|Global Change and Estuarine Carbon Dynamics
|Year of Publication
|Hopkinson C, Weston N, Cai W-J
|Climate Change and Estuaries
Carbon (C) is the central building block of all organic matter and the currency by which ecologists and biogeochemists often measure the performance of natural ecosystems and human-controlled systems, including forests, agriculture, and aquaculture. CO2 gas in the atmosphere plays a major role in defining the earth's climate and it is the global C cycle operating on geologic time scales that dictates its long-term concentration. Since the industrial revolution and the large-scale burning of fossil fuels in the 1800s, however, the atmospheric concentration of CO2 has increased by over 120 ppm and is now out of balance with geological cycles of weathering and subduction. This has led to an alteration of the earth's heat balance and temperature, which has been affecting the performance of all ecosystems. Here, we discuss the effects of climate change and many other human activities, such as land-use change, on estuarine C budgets and dynamics. We evaluate the processes of primary production, autotrophic and heterotrophic respiration, net ecosystem production, C burial, and the exchange of dissolved and particulate forms of organic and inorganic carbon with adjacent land and ocean realms. We examine a suite of external drivers (including nitrogen deposition, human population, river engineering, land use and land cover, climate variability and extreme events, and land management practices on the timing, quantity, and quality of watershed inputs to the coast. We examine drivers of estuarine ecosystem performance also, including light, temperature, precipitation, tides, currents, waves, and sea-level rise. Our interest is not only in the rates of key ecosystem processes, such as primary production, but also in the shift in the relative habitat makeup of estuarine ecosystems, including tidal wetlands, seagrass meadows, open water tidal creeks, sounds, and bays. Finally, we summarize a recently completed C budget for estuaries of the continental USA.