Aquatic Sciences

Nicholas S. Marzolf, Ph.D.

Variability of River Greenhouse Gas Emissions

Rivers are sources of greenhouse gases to the atmosphere. Gases are produced by in situ biological processes or contributions from external sources (e.g. terrestrial respiration, groundwater). Thus, the magnitude of GHG emissions from rivers varies widely within a river. In this project, we collect dissolved gas data (CO2, O2) continuously and the more potent methane (CH4) to determine the variability of production, emissions, and the relative contributions of gas concentrations. We use river ecosystem models to estimate gas exchange, primary productivity, and respiration and use a variety of empirical methods to quantify the hydrology and morphology of river ecosystems.

Carbon Cycling in Coastal Plain Wetlands

Freshwater wetlands store tremendous amounts of carbon in their soils and can play a major role in the global carbon cycle. The C storage capacity can be considered in land management plans to promote carbon sequestration. To understand the carbon cycle in wetlands of the SE Coastal Plain, our efforts aim to understand the interaction of water availability (e.g. rainfall and groundwater) and fire on the C stored in wetlands using paleo-ecological methods. We also quantify greenhouse gas emissions from wetlands, both with and without water present. The role of wetlands to the C cycle can be upscaled in evaluations of regional C models and management plans for longleaf pine ecosystems.

River Energetics and Biodiversity

Rivers are among the most modified ecosystems on Earth, and these modifications coupled with direct human uses of rivers, have altered the energy available to animals. In this project, we aim to explore the coupling of energy availability (e.g. primary productivity, terrestrial organic matter) with animal production and diversity to determine the (a)synchrony of energy flows and the drivers of this (a)synchrony. This project is being executed at both broad and focal scales, with our efforts in the Lower Flint River measuring energy inputs to rivers through ecosystem models and measures of animal biomass and diversity. Broad scale efforts will contribute empirical results to on-going syntheses and determining the effects of warmer temperatures and modified flow regimes on the energetics in rivers.