Data from: The effects of nutrient enrichment and invasive mollusks on freshwater environments

The effects of invasive species might be altered by anthropogenic
activities such as nutrient pollution or the presence of additional
invasive species with similar or unique traits. Using experimental
mesocosms, we tested the separate and combined effects of three invasive
mollusks (zebra mussels, Asian clams, and banded mystery snails) on
freshwater environments in nutrient-poor and nutrient-enriched conditions.
We predicted that in nutrient-poor conditions, single mollusk species
would reduce the abundance of algae and zooplankton, but nutrient
enrichment would mitigate these effects. Regardless of nutrient additions,
paired bivalve species would reduce phytoplankton and zooplankton
abundance, increasing periphyton biomass. Bivalves and snails paired
together would reduce periphyton, phytoplankton, and zooplankton compared
to communities with paired bivalve species. Finally, nutrient enrichment
would increase the survival or biomass of paired bivalves and snails.
Single, paired, and three co-occurring invasive mollusks did not affect
algae or zooplankton abundance. Banded mystery snails reduced nutrient
concentrations in high-nutrient conditions more than other invasive
species, but the reduced nutrients did not affect algal abundance. Paired
invasive species did not affect the survival or biomass of other invasive
species. Nutrient enrichment increased the biomass of zebra mussels and
mystery snails, but not Asian clams. Additionally, zebra mussel
reproduction increased in the high nutrient treatment when banded mystery
snails were present, but not when all three species were together. We
conclude that human-induced trophic states might determine the effects
that single and multiple invasive species have in freshwater
environments.