Impacts of infauna on acoustic and geotechnical properties of sediments (ONR funded)
Through burrowing, tube and burrow construction, and ingestion and egestion of sediments, animals modify the geological and geotechnical properties of marine sediments and therefore the propagation of sound through sediments. Geotechnical and acoustic properties of sediments are important to seafloor mapping, acoustic detection of targets, and sediment stability. This project aims to characterize the impacts of infauna with different functional traits on bulk cohesive sediments by measuring sound speed, attenuation, and geotechnical properties of laboratory mesocosms and sediment cores.
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Mechanisms of bioturbation and ecosystem engineering by benthic infauna (NSF funded)
This project integrates field and lab experiments to assess the relative importance of infaunal community structure and activities to bioturbation rates. Additionally, this project builds on recent work showing that muddy sediments are elastic gels through which worms extend burrows by fracture to propose that geotechnical properties of sediments mediate bioturbation by governing the release of particles from the sediment matrix during burrow extension. Finite element modeling will determine how the release of particles by fracture during burrowing depends on the fracture toughness (cohesion) and stiffness (compaction) of sediments and will complement laboratory experiments characterizing the impact of geotechnical properties on burrowing behaviors.
Sediment infauna have long been considered ecosystem engineers, and the ecological implications of their impacts on biogeochemical cycling and on surface roughness are well established. Infauna also modify bulk geotechnical properties, and the proposed research aims to determine whether these impacts are ecologically important, e.g., through positive feedbacks between infaunal activities and sediment properties that may promote community stability and maintain patchiness of infaunal communities and sediment properties. Changes in infaunal communities and geotechnical properties following an experimental physical disturbance will address the hypothesis that ecosystem engineering of bulk sediment properties facilitates succession.
Sediment infauna have long been considered ecosystem engineers, and the ecological implications of their impacts on biogeochemical cycling and on surface roughness are well established. Infauna also modify bulk geotechnical properties, and the proposed research aims to determine whether these impacts are ecologically important, e.g., through positive feedbacks between infaunal activities and sediment properties that may promote community stability and maintain patchiness of infaunal communities and sediment properties. Changes in infaunal communities and geotechnical properties following an experimental physical disturbance will address the hypothesis that ecosystem engineering of bulk sediment properties facilitates succession.
Impacts of the Deepwater Horizon oil spill on infaunal communities
(Alabama Center for Ecological Resilience, GOMRI funded)
This project aims to assess the impacts of the DWH spill on infaunal communities in shallow sediment habitats around the Chandeleur Islands, LA. We sampled infaunal communities and measured sediment oxygen flux over two years (2015, 2016), two seasons (spring, fall), and in Ruppia habitat and nearby unvegetated sites at an oiled and unoiled site. We quantified functional and phylogenetic diversity to assess impacts of oiling. Mesocosm experiments were conducted to determine sublethal effects of the water accommodated fraction of oil (WAF) on two infaunal taxa (Dorgan et al. 2020, MEPS).
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Mud blister worms and oyster aquaculture (Mississippi-Alabama Sea Grant funded)
This project aims to determine the factors that contribute to infestation to inform farmers of when to implement potentially costly treatment, both seasonally and in response to environmental variables, and how important or effective it is to treat oysters. We are working with 4 oyster growers on the Alabama coast, including sampling at their farms and sharing the results of our research with them and the industry broadly. Mudblister worm abundances peak during summer, but show high spatial and interannual variability, possibly driven by salinity. Our results indicate that recovery from blisters occurs but is fairly slow.
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