Impacts of exotic mangrove forests and mangrove deforestation on carbon remineralization and ecosystem functioning in marine sediments

[摘要] To evaluate how mangrove invasion and removal can modify short-term benthiccarbon cycling and ecosystem functioning, we used stable-isotopicallylabeled algae as a deliberate tracer to quantify benthic respiration andC-flow over 48 h through macrofauna and bacteria in sediments collectedfrom (1) an invasive mangrove forest, (2) deforested mangrove sites 2 and 6years after removal of above-sediment mangrove biomass, and (3) twomangrove-free control sites in the Hawaiian coastal zone. Sediment oxygenconsumption (SOC) rates averaged over each 48 h investigation weresignificantly greater in the mangrove and mangrove removal site experimentsthan in controls and were significantly correlated with total benthic(macrofauna and bacteria) biomass and sedimentary mangrove biomass (SMB).Bacteria dominated short-term C-processing of added microalgal-C and benthicbiomass in sediments from the invasive mangrove forest habitat and in the6-yr removal site. In contrast, macrofauna were the most important agents inthe short-term processing of microalgal-C in sediments from the 2-yrmangrove removal site and control sites. However, mean faunal abundance andC-uptake rates in sediments from both removal sites were significantlyhigher than in control cores, which collectively suggest that communitystructure and short-term C-cycling dynamics of sediments in habitats wheremangroves have been cleared can remain fundamentally different fromun-invaded mudflat sediments for at least 6-yrs following above-sedimentmangrove removal. In summary, invasion by mangroves can lead to dramaticshifts in benthic ecosystem function, with sediment metabolism, benthiccommunity structure and short-term C-remineralization dynamics beingaffected for years following invader removal.

[学科分类] 地球化学与岩石