Marine and atmospheric sciences.
Vice-chair: Judith William, USM-Gulf Coast Research Lab
Meeting Room 2
9:00 CHARACTERIZATION OF MID-SHELF CURRENT VARIABILITY
Colleen Finnegan (1*), Stephan Howden (1), and William Teague (2), (1) University of Southern Mississippi, Stennis Space Center, MS 39529 and (2) Navel Research Laboratories, Stennis Space Center, MS 39529
Current variability in the western Mississippi Bight will be characterized using in situ data from a mid-shelf location. In this region, fresh water input is substantial, tides are relatively weak, coastline geometry is complex, and Loop Current eddies at the shelf break have been observed to advect water far across the shelf. Analysis will include a descriptive discussion involving the forcing mechanisms upon mid-shelf waters, such as eddies and winds. Various statistical and graphical representations will be used to describe the data set collected from the Central Gulf of Mexico Ocean Observing System (CenGOOS) buoy between mid-December 2004 and August 2005. Current variability and shelf water circulation in the Mississippi Bight region will be characterized by basic statistics including season and monthly averages, standard deviations, and speed analysis for both depth averaged data and individual bin depths. The results of the described study will be presented and are expected to further the research and understanding of coastal processes, shelf circulation, biological phenomenon, pollutant dispersion and impact of forcing mechanisms on the transport of shelf waters.
9:15 ANALYSIS OF HEME OXYGENASE IN SHEEPSHEAD MINNOWS, CYPRINODON VARIEGATUS
Christina Vorhoff (1*), Matthew A. Reudelhuber (1*), Rachel Ryan (2), Erik Carlson (2), and Marius Brouwer (2), (1) University of Southern Mississippi, Long Beach, MS 39560 and (2) Gulf Coast Research Laboratory, Ocean Springs, MS 39564
Inadequate dissolved oxygen can be a major stressor in estuarine habitats. Hypoxic conditions often result from increasing urban development, agricultural runoff, and industrial pollution. This laboratory is currently using the sheepshead minnow, Cyprinodon variegatus, as a model for the molecular response of fish to hypoxia exposure. For this study, the hypoxia-responsive gene, heme oxygenase, was cloned and its expression monitored during laboratory exposures. The role of heme oxygenase in cytoprotection cascades makes it an integral part of hypoxia response. A partial sequence of heme oxygenase was obtained using degenerate primers based upon previously-published, homologous sequences in other teleost fish species. Degenerate primers were designed using Basic Local Alignment Search Tool (BLAST) engine hits and compiled to form a sequence with the Consensus--Degenerate Hybrid Oligonucleotide Primers (CODEHOP) algorithm. The sequence was then added to ongoing research through the creation of a qRT-PCR assay to obtain preliminary data on levels of expression in different tissues. Current experiments include the integration of heme oxygenase into microarray assays and Rapid Amplification of cDNA Ends (RACE) to determine heme oxygenase regulation and expression. These studies will allow for more in-depth analyses of hypoxia response mechanisms in aquatic organisms.
9:30 MEASURING BUBBLE VOLUME USING AN ELECTROMAGNETIC DETECTOR
Kevin Martin* and Vernon Asper, University of Southern Mississippi, Stennis Space Center MS 39529
This study looks at a new technique to quantify the bubbling volumes using an inductive conductivity cell. The principle behind this device is that a bubble passing through the inductive cell will displace seawater, changing the conductivity of the volume detected by the sensor. The changes in conductivity can be empirically related to bubble volume. The prototype device, based on a Brancker analogue conductivity cell, uses a Tattletale Model 8 data logger to digitize and record the analogue signal. Using calibrated volumes of air, under laboratory conditions of 1 atm, 20[degrees]C and S=40-15 (changing by 5), results confirm the expected drop in conductivity resulting from a bubble displacing the volume of seawater detected by the sensor. These conductivity changes appear to be proportional to the bubble volume. Furthermore, by adding a salinity factor error between the actual gas volume and the calculated volume from the sensor, output is less than 5%, in most cases. Field test of the system at Cape Lookout, NC, where methane seeps naturally from the seafloor, yielded excellent results.
9:45 MATRIX ELIMINATION USING HYDROFLUORIC ACID FOR ANALYSIS OF BIOGENIC CARBONATES BY ICP-MS
Zikri Arslan, Jackson State University, Jackson, MS 39217
Spectral and matrix interferences originating from molecular ions of calcium oxide and hydroxides hinder accurate determination of trace elements from calcium carbonate minerals by inductively coupled plasma mass spectrometry (ICP-MS). It is therefore critical to alleviate the effects of the interferences by removing calcium from sample solutions. We have investigated precipitation of calcium as calcium fluoride by micro liters of concentrated hydrofluoric acid. Precipitation efficiency was as high as 99.5% with successful determination of 11 trace elements. Recoveries for the trace elements ranged from 90 to 103%. Performance characteristics of pneumatic nebulization and electrothermal vaporization (ETV) sample introduction techniques were evaluated. The procedure was a validated by analysis of otolith reference material and samples from different fish.
10:00 DEVELOPING A REGIONAL MODEL OF THE INDONESIAN SEAS CIRCULATION BASED ON THE POM
Kieran T. A. O'Driscoll*, Vladimir M. Kamenkovich, and Dmitri A. Nechaev, University of Southern Mississippi, Stennis Space Center, MS 39522
A regional numerical model of the circulation of the Indonesian Seas, based on the Princeton Ocean Model, has been developed. The model reproduces satisfactorily the fundamental features of the circulation. The horizontal grid cell size is on the order of 10 km which allows for the resolution of all important flows within straits and passages in the region. The model has horizontal extent of 250 X 250 grid cells with 29 sigma levels in the vertical. The sigma levels have been carefully chosen for proper resolution of surface and bottom Ekman boundary layers and the salinity maximum and minimum located at 150-250m. The ETOPO5 bottom topography was properly smoothed to retain all important passages, sills and straits. The model has four open ports; three in the Pacific part of the domain and one in the Indian Ocean part of the domain. The open ports correspond to three well known currents in the Pacific ocean and a transport out of the model domain in the Indian ocean. Transports through the open ports have been calculated from observations and are used to provide simple barotropic boundary conditions at these open ports. Baroclinic boundary conditions of the Orlanski type are used at the open ports, where the velocities have been nudged toward observed values. The effects of tidal friction are not included explicitly in the model, however some additional friction has been added to the model to incorporate implicitly this important effect. Model results with no wind stress and with mean annual wind stress are presented and discussed.
10:15 CLIMATE VARIABILITY, FECAL COLIFORM DYNAMICS AND SHELLFISH MANAGEMENT IN MISSISSIPPI SOUND
Paulinus Chigbu (1*), Scott Gordon (2), and Thomas Strange (3), (1) Jackson State University, Jackson, MS 39217, (2) Mississippi Department of Marine Resources, Biloxi, MS 39530, and (3) Radiance Technology, Inc., Stennis Space Center, MS 39529
Fecal coliform (FC) levels in Mississippi Sound are strongly correlated with local rainfall amounts and Pearl River (a major inflow into the western Mississippi Sound) stage. For shellfish harvesting waters to meet the approved criteria for harvest, in addition to a FC geometric mean of<14 MPN per 100 ml, no more than 10% of the water samples collected during the shellfish harvesting season while the area is open for harvesting should have FC counts of 43 MPN per 100 ml. We used eleven years of data to determine mean Pearl River stage beyond which the geometric mean FC level of 14 MPN per 100 ml would be exceeded in each shellfish growing area of Mississippi Sound. Our results indicate that FC levels would exceed the geometric mean MPN of 14 when Pearl River stage is >9.5ft (for area II-D), >10ft (for areas I-B, II-A, II-B), >12.5ft (for area II-C) and >13ft (for areas III and VIII-B). These area-specific Pearl River stage values beyond which shellfish harvesting areas would be closed are generally consistent with the criteria currently being used for managing shellfish areas in Mississippi Sound.
10:45 Divisional Poster Session
COPRECIPITATION OF TRACE ELEMENTS BY SODIUM HYDROXIDE FOR ELEMENTAL DETERMINATION IN FISH OTOLITHS
Stephanie Daniels* and Zikri Arslan, Jackson State University, Jackson MS 39217
Otolith structures in the head of vertebrate fish are calcium carbonate accretions on a proteinaceous material. These structures are very inert in nature and grow throughout the fish's life. During the growth, trace metals from the surrounding water incorporate into the otoliths. It is assumed that trace element composition of the otoliths reflect that of the resident water, and therefore has been used to delineate fish populations and to draw inferences about the fish's life history. Otoliths are, however, complex samples containing low levels of trace metals. Moreover, when dissolved otolith solutions become very saline due to the presence of calcium matrix that reduces the accuracy and measurement capabilities of inductively coupled plasma mass spectrometry (ICP-MS). In this study, we have investigated the possibility of coprecipitating the trace elements in otolith solutions by using sodium hydroxide to alleviate the interferences of calcium matrix and thereby to achieve accurate determination of trace elements by ICP-MS. Because otoliths are predominantly (e.g., 96% CaC[O.sub.3]), optimization of the precipitation conditions were carried out with CaC[O.sub.3] (99.999%). Several elements, including iron, arsenic, manganese, chromium and cadmium were quantitatively precipitated as hydroxides at pH above 12. The precipitation of the calcium was controlled by optimizing the volume of sodium hydroxide. The procedure was applied to the analysis of fish otolith reference material for the determination of abovementioned by ICP-MS.
A NUMERICAL STUDY OF THE MESOSCALE VARIABILITY IN THE NORWEGIAN COASTAL CURRENT
Jens Christian Roth (1*), Patrick J. Hogan (2), and Vladimir M. Kamenkovich (1), (1) University of Southern Mississippi, Stennis Space Center, MS 39529 and (2) Naval Research Laboratory, Stennis Space Center, MS 39529
The Norwegian Coastal Current (NCC) is located off the coast of Norway, and flows north through the North Sea and the Norwegian Sea. It is influenced partly by winds and partly by a large freshwater flux from the Baltic Sea and a large number of rivers. One particular aspect of the NCC is a tendency to develop instabilities and to generate eddies. The subject of this study is to simulate the mesoscale variability of the NCC with a numerical model, and to investigate the impact of different forcing terms on the behavior of the NCC. A comparison between results from our numerical model, the HYbrid Coordinate Ocean Model (HYCOM), with 1/12 degree horizontal resolution and 26 vertical layers, and observed data, demonstrates that the model reproduces the major features, such as the polar front, the Norwegian Atlantic Current and the NCC. The vertical and horizontal distributions of salinity and temperature are in good agreement with observations. Seasonal variations in the NCC are also captured by the model, and compare well with earlier research performed in the area. Results from model runs show that during summer, increased freshwater flux to the NCC and less intense winds act to stabilize the NCC. As a result, there are less instabilities formed during the summer period compared to the winter period. Figures of the horizontal distribution of mixed layer velocity show that the instabilities formed in the NCC are mainly of a baroclinic character, with a lifespan of about three to four days.
A STUDY OF OCEAN-ATMOSPHERIC INTERACTIONS AND HURRICANE PREDICTIVE INDEX (HPI) ASSOCIATED WITH LAND FALLING HURRICANE CHARLEY
R. Suseela Reddy*, Arundhati Surakanti, and Haritha Chekuru, Jackson State University, Jackson, MS 39217
Previous studies by Reddy et.al., (1998, 2003) have indicated a strong Ocean-Atmospheric coupling during the development of tropical cyclone/hurricane activity over the Gulf of Mexico. We extend these investigations to the hurricane Charley, which developed over the Caribbean and made land fall over the west coast of Florida during August 9-14, 2004. NOAA GOES satellite, NDBC Buoy and NHC dropsonde data for sea surface temperature and meteorological variables including air temperature, wind speed and sea level pressure were used for computations. A Hurricane Predictive Index (HPI) has been developed for land falling hurricane forecast of Charley over the Gulf of Mexico. HPI computes air-sea interface over the marine boundary, pressure tendency, intensity change and stability using the satellite and buoy data. A positive index indicates the weakening of the system and a negative index indicates developing the system into hurricane activity. The study suggested strong heat flux before and during the formation of the hurricane with an evidence of 2-5 day oscillations in heat flux. These findings are in conformity with the previous studies. The HPI indicated a strong negative index during the development of hurricane Charley.
THE EFFECTS OF TRICLOSAN ON MARINE ALGAE SPECIES
Melanie McHenry*, Vasile Suchar, and Paulinus Chigbu, Jackson State University, Jackson, MS 39217
Triclosan, an antibacterial agent found in three-quarters (3/4) of liquid soaps and one-quarter (1/4) of bar soaps as well as in various other products, has been reported in surface waters, fish and other aquatic biota. Studies show significant reductions of freshwater algae such as Chlamydomonas and Sphaerocystis at concentrations >0.15 ug/L and 1.5 ug/L, respectively. Reduction in algal species richness has been observed with increasing concentrations from 0.015 ug/L to 1.5 ug/L. Little is known about the toxicity of triclosan to marine microalgae. Two marine algae species, Tetraselmis chuii, and Nannochloropsis oculata were exposed to concentrations of triclosan, ranging from 0 to 250ug/L for 96 hours to assess toxicity. The seven concentration treatments had three replicates. The initial algae density was 100,000 algae/mL. Salinity was at 25ppt, temperature ranged from 23-27[degrees]C, and light intensity was 4,000 lux. After 72 hours, percent inhibition due to treatments varied from 8.9% at 0.2ug/L to 65.8% at 250ug/L for Tetraselmis, and from 4.9% at 0.2 ug/L to 55.9% at 250ug/L for Nannochloropsis. The EC50 values increased from 0.72 ug/L (24 hr) to 72.93 ug/L (72 hr), and 3.52 ug/L (24 hr) to 387.6 ug/L (72 hr) for Tetraselmis and Nannochloropsis, respectively. Values are higher than the 72 hr EC50 values (0.7 to 4.5 ug/L) reported for freshwater algae, Scenedesmus sp., Anabaena flos-acuae and Selenastrum capricornutum. Triclosan significantly inhibited the growth of Tetraselmis and Nannochloropsis (p<0.001) thereby triclosan can significantly impact phytoplankton production. The results suggest that Tetraselmis is more susceptible than Nannochloropsis.
Meeting Room 2
1:30 Divisional Business Meeting
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|Publication:||Journal of the Mississippi Academy of Sciences|
|Date:||Jan 1, 2006|
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