Exergy and biodiversity: the Valli di Comacchio study case

Temporal trends of exergy and biodiversity of macrofaunal assemblages were compared along a gradient of disturbance in the Valli di Comacchio, at four reference sites. Biodiversity parameters fluctuated through space and time, with higher values at the minimally disturbed site. Exergy was higher at the minimally disturbed site, but exhibited a zigzag pattern, being characterized both by very high and very low values. This pattern was primarily dictated by the fluctuations in the amount of bivalve biomass. In Annelida-dominated benthic communities, the presence of just a few bivalves has the capacity to increase greatly exergy values.