## 3 Results
### Correlations between Extract Traits and Bacterial Densities  
The density of bacteria settled on eelgrass surfaces was significantly correlated with the mean defence activity against four bacterial isolates, which tended to be higher (= more negative) when the bacterial density was also high (linear regression, \(p<0.05\), Figure 4, Table 4). A similar correlation between the density of bacteria settled on eelgrass and the mean defence activity one month later was also observed (Figure 4, Table 4). In contrast, the density of bacteria on eelgrass leaves was not significantly correlated with the antifouling defence activity in the preceding month (Figure 4, Table 4). Bacterial fouling pressure also exhibited a significant correlation with the mean antifouling activity strength defence (Figure 4, Table 4). Bacterial fouling pressure was similarly correlated with the lagged mean antifouling defence that was observed one month after the fouling pressure (Figure 4, Table 4). As was to be expected, no significant correlation was detected between the defence activity strength and the density of bacteria on glass slides one month later (data not shown).  
The concentration of rosmarinic acid on the surface of eelgrass was positively correlated with fouling pressure in the same month and even stronger with fouling pressure in the preceding month (Figure 4, Table 4). However, it was not significantly correlated with the density of bacteria on the surface of eelgrass in the actual or preceding month (Figure 4, Table 4). Instead, rosmarinic acid concentrations were weakly (\(p<0.055\)) negatively correlated with bacterial densities on eelgrass leaves in the following month.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & & **AS** & **B** & & **C** \\ \hline
**Parameters** & **r** & \(p\)**-Value** & **R** & \(p\)**-Value** & **R** & \(p\)**-Value** \\ \hline BD to AS & \(\mathbf{-0.7395}\) & \(\mathbf{0.0116}\) & \(\mathbf{-0.7330}\) & \(\mathbf{0.0237}\) & \(0.6368\) & \(0.123\) \\ FP to AS & \(\mathbf{-0.7075}\) & \(\mathbf{0.0256}\) & \(\mathbf{-0.7112}\) & \(\mathbf{0.0376}\) & & \\ BD to RA & \(0.4989\) & \(0.3709\) & \(0.6195\) & \(0.3021\) & \(-0.6913\) & \(0.0545\) \\ FP to RA & \(\mathbf{0.7272}\) & \(\mathbf{0.016}\) & \(\mathbf{0.7580}\) & \(\mathbf{0.013}\) & & \\ \hline \hline \end{tabular}
\end{table}
Table 4: Pearson correlations of bacterial densities on \(Z\). _marina_ (BD) and on glass slides (FP) with the mean activity strength of \(Z\). _marina_ surface extracts against bacterial isolates (AS) and the rosmarinic acid concentration (RA) in these extracts. In (A), bacterial densities were correlated with AS and RA in extracts sampled in the same month. In (B), bacterial densities were correlated with AS and RA in extracts sampled one month later (=lagged responses). In (C) BD was the lagged response and correlated with AS and RA in extracts sampled one month earlier. Bold types indicate significant correlations (\(p<0.05\)).  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & & **SS** & **DF** & **MS** & **F** & \(p\)** \\ \hline A & Intercept & \(0.08607\) & \(1\) & \(0.08607\) & \(0.21\) & \(0.8885\) \\  & Error & \(0.00070\) & \(3\) & \(0.000233\) & & \\  & Month & \(0.06532\) & \(6\) & \(0.01089\) & \(9.77\) & \(<0.0001\) \\  & Error & \(0.02005\) & \(18\) & \(0.001114\) & & \\ \hline B & Intercept & \(0.0171\) & \(1\) & \(0.0171\) & \(118.57\) & \(0.0017\) \\  & Error & \(0.0004\) & \(3\) & \(0.0001\) & & \\  & Month & \(0.0005\) & \(6\) & \(<0.0001\) & \(1.58\) & \(0.2097\) \\  & Error & \(0.0010\) & \(18\) & \(<0.0001\) & & \\ \hline \hline \end{tabular}
\end{table}
Table 3: Repeated measures ANOVA of (A) the mean antisettlement activity of propan-2-ol surface extract from \(Z\). _marina_ against four different bacteria (\(B\). _aquimaris_, _A. stellipolaris_, _L. rosea_, and _P. dokdonensis_) and (B) rosmarinic acid concentrations on \(Z\). _marina_ surfaces. Within-measures factor was the month of sampling.