## 3 Results
### Analyses of Mussel CPUIE and Richness
Mussel estimated richness did not have a statistically significant zero-inflation component in the finite mixture model (\(\beta=0.24\) (\(\pm 0.40\) SE), z = 0.60, \(p=0.55\)), which explained 56.0% of the probability in the model. Mussel richness was positively related to higher PC 4 (\(\beta=1.05\) (\(\pm 0.81\) SE), z = \(4.94\), \(p<0.01\)), PC 5 (\(\beta=0.81\) (\(\pm 0.15\) SE), z = \(5.54\), \(p<0.01\)), PC 7 (\(\beta=0.81\) (\(\pm 0.16\) SE), z = \(5.11\), \(p<0.01\)), and negatively associated with higher PC 1 (\(\beta=-0.47\) (\(\pm 0.95\) SE), z = \(5.25\), \(p<0.01\)), PC 2 (\(\beta=-0.51\) (\(\pm 0.06\) SE), z = \(-8.27\), \(p<0.01\)), % less than 0.250 mm (\(\beta=-0.10\) (\(\pm 0.02\) SE), z = \(-4.96\), \(p<0.01\)), and % less than 0.125 mm (\(\beta=-3.56\) (\(\pm 0.66\) SE), z = \(-5.34\), \(p<0.01\)). Mussel richness was higher in upstream sites with higher DO (PCs 1, 7), % evergreen forest (PC 1), % Deweyville Terraces (PC 5), % Pascagoula Hattiesburg (PC 1), % Citronelle Formation (PC 1), and lower temperature (PC 1), % less than 0.125 mm, % mixed forest (PCs 2, 4), % deciduous forest (PC 2), % wetland (PC 2), % Alluvium (PC 1), % High Terraces (PC 1), and % Coastal Deposits (PC 2). \begin{table}
\begin{tabular}{c|c|c|c|c|c|c|c} \hline
**Variable** & **PC 1** & **PC 2** & **PC 3** & **PC 4** & **PC 5** & **PC 6** & **PC 7** \\ \hline Temperature & \(0.59\) & \(0.17\) & \(-0.31\) & \(0.43\) & \(-0.41\) & \(0.07\) & \(0.22\) \\ Dissolved oxygen & \(-0.55\) & \(0.12\) & \(0.23\) & \(0.28\) & \(-0.20\) & \(-0.10\) & \(0.52\) \\ Specific conductance & \(0.46\) & \(0.27\) & \(-0.36\) & \(0.23\) & \(0.44\) & \(0.32\) & \(0.15\) \\ pH & \(-0.09\) & \(0.59\) & \(0\) & \(0.24\) & \(0.50\) & \(-0.08\) & \(-0.09\) \\ Turbidity & \(0.27\) & \(-0.29\) & \(0.39\) & \(-0.27\) & \(0.44\) & \(0.23\) & \(0.08\) \\ \% Developed & \(-0.33\) & \(-0.31\) & \(-0.38\) & \(0.38\) & \(0.28\) & \(0.27\) & \(0.18\) \\ \% Agriculture & \(-0.60\) & \(-0.24\) & \(-0.69\) & \(-0.13\) & \(0.03\) & \(-0.02\) & \(0.10\) \\ \% De deciduous forest & \(-0.48\) & \(0.64\) & \(-0.08\) & \(-0.37\) & \(0.04\) & \(0.28\) & \(-0.02\) \\ \% Evergreen forest & \(0.56\) & \(-0.45\) & \(0.20\) & \(0.06\) & \(0.15\) & \(-0.56\) & \(-0.04\) \\ \% Mixed forest & \(-0.36\) & \(0.60\) & \(-0.08\) & \(-0.62\) & \(0.18\) & \(0.05\) & \(0.06\) \\ \% Wetland & \(0.24\) & \(0.54\) & \(0.61\) & \(0.21\) & \(-0.13\) & \(0.36\) & \(-0.08\) \\ \% Barren & \(0.33\) & \(-0.35\) & \(0\) & \(-0.02\) & \(-0.48\) & \(0.38\) & \(-0.08\) \\ \% Prairie & \(0.17\) & \(0.67\) & \(-0.08\) & \(-0.46\) & \(0.02\) & \(0.37\) & \(0.06\) \\ \% Alluvium & \(-0.54\) & \(0.01\) & \(0.53\) & \(0.48\) & \(-0.13\) & \(0.35\) & \(-0.10\) \\ \% High Terrace & \(-0.80\) & \(0.13\) & \(0.01\) & \(0.27\) & \(0\) & \(-0.37\) & \(-0.11\) \\ \% Deweyville & \(0.08\) & \(-0.38\) & \(0.17\) & \(0.37\) & \(0.73\) & \(0.11\) & \(-0.01\) \\ \% Pascagoula & \(0.80\) & \(0.48\) & \(-0.19\) & \(0.02\) & \(-0.01\) & \(-0.10\) & \(0.09\) \\ \% Citronelle & \(0.63\) & \(0.43\) & \(-0.47\) & \(0.16\) & \(0.01\) & \(0.02\) & \(-0.17\) \\ \% Coastal & \(0.45\) & \(0.21\) & \(0.54\) & \(-0.32\) & \(0.10\) & \(-0.20\) & \(0.31\) \\ Variance Explained & \(23.5\%\) & \(16.6\%\) & \(12.3\%\) & \(10.3\%\) & \(9.4\%\) & \(7.2\%\) & \(5.9\%\) \\ \hline \end{tabular}
\end{table} 
Table 5: Standardized scoring coefficients between variables with principal components (PCs). Shaded numbers were considered informative in interpretation of each PC. Many variables were correlated with multiple PCs and were also usually associated with richness. However, pH was both positively (PC 5) and negatively (PC 2) associated with richness, as was % mixed forest (positively with PC 4, negatively with PC 2. Although interannual variability was a potential explanation of low relative abundance, richness, and frequency of occurrence, analyses did not support strong evidence of interannual variability in CPUE or richness. Fewer mussels were sampled during the second visit to the nine revisited sites.