Ecotoxicological responses of the mayfly Baetis tricaudatus to dietary and waterborne cadmium: Implications for toxicity testing

Abstract

Trace metals readily accumulated by stream periphyton may enter aquatic food chains through grazer ingestion. Hence, experiments were conducted to determine the ecotoxicological responses of the grazing mayfly Baetis tricaudatus to dietary cadmium. Short-term feeding experiments indicated that B. tricaudatus nymphs did not initially avoid grazing on cadmium-contaminated diatom mats. During a partial life-cycle experiment, 4 and 10 microg/g of dietary cadmium significantly inhibited grazing, whereas 10 microg/g significantly inhibited growth. Feeding inhibition was the likely mechanism that inhibited growth (i.e., through reduced energy intake). Conversely, when exposed to waterborne cadmium using lethal toxicity test procedures, B. tricaudatus nymphs were relatively tolerant (96-h median lethal concentration, 1,611 microg/L). Thus, sublethal responses to dietary exposure appeared to be more sensitive than lethal responses to waterborne exposure. Because adult mayfly fecundity is a function of nymph size at emergence, dietary cadmium exposure could increase the extinction probability within mayfly populations. The present study highlights the importance of dietary exposure routes in determining the ecotoxicological responses of an organism to a contaminant. Furthermore, the findings emphasize the advantage of evaluating a combination of ecologically relevant, lethal and sublethal endpoints in laboratory methods used to generate data for ecological risk assessment and regulation.

Using Benthic Indicator Species and Community Gradients to Optimize Restoration in the Arid, Endorheic Walker River Watershed, Western USA

“…For example, growth and productivity curves for specific model organisms can be interpreted and applied to the parts of the watershed where the model organism is most representative. B. tricaudatus (Ephemeroptera) is often used as a model organism in lotic systems because of its abundance, multivoltine life history, and widespread occurrence (Robinson et al, 1992;Irving et al, 2003). The species can be used to develop detailed models linking changes in discharge, temperature, or water quality to changes in annual production that can be extrapolated to the larger BMI community.…”

Trophic transfer of metal-based nanoparticles in aquatic environments: a review and recommendations for future research focus

“…Yet, caution must be taken, as most studies have included relatively short exposure durations and few trophic levels. These studies do highlight the importance of the dietary exposure route, which results in a higher body burden [39][40][41][42] and differential levels of toxicity [40][41][42] when compared to water-only exposure. Despite the evidence for trophic transfer, the main factors and mechanistic processes that control this, in the case of Me-ENPs, remain largely unknown.…”

Uranium Bioaccumulation Dynamics in the Mayfly Neocloeon triangulifer and Application to Site-Specific Prediction

“…4,5 Insect larvae accumulate metals from both aqueous and dietary exposure routes, 6,7 triggering adverse effects ranging from feeding and growth inhibition to death. 8 Elevated metal exposures, such as those occurring in water bodies in mined watersheds, can eliminate sensitive species, thus altering the structure of insect communities 9 and the trophic linkages of aquatic food webs. 10 Furthermore, the consumption of metalcontaminated aquatic insects can impair physiological functions and reduce the growth and survival of fish, 11,12 implying that metal trophic transfer can decrease fitness and population sizes of aquatic insectivores.…”

“…Metal contamination of aquatic ecosystems is a global environmental issue that is often related to mineral extraction. − It is linked to a variety of negative impacts on aquatic ecosystems including detrimental effects on aquatic insect communities that form the prey base for many aquatic and terrestrial organisms and play a vital role in many ecosystem functions such as organic matter processing. , Insect larvae accumulate metals from both aqueous and dietary exposure routes, , triggering adverse effects ranging from feeding and growth inhibition to death . Elevated metal exposures, such as those occurring in water bodies in mined watersheds, can eliminate sensitive species, thus altering the structure of insect communities and the trophic linkages of aquatic food webs .…”