## 2 Materials and Methods
### Data Analysis  
To determine the impact of Common Carp, fish community composition and health were compared at OSM before and after Common Carp recolonization and between OSM and Excellent health sampling events in other DRCWMP wetlands. The Excellent group represents all sites that scored an Excellent fish IBI score using the DRCWMP fish IBI; OSM_Pre represents OSM sampling from 2005 to 2009 during Common Carp exclusion; and OSM_Post represents OSM sampling from 2010 to 2015, excluding 2012, after Common Carp had colonized. The DRCWMP coastal wetland fish IBI was used as a measure of fish community health [20]. Means of biomass, abundance, Shannon-Wiener diversity index, and richness were calculated for each sampling event and group. Due to varying numbers of transects per sampling event, total biomass and abundance were standardized by area (m\({}^{2}\)). Differences in environmental variables between groups were evaluated by a one-way analysis of variance (ANOVA), and [PERSON]'s post-hoc pairwise test [22] was used to identify significant pairwise differences. If data were non-parametric, as determined by the Shapiro-Wilk test, the Kruskal-Wallis one-way analysis of variance was used, and pairwise differences were determined using the Mann-Whitney U-test statistic [22]. For multivariate analysis, species data were square-root transformed to reduce the impacts of dominant species [23]. To determine the most appropriate ordintion technique, a Detrended Correspondence Analysis (DCA) was completed on the species assemblage matrix [23]. A Canonical Correspondence Analysis (CCA) was subsequently used as the length of the longest DCA gradient was greater than 2.5 and CCA tolerates skewed species and environmental data [24; 25; 26; 27]. Eight environmental variables significantly correlated with fish IBI were included in the CCA. Because of the multicollinearity between conductivity, salinity, and total dissolved solids, only conductivity was used in the analysis as it had fewer missing values. Further examination of CCA results was undertaken using ANOSIM and SIMPER [28]. ANOSIM is a non-parametric permutation MANOVA that measures the variation between groups to determine if the distance is significant. Using OSM_Pre, OSM_Post, and Excellent groups, ANOSIM was run using the Bray-Curtis similarity index based on 9999 permutations. ANOSIM pairwise-relationship significance was based on Bonferroni-corrected \(p\) values less than 0.05. SIMPER is based on total dissimilarity between groups and identifies which species most influence the difference between groups. All data analyses were completed using PAST [29].  
To determine if the fish community composition was becoming more similar to the Excellent community, the distance of each OSM sampling event to the Excellent group centroid was measured. Distance and change in distance were used to determine if the site was moving toward the reference Excellent group, using the assumption that movement toward the reference Excellent group is an improvement in health.  
To further interpret species composition between different groups and species locations on the CCA, species were classified based on anthropogenic stressors [30]. To determine the relative abundance of piscivores, feeding diets were determined using [PERSON] et al. [31]. Species with a diet high in fish were classified as piscivores. Outliers were removed if their z score was greater than three to reduce the influence of these points on subsequent analysis [32; 33].