Vincent G. Guida

Stable Isotope and Biochemical Composition of White Perch in a Phragmites Dominated Salt Marsh and Adjacent Waters

Tissue stable isotopes and biochemical condition were compared in two populations of white perch, Morone americana, residing in a Phragmites australis-dominated tidal salt marsh and adjacent open waters of Haverstraw Bay, in the Hudson River estuary, USA. As reported previously for other taxa in this system, stable isotope composition of M. americana was influenced by the dominant vegetation present, in this case a near monoculture of P. australis and other C3 vegetation, mainly deciduous trees, that lined the immediate upland shoreline of the marsh. However, all three stable isotopes, δ13C, δ15N, and δ34S, differed significantly between the two populations, with all three parameters displaying enrichment in the open water collections. Both fish populations exhibited the expected allometric relationships among mass components (total protein, total lipids, dry weight) but energy reserves in the form of triacylglycerols and total lipids were significantly greater in the Haverstraw Bay population. These results were interpreted to not only be a function of fish size but also to originate from differences in habitat quality at the two locations.

Lipid class dynamics and storage depots in juvenile weakfish Cynoscion regalis and their application to condition assessment

Lipid class dynamics, the pattern of change in the primary form and location of lipid stores and their relationship with standard length (L(S) ), were investigated in collections of young-of-the-year weakfish Cynoscion regalis for the purpose of determining the utility of this analysis as an indication of condition. The separation of total lipids into individual classes and the analysis of potential storage depots revealed the general patterns of lipid class dynamics and energy storage in C. regalis during their period of juvenile estuarine residency. Phospholipid and cholesterol exhibited moderate but variable (8·1-40·0 and 1·3-21·5 mg g(-1) , respectively) concentrations across the entire juvenile period and were the predominant lipid classes in juveniles <100 mm L(S) , while wax ester concentrations were low (c. 1 mg g(-1) ) and exhibited the least amount of variability among lipid classes. Triacylglycerols (TAG) and free fatty acids (FFA) exhibited similar dynamics, with relatively low concentrations (<15 mg g(-1) ) in individuals ≤100 mm L(S) . In larger juveniles both TAG and FFA concentrations generally increased rapidly, though there was considerable variability in both measures (0·0-199·7 and 0·0-49·7 mg g(-1) , respectively). Increasing levels of lipids, primarily in the form of TAG, with size indicated an accumulation of energy reserves with growth, thus providing an indication of individual condition for larger juveniles. Separate analysis of liver, viscera and the remaining carcass indicated that liver and viscera did not represent a significant depot of TAG reserves. Analysis of samples derived from whole juvenile C. regalis thus provided an accurate estimate of energy reserves.

A Framework for Incorporating Species, Fleet, Habitat, and Climate Interactions into Fishery Management

Marine ecosystems are characterized by many complex interactions. Fisheries managers face the challenge of maintaining or restoring sustainability for individual living resources which are affected by both ecological and economic interactions with other species, through processes like predation and fishing fleet interactions. These species interactions are further complicated by interactions with habitats that are changing due to both human activities and climate change. Often, fishery management systems designed to promote sustainability of individual resources have few tools or processes that also address interactions between species, fleets, habitat, and climate. Here, we review existing and potential fishery assessment and management information and tools, and we develop a potential framework for addressing interactions in management at the request of the U.S. Mid-Atlantic Fishery Management Council. The structured framework can be used to first prioritize interactions, second specify key questions regarding high priority interactions, and third tailor appropriate analyses to address them. The primary tools for the initial steps in the framework are risk assessment and Management Strategy Evaluation (MSE). Finally, implemented management would be evaluated to ensure that objectives are being met, or to adjust measures as conditions change. In the final section, we outline an example to illustrate how a structured decision making process within the framework could work.

NIUST AUVs - Expanding possibilities

The National Institute of Undersea Science and Technology (NIUST)s Underwater Vehicle Technology Center (UVTC) expanded their operational capabilities by acquiring a SeaBED class AUV in early 2009. This vehicle dubbed, Mola Mola after the Ocean Sunfish, is a superb addition to the UVTC, as it adds photographic capabilities at very slow moving speeds to the centers repertoire. The vehicle is designed to fly at speeds of 0.2 ms-1 about 3m above the seafloor, snapping high resolution digital images of the seafloor at preset intervals of 4 to 5 seconds. Normal mission behavior, programmed prior to launch of the vehicle, is to cover a certain area on the seafloor in a lawn mowing track, with parallel lines covering the entire area. At the end of the mission, geo-referenced photo mosaic maps of the target of interest on the sea floor are computed. The vehicle was deployed for several missions on the NASA vessel Liberty Star in the Bahamas. High resolution imagery of the bottom fauna and flora from depths too deep for deep divers to reach, provided insight into the distribution of Lion Fish in the coral reefs of the Bahamas. At the end of the field season engineering efforts were started to reorganize and replace certain hardware components to allow for improved navigation and data handling within the vehicles software architecture. They vehicle itself has since been modified from its original design, adding guided inertial navigation and improvements in its image acquisition process. Changes further include obstacle avoidance, GPS positioning and addition of a VHF radio beacon. In October 2009 combined efforts of both AUVs, the Mola Mola and the Explorer class Eagle Ray were needed in the Gulf of Mexico aboard the NOAA ship Nancy Foster, to locate and retrieve information about sunken ships of historic interest, some of which may have disappeared below the water surface of the northern Gulf of Mexico, almost 200 years ago. In a collaboration between NIUST, MMS and NOAA Office of Ocean Exploration and Research, targets identified in side scan sonar images, were selected and investigated by the AUVs. Eagle Ray, due to its large size and design features, performed initial multibeam surveys of the target areas, producing high-resolution maps of the seafloor. These maps were used to determine safe working areas for the Mola Mola, which was subsequently launched to take a continuous series of photographs in close proximity to the seafloor, producing a photo-mosaic map of the target area. Eagle Ray served as a platform for a mass spectrometer mapping of the Mississippi Canyon Block 118 Hydrate Mount as a part of the Gas Hydrate Observatory efforts. Results o this dive produced a high resolution spatial map of methane gas distribution 6m above the seafloor, discovering three new methane seeps in the area Continued mapping efforts in the Hudson Canyon together with the National Marine Fisheries Service and Rutgers University. High resolution multibeam data from the canyon revealed interesting never before seen detail and bottom features in this area. Enough data to spark new and diverse interest about sub bottom composition and marine live within the canyon.

Semidiurnal Temperature Changes Caused by Tidal Front Movements in the Warm Season in Seabed Habitats on the Georges Bank Northern Margin and Their Ecological Implications

Georges Bank is a large, shallow feature separating the Gulf of Maine from the Atlantic Ocean. Previous studies demonstrated a strong tidal-mixing front during the warm season on the northern bank margin between thermally stratified water in the Gulf of Maine and mixed water on the bank. Tides transport warm water off the bank during flood tide and cool gulf water onto the bank during ebb tide. During 10 days in August 2009, we mapped frontal temperatures in five study areas along ∼100 km of the bank margin. The seabed “frontal zone”, where temperature changed with frontal movment, experienced semidiurnal temperature maxima and minima. The tidal excursion of the frontal boundary between stratified and mixed water ranged 6 to 10 km. This “frontal boundary zone” was narrower than the frontal zone. Along transects perpendicular to the bank margin, seabed temperature change at individual sites ranged from 7.0°C in the frontal zone to 0.0°C in mixed bank water. At time series in frontal zone stations, changes during tidal cycles ranged from 1.2 to 6.1°C. The greatest rate of change (−2.48°C hr−1) occurred at mid-ebb. Geographic plots of seabed temperature change allowed the mapping of up to 8 subareas in each study area. The magnitude of temperature change in a subarea depended on its location in the frontal zone. Frontal movement had the greatest effect on seabed temperature in the 40 to 80 m depth interval. Subareas experiencing maximum temperature change in the frontal zone were not in the frontal boundary zone, but rather several km gulfward (off-bank) of the frontal boundary zone. These results provide a new ecological framework for examining the effect of tidally-driven temperature variability on the distribution, food resources, and reproductive success of benthic invertebrate and demersal fish species living in tidal front habitats.