2.5. Epifauna diversity indices
Epifaunal community structure was described using the diversity indices related to the number and abundance of species recorded. Abundance was determined as the total number of individuals (N ) recorded across all sites and seasons. Species richness was defined using the Margalef index (d) that calculates the average number of species per unit number of organisms collected (Margalef, 1989). Species diversity was first determined after the Shannon-Wiener index (H’) (Shannon 1963), and thereafter converted to “effective number of species” by calculating the exponential (exp (H)) of each diversity value after Hill (1973). This transforms the non-linear H’ to a linear form that permits statistical comparisons that are intuitive, while the unit “number of species” allows for diversity comparisons across metrics (Jost et al. 2006, Jost et al. 2010).