Carbon Dynamics on Floodplains of the Yangtze and Mekong Rivers PDF Download

Author: Benjamin L. Miller
Publisher:
ISBN:
Category :
Languages : en
Pages : 182

Get Book

Book Description
The lateral expansion and contraction of rivers across their floodplains inextricably links aquatic and terrestrial ecosystem processes for part of each year, yet our understanding of the ecological responses to this seasonal hydrologic forcing is distinctly incomplete. The Flood Pulse Concept (FPC) predicts how in-situ primary production and respiration respond to this forcing. Although many of its predictions remain untested, the FPC is highly-cited and continues to guide hypotheses of ecosystem studies in tropical and subtropical flood-pulse rivers. In Chapter 1 of this dissertation, I reviewed the literature published from 1989 to 2019 on tropical rivers to provide an updated narrative of how primary production and respiration change in response to the seasonal flood-pulse. The literature shows that the in-situ respiration of a combination of aquatic and terrestrial organic carbon (C) exceeds primary production in tropical and subtropical flood-pulse rivers (i.e.,ecosystems are net heterotrophic). For the remainder of the dissertation, I propose that this net heterotrophy changes in response to flood-pulse hydrology and is sustained by both aerobic and anaerobic metabolism, contributing to the composition of dissolved C gases in water, atmospheric emissions of C gases, and the energetic base of aquatic food webs. I further propose that such cycling of C in flood-pulse rivers is fundamentally changed by hydropower development, which alters the magnitude and timing of the seasonal flood-pulse. A central theme that has emerged from the dissertation research presented here is the importance of anaerobic metabolism, specifically CH4 production and oxidation, within inland waters. Anaerobic metabolism has been largely ignored in studies of aquatic C cycling and ecosystem metabolism, with implications for C accounting in other flood-pulse and anaerobic ecosystems, worldwide. Collectively, this work demonstrates that CH4 production and oxidation contribute significantly to CO2 oversaturation, atmospheric C fluxes, and aquatic biota, challenging existing assumptions about terrestrial-aquatic transfers, net heterotrophy, and food web support within flood-pulse rivers and lakes.