Figure 1.
General overview of the geographical setting of the 83 sampled sites.
All sites are located in regions where seagrass is present or has been present in the past.
Figure 2.
Diagram of a conceptual structural equation (SE) model describing possible relationships between sediment grain size (D10), total nitrogen, light attenuation and seagrass density.
Bidirectional dashed arrow lines depict relationships of which the causality and relevance are not sure. We also tested for covariance between residuals of total nitrogen and sediment D10, which is indicated by the dotted arrow line.
Table 1.
Results from the multiple linear regression analysis with stepwise backward selection of explanatory variables.
Figure 3.
Diagram of the three stable and significant structural equation models.
A) Model 1 provided the best fit to the data. It includes a positive feedback loop between sediment grain size (D10), light attenuation and seagrass density. B) The second best model (2) describes the relation between seagrass and sediment grain size in the opposite direction compared to model 1. C) The third, lowest-ranking model (3) was the simplest of the three model and did not include a direct relation between seagrass and sediment grain size. Note that light attenuation was reciprocally transformed and that the effect of nitrogen is therefore negative, while the effect of sediment D10 is positive (higher value for light attenuation = increased water clarity). Values above the arrow lines depict the standardized regression weights.
Table 2.
Results from the structural equation modeling (SEM) specification search.