The role of parasites in the invasion success of the exotic brine shrimp Artemia Franciscana in the Meditarranean region

Trabajo presentado en el Symposium for European Freshwater Science, celebardo en Girona del 27 de junio al 1 de julio de 2011.Biological invasions are main threats to biodiversity at global scale and increasing numbers of studies suggest that parasites may have a role. However, the mechanism through which parasites may influence the outcome of the invasion is poorly understood. Here we provide evidence supporting the role of parasites as potential agents mediating the competitive exclusion of Mediterranean brine shrimps Artemia (A. parthenogenetica and A. salina) by the exotic American A. franciscana, using different native and invasive populations from South Spain and South France. Our results revealed high rates of infection by cestodes in native brine shrimps, sometimes with extreme prevalences of up to 100%. In contrast, A. franciscana populations showed very low diversity, prevalence and burden of cestodes. The effect of parasites in native populations was multiple, ranging from reproduction and survival, to life history traits, microhabitat selection and diet. Infection strongly reduced host fitness by both, reducing fecundity (parasite castration) and indirectly increasing predation by birds final hosts as revealed by prey choice experiments. We found evidence that high rate of parasitism (particularly the castrating parasite Flamingolepis liguloides, the most prevalent cestode in natives but nearly absent in the exotic Artemia), indirectly affected the life-history strategy of non infected individuals, inducing for example earlier maturation. Moreover cestodes influenced spatial (vertical and horizontal) distribution of the host, altering the diet as revealed by isotopic analysis. Contrasting with the strong impact of parasites in native populations, we have never observed any pathology (castration, behavioural alteration, etc) associated with infection in the exotic species. Overall, the results of this study suggest that the large impact of cestode on the native, but not the invading species, is likely to confer a decisive competitive advantage to the invader, contributing to explain the demographic success of A. franciscana in the Mediterranean region.Peer reviewe

Participation of metanauplii and juvenile individuals of Artemia parthenogenetica (Branchiopoda) in the circulation of avian cestodes

Peer reviewe

Participation of metanauplii and juvenile individuals of Artemia parthenogenetica (Branchiopoda) in the circulation of avian cestodes

Adult crustaceans of the genus Artemia (brine shrimps) are intermediate hosts in the life cycle of cestode species parasitic in aquatic birds as their definitive hosts. However, there are no data on the role of larval and juvenile brine shrimps in the transmission of avian helminth parasites. In order to examine the possible role of early developmental stages (nauplii, metanauplii and juveniles) of Artemia for the circulation of avian cestodes, the natural cestode infection in the population of Artemia parthenogenetica from La Mata Lagoon, Mediterranean coast of Spain, was studied. Metacestodes (cysticercoids) of four cestode species were recorded in adult brine shrimps: Flamingolepis liguloides and Flamingolepis flamingo (hymenolepidids parasitic in flamingos), Confluaria podicipina (a hymenolepidid species parasitic in grebes) and Eurycestus avoceti (a dilepidid species parasitic in avocets, stilts, plovers and, to a lesser extent, in flamingos). No cysticercoids were found in nauplii. Two species, F. liguloides and F. flamingo, were found in metanauplii and juvenile brine shrimps. Only 36.3% of the cysticercoids of F. liguloides occurred in adult brine shrimps; the remaining 63.7% were parasitic in metanauplii (39.6%) and juveniles (24.1%). Similarly, the metacestodes of F. flamingo were also distributed among various age groups: in adults (44.4% of cysticercoids), juveniles (27.8%) and metanauplii (27.8%). These results indicate that the early developmental stages of Artemia have an important role for the circulation of certain parasite species. No cysticercoids of C. podicipina and E. avoceti were recorded in larval and juvenile brine shrimps. The selective infestation of larval brine shrimps with flamingo parasites is probably associated with the feeding behaviour of definitive hosts, which are filtering predators; in contrast, grebes and waders pick brine shrimps individually one by one. The possible underlying mechanism for selective infestation of metanauplii and adults by certain cestode species is associated with the size of parasite eggs, allowing only cestode species with small eggs to be ingested by larval brine shrimps.This work was financed by the Spanish National Plan R & D (project CGL-2005- 02306/BOS) and by the EC-funded project WETLANET to the Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences. The first author is supported by a Ph.D. grant (FPI) from the Spanish Ministry of Science and Innovation.Peer reviewe

Cestodes from hector's beaked whale (Mesoplodon hectori) and spectacled porpoise (Phocoena dioptrica) from argentinean waters

Single individuals of 2 little-known cetacean species, Mesoplodon hectori and Phocoena dioptrica, stranded and died on the coast of Argentina (Buenos Aires and Chubut provinces, respectively) and were studied for the presence of helminths. The cestodes found were described and illustrated using light microscopy. The following cestode taxa were recovered: Tetrabothrius (Tetrabothrius) hobergi n. sp. (several fragmented specimens, at least 1 gravid) and Tetrabothrius (s.l.) sp. 1 (several fragmented immature specimens) from M. hectori, and Tetrabothrius (s.l.) sp. 2 (single fragmented immature specimen) and 2 morphotypes of tetraphyllidean larvae from P. dioptrica. Tetrabothrius (T.) hobergi n. sp. can be distinguished from Tetrabothrius (T.) forsteri by the greater number of testes and larger eggs and oncospheres, from Tetrabothrius (T.) curilensis by the smaller testes and vitellarium, the shape and size of the ovary, and the larger oncospheres and longer embryonic hooks, and from Tetrabothrius (T.) sp. from Ziphius cavirostris by the narrower strobila, smaller scolex, and smaller number of testes. The generic designations of Tetrabothrius (s.l.) sp. 1 and Tetrabothrius (s.l.) sp. 2 were based on the scolex morphology. Tetrabothrius (s.l.) sp. 1 is closest to Tetrabothrius (T.) forsteri and Tetrabothrius (Biamniculus) innominatus based on the number of testes, while the scolex size of Tetrabothrius (Tetrabothrius) sp. 2 is within the variability range reported for Tetrabothrius (T.) forsteri. More definite identification of the 2 species was not possible due to the condition of the available material. The present study provides the first descriptions of cestodes from M. hectori and P. dioptrica, thus enriching the knowledge regarding the helminths of insufficiently studied marine mammals.Fil: Nikolov, Pavel N.. Bulgarian Academy of Sciences; BulgariaFil: Cappozzo, Humberto Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentina. Bulgarian Academy of Sciences; BulgariaFil: Beron Vera, Barbara. Bulgarian Academy of Sciences; Bulgaria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Crespo, Enrique Alberto. Bulgarian Academy of Sciences; Bulgaria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Raga, J. Antonio. Bulgarian Academy of Sciences; Bulgaria. Universidad de Valencia; España. Universidad Virtual del Estado de Guanajuato; MéxicoFil: Fernández, Mercedes. Bulgarian Academy of Sciences; Bulgaria. Universidad de Valencia; España. Universidad Virtual del Estado de Guanajuato; Méxic

Records of cysticercoids of Fimbriarioides tadornae Maksimova, 1976 and Branchiopodataenia gvozdevi (Maksimova, 1988) (Cyclophyllidea, Hymenolepididae) from brine shrimps at the Mediterranean coasts of Spain and France, with a key to cestodes from Artemia spp. From the Western Mediterranean

Cysticercoids of two cestode species isolated from brine shrimps from the Mediterranean coasts of Spain and France are described. Fimbriarioides tadornae Maksimova, 1976 (adults known as parasites of Tadorna tadorna) was recorded from Artemia parthenogenetica and A. franciscana from Spain (Bras del Port and River Ebro Delta, respectively), and from A. franciscana from Aigues-Mortes, France (new geographical record). Branchiopodataenia gvozdevi (Maksimova, 1988) (adults known as parasites of Larus genei) was recorded from A. parthenogenetica (Bras del Port, Spain), A. salina (San Pedro del Pinatar, Spain) and A. franciscana (River Ebro Delta, Spain); this is the first record of the species in Europe. An illustrated key to cysticercoids of 12 cestode species from Artemia spp. from the Western Mediterranean is proposed. © 2009 Versita Warsaw and Springer-Verlag Berlin Heidelberg.This study was partly carried out in the framework of a co-operative project between the Bulgarian Academy of Sciences (BAS) and the Consejo Superior de Investigationes Científicas (CSIC), Spain, entitled "Invasive and native brine shrimps: do cestode parasites control their competitive interactions" (2006-2007). It was also facilitated by visit grants in the frames of the cooperative agreement between CSIC and BAS (2008-2009) and CSIC programme for visiting researchers.Peer Reviewe

High prevalence of cestodes in Artemia spp. throughout the annual cycle: relationship with abundance of avian final hosts

Brine shrimp, Artemia spp., act as intermediate hosts for a range of cestode species that use waterbirds as their final hosts. These parasites can have marked influences on shrimp behavior and fecundity, generating the potential for cascading effects in hypersaline food webs. We present the first comprehensive study of the temporal dynamics of cestode parasites in natural populations of brine shrimp throughout the annual cycle. Over a 12-month period, clonal Artemia parthenogenetica were sampled in the Odiel marshes in Huelva, and the sexual Artemia salina was sampled in the Salinas de Cerrillos in Almería. Throughout the year, 4–45 % of A. parthenogenetica were infected with cestodes (mean species richness = 0.26), compared to 27–72 % of A. salina (mean species richness = 0.64). Ten cestode species were recorded. Male and female A. salina showed similar levels of parasitism. The most prevalent and abundant cestodes were those infecting the most abundant final hosts, especially the Greater Flamingo Phoenicopterus ruber. In particular, the flamingo parasite Flamingolepis liguloides had a prevalence of up to 43 % in A. parthenogenetica and 63.5 % in A. salina in a given month. Although there was strong seasonal variation in prevalence, abundance, and intensity of cestode infections, seasonal changes in bird counts were weak predictors of the dynamics of cestode infections. However, infection levels of Confluaria podicipina in A. parthenogenetica were positively correlated with the number of their black-necked grebe Podiceps nigricollis hosts. Similarly, infection levels of Anomotaenia tringae and Anomotaenia microphallos in A. salina were correlated with the number of shorebird hosts present the month before. Correlated seasonal transmission structured the cestode community, leading to more multiple infections than expected by chance.Peer reviewe