In collaboration with Stephen Brandt, Stuart Ludsin & Doran Mason,
NOAA Great Lakes Environmental Research Laboratory; Michael Roman, William Boicourt, &
U. of Maryland Center for Environmental Sciences; Peter Lavrentyev, U.
As a direct consequence of eutrophication, there has been an alarming increase in the
spatial and temporal extent of low oxygen bottom waters in estuarine and coastal waters. Although
hypoxia is prevalent in many U.S. coastal systems, such as Chesapeake Bay and the Laurentian Great Lakes,
most prominent has been the advancement of hypoxia in the northern Gulf of Mexico (NGOMEX). The
temporal and spatial extent of hypoxia in the NGOMEX has increased as a result of excessive nitrogen
inputs from the Mississippi River. Despite this increase in hypoxia, the trophic consequences of low
oxygen waters on pelagic communities remain poorly understood. Given the economic importance of the
Gulf of Mexico commercial fisheries (about 20% of the U.S.’s total domestic fishery landings representing
about $991 million) and recreational fishing (generating ~30% of the nation’s saltwater fishing
expenditures and supporting nearly 25% of the nation’s recreational saltwater jobs), it is imperative
that knowledge of the ecosystem effects of hypoxia in NGOMEX be increased.
The objectives of this project are to:
• conduct high-resolution mapping of the NGOMEX pelagic food web (including bacteria, phytoplankton,
microzooplankton, mesozooplankton, and fish) in relation to hypoxia;
• integrate these ecosystem measurements through a variety of models designed to assess the effects of
hypoxia on NGOMEX pelagic food webs and production;
• quantify habitat suitability for economically and economically important fishes; and
• provide tools to forecast food-web interactions, habitat suitability, and fish production in relation
High-resolution mapping of the major ecosystem components of the NGOMEX is conducted during the early
and peak hypoxia season in the northern Gulf of Mexico on the Louisiana shelf aboard R/V Pelican. Automation
of sampling, analysis, and classification of pelagic organisms using new technologies offers a practical,
cost-effective way to intensify survey efforts in the NGOMEX so that ecosystem components are sampled
at the fine-scale and broad-scale resolutions necessary to understand the effects of hypoxia. This
approach will yield information on phenomena that would have been missed by a fixed or bottom-focused
sampling regime, and enhance the functionality of monitoring and observations. Mapping results will be
incorporated into spatially-explicit bioenergetics-based growth rate potential, size-spectrum, dynamic
optimization, food-web, and statistical models to provide managers with essential information for
improved ecosystem-based management of the NGOMEX, including information to quantify and forecast the
ecological consequences of changes in hypoxia on the living resources of the NGOMEX. Undergraduates,
graduate students, postdoctoral scholars, and teacher interns are involved in all aspects of this
The working group at FIU is conducting high-resolution mapping of bacteria and phytoplankton. Nano- and
microplankton communities are analyzed by ship-board imaging-in-flow cytometry with a FlowCAM system.
Picophytoplankton and bacteria communities are analyzed by lab-based flow cytometry on a
Becton-Dickinson FACSort flow cytometer. In addition to high-resolution mapping, bacterial and eukaryotic
microbial communities are assessed by genetic fingerprint profiling through DGGE (denaturing gradient
gel electrophoresis) of rRNA gene fragments.
This project is funded by the NOAA Coastal Ocean Program.