp.), 3 nematodes (Uncinaria hamiltoni, Contracaecum ogmorhini s.s., Pseudoterranova cattani) and 1 acanthocephalan (Corynosoma australe). In addition, third-stage larvae of 2 nematodes (Contracaecum sp. and Anisakis sp. type I) and 3 juvenile acanthocephalans (Andracantha sp., Profilicollis chasmagnathi and Corynosoma cetaceum) were also collected. Andracantha sp., C. ogmorhini s.s. and P. chasmagnathi represent new host records. A total of 1516 helminth specimens were collected from fur seals. Gravid individuals were represented by three species of parasites, namely, Diphyllobothrium spp., C. ogmorhini s.s. and C. australe. In addition, larvae of Contracaecum sp. and P. cattani, juveniles of C. cetaceum and immature cestodes (Tetrabothriidae gen. sp.) were also collected. Corynosoma australe was the most prevalent and abundant parasite in both hosts, accounting for >90% of all specimens. Sea lions and furs seals from northern Patagonia harbour the intestinal helminth communities that could be predicted for otariids, i.e. the combination of species of the genera Corynosoma, Diphyllobothrium, Pseudoterranova, Contracaecum and, in pups, Uncinaria. Additionally, both species of otariid are apparently unsuitable hosts (i.e. non-hosts) for as many as five parasite taxa. The inclusion or exclusion of these species affects estimation of species richness at both component community (11 versus 6 species in sea lions; 7 versus 3 species in fur seals) and infracommunity (mean: 3.1 versus 2.6 in sea lions; 2.2 versus 1.7 species) levels. Information about the reproductive status of helminth species is often lacking in parasitological surveys on otariids and other marine vertebrates, but it is of significance to improve precision in parascript studies or ecological meta-analyses.

Aporocotyle mariachristinae n. sp., and A. ymakara Villalba & Fernández, 1986 (Digenea: Aporocotylidae) of the Pink Cusk-Eel, Genypterus blacodes (Ophidiiformes: Ophidiidae) from Patagonia, Argentina

Aporocotyle mariachristinae n. sp. and A. ymakara Villalba & Fernández, 1986 were collected from the bulbus arteriosus and ventral aorta of pink cusk-eels, Genypterus blacodes (Forster, 1801) from Patagonia, Argentina. A. mariachristinae n. sp. can be distinguished from all the species of Aporocotyle by the asymmetrical extension of posterior caeca (right posterior caecum longer, terminating at the area between mid-level of ovary and posterior body end; left posterior caecum shorter, terminating at the area between mid-level of cirrus sac and posterior to reproductive organs), the distribution of spines along the ventro-lateral body margins and the number of testes. The new species clearly differs from A. ymakara, from the same host species, in the esophagus / body length ratio, the absence of distal loops at caeca, the anterior caeca / posterior caeca length ratio, and the number of testes. Additionally, in A. ymakara the left posterior caecum may be longer than right posterior caecum, while in the new species left posterior caecum is always shorter. The specimen of A. ymakara collected from Argentina is also described. We also provide observations of the distribution of spines in different species of Aporocotyle, including new specimens of A. argentinensis Smith, 1969 from Merluccius hubbsi Marini, 1933. Molecular sequence data obtained from partial 18S and 28S rDNA regions were compared between the new species and other two species of Aporocotyle (A. argentinensis and A. spinosicanalis Williams, 1958). This is a new locality record for A. ymakara, extending the known geographical distribution for this species from Chile to Argentina, and the first report of two species of Aporocotyle in the same host species and locality.

Parasitisation by Bathycreadium elongatum (Digenea, Opecoelidae) in pyloric caeca of Trachyrincus scabrus (Teleostei, Macrouridae)

A novel process of transmural passive displacement of a digenean parasite was studied in the digestive tract of the roughsnout grenadier Trachyrincus scabrus, which is found in the northwestern Mediterranean Sea. This mechanism seems to facilitate the elimination of a significant portion of intestinal parasites. The digenean parasite Bathycreadium elongatum was found in the intestine, mainly within pyloric caeca, in 74.4% of T. scabrus, with a mean abundance of 44 individuals per fish. Nodule-like lesions were also found in the mesentery of pyloric caeca of infected T. scabrus. Histological sections of the nodules revealed granulomatous inflammatory responses surrounding degraded digeneans. Partial nucleotide sequences of the 28S rRNA gene obtained from intracaecal B. elongatum and from the core of the nodules of the mesentery of pyloric caeca showed 100% mutual identity with an overlap of 971 bp. The greatest abundance of both intracaecal B. elongatum and nodules occurred in spring. During summer, and especially autumn, the abundance of intracaecal B. elongatum decreased. Prevalence and abundance of nodules increased in autumn. In winter intracaecal parasite abundance and prevalence began to increase, but decreased again in nodules. During spring and summer, parasites pass into the visceral cavity, hypothetically owing to the fragility of the wall of pyloric caeca in their apical zone, and become degraded through a granulomatous inflammatory response. This process seems to have a detrimental effect on the B. elongatum cycle since some of parasites are trapped and degrade in the connective tissue in which they are unable to complete their life cycle.