Assisted colonization of a regionally native predator impacts benthic invertebrates in fishless mountain lakes

The intentional introduction of native cold-water trout into high-elevation fishless lakes has been considered a tool to build resilience to climate change (i.e. assisted colonization); however, ecological impacts on recipient communities are understudied. The purpose of this study was to inform native cold-water trout recovery managers by assessing potential consequences of translocating a regionally native trout (westslope cutthroat trout; Oncorhynchus clarkii) into fishless mountain lakes. This study compared littoral benthic invertebrate richness, diversity, community structure, and density between three groups of lakes (fishless, native trout, nonnative trout) in the Canadian Rocky Mountains. While richness and diversity were preserved across all lake groups, other lines of evidence suggested that the introduction of native westslope cutthroat trout into fishless lakes can alter littoral benthic invertebrate communities in similar ways as nonnative brook trout (Salvelinus fontinalis). The community structure of cutthroat trout lakes resembled brook trout lakes compared to that of fishless lakes. For example, both trout-lake groups contained a lower density of free-swimming ameletid mayflies and a higher density of certain burrowing taxa. Risk assessments for trout-recovery actions should consider the potential for collateral damage to recipient invertebrate communities. Future research should identify possible cascading trophic effects on species subsidized by invertebrate prey.The data package includes: 1) raw count data collected from 202 sample sites at 36 alpine and sub-alpine lakes (including zooplankton) (RAW_taxa_2015_2016.xlsx); 2) density values (individuals·m2) for 26 common (present in >10 % of lakes) littoral invertebrate (rare taxa and zooplankton excluded), categorized by lake group (fishless, nonnative, native) (taxa.csv); 3) density values (individuals·m2) for 50 littoral invertebrate families (rare taxa included, zooplankton excluded), categorized by lake group (fishless, nonnative, native) (taxa_diversitymeasures.csv), and; 4) environmental predictor variables for each lake, categorized by lake group (fishless, nonnative, native) (env.csv). All anlayses performed in the publication are combined into one R script (R_Script_Banting_etal.R). All data comes from Kootenay National Park, B.C., and Banff National Park, Alberta. Date of data collection: June & July of 2015 & 2016 Funding provided by: Parks CanadaCrossref Funder Registry ID: http://dx.doi.org/10.13039/100014612Funding provided by: Alberta Conservation AssociationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100007583Award Number: 020‐00‐90‐230For a full description of methodology, please refer to "Assisted colonization of a regionally native predator impacts benthic invertebrates in fishless mountain lakes", published in Conservation Science and Practice