<p>The chironomid community is a key component of lacustrine systems, with their larvae acting as a potential pathway of trace elements from benthic substrates to higher trophic levels. In Lake Moreno Oeste, a northern Patagonian lake (Argentina), arsenic (As), a nonessential and toxic metalloid, and zinc (Zn), an essential metal, were seasonally measured in several substrates (submerged leaves of riparian vegetation, macrophytes, and sediment from vegetated littoral to non-vegetated deeper zones), and in their associated chironomid assemblages, to assess metal bioavailability by examining larval bioaccumulation and excretion in relation to their functional feeding habits. The highest As concentrations were found in sediment from littoral vegetated areas and deep zones, while the highest Zn values were recorded in <i>Myriophyllum</i> sp. leaves. Functional feeding strategies influenced bioaccumulation patterns: collectors recorded higher As levels (suggesting sediment ingestion as the main As pathway), and predators and shredders showed elevated Zn values (associated with its environmental availability and specific larval requirements). In feces from purged larvae, both elements reached their maximum excretion factors in biological substrates (<i>Myriophyllum</i> sp. and submerged riparian leaves); however, As concentrations exceeded those measured in both substrates and larvae, while Zn surpassed values in substrates but remained lower than in larvae. Our findings explore chironomid assemblages as vectors of trace elements from benthic substrates to upper trophic levels in the food web, highlighting their potential as sensitive indicators of metal(loid) bioavailability, even in low-impact systems.</p>