Macroinvertebrate responses to nickel in multisystem exposures

Area of Science:

• Environmental Chemistry
• Ecotoxicology
• Aquatic Ecology

Background:

• Metal bioavailability in sediments is influenced by complexation and partitioning.
• Nickel (Ni) introduces toxicity concerns in aquatic ecosystems.
• Predictive models are crucial for assessing metal bioavailability and ecological risk.

Purpose of the Study:

• To evaluate nickel toxicity and bioavailability in aquatic sediments.
• To assess the efficacy of simultaneously extracted metal (SEM)/acid volatile sulfide (AVS) and organic carbon (f(OC)) models in predicting Ni effects.
• To determine Ni toxicity at individual, population, and community levels.

Main Methods:

• Conducted two field studies: streamside mesocosms and in situ colonization.
• Performed laboratory toxicity tests with Ni-spiked sediments.
• Utilized SEM/AVS and f(OC) models to assess Ni bioavailability.
• Assessed impacts on benthic community structure (abundance, taxa richness) and sensitive invertebrate species.

Main Results:

• Benthic community metrics (abundance, taxa richness, Ephemeroptera) declined with increasing SEM(Ni)/AVS and (SEM(Ni)-AVS)/f(OC) values in mesocosm experiments.
• In situ colonization showed reduced taxa richness, abundance, and EPT taxa with higher SEM(Ni) and SEM(Ni)/AVS.
• Hyalella azteca (amphipod) was the most sensitive organism; Anthopotamus verticis and Stenonema spp. (mayflies) were the most sensitive indigenous organisms.

Conclusions:

• SEM/AVS and f(OC) models effectively indicated nickel toxicity and bioavailability in aquatic sediments.
• Nickel exposure negatively impacts benthic invertebrate communities and sensitive species.
• Understanding metal bioavailability is key to predicting ecological risk and informing environmental management.