Current Lab Activities and Projects
Gulf of Mexico Deep Pelagics
DEEPEND (Deep-Pelagic Nekton Dynamics) is a recently funded GOMRI consortia that will investigate deep-pelagic communities on short-term (sub-generational) and long-term (evolutionary) timescales to appraise extant recovery and potential future recovery of these communities using a suite of integrated approaches. These approaches include: 1) a direct assessment of GoM deep-pelagic community structure, with simultaneous investigation of the physical and biological (including microbial) drivers of this structure, in order to document biodiversity and 'natural' variability; 2) a time-series, 'hindcast,' comparison of biophysical data from 2015-2017 (DEEPEND sampling) to 2010-2011 DWHOS data; 3) an examination of differences in genetic diversity among key species; and 4) an assessment of the extant and potential future consequences of the DWHOS on the shallow and deep-pelagic biota.
Vertical Migration of
Sound Scattering Layers
Sound scattering layers (SSLs) are ubiquitous features throughout the world’s oceans and the organisms comprising these layers are important components of these vast ecosystems. The depths at which SSLs occur are dynamic and often dependent on the depth of the water column and time of day, which gives rise to well-recognized and remarkable diel vertical migration (DVM) patterns. Commonly, the main organisms that comprise SSLs are euphausiids, crustaceans, siphonophores and myctophids which serve as primary prey resources for larger predators, like marine mammals. The dramatic vertical movement between biomes offers opportunities for intense ecological interactions between SSLs and surface-oriented communities including predator-prey relationships and energy transfer. Understanding how the community structure within SSLs varies will help to better characterize the important ecological role these organisms play.
Broadband Acoustic Swimbladder Modeling
A central challenge to quantifying change in marine ecosystems and evaluating ecosystem services is the acquisition of spatially and temporally appropriate data to examine patterns in diversity and abundance of dominant scatterers, and in particular exploited target species and important prey resources. Broadband acoustic technology offers a promising tool that might allow inference at relevant taxonomic and spatiotemporal scales. We are investigating use of a boundary element method with high-resolution computed tomography data to examine numerically modeled acoustic scattering responses (12-250 kHz) of dominant fishes across a range of orientations. The modeled broadband scattering responses will be compared with in situ measurements of broadband scattering from fishes obtained using newly avaialble Simrad EK80 echosounders. Preliminary analyses suggest that broadband scattering responses in this frequency range are sensitive to the fine-scale morphological variations among common fish species. Further analysis will give insight into the appropriate frequency domain to examine the efficacy for taxonomic resolution.
Goliath Grouper Spawning Aggregation Study
The goliath grouper fishery has been closed since 1990 due to declines in their population after extended periods of overfishing. However, the population has made a significant recovery since protection was put into place, and years of research indicate that Goliath Grouper populations are on the rise. An important part of their recovery has been the occurrence of large spawning aggregations in the fall months throughout Florida. To better understand their population dynamics, characterize the effect of aggregations on surrounding reef fish communities, and to develop an accurate but rapid acoustic survey design to remotely estimate abundance, we initiated an annual goliath grouper survey with colleagues from MOTE Marine Laboratory in 2016. Since then, a combination of active and passive acoustic surveys, along with visual and camera surveys are conducted in Jupiter, Florida to capture the seasonal changes in Goliath Grouper abundance during the spawning season. Photo Credit: Liz McNamee
Arctic Nearshore Ecosystems
Recent research efforts aimed at understanding the marine ecosystem in the US Arctic have overlooked the nearshore habitat. The Arctic shoreline comprises a matrix of shallow lagoons and barrier islands on the edge of an expansive shallow shelf. Despite this area’s importance for subsistence fisheries and as foraging habitat for protected marine mammals and seabirds its contribution to Arctic productivity is unknown. Further, it is unknown if Arctic barrier island systems function in the same manner as lower latitude systems, particularly given that fast ice conditions in lagoons have the capacity to extend through the entire water column displacing or injuring animals, and potentially resetting the pelagic ecosystem annually. Thus, it is unknown what role these lagoons serve (e.g., nursery areas) or if these shallow habitats should be classified as essential fish habitat as suggested by the North Pacific Fishery Management Council under the Sustainable Fisheries Act of 1996.
Autonomous Survey Platforms
Our lab has worked closely with SeaRobotics to develop a modular unmanned 4m long vessel to perform acoustic surveys in shallow coastal waters (e.g., estuarine systems). The modular design permits the vessel to be broken down and shipped for operations in remote regions (e.g., Arctic). The vessel is capable of executing a pre- programmed transect series collecting repeatable, high-resolution, spatially-referenced physical and biological data which is telemetered in real-time back to the base station. In its current configuration it is equipped with a calibrated split-beam echosounder (Simrad EK60, 120 kHz), an imaging sonar (Soundmetrics DIDSON, 1.8MHz) and wide-swath multibeam echosounder (Mesotech M3 multimode sonar). Most recently this has been modified to participate in a dye-tracer study in a shallow water tropical lagoon and instrumented with a CTD. The ASV is capable of simultaneously collecting high-resolution data of the substrate characteristics, bathymetry and the organisms distributed above the seabed and capable of carrying additional payload components (e.g., water samplers, passive acoustic receivers, etc.).
Red Snapper Abundance Survey
We are currently working to understand absolute abundance of red snapper (Lutjanus campechanus) in the Gulf of Mexico. This research addresses one of the most urgent problems currently facing U.S. Gulf of Mexico (Gulf) fisheries management. The notable Red Snapper supports one of the most economically valuable finfish fisheries in the Gulf of Mexico. Their profound popularity led to severe stock depletion through overfishing, and the stock is still overfished. The best possible management is obstructed by the lack of robust abundance data. Thus, our overarching goal is to provide an independent estimate of Age-2 and older Red Snapper absolute abundance in the northern Gulf of Mexico.
Coupled Stressors Affecting Fish Behavior
Estuarine mangrove systems are essential fish habitats that provide important ecosystem services for a wide range of inhabitants as nurseries and foraging grounds. As climate change is projected to increase global temperature over the next 50 years, and coastal development is expected exacerbate the issue, increasing stress on these environments will result in the degradation of habitat quality and ecosystem function. A factorial design consisting of two temperature levels and two turbidity levels (high and low) was used to document changes in fish schooling behavior and predator-prey interactions using an acoustic imaging sonar (DIDSON). We are trying to quantify predation rate during high thermal stress and high turbidity periods to determine if prey fish mortality changes. Recent studies have focused on a single stressor at the species level, but by investigating the relationship between multiple stressors and their effect on behavior at the community level, we will gain a better understanding of how fish communities will respond to increases in temperature and turbidity related to climate change and coastal development.