Metal uptake in Psettodes erumei and Hysterothylacium spp. larvae in the Persian Gulf: Evaluation of larvae as bio-indicator.

This study aimed to compare the concentrations of heavy metals in Psettodes erumei as host fish and larvae of Hysterothylacium spp. as its parasite. Moreover, to evaluate the larvae as bio-indicators the uptake of heavy metals, the infected and non-infected fish were also compared. Fresh P. erumei species (n = 19) were randomly sampled during four months from Bushehr County, Iran. The digestive tract of each fish was examined for nematode parasites using a stereomicroscopy. The isolated nematodes were identified, and content of Fe, Cu, Zn, Co, Ni, Cr, As, Cd, Hg, and Pb were measured using ICP-OES. The metal concentrations were simultaneously analyzed for the muscles of infected fish and their parasites, as well as non-infected ones. Of the 19 P. erumei examined, 13 (68.4%) P. erumei were infected with Hysterothylacium spp. larvae. The parasites had significantly higher level of Fe, Cu, Zn, and Ni (with mean value of 7.59, 0.572, 1.223, and 4.623 mg/kg, respectively) than the muscles of the host fishes (with mean value of 3.29, 0.0010, 0.586, and 0.277 mg/kg, respectively) (p < 0.05). Infected hosts showed significantly lower amounts of As element in their muscles (0.050 mg/kg) than non-infected hosts (0.113 mg/kg) (p < 0.05). The findings emphasize the potential role of Hysterothylacium spp. larvae as bio-indicators for monitoring heavy metals pollution in marine ecosystems. © Indian Society for Parasitology 2021.