Our current research evaluates the influence of habitat restoration, nutrient enrichment, climate change, and other anthropogenic disturbances on coastal wetlands, mangroves, and subtidal seagrass beds. Current projects include:
Ecosystem restoration: ecological restoration of emergent coastal marshes and aquatic habitats
As our understanding of complex biotic and abiotic links between emergent marshes and adjacent aquatic habitats increases, restoration approaches must also increase in complexity. The development of plant canopy features is often considered to be a sign of successful coastal marsh restoration, but a robust plant canopy may not correspond with the recovery of other ecosystem attributes such as nutrient retention or energy flow through food webs. Furthermore, construction designs that incorporate different soil sources and elevation gradients can also influence the ecosystem characteristics of a restored marsh. Therefore, we are performing a series of monitoring and experimental series in order to understand patterns of ecosystem attribute recovery in restored coastal wetlands. Since 2009, we have been comparing the success of several emergent marsh restoration techniques by monitoring plant and animal assemblages in restored brackish marshes near Port Arthur, Texas. We are also conducting a number of experiments to understand how interactions between plants and herbivores are influenced by marsh restoration methods. An exceptional drought in 2011 provided us with the opportunity to examine how drought affected the development and recovery of these restored marshes. This research is supported through 2015 by the Texas General Land Office – Oil Spill Prevention & Response Division of Research and Development and Scientific Support and by the Texas General Land Office – Coastal Management Program.
Native mangrove invasion into northern Gulf of Mexico salt marshes: the influence of climate change
On the Texas coast, black mangroves (Avicennia germinans) regularly expand from persistent populations into salt marshes during periods with warm winters, and occasionally contract in distribution during periods with severe freezes. Over the coming decades, mangrove distributions are expected to continue expanding due to rising global temperatures and milder winters. As a result, large areas of the Texas coast that historically have been dominated by salt marshes will become dominated by mangroves. Will this matter? In a collaborative project with Dr. Steven Pennings (University of Houston), we hypothesize that that changes in coastal vegetation are likely to change the quality of coastal wetlands for supporting shrimp, fish and birds, and change the ability of coastal habitats to buffer wind and wave energy. We will test these hypotheses using a combination of field sampling and a manipulative experiment, working around and within the domain of the Mission-Aransas National Estuarine Research Reserve. Our work will provide information on which ecosystem services provided by coastal wetlands are most likely to be affected by the change from salt marsh to mangroves. This information will allow coastal industries such as fisheries and tourism to be adaptively managed in response to ongoing and future changes in the biological environment. This project is funded through 2016 by Texas Sea Grant.
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Blue carbon in coastal wetlands: the effects of restoration and woody encroachment
Carbon can be absorbed from the atmosphere and stored by microbial and plant communities in a process called sequestration. A portion of this carbon is respired by the plants and released back into the atmosphere, but the remainder is converted into biomass that may become sequestered in the soil for decades. Carbon that is sequestered in marine habitats such as marshes, mangroves, and seagrasses, is known as “blue carbon.” The carbon sequestration role of coastal habitats is likely to be of paramount importance in the maintenance of global atmospheric carbon levels, but the burgeoning field of blue carbon still lacks quantitative estimates of carbon storage in many marine habitats. Therefore, our research in this area addresses two general questions: (1) How does carbon storage in restored coastal wetlands compare to reference wetlands? (2) How does the encroachment of mangroves into salt marshes change the carbon storage potential of the ecosystem? To address these questions, we are collaborating with Dr. Patrick Louchouarn, Dr. Wes Highfield, and Dr. Sam Brody to integrate remote sensing with biogeochemical and biological estimates of carbon flux and storage on the Texas coast. This research is funded through 2014 by the Texas General Land Office – Coastal Management Program and the NASA Carbon Cycle Science Program.