Research

Zooplankton in the Redoxcline: Impact on Biogeochemical Cycling. NSF/OCE 0526545. Two cruises during October/November 2007 and December 2008/January2009 in the eastern tropical north Pacific allowed us to investigate food web structure and initial studies of the role of crustacean zooplankton in the production and transformation of particulate and dissolved material. The distribution and feeding by microzooplankton and mesozooplankton were investigated. In addition, egestion and metabolic byproducts of dominant mesozooplankton were assessed. One of our primary hypotheses is that zooplankton graze on chemosynthetically-produced biomass at the upper and lower oxyclines of the Oxygen Minimum Zone and, in doing so, provide a mechanism by which slowly sinking bacterial aggregates are packaged into more rapidly sinking fecal pellets (or aggregates). This would provide a mechanism for transporting part of the chemoautotrophic biomarker signal to the seafloor. This work will contribute to our knowledge of the role of mesozooplankton in biogeochemical cycles, especially in relation to how processes may be modified in regions of suboxic environments and strong redox gradients. Further iinformation on our cruise may be viewed at http://etpcruise.blogspot.com/. In addition, zooplankton images obtained from vertical profiles of the SIPPER imaging system may be viewed at http://www.marine.usf.edu/sipper/.

Southern Ocean GLOBEC Program. NSF/OPP-9910610, OPP-0196489. We participated on four cruises (two fall and two winter) during 2001 and 2002 as part of GLOBEC program. Photos from these cruises can be seen in the Images Section. This project was designed to assess the overwintering strategies for feeding, development, and growth of life history stages of Euphausia superba, west of the Antarctic Peninsula. Acoustics, nets, and divers also were used to assess the abundance and distribution of krill. In addition, target strength measurements of Antarctic fishes were aquired in situ and are being compared with that of krill and other potential targets. To date there have been 15 presentations and eight publications acknowledging this award. This award supported one master's and one Ph.D. student. http://www.ccpo.odu.edu/Research/globec_menu.html

US GLOBEC Synthesis and Modeling Phase. NSF/OPP-0814405. We will collaborate with 21 interdiciplinary investigators from academia, NOAA/NMFS, and the British Antarctic Survey to examine the extent to which marine food webs that support fisheries are controlled by bottom-up (physical processes) versus top down (predation, fishing) forcing. Food web models will be developed for the Southern Ocean. A comparative analysis of models for the three US GLOBEC regional field programs (Southern Ocean, Georges Bank, NE Pacific) will be evaluated, the skill of the models will be assessed, and diagnostic measures will be developed. /http://www.usglobec.org/

Tampa Bay Hot Spots Program. USGS. "Hot Spots" are regions of enhanced biological biomass and activity in marine systems. Hot Spots in estuaries are often ephemeral, changing with time and location depending on variability in winds, tidal currents, and rainfall. These regions are important for biogeochemcical cycling, regional productivity and reproduction, growth, and recruitment in fish, marine mammals, and birds, yet little is known about the dynamics of these important habitats. Tampa Bay is the largest open-water estuary in Florida and one of the largest along the Gulf of Mexico. It is very productive and has more than 200 species of fish, many of which depend on zooplankton prey to support reproduction and larval recruitment. Recently, 25 people on eight boats sampled in the vicinity of a tidal intrusion front using a variety of instruments, including moorings instrumented with sensors that had two-way communication via a radio link, an autonomous surface vehicle which relayed back data in real-time, a towed vehicle with sensors, and flow-through sensors. The results will be analyzed to better understand the physical-biological interactions that promote and maintain biological Hot Spots. This program was jointly supported by USGS, ONR, and USF.