Artificial substrate experiments to investigate potential impacts of invasive quagga mussel (Dreissena rostriformis bugensis, Bivalvia: Dreissenidae) on macroinvertebrate communities in a UK river

摘要

Predicting potential impacts of a new invasive species remains difficult. A group ofparticular concern in the UK are freshwater invertebrates from the Ponto-Caspianregion, including the recently established quagga mussel (Dreissena rostriformisbugensis, Bivalvia: Dreissenidae). We explored invertebrate colonisation across aseries of manipulated substrate tiles with gradated densities of D. r. bugensis shellsfixed to their surface (2220, 1111, 666, 222 and 0 individuals m -2 ). Across threeexperiments of different substrate tile deployment duration (14, 30 and 62 days),we observed significant differences in invertebrate density and richness amongshell density treatments. Variation was primarily driven by low and high values onour control and highest substrate shell treatments, respectively. Within eachexperiment, similar taxa appeared to benefit from the physical effects of D. r. bugensisshells (e.g. Gammarus pulex, Chironomidae spp., Elmidae spp. and Hydropsyche spp.)being found with greater abundance on substrate tiles with higher D. r. bugensisshell treatments. Compared to invertebrate density, the response of taxonomicrichness was weaker and only significant within our 30 and 62 day experiments oflonger substrate tile deployment duration. Regardless, increased invertebratedensity and richness across the highest shell treatments provided a strong indicationof potential D. r. bugensis impacts on macroinvertebrates in the study river. Ifmussel densities were to increase to equivalent levels in other UK rivers, we couldexpect similar impacts to benthic fauna. While the likelihood of D. r. bugensisachieving such population densities are uncertain in such environments, our resultswere considered conservative because they did not account for additionalfacilitative impacts associated with live mussels. We add that, in the context ofinvasive species management, potential facilitation of native benthic faunaassociated with D. r. bugensis in the UK should not be considered positively, nornecessarily sustainable over longer time periods. Further, facilitative effects couldassist the establishment of other invasive invertebrates such as amphipods ofDikerogammarus spp., which were first recorded in the study river during thisinvestigation.