Current Research

Zooplankton Time Series of North Inlet, SC
We collect zooplankton samples every 2 weeks from North Inlet, SC as a continuation of a time series of zooplankton started in 1981 by Dr. Dennis Allen. Not only is this one of the longest ongoing time series of zooplankton in the world, but it is collected from North Inlet, a small estuary that is almost completely unimpacted by human development. Using this wealth of data, we are examining the role that temperature increases and climate change are having on zooplankton communities, including shifts in abundance, sizes of organisms, and community composition.

Ecology of Cannonball Jellyfish

Cannonball jellyfish (Stomolophus meleagris) are the most abundant jellyfish in the coastal waters of the South Atlantic Bight (SE USA from Cape Hatteras to Cape Canaveral). While they are incredibly abundant seasonally, very little is known about their ecology. Using a long-term dataset (SEAMAP) and experiments, we are investigating the environmental drivers of their population dynamics and how they fit into the coastal food web. They are also fished commercially in Georgia, and we are investigating the impacts of that fishery on the ecosystem.

Role of Vision in Diel-vertical Migration
Using an Underwater Vision Profiler (UVP5-DEEP) we are able to collect high-resolution, in situ images of mesozooplankton. By coupling this with image processing software that can be trained to automatically identify zooplankton, we can collect high-resolution spatial information on individual zooplankters in their natural environment. We are currently testing this equipment in the Sargasso Sea as part of the Bermuda Atlantic Time-series Study (BATS). We hope to use these data to analyze how individual species of zooplankton respond to changes in light level, how light level and visual systems affect predator-prey interactions, and what are the drivers of diel-vertical migration in the open ocean.
(Image at left is a UVP image of a jellyfish at 2059 m off of Bermuda)

Effects of OMZs on Zooplankton Communities
Oxygen Minimum Zones (OMZ) are persistent regions of low oxygen throughout the world's oceans. We are studying how these low oxygen zones impact zooplankton communities, their vertical migration, and food-web interactions in the North Tropical Pacific, an area with particularly low oxygen. By examining the fine-scale vertical resolution of zooplankton, we are discovering how OMZs affect diel-vertical migration, overlap with predators and prey, and biogeochemical cycling.

Ecology of Rhizaria in the Oligotrophic Ocean
Rhizaria are large, single-celled eukaryotes that are common throughout the world's marine environments. However, due to limitations in sampling technologies, the ecology of planktonic Rhizaria has historically been understudied. Using the UVP imaging system to surmount some of these limitations has allowed us to investigate the seasonal and vertical variability of large Rhizaria populations in the Sargasso Sea. We are also using the UVP in conjunction with the Bermuda Atlantic Time-series Study (BATS), which allows us to investigate the environmental niches that Rhizaria occupy and how changes in the environment drive changes in Rhizaria populations.

Ecology of Freshwater Jellyfish
Craspedacusta sowerbii, is a freshwater jellyfish that alternates its life history between a small benthic polyp and a free-swimming medusa. Thought to be native to China, this species has been introduced to many freshwater systems worldwide, including many in South Carolina. While it is extremely widespread, very little is known about its life history or ecology. Using a combination of field surveys, lab culturing, and diet analysis, we are currently exploring the life history of this species and its impact on lake food webs.