Fisheries Oceanography Laboratory
Research in Dr. Hernandez's lab focuses on the early life history of fishes: egg, larval stage, and juvenile stage. Variability in the recruitment of marine fishes to adult populations is largely related to the variability encountered in vital rates, such as growth, during these early life stages. Understanding the processes that affect fish egg and larval survival provide insights into future recruitment and fishery yields.
Although Dr. Hernandez has been at GCRL only since 2012, his lab has grown quickly and includes a diverse mix of postdoctoral researchers, research technicians, graduate students and high school and undergraduate interns. Much of the current work is related to potential impacts of the Deepwater Horizon oil spill on the fisheries resources of the northern Gulf of Mexico. A summary of a few projects is provided below.
Deepwater Horizon Oil Spill Impacts on Ichthyoplankton
The impacts of the Deepwater Horizon (DWH) oil spill on marine fish populations of the northern Gulf of Mexico are largely unknown. Of particular concern was the fate of pelagic fish eggs and larvae present in the water column at the time of the spill, as these are the most vulnerable life stages. DWH-related impacts on ichthyoplankton may have profound effects on future recruitment and fishery yields.
In order to detangle DWH impacts from the highly variable "background noise" in the marine environment, a time series that covers a wide range of environmental conditions, as well as 'baseline,' impact,' and 'recovery' periods, is critical. Preliminary analysis of plankton samples collected during a long-term survey conducted in 2004-2011 has identified changes in both zooplankton and ichthyoplankton assemblage structures in the northern Gulf during the DWH oil spill. The study was funded by funded by the Gulf of Mexico Research Initiative with the overall goal of examining how the documented shifts in zooplankton community structure (the larval "fish food") during the DWH event affected larval fish feeding, growth, and condition. These are critical factors related to survivorship and recruitment success. To address these objectives, we are combining field surveys with established laboratory methodologies to compare these parameters among 'baseline,' 'impact,' and 'recovery' periods.
Natural Resources Damage Assessment (NRDA) - Sargassum and Plankton Projects
The Oil Pollution Act authorizes the Natural Resource Trustees, which includes the state of Mississippi, to evaluate the impacts of the Deepwater Horizon oil spill on natural resources through a process known as the Natural Resource Damage Assessment (NRDA).
As part of the NRDA process, scientists from each trustee entity work together to identify potential injuries to natural resources resulting from the spill and to design studies that will be used to determine and measure spill-related injuries (impacts) to natural resources and their human uses.
Highly trained taxonomists in the Fisheries Oceanography Lab are currently sorting and identifying organisms collected during assessment surveys as part of the NRDA effort. We are collaborating with colleagues at many laboratories in the Gulf region, including NOAA/NMFS labs in Pascagoula, Galveston, and Miami, as well as the University of Miami, the Dauphin Island Sea Lab, Louisiana State University, USM's Department of Marine Science. As an added benefit, this work is helping to train the next generation of marine scientists.
Ecosystem-Based Management Metrics for Forage Fish Using Jellyfish
Jellyfish are major consumers of plankton in some ecosystems and may compete with forage fishes, such as Gulf menhaden, for this resource. The competition is particularly significant under rapid growth or "bloom" conditions when plankton prey are abundant. Scientists are increasingly concerned that overfishing may exacerbate naturally occurring jellyfish blooms by increasing plankton availability. This might tip the balance toward jellyfish dominance, which could have adverse economic and ecological consequences.
This project, led by Dr. Monty Graham of the USM Department of Marine Science and funded by the Lenfest Ocean Program, explores a variety of metrics to represent jellyfish as an ecosystem indicator in five marine ecosystems: the Gulf of Mexico, the Northern California Current, the Bering Sea, the Peruvian Upwelling, and the Sea of Japan.
Using existing datasets from these regions, we hope to model the relationships between jellyfish and forage fish and try to identify tipping points in the ecosystem. This work is highly collaborative, and Monty's team includes a diverse team of colleagues from USM, Oregon State University, Yale University, and the NOAA Northwest Fisheries Science Center.