Bioaccumulation of Arsenic and Zinc by Chironomid larvae in Lacustrine Environments: Exploring this Community as Indicator of Trace Element Dynamics in Patagonian Food Webs

Abstract The chironomid community is a key component of lacustrine systems, considering their larvae as a doorway for trace elements from benthic substrates to higher trophic levels. In Lake Moreno Oeste, a northern Patagonian lake (Argentina), arsenic (As), a non-essential and toxic metalloid, and zinc (Zn), an essential metal, were measured in several substrates and their associated chironomid larvae to evaluate their dynamics by understanding their distribution, and bioaccumulation and excretion patterns in this community. The highest As concentrations ([As]) were observed in sediment from littoral vegetated areas and deep zones, while the highest [Zn] were recorded in Myriophyllum sp. leaves. Larval feeding strategies influenced bioaccumulation patterns: collectors accumulated higher [As] (suggesting that the main As pathway is through the sediment ingestion), and predators and shredders recorded higher [Zn] (associated with its environmental availability and specific larval requirements). In purged material, both elements reached their maximum excretion factors in biological substrates (Myriophyllum sp. and submerged riparian leaves); however, [As] exceeded values in both substrates and larvae, while [Zn] surpassed values in substrates but remained lower than in larvae. Our findings explore chironomid larvae as vectors of trace elements from benthic substrates to upper trophic levels, highlighting their potential as metal bioindicators.