Exploring the relationship between pollution and parasites in Corbicula fluminea

LIQUIN, FLORENCIA; HUNICKEN, LEANDRO; PAOLUCCI, ESTEBAN; ARRIGHETTI, FLORENCIA; DAVIES, DORA; FRANCISCO SYLVESTER

Montevideo

Congreso; SETAC Latin America 15th Biennial Meeting; 2023

SETAC Latin America

Studies about impacts of pollution on aquatic organisms have largely been proceededwithout taking into account other natural stress factors such as parasites. The majorityof aquatic organism exposed to pollutants are infected with at least one parasitespecies. However, the studies about the responses in individuals being simultaneouslyinfected with parasites and exposed to environmental pollutants are scarce. This studyaimed to compare the infection rate and effects of Chaetogaster limnaei parasite onCorbicula fluminea clams in two areas of the Rio de la Plata, a river with a pollutiongradient. The sampling sites were Parque de los Niños related to city activities, andPunta Lara which was away from city influence. Physicochemical datasets of each sitewere obtained from databases published by monitoring programs of the NationalMinistry of Environment and Sustainable Development on its website. Body conditionindex (i.e., dry tissue weight divided by shell length), histological alterations, and respiration rate were used as biomarkers to determine parasite effect. Parque de los Niños was the most contaminated site associated with high average concentrations of hydrocarbons (211 mg/l) and coliforms (106196 NMP/100ml). The condition index of clams of this site was lower than clams from Punta Lara and the proportion of clams infected by the parasite was 33%. Histological analyzes revealed gill damage in both infected and uninfected clams, and respiratory rate did not vary with the presence of the parasite. In Punta Lara, the site with less average concentrations of hydrocarbons (0.12 mg/l) and coliforms (16432 NMP/100ml), the proportion of clams infected by the parasite was 85%. Infected clams showed damage to their gills, which was more severe at high parasite loads. Furthermore, the respiration rates of infected clams were higher than those of uninfected ones. The presented results suggest differences in parasites load and in their effects on clams from two sites with different pollutant concentrations. Toxicological and parasitological studies should be integrated to understand properly if pollution influence the host-parasites interactions.