Evaluation of gill nets, fyke nets, and mark-recapture methods to estimate the number of Hirudinea and Crustacea on fish.

Twenty species of fishes (n = 20,759) were collected from Dauphin Lake, Manitoba, Canada, to determine the types and numbers of ectoparasites they harbored. Counts of ectoparasites on fishes collected with different gear were compared to evaluate different methods of collection and to estimate rates of recruitment of ectoparasites by fishes. Ectoparasites were found on 11 species of fishes and the majority of these were parasitic leeches (Myzobdella moorei, Cystobranchus verilli, and Placobdella montifera) and parasitic Crustacea (Argulus appendiculosus and Lernaea cyprinacea). Some fishes also were infested by neascus-type metacercariae (blackspot) or had tumors (lymphocystis). The prevalence of ectoparasites was correlated with the abundance, feeding habits, and spatial distribution of fish species. Argulus appendiculosus and blackspot were more prevalent on benthic fishes, whereas M. moorei and tumors were more prevalent on limnetic fishes. Mark-recapture records showed that fishes occupying shallow (less than or equal to 1.5 m) water had a higher prevalence of infestation and 28 of 29 infected fishes caught by gill nets were captured in shallow water. Placobdella montifera was the only ectoparasite found on fishes from deep (1.5-3.5 m) water and the only species that was acquired by fishes previously released with no ectoparasite (2 of 239 fishes). The littoral zone (less than or equal to 1.5 m) comprises only 14% of the surface area and 3% of the volume of Dauphin Lake, yet 72% of all gill-netted fishes harboring ectoparasites were collected there. Intensities of ectoparasites estimated from gill net and pound net samples were similar, but prevalence of ectoparasites estimated from samples obtained with gill nets was lower.

Epizootiology of Amblyospora connecticus (Microsporida) in field populations of the saltmarsh mosquito, Aedes cantator, and the cyclopoid copepod, Acanthocyclops vernalis.

The natural ecology of a heterosporous microsporidium, Amblyospora connecticus was investigated at three different salt marsh habitats during 1986-1989. The parasite has a well-defined seasonal transmission cycle that occurs regularly each year and intimately involves the primary mosquito host, Aedes cantator, and the intermediate copepod host, Acanthocyclops vernalis. In the spring, the microsporidium is horizontally transmitted from the copepod, where it appears to overwinter, to the mosquito via the ingestion of haploid spores produced in the copepod. Mosquitoes develop a benign infection, and females transmit the microsporidium transovarially to their progeny via infected eggs. Oviposition occurs during the summer and infected eggs hatch synchronously in the fall causing widespread epizootics. Infected larvae die, and the cycle is completed when meiospores are released into the pool and subsequently are eaten by A. vernalis, which reappears in the fall and early winter. Amblyospora connecticus thereby persists by surviving in one of two living hosts throughout most of its life cycle rather than in the extra-corporeal environment. This represents an important survival strategy for A. connecticus as results show the salt marsh habitat to be a relatively unstable environment that is subject to periodic flooding and drying. The adaptive significance of utilizing an intermediate host in the life cycle is discussed as it directly facilitates transmission and enhances survival of the microsporidium.

[Parasitic copepods of fish from the coasts of Montenegro (South Adriatic)]. / Copépodes parasites des poissons des côtes du Montenegro (Adriatique Sud).

Twenty-five species of parasitic copepods are presented, collected on fishes living in the Montenegro sea coasts. Among these species, belonging to ten families and sixteen different genera, fifteen are new records for the Adriatic Sea.

Thersitina gasterostei (Pagenstecher, 1861) (Copepoda: Ergasilidae) infecting the stickleback Pungitius pungitius L. at Chalk Marshes, Gravesend, Kent.

10-spined sticklebacks, Pungitius pungitius, taken from a drainage dyke at Chalk Marshes, Kent, between October 1979 and July 1980 were infested with adult females of the parasitic copepod Thersitina gasterostei. Relative density of the overwintering parasite population fell during the winter months to a minimum in April; however during this winter period the proportion of ovigerous females rose, reaching 100% in April. Young infective adults were first seen in May, and the peak of infection by the first summer generation occurred in June. The parasite was found to be overdispersed within the host population: in 8 of 10 monthly samples the negative binomial distribution was a good model for the observed data. Relative density was related to host length in only 3 of the 10 samples. Evidence is presented to suggest that infected fish are more likely than non-infected fish to recruit young parasite.

[Metazoan parasites of Boops boops (Linnaeus, 1758) (Teleostean Sparidae) in the "Golfe du Lion", faunistic and ecology (author's transl)]. / Faunistique et ecologie des metazoaires parasites de Boops boops linnaeus (1758) (Teleosteen Sparidae) dans le Golfe du Lion.

A global study of the Metazoan parasites of Boops boops (L., 1758) have been made in the "golfe du Lion". Fourteen different species (eight Platyhelmintha, one Nematoda and five Crustacea) have been inventorized. Their respective localisation on the hosts, globals and specifics corresponding prevalences as well as their variations according to the size of the fish, and their abundance have been precised. Parasitics associations have also been examined.