Acta Limnologica Brasiliensia
http://www.alb.periodikos.com.br/article/doi/10.1590/S2179-975X0719
Acta Limnologica Brasiliensia
Short Research Note

Record of parasitic oomycetes on neotropical copepods in aquatic environments of Northwestern Patagonia (Argentina)

Registro de oomicetos parasíticos em copépodes neotropicais em ambientes aquáticos da Patagônia Noroeste (Argentina)

Roberto Daniel Garcia; Fabián Gastón Jara; Mónica Mirta Steciow

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Abstract

Abstract:: Aim: Oomycetes are one of the most widespread and destructive parasitic groups in the world. The first infection of oomycetes on copepod Parabroteas sarsi Daday 1901 was recently recorded in America. Oomycetes infection on this species makes their eggs unviable and could differentially affect the survival of females. The aim of this study was to track the incidence of oomycetes in two populations of P. sarsi.

Methods: Two Patagonian ponds were monitored during spring-summer of 2014-2018, measuring environmental variables and the prevalence of oomycete infections on P. sarsi populations. Taxonomic determination of the oomycetes was performed in laboratory. Sex ratios also were recorded in each survey.

Results: The presence of Aphanomyces ovidestruens Gicklhorn 1923 and Pythium flevoense Van der Plaats-Niterink 1972 was detected in females of P. sarsi in both ponds. We observed a decrease in the parasite prevalence over time, from ~25% (assessed on the total number of adults) to almost disappear completely. Besides, a lower proportion of females than males were observed in samples with high prevalence of parasitism. No temperature differences were found during the sampling years and the monthly temperatures between the maximum and minimum prevalences were similar.

Conclusions: Our study presents a new record of oomycetes parasitizing copepods in America. Temperature can play a key role in the dynamics of parasite species, but in our study this variable not affected the incidence of the infection. However, other variables could be affect the pattern of the infection such as the presence of predators of oomycetes spores (cladocerans). The lower females proportion when the infection was higher, could support the idea of differential sex/mortality induced by the infection. Recording and identification of parasites is a critical starting point for wildlife management, which will provide an early warning to prevent the spread of harmful parasites such as oomycetes.

Keywords

zooplankton, parasitism, calanoids, wetlands, sex ratios

Resumo

Resumo:: Objetivo: Os oomicetos são um dos grupos parasitários mais difundidos e destrutivos do mundo. A primeira infecção de oomicetos no copépode Parabroteas sarsi Daday 1901 foi recentemente registrada na América. A infecção por Oomycetes nesta espécie torna os seus ovos inviáveis e pode afetar diferentemente a sobrevivência das fêmeas. O objetivo deste estudo foi rastrear a incidência de oomicetos em duas populações de P. sarsi.

Métodos: Duas poças na patagônia foram monitoradas durante a primavera-verão de 2014-2018, medindo variáveis ambientais e a prevalência de infecções por oomicetos em populações de P. sarsi. A determinação taxonômica dos oomicetos foi realizada em laboratório. As proporções de sexo também foram registradas em cada pesquisa.

Resultados: A presença de Aphanomyces ovidestruens Gicklhorn 1923 e Pythium flevoense Van der Plaats-Niterink 1972 foi detectada em fêmeas de P. sarsi em ambas as poças. Observamos uma diminuição na prevalência de parasita ao longo do tempo, com uma redução que foi de aproximadamente 25% (considerando o número total de adultos) até próximo de desaparecer completamente. Além disso, uma proporção menor de fêmeas do que de machos foi observada em amostras com alta incidência de parasitismo. Não foram encontradas diferenças de temperatura durante os anos de amostragem e as temperaturas mensais entre as prevalências máxima e mínima foram semelhantes.

Conclusão: Nosso estudo apresenta um novo registro de parasitismo por oomicetos em copépodes na América. A temperatura pode desempenhar um papel fundamental na dinâmica das espécies parasitárias, mas em nosso estudo esta variável não afetou a incidência da infecção. No entanto, outras variáveis podem afetar o padrão da infecção, como a presença de predadores de esporos de oomicetos (cladóceros). A menor proporção de fêmeas quando a infecção foi maior indicam mortalidade diferencial por sexo induzida pela infecção. O registo e identificação de parasitas é um ponto de partida crítico para a gestão da vida selvagem, o que proporcionará um alerta precoce para prevenir a propagação de parasitas nocivos como os oomicetos.
 

Palavras-chave

zooplâncton, parasitismo, calanóides, zonas húmidas, proporção de sexos

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Submitted date:
01/28/2019

Accepted date:
05/26/2020

Publication date:
08/03/2020

5f28633a0e8825781e0e4938 alb Articles
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Acta Limnol. Bras. (Online)

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