Patrones de distribución de dos especies de Corynosoma (Acanthocephala: Polymorphidae) en peces del Atlántico sudoccidental

Corynosoma australe Johnston, 1937 y C. cetaceum Johnston and Best, 1942 son los acantocéfalos más frecuentemente reportados en peces del Mar Argentino. Sus hospedadores definitivos son otáridos y cetáceos respectivamente, aunque también han sido reportados en otros mamíferos, aves e, incluso, en humanos. Los peces, por su parte, actúan como hospedadores intermediarios de los mismos alojando a las larvas cistacantas. Dada su amplia distribución, el género Corynosoma es útil para la determinación de stocks y estudios zoogeográficos.Asociación Parasitológica Argentin

Distribution of parasites of slimy sculpin Cottus cognatus Richardson, 1836 (Scorpaeniformes: Cottidae) in the Athabasca drainage, Alberta, Canada, and their relation to water quality

The composition and diversity of parasite communities are useful tools to characterise ecosystem health and integrity.Environmental disturbances may affect parasite infection in fish directly, by their effects on the free-living stages, or indirectly,on the intermediate hosts. Slimy sculpins, Cottus cognatus, a small fish inhabiting cold waters of North America, have beenconsidered as sentinels due to their limited mobility, often occupying relatively small areas throughout their lives and thusreflecting the local environment. Ninety-six specimens of C. cognatus were sampled from four tributaries of the AthabascaRiver to assess patterns of helminth parasite community structure in this fish and to study the composition and diversity of itsparasite communities in relation to water quality. The localities included single samples from High Hills, Horse and Dunkirkrivers, and two from the Steepbank River. Twelve metazoan parasite species were found, most of them being larval forms.Significant differences occurred in the structure and composition of parasite assemblages of sculpins from the tributaries,although similarities were observed in connected and nearby sites. Parasite communities were influenced mainly by a combinationof local environmental conditions, distance and connectivity, and were separated based on the distribution and abundance ofautogenic and allogenic parasites.Water quality appeared to influence the distribution of trematode species that use gastropods asintermediate hosts, while proximity and connectivity of sites led to sharing allogenic parasite species in slimy sculpin.Fil: Braicovich, Paola Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: McMaster, M.. Environment and Climate Change Canada; CanadáFil: Glozier, N. E.. Environment And Climate Change Canada; CanadáFil: Marcogliese, D. J.. Environment and Climate Change Canada; Canad

Assessing the role of host traits as drivers of the abundance of long-lived parasites in fish-stock assessment studies

In order to identify the best tools for stock assessment studies using fish parasites as biological indicators, different host traits (size, mass and age and their interaction with sex) were evaluated as descriptors of cumulative patterns of both parasite abundance and infracommunity species richness. The effect of such variables was analysed for a sample of 265 specimens of Percophis brasiliensis caught in the Argentine Sea. The abundances and species richness were modelled using generalized linear mixed models (GLMMs) with negative binomial and Poisson distribution respectively. Due to collinearity, separate models were fitted for each of the three main explanatory variables (length, mass and age) to identify the optimal set of factors determining the parasite burdens. Optimal GLMMs were selected on the basis of the lowest Akaike information criteria, residual information and simulation studies based on 10 000 iterations. Results indicated that the covariates length and sex consistently appeared in the most parsimonious models suggesting that fish length seems to be a slightly better predictor than age or mass. The biological causes of these patterns are discussed. It is recommended to use fish length as a measure of growth and to restrict comparisons with fish of similar length or to incorporate length as covariate when comparing parasite burdens. Host sex should be also taken into account for those species sexually dimorphic in terms of morphology, behaviour or growth rates.Fil: Braicovich, Paola Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Ieno, E. N.. Highland Statistics; EspañaFil: Sáez, M.. Instituto Nacional de Investigaciones y Desarrollo Pesquero; ArgentinaFil: Despos, J.. Instituto Nacional de Investigaciones y Desarrollo Pesquero; ArgentinaFil: Timi, Juan Tomas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin

Parasites of the Brazilian flathead Percophis brasiliensis reflect West Atlantic biogeographic regions

With the aim of evaluating the utility of marine parasites as indicators of zoogeographical regions in the South West Atlantic, we analyzed data on assemblages of long-lived larval parasites of 488 specimens of Percophis brasiliensis distributed in 11 samples from nine localities covering the entire distribution of the species in the Argentine biogeographical Province. Near half a million long-lived parasite individuals belonging to 17 species present in the whole sample displayed clear latitudinal patterns. Data for parasite assemblages at infracommunity and component community levels were analysed in relation to the geographical distance. Significant similarity decay of parasite assemblages over distance was observed, with those based on abundances and mean abundances showing departures from predicted values of regressions. These departures were represented by higher dissimilarities between samples coming from different zoogeographical regions than between those caught within the same region, independently of the distance separating them. Consequently, zoogeographical regions were identified in a distance-decay context. Multivariate analyses corroborated a close fit of similarity between assemblages to existing zoogeographical classifications. Regressions representing distance decay of similarity, and the identification of their outliers, can therefore shed light on the existence of discontinuities or uniformities in the geographic distribution of parasite assemblages and, in turn, in the zoogeography of their fish hosts

Influence of confluent marine currents in an ecotonal region of the South-West Atlantic on the distribution of larval anisakids (Nematoda: Anisakidae)

Abstract Background In the marine environment, transitional zones between major water masses harbour high biodiversity, mostly due to their productivity and by containing representatives of species characteristic of adjacent communities. With the aim of assessing the value of larval Anisakis as zoogeographical indicators in a transitional zone between subtropical and sub-Antarctic marine currents, larvae obtained from Zenopsis conchifer were genetically identified. Larvae from Pagrus pagrus and Merluccius hubbsi from two adjacent zoogeographical provinces were also sequenced. Results Four species were genetically identified in the whole sample, including Anisakis typica, A. pegreffii, A. berlandi and a probably new species related to A. paggiae. Anisakis typica and A. pegreffii were identified as indicators of tropical/subtropical and sub-Antarctic waters, respectively, and their presence evidenced the transitional conditions of the region. Multivariate analyses on prevalence and mean abundance of Anisakis spp. of 18 samples represented by 9 fish species caught south of 35°S determined that host trophic level and locality of capture were the main drivers of the distribution of parasites across zoogeographical units in the South-West Atlantic. Conclusions Most samples followed a clear zoogeographical pattern, but the sample of Z. conchifer, composed mostly of A. typica, was an exception. This finding suggests that population parameters of A. typica and A. pegreffii could differ enough to be considered as a surrogates of the identity of larvae parasitizing a given host population and, therefore, a step forward the validation of the use of larval Anisakis as biological indicators for studies on host zoogeography

Parasites of Percophis brasiliensis (Percophidae) benefited from fishery regulations: Indicators of success for marine protected areas?

Fishing is the greatest source of anthropogenic impact on global marine resources and the ecosystems supporting them. The decline of many fish stocks has led to the need to apply control and protection measures to promote the recovery of these resources.In the Argentine Sea, a multispecies coastal fishery in the El Rincón region has displayed signs of overexploitation since the beginning of the century. Consequently, temporal and spatial protection measures were implemented in 2004.In previous studies, an independent stock of Percophis brasiliensis in El Rincón was identified based on the parasite communities of fish caught in 2005. However, no subsequent studies using parasite communities have been performed since the protective fishery closure measures were applied.To evaluate parasites as indicators of temporal change in the El Rincón stock of P. brasiliensis after the implementation of these protection measures, a sample from 2018 was compared with that from the previous study, as well as with three other samples. Two of the latter (Argentine Common Fishing Zone and San Matías Gulf) corresponded to previously identified independent stocks in the Argentine biogeographical province and the third was a new sample from the Magellanic Province in southern Patagonian waters.The structure and composition of parasite assemblages of the El Rincón stock of P. brasiliensis differed significantly in 2018, after several years of protective measures. The increased loads observed in several parasite species constitute a promising signal of successful ecosystem recovery. A discrete stock in the Magellanic Province was also identified, providing insights into the population structure of P. brasiliensis along its distributional range, with applications for the sustainable management of this resource.Fil: Braicovich, Paola Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Irigoitia, Manuel Marcial. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Bovcon, Nelson Darío. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales - Sede Trelew; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Timi, Juan Tomas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin