## 3 Results
macrochirus_), and Brown Bullhead contributed the most to dissimilarities (Table 2). The largest overall difference was between the Excellent group and OSM_Post (88.99%), and the smallest difference was between OSM_Pre and OSM_Post \begin{table}
\begin{tabular}{c c c c} \hline  & **Excellent** & **OSM\_Pre** & **OSM\_Post** \\ \hline Abundance (fish/m\({}^{2}\)) & 0.334 & 0.354 & 0.531 \\ \hline Piscivore abundance (fish/m\({}^{2}\)) & 0.183 & 0.004 & 0.006 \\ \hline Common Carp abundance (fish/m\({}^{2}\)) & 0.001 & 0.001 & 0.036 \\ \hline Biomass (g/m\({}^{2}\)) & 2.32 & 1.07 & 2.69 \\ \hline Richness & 12.1 & 7.4 & 6.4 \\ \hline Shannon–Wiener Diversity Index & 1.54 & 1.43 & 0.99 \\ \hline \end{tabular}
\end{table} 
Table 1: Average species richness, biomass, abundance, and Shannon–Wiener diversity index scores for the Excellent reference sites, Oshawa Second Marsh pre-Common Carp monitoring (OSM_Pre), and Oshawa Second Marsh post-Common Carp (OSM_Post) monitoring. (58.9%, Table 2). The overall dissimilarity between the OSM_Pre and Excellent groups was 17% less than between the OSM_Post and Excellent groups. OSM_Post had the largest ellipse size, followed by OSM_Pre, and the Excellent group had the smallest, suggesting that the Excellent group had the least within-group variation (Figure 3). Figure 2: Box-and-whisker plots for the 10 environmental variables significantly differing between the Excellent, pre-Common Carp monitoring (OSM_Pre), and post-Common Carp (OSM_Post) monitoring. Lower-case letters represent significant pairwise differences based on Tukey’s or Mann–Whitney pairwise tests (depending on normality). To track the trajectory of the OSM fish community, the distance between each OSM sampling point and the centroid of the Excellent group ellipse was measured, and the distances were averaged by group (Figure 4). The average distance to the Excellent group was significantly different when comparing OSM_Pre to OSM_Post (\(p<0.001\)). The largest change in distance was between 2009 and 2010, when OSM transitioned from OSM_PRE to OSM_POST (1.21), which was over double the average change in distance (0.52). The coefficient of variation for the distance to the Excellent centroid was 0.28. Sampling events OSM_2006 to OSM_2009 show a general movement toward the Excellent group, but, at OSM_2010, the dissimilarity between the Excellent group increased considerably. OSM_Post has high variability (distance between CCA plot points), but the majority is on axis 2, remaining far from the Excellent group on axis 1. \begin{table}
\begin{tabular}{c c c c c} \hline Group 1 & Excellent & Excellent & OSM\_Pre & All pooled \\ \hline Group 2 & OSM\_Pre & OSM\_Post & OSM\_Post & \\ \hline Overall & & & & \\ dissimilarity (\%) & 71 & 88.99 & 58.9 & 78.2 \\ \hline \multirow{6}{*}{Species} & Yellow Perch & Fathead & Fathead & Yellow Perch \\  & (18.12) & Minnow (16.61) & Minnow (22.39) & (15.05) \\ \cline{2-5}  & Goldfish (11.75) & Yellow Perch & Pumpkinseed & Fathead \\  & & (14.08) & (16.89) & Minnow (13.47) \\ \cline{2-5}  & Brown Bullhead & & & \\ (10.48) & Goldfish (12.61) & Goldfish (15.22) & Goldfish (12.42) \\ \cline{2-5}  & Bluegill (8.489) & Bluegill (8.621) &
\begin{tabular}{c} Common Carp \\ (12.58) \\ \end{tabular} & Bluegill (8.33) \\ \cline{2-5}  & Fathead & Common Carp & Brown Bullhead & Brown Bullhead \\ Minnow (8.154) & (7.28) & (10.27) & (8.09) \\ \hline \end{tabular}
\end{table} 
Table 2: SIMPER results showing overall dissimilarity of fish community composition and species with the largest contribution to dissimilarity between groups. Figure 3: Ordination plot (CCA) for 39 coastal wetland fish sampling events representing three groups: Excellent condition, OSM_Pre, and OSM_Post. (**A**)—group centroids, 95% ellipses, and environmental variables. (**B**)—fish species. The DRCWMP fish IBI is used as a measure of fish community health. Changes in fish IBI over time at OSM were tracked (Figure 4). The highest fish IBI score was in 2005 with 2009 s (46.0 and 44.8, respectively).