Some structural and functional aspects of the epiphytic component of four seagrass species (Cymodoceoideae) from Papua New Guinea

Abstract

The epiphytic component of four monospecific seagrass beds from Papua New Guinea was studied structurally and functionally. The floristic composition and abundance of the epiphytes on leaves of four seagrass species (Cymodoceoideae) showed considerable variation, but on all four seagrass species, the same algae were among the five quantitatively most important epiphytes: encrusting coralline algae, Cyanophyta, Ceramium gracillimum (Harv.) Mazoyer, Polysiphonia savatierii Hariot and Audouinella spp. The temporal pattern of the epiphytic algae showed more or less the same features on the four seagrass species. Annual mean biomass of epiphytes and seagrass leaves ranged from 54 g ADW m −2 in a community of Cymodocea rotundata Ehrenb. and Hempr. ex Aschers. to 169 g ADW m −2 in a community of Syringodium isoetifolium (Aschers.) Dandy. The contribution of the epiphytic component to the total above-ground biomass ranged from 22 to 24%. Productivity of epiphytes was highest on leaves of Halodule uninervis (Forssk.) Aschers. (2.12 g ADW m −2 sediment surface day −1) and the epiphytic community contributed 35–44% of the total above-ground production of these four seagrass communities.