The effect of untreated sewage discharge in food availability, egg production, and female survival of the copepod Acartia tonsa in a southwestern Atlantic estuary

Abstract

Estuarine copepods are considered ecological relevant components in the marine trophic webs and have high phenotypic plasticity and adaptability to face the environmental variations coastal marine ecosystems typically show. This work aims to assess the Acartia tonsa food availability, egg production, and female survival in an urban-industrial sewage discharge site (Canal Vieja, CV) and a non-disturbed site by sewage (Bahía del Medio, BM) from the Bahía Blanca Estuary, Argentina. Acartia tonsa females and microplankton samples, used as natural food, were taken during the austral warm season 2008–2009. The experimental incubations of the females were performed in a laboratory simulating the in situ environmental conditions. The microplankton showed different composition and abundance values between both studied sites. The survival of females showed significant differences between the sites, but the egg production did not show clear differences between them. A positive correlation was found among egg production, diatom, and tintinnid-ciliate abundances. A low female survival (16.5%) was observed when high ammonium concentrations (35.15μM) were recorded at CV. The concentration of nitrogenous nutrients, especially ammonium, along with pH and turbidity, were the drivers explaining the variation in the reproductive performance and survival of A. tonsa. Our findings further understand the reproductive performance, plasticity, and survival of key planktonic organisms in polluted coastal areas.