OS25J-01
Sedimentary Record in Tampa Bay, FL: Anthropogenic Implications
A suite of 85 sediment cores collected in Tampa Bay, FL indicates that the estuary has experienced a complex depositional history, which has been impacted by recent anthropogenic activities. Ten sedimentary facies have been identified representing a variety of terrestrial (lacustrine, fluviodeltaic), transitional (paralic), and marine (estuarine, open marine) depositional environments. Facies successions differ among the 6 main physiographic regions of Tampa Bay, thus generalized facies architecture for the entire estuary is problematic. However, all facies successions show a similar history of estuarine sedimentation throughout the Holocene sea-level rise. Radiocarbon dates show Tampa Bay was flooded approximately 6 ka - 3.5 ka and overlying estuarine sediments have accumulated at averages rates of approximately 0.03 - 0.06 cm/yr. Surficial facies show no appreciable differences in texture and/or composition from underlying sediments, but Pb-210 and Cs-137 data indicate accumulation rates have increased dramatically, ranging from 0.28-0.44 cm/yr likely due to anthropogenic activities over the past 100 years. This suggests that sediment distribution patterns in Tampa Bay are not strongly controlled by anthropogenic activities. Conversely, the sediment accumulation rates have been strongly influenced by anthropogenic activities with an approximate one order-of-magnitude increase over the past 100 years. These natural and anthropogenic depositional patterns and accumulation rates are being integrated into the Tampa Bay predictive modeling effort to better understand how this dynamic system operates.
OS25J-02
Rapid Evolution of a Coastal System in Southwest Florida: Response to an Anthropogenic Catalyst
The coastlines of southwest Florida include vulnerable ecosystems that provide valuable information on the nature and dynamics of coastal change in anthropogenically modified systems. In these complicated systems, subtle changes in boundary conditions appear to drive large hydrodynamic and morphological changes. The purpose of this research is to 1) document historical patterns and rates of change of the various subenvironments in the Cape Sable area in Everglades National Park; 2) define the relative role of human influence versus tidal processes and major storms in geomorphologic and ecosystem evolution; 3) establish principles for system dynamics to be used as a protocol for the evolution of other, anthropogenically modified, coastal complexes. This project integrates analysis of aerial photography and high-resolution Ikonos satellite imagery, and links sedimentologic and biogeochemical data to nearshore oceanography. Portions of Cape Sable, a large coastal wetland complex in Everglades National Park, have undergone rapid changes over the past 80 years. Subtle human modifications, such as canals dredged in the 1920s, act in concert with changes driven by recent sea-level rise. Before the 1920s, there was no connection from a large (~ 20 km2) inland freshwater lake to the marine environments of Florida Bay and the Gulf of Mexico. Since the opening of the canals, the freshwater lake has transformed into an estuary. Sediments have been deposited in the estuary, filling 25% of its area to supratidal levels. The rapid rate of widening of the canals (up to 4 ft/year) and natural creeks reflects a system out of equilibrium in which the channels are still seeking to accommodate the increased tidal prism. Especially critical is the incursion of marine waters across a bounding marl ridge that used to separate the interior freshwater marsh from the marine environment. With saline water intrusion, large areas of the freshwater marsh have died out. The organic matter has oxidized and disappeared, which has resulted in the collapse of the marsh and conversion to a shallow subtidal water body. Detailed oceanographic studies reveal that with each tidal cycle, approximately 350 x 103 kg of sediment is redistributed from former interior freshwater wetlands to the marine environments of the estuary. The results of this research illustrate the complicated connectivity of processes and products on this coast. Understanding the processes will make possible a better understanding of the causes for observed changes along other Gulf of Mexico low-energy coastlines, areas as well influenced by human modifications to water flow and seascape.
OS25J-03
Sediment Quality Baseline Data for Coastal Resource Management in Two Protected Areas in Puerto Rico
For many years the US NOAA Jobos Bay National Estuarine Research Reserve (JBNERR) and US FWS Vieques National Wildlife Refuge (VNWR) received significant amounts of anthropogenic contaminants from nearby agricultural and industrial activities. In addition to these two sources of anthropogenic contaminants, the VNWR was also impacted by military exercises at the US Navy Atlantic Fleet Weapons Training Facility, resulting in the release of several contaminants, including heavy metals and depleted uranium. With the purpose of establishing baseline data for sediment quality, sediment cores were collected in the island of Vieques at Kiani Lagoon and in the JBNERR at Mar Negro. Both study sites indicate the presence of Cs-137. Cs-137 present at the VNWR Kiani Lagoon sampling site range from below detection limits to 0.021 (Bq/g). At the JBNERR Mar Negro site, Cs-137 activities range from below detection limits to 0.00798 (Bq/g). The majority of Cs-137 activity at Mar Negro was identified in the upper 20 cm of the core. Cs-137 activities were detected throughout the Kiani Lagoon core. Cs-137 retention is strongly influenced by particle grain size and clay mineralogy. Preliminary analysis indicated that clay size particle in the VNWR Kiani Lagoon ranges between 2.7 % and 9.2 %, averaging 4.5 %. Clay size particles present in JBNERR Mar Negro ranges between 0.71 % and 65.9 %, averaging 11.2 %. At Mar Negro sediments deeper than 20 cm exhibit slightly higher concentrations of clay size particles than the shallower sediments. The radiogeochemistry findings from this on-going study will provide data that will be utilized by VNWR and JBNERR reserve managers as they design and implement future environmental monitoring and restoration activities.
OS25J-04
Development of Near-shore Hydrodynamic Models for Beach Closure Forecasting in the Great Lakes
Contamination of swimming beaches by bacteria and viruses and is a major health risk and having accurate information about water quality in coastal areas is critical to human health. In order to address this problem, we are developing a hydrodynamic modeling approach for linking lake-scale hydrodynamic simulations with a nested local grid (covering on the order of 25 km of shoreline with a horizontal resolution on the order of 100 m) for beaches in the Great Lakes. Lake-scale hydrodynamic forecasts are produced daily by the Great Lakes Coastal Forecasting System. Results from the whole-lake simulations will be used to specify the open water boundary conditions for the nested grid simulations. Bacterial transport models will be linked to the nearshore hydrodynamic model to forecast the probability of contamination along the beach. The initial test site for model simulations and field validation experiments is Burns Ditch, Indiana on Lake Michigan. This tributary to Lake Michigan is known to contain high levels of coliform bacteria and is adjacent to the Indiana Dunes National Lakeshore. Field activities in 2005 included deployment of three acoustic Doppler current profilers and a dye-release experiment. In the tracer experiment, the inert gas sulfur hexaflouride was introduced into the tributary and the plume was tracked using a shipboard-based gas chromatography system for several days after the release. The results of the experiment are compared to the acoustic Doppler current meter measurements and are used as a test case for the hydrodynamic nested grid model.
OS25J-05
Predictability of seabed change due to underwater sand mining in coastal waters of Korea
Underwater sand extraction has been conducted for last 20 years to supply the construction materials of ever-growing metropolitan area. Wide and deep disturbances in the sea bottom threaten the bottom dwellers, and high concentration of SS drops the productivity of biomass. The reworking processes of huge underwater pits could drive the costal erosion. To understand the sediment transport processes, a 3-D numerical model directly coupled with hydrodynamics and sediment modules are applied to Kyunggi Bay in Korea. Some supporting data obtained from field experiment are used for model validation. For the numerical simulation of the sediment transport processes, we use the ROMS (Regional Ocean Modeling System) model that is originally developed by ocean modeling group of Rutgers University, NJ. The ROMS is a full 3-D hydrodynamic model directly coupled with sediment modules. The horizontal grid adopts the curvilinear coordinates allowing variable cell sizes in the computation domain. In vertical coordinates, the ROMS uses the terrain-following coordinate that can resolve the surface and bottom layers in very high resolution compatible to wave-induced BBL thickness. The model has been implemented for Kyunggi Bay for the Year 2003. High-resolution surface forcing of winds, heat flux and precipitation, tides, river inputs, and waves are provided. The open boundaries are treated as nudging sponge buffer.The surface forcing data are obtained from the modified MM5 hindcasting result of every 6 hours at every 6 km cell, and major tidal constituents are incorporated. To consider the wave-current interaction in the BBL, the wave fields are estimated by using the SWAN model. Results In the surface layer, the SS dispersion and vertical structure are predicted in time and space, while the bottom layer is simulated for sediment resuspension and depositional processes. The 3-dimensional modeling of coastal hydrodynamics and sediment processes are presented. The model predicts the wave-current coupled hydrodynamic process in the benthic boundary layer, the dispersion of suspended sediment, and the seabed geomorphologic change.
OS25J-06
The Degradation of Terrestrial Biomass Residues in Deep-Sea Sediments: Candidates for Long-Term Carbon Sequestration
It has been proposed that the addition of terrestrial carbon to deep-sea sediments could reduce atmospheric carbon dioxide by permanently sequestering a portion of the active carbon pool (Metzger and Benford, 2001, Climatic Change, 49, 11-19). Although terrestrial materials are generally thought to be relatively refractory in the marine environment, their effectiveness in sequestering carbon long-term depends upon their degradation rates in the benthos. Agricultural crop residues are likely candidates for deep-sea carbon sequestration because they are readily available and not commercially valuable. In this laboratory study the degradation of soy and corn crop residues, as well as wood, wastewater biosolids, and plankton was monitored after being added to deep-sea sediments. An oxygen micro-electrode was used to determine the dissolved oxygen profile for each sediment treatment over the course of 290 days. The calculated oxygen fluxes allowed for the determination of carbon remineralization rates of the various materials. Soy residue experienced the least amount of degradation, with only 2.1% of the added carbon remineralized during the incubation, making it the best candidate for sedimentary sequestration. The plankton-containing treatment displayed the greatest carbon remineralization (5.4%), followed by the corn (3.2%), wood (3.0%), and biosolids (2.9%).
OS25J-07
Three-dimensional Modeling of the Tidal Dispersion of Radionuclides in the Irish Sea
A spent nuclear fuel reprocessing plant would release artificial radionuclides from a discharge pipe to the marine environment. These readionuclides spread by advection and diffusion of ocean currents, but their migration processes are different due to physical and chemical forms of radionuclides. We have developed a numerical simulation model system that consists of an ocean current model and a particle random-walk model to describe the radionuclide migration behavior in a shallow water region. The ocean current model is the modified Princeton Ocean Model (POM). The POM calculates tidal currents by giving tide levels at the open boundary. The particle random-walk model, SEA-GEARN, calculates the radionuclides migration in the ocean. Radionuclides that exist in the ocean are modeled in three phases, such as dissolved in seawater, adsorbed with suspended solids and adsorbed with active bottom sediment. The adsorption and desorption processes between the dissolved and solid phases are solved with the kinetic transfer coefficients by the stochastic method. Deposition of suspended solids and resuspension of bottom sediment are also considered. The system has been applied to simulate the long-term dispersion of $^{137}$Cs and $^{239,240}$Pu actually released from a spent nuclear fuel reprocessing plant in the Irish Sea. The calculation results and observations have been compared at several points in order to validate the developed models.
OS25J-08
Assessing the Health of Estuaries
Healthy, functioning estuaries serve as a valuable source of goods and services to human populations. Yet, in the United States, many estuaries have been and are currently being degraded such that these goods are services are being diminished. A major barrier to writing regulations to ensure maximizing the value of this country's estuaries is our ability to measure the past, current and future health of estuaries. There is a wide variety of environmental, socio-economic, and governance indicators for determining that can be used to measure the health of estuaries, but no common set has been proposed or accepted. This presentation will review current indicators of estuarine health that are utilized by managers such as those at the USDA, EPA, NOS, and NOAA. Those indicators sets will be assessed with commonalities and essential differences highlighted. Challenges to assessing overall service value and to effective governance will be detailed.
OS25J-09
A Survey of Heavy Metal Accumulation in the Foraging Habitats of Green Sea Turtles (Chelonia mydas) Around St. Croix, United States Virgin Islands.
Sea grass meadows serve as important foraging habitats for the endangered green sea turtle (Chelonia mydas) around St. Croix, United States Virgin Islands. Those meadows, restricted to shallow coastal waters, are susceptible to both direct and indirect anthropogenic impacts from land. On St. Croix, United States Virgin Islands, there are a number of sites that may degrade sea grass meadows and overall water quality along the southwestern coast of the Caribbean island. In addition to possible impacts from an oil refinery, aluminum plant, and a landfill, the direct discharge of sewage as well as the waste products from a rum distillery into the ocean may have some negative effects on the marine environment. Globally, near-shore habitats, adjacent to large human populations and industrial regions, as well as habitats with low water turnover rates are all areas where diagnosis of green turtle fibropapillomatosis (GTFP) has been prevalent. GTFP is an epizootic disease primarily affecting, but not limited, green sea turtles. The primary purpose of this study is to quantify the levels of metal accumulation in various sea grass meadows around St. Croix, comparing industrially impacted and non-impacted sites. The levels of metals in the sediment from these sea grass meadows are currently being analyzed using total digestion and inserted in an Inductively Coupled Plasma Optical Emissions Spectrometer (ICP-OES). Because sea grass is the primary food source of green sea turtles around St. Croix, the loading of metals into these meadows is an issue of concern and some implications to management may be needed to enforce, or amend current regulations.
OS25J-10
Interaction Between Nutrients, Phytoplankton Blooms, and Mercury Concentrations in San Francisco Bay
We studied the connection between nutrient discharges, phytoplankton blooms, and mercury concentrations to evaluate anthropogenic impacts on the southern reach of the San Francisco Bay estuary (South Bay). One objective of this research was to determine if a phytoplankton bloom could deplete dissolved methyl mercury (MeHg) from water in a highly contaminated estuary. That objective was based on experiments by other researchers that showed algal blooms decreased dissolved MeHg concentrations in mesocosm experiments. We also determined the effect of decay of the bloom on MeHg concentrations and assessed the contribution of wastewater treatment plants to the high nutrient concentrations in South Bay. To study mercury cycling during a South Bay bloom, we used trace metal clean techniques to collect MeHg and total mercury (Hg$_{T}$) samples of filtered (0.45 $\mu$m) and unfiltered surface water. Samples were analyzed by cold vapor atomic fluorescence spectrophotometry. We also measured 15 water quality variables, such as chlorophyll-a and suspended particulate matter. We used principal component analyses to reduce those variables to 3 factors: bloom, amount of adsorbent, and decay. We then used a model building approach to determine which of the PCA factors best described concentrations of MeHg and Hg$_{T}$. Dissolved MeHg concentrations significantly (p=0.03) decreased during the bloom, indicating that bloom assimilated MeHg. During decay of the bloom, dissolved MeHg concentrations significantly (p=0.04) increased. That result was consistent with our previous research showing that Mn, Pb, Zn, and Co were remobilized from Bay sediments during decay. To determine the anthropogenic contribution to the bloom, we used a mass balance approach to compare self-reported nutrient discharges from the Palo Alto, San Jose and Santa Clara, and Sunnyvale wastewater treatment plants to our observed nutrient depletion. The diatom bloom consumed 54 $\mu$mol/L of dissolved inorganic nitrogen and 90 $\mu$mol/L of dissolved silica. In conclusion, these interdisciplinary methods allowed us to determine that nutrient-enriched phytoplankton blooms affect mercury cycling in South Bay.
OS25J-11
Drastic environmental change reconstruction based on diatom assemblage analysis during the last century in the Saroma lagoon in Japan
The Saroma Lagoon is the biggest and seasonal sea-ice lagoon adjoining the Okhotsk Sea, and this lagoon is located at the lowest latitude of all of sea-ice areas in the Northern hemisphere. The environment of Saroma Lagoon was changed drastically by artificial excavations at 1929 and 1978. Furthermore, sea-ice cover area in this lagoon has been reduced in recent years. Hence, the analysis of the Lagoon sediments change has a paramount importance for deciphering the local and global environmental changes. The sediment core 05SAROMA-2 ($44\deg$ 07.265' N, $143\deg$ 48.055' E, Water depth: 13.5 m, core length: 33 cm) was raised from in the central Saroma Lagoon, and 57 surface sediments was collected in the lagoon at 2005. These sediment samples included numerous diatom valves. At first, we discuss the relation between the lagoon surface environments and diatom assemblages based on surface sediments analysis. In comparison with Kashima (1996), which reported about diatom assemblages in surface sediments of this lagoon at 1995, environment of the Saroma Lagoon changed during these ten years. Secondly, we argue the extent of the past changes on productivity, sea-ice cover, and surface water qualities as temperature and salinity on the basis of diatom assemblage analysis in that sediment core samples. It is noteworthy that the total diatom valves and the relative abundance of diatom assemblages have been changed on each phase. It is probably that these diatom assemblage changes are reflected by the artificial excavations.
OS25J-12
Aquaculture Impact Modelling in Eastern Ligurian Coastal Waters (Mediterranean Sea)
The Eastern Ligurian coastal waters are a precious resource for several human activities: navigation, tourism, fishing and, more recently, aquaculture. Many political and social conflicts can arise from the contrast between the high turistical pressure and the need for an appropriate management of natural resources. In this framework, an understanding of the local sea water circulation and of its impact on transport and dispersion is of great relevance in order to correctly manage the maritime and coastal activities of the area. Mathematical models are a useful tool in evaluating the environmental impact following dispersion of pollutants from recorded point sources. The Lagrangian particles model LAMP3D has been coupled with the high-resolution hydrodynamical numerical model POM in order to simulate the dispersion of wastes coming from a marine fish-farm. Estimates of the regional dispersion patterns of nitrogen, phosphorous and organic carbon have been calculated using a three dimensional mesoscale grid and have been compared with in situ experimental data. In the numerical simulation the dispersion of faecal matter and feed waste was evaluated by changing the sinking rates, varying the condition of particles release (continuous or periodical) and considering the biodegradation of settled matter. Results of the simulations clearly showed that particles remain mainly confined in the fish farm area and readily sink to the bottom sediment. Modelled impact is low in both water column and sediment compartments and never exceeded the superior bound warned in environmental risk assessments.
http://www.fisica.unige.it/$\sim$doglioli/lamp.htm
OS25J-13
Bacterial Survey On the Coastal Aquacultural Environment In China
At present, viruses including HHNBV and HPV are believed as the main pathogen resulting in the explosive epidemic disease of shrimp in China. To understand the role of marine bacteria on the disease, a survey was carried out on the bacterial flora of the coastal aquacultural environment in China. The statistic data showed that the bacterial population in the shrimp aquacultural water and sediments grew rapidly after June. The total number in marine water grew from 5.1 \times10$^{4}$ cells/ml (AODC) or 1.2 \times10$^{3}$ CFU/ml (Plate counting, PC) in early May to 4.8 \times10$^{7}$ cells/ml (AODC) or 5.1 \times10$^{6}$ CFU/ml (PC) at the end of July. The total number in sediments grew from 8.3 \times10$^{7}$ cells/g (AODC) or 1.3 \times10$^{5}$ CFU/g (PC) in early May to 5.1 \times10$^{9}$ cells/g (AODC) or 8.1 \times10$^{7}$ CFU/g (PC) at the end of July. In July, the shrimp disease began to occur in the experimental zones and resulted in a heavy death. The bacterial strains were isolated from the gill, heart and hepatopancreas of morbid shrimps and identified. Nine different bacterial species belonging to the genus of Vibrio, Aeromonas and Bacillus respectively were purified and tested for the pathogenicity. The tested strains could induce the disease of shrimps under artificial infection with an evidence of red appendages. However, the lethality was not too high, with the maximum of 87.5 % after infection for 5 days and the minimum of only 13 %. We found that the bacterial infection could promote the invasion of virus and speed up the death of shrimp. When the tested shrimps were attacked by virus along with various bacteria, the half-lethal time (LT $_{50}$) might reduce by half. Moreover, the toxicity of single pathogenic bacterium is not enough to result in a large-scale disease. The main reasons for the shrimp explosive epidemic disease happened in the passing ten years in China are the terribly worsening of coastal ecological environment and the rapid decrease of germplasm quality of shrimps. In our experiment, bacteria were detected in the haemolymph and organs of most of the cultured shrimps, which showed that the cultured shrimps were not so healthy as to be easy to suffer from disease when the environmental condition began to worsen.
OS25J-14
Stable Carbon Isotopes in Coastal Puerto Rico Corals and Adjacent Natural Waters: Implications for Land-Ocean Connectivity and Land-Use History.
Over the last century, the terrestrial landscape in Puerto Rico has gone from 94% deforested in the 1940's to 35% deforested by 1995. During the period of peak agriculture (1900-1940), sugar cane crops (C4 plants, average δ$^{13}$C of -15 per mil) dominated the coastal plain, while after 1940, agricultural practices steadily diminished and today the landscape is predominantly forested (C3 plants, average δ$^{13}$C of -26 per mil). This land-use change has resulted in a shift in the average stable carbon isotopic composition of the living plant material and surface soil organic matter. Thus, average δ$^{13}$C of the dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) in the coastal marine waters immediately adjacent to a freshwater input should decrease as forest cover in the catchment increases. In particular, this `land-print' isotopic signature should be more noticeable following large river discharge events during the rainy seasons. Corals may serve as recorders of such changes in land-use over time because they deposit calcium carbonate skeletons in distinct annual bands, can grow for several centuries, and draw on seawater carbon for calcification. In October 2004, two Montastraea faveolata coral cores were collected in Puerto Rico: one approximately 400 m from the mouth of the Fajardo River at 4 m depth; and one approximately 500 m from the mouth of the Rio Loco River in Guanica Bay at 6 m depth. X-radiograph analysis combined with stable isotope data revealed that the Fajardo core was 55 years old covering the period 1949-2004. A long-term decreasing trend in δ$^{13}$C values over the course of the record is consistent with the expected decrease due to reforestation. However, additional calculations are needed in order to determine how much of the decrease is due to changes in land-use and how much may be due to the Seuss Effect. Cross-spectral analysis of the detrended coral δ$^{13}$C values and the Fajardo River discharge rates revealed significant coherence on an annual and 4.5-year basis. The annual periodicity of both records indicates a strong relationship between river discharge and coral skeletal δ$^{13}$C, corresponding with known seasonal (rainy vs. dry season) differences in precipitation and river discharge. The 4.5-year period coherence is most likely due to periodic large flood events resulting from naturally episodic tropical weather patterns such as tropical storms and hurricanes. Results from the Guanica core are currently being analyzed and will also be presented.