Leaf productivity of the seagrass, Posidonia australis, in eastern Australian waters

Abstract

Leaf blade production rates of Posidonia australis Hook. f. have been found to range from 0.7 to 5.5 g dry wt. m −2 day −1, depending on site and season. Leaf-blade production (m −2) was significantly higher in Jervis Bay (New South Wales) compared to Botany Bay (New South Wales) and summer and winter values from a Spencer Gulf (South Australia) site were higher than those of Jervis Bay. In Botany Bay, the average turnover rate of Posidonia leaves is about 0.8–1.1% of leaf biomass per day (i.e. three to four crops of leaves produced per year). Biomass, shoot density and some leaf characteristics are also presented for each site. The contribution of seagrass communities to total primary production in the waters of Botany Bay is estimated to be of major importance, and the continued reduction in this contribution, due to urban development, is a matter of concern.