Oomycete parasites in freshwater copepods of Patagonia: effects on survival and recruitment

JARA.; GARCIA R.D.; REISIG M.; GARCIA R.D.; REISIG M.; M. M. STECIOW.; M. M. STECIOW.; JARA.

DISEASES OF AQUATIC ORGANISMS

INTER-RESEARCH

Lugar: Oldendorf/Luhe; Año: 2018 vol. 129 p. 123 - 134

0177-5103

Copepods are hosts to various oomycete parasite species, but the effects of pathogenson copepod populations have rarely been studied. This study aimed to characterize oomyceteinfection in the freshwater copepod Parabroteas sarsi in a temporary pond in Patagonia (Argentina).A complete hydroperiod was monitored, evaluating environmental variables as influencing factors in the oomycete infections. Laboratory experiments were performed to evaluate the susceptibility of infected copepods to consumption by predators. Although 5 species of copepods werepresent in the pond, only ovigerous P. sarsi females were parasitized by oomycetes. Two speciesof oomycetes were always found together: Aphanomyces ovidestruens and Pythium flevo ense.Infections were detected at water temperatures >20°C, with a positive relationship between temperature and parasite prevalence. Infection occurred after a decrease in large filter-feeder densities. The pathogens were not lethal to P. sarsi females in the short-term, but did produce mortalityof entire egg sacs, thus negatively impacting subsequent recruitment. Mean prevalence of infection in females was 53%, reaching 83% in December. Females have the capacity to release aninfected egg sac and generate a new one in a few days. This infection does not affect the susceptibility of P. sarsi to the predator Notonecta vereertbruggheni. The decrease in female abundanceregistered towards the end of the hydroperiod could be related to a combination of factors thatmay have a differential effect on female survival, such as increasing temperature, the energy costof egg sac development and carrying and oomycete infection.