Length of zebra mussels in June attached to rocks (white boxplots) and hydrilla (light grey) and attached to hydrilla in September (dark grey). The lower and upper lines of the boxplots represent the 25th and 75th percentiles and the bold line represents the median. Data falling outside the percentile range are plotted as outliers. Asterisks above the boxplots denote statistically significant differences between mussels on rocks vs. hydrilla in June (Mann Whitney U tests with Bonferroni corrections, * p-value < 0.05, ** p-value < 0.01. There were no significant differences between June and September except for Crane A and BR1 Cove G (denoted by a plus, pairwise t-test, p-value < 0.05).