Role of macrobenthic fauna in mangrove carbon fluxes indicated by their cellulase and hemicellulase activities

Abstract

Numerous studies have focused on the impact of biotic factors under the role of organic matter in the dynamics of mangrove ecosystems during the last decades, but an overall view of the role of macrobenthic fauna in organic matter processing has not yet been established. Cellulase and hemicellulase (xylanase and laminarinase) activities were measured in the extracts from eight native mangrove macrobenthic species (two gastropods, three crabs and three bivalves) of southern China with plate assay and colorimetric assay. All enzyme activities were detected in the eight species except for negligible exoglucanase activity in the crabs and the bivalves. The crabs generated the largest halo zones in the plate assays, but produced the lowest amount of reducing sugar in the colorimetric assays. The highest endoglucanase, β-1,4-glucosidase and xylanase activities were detected in Crassostrea rivularis with colorimetric assays. For each mangrove macrobenthic species, the laminarinase activity was highest among the enzyme activities that were detected. The results suggest that mangrove macrobenthos participates in the carbon cycling of the mangrove ecosystem via the consumption and conversion of mangrove primary production at different ecological niches and that they prefer algae as a major food source rather than mangrove leaf litter from September to October.