The size-at-maturity of female blue crabs is declining and the proportion of very small mature females (<100mm carapace width (CW)) is increasing North Carolina. Decreasing mature size of the female may have an effect on the mating success and mortality of size-disparate mating pairs. To test the effect of body size on mating behavior, I used controlled mating experiments comparing size-disparate mating pairs with similarly-sized mating pairs. Small males handled large females longer than any other mating pair combination; however, no increase in injury or mortality was found. Neither large nor small males transferred significantly different numbers of sperm to large and small females. Size-disparity appears to have no effect on mating success in blue crabs, suggesting that diversity of size-related genotypic traits can be preserved in the population. I also designed a mathematical model to estimate the lifetime spawning potential of different size-cohorts of female blue crabs subject to different mortality pressures. Cohorts of very small females (<100mm CW) that are not subject to fishery mortality produce 5.1 ? 58.1% more eggs over two spawning seasons than larger, harvestable females (127-159mm CW), suggesting an evolutionary advantage to maturing at smaller sizes. I also used the model to estimate the efficacy of a proposed restriction on the commercial harvest of large females (>172mm CW), intended to increase the spawning potential of large females in order to increase population-wide recruitment, as well as the number of recruits that may possess a larger-size genotype. The proposed seasonal (Sept. ? Apr.) commercial harvest of large females produced an estimated 23.2 ? 35.1% increase in egg production over two spawning seasons. However, since the large females compose less than 2% of the population, on average, the estimated increase in spawning potential for the entire population was negligible (0.46%). Additionally, the 5% tolerance of the regulation allows for the harvest of the entire population of large females, suggesting that the proposed restriction will be ineffective.

An analysis of fine particulate mass concentrations in eastern North Carolina was conducted in order to investigate the impact of the hog industry and its emissions of ammonia into the atmosphere. This analysis included collecting acidic gas and inorganic fine particulate concentrations at a hog facility and at a site ~10 miles away, while the regional impact of hog industry was studied with data, which was obtained from the North Carolina Division of Air Quality, for multiple regional sites (Fayetteville, Goldsboro, Jacksonville, Kenansville, Kinston, Raleigh, Wilmington). This regional fine particulate data was then simulated using ISORROPIA, a thermodynamic model that simulates the gas and aerosol equilibrium of inorganic atmospheric species. The local analysis showed the dominance of the ammonium sulfate aerosol, and the seasonal observations showed the impact of both urban areas and marine areas on this region. While no meteorological trends were seen in the local data, the time series plots showed an environment where regional sulfate plays a large part. While nitrate is present in this environment, it is present 1 order of magnitude less then the sulfate aerosol. The ammonium and sulfate values are highly correlated, and the molar ratio is consistent with the relative values of ammonium, sulfate, and nitrate present. The regional observational data analyses show that the major constituents of fine particulate matter are organic carbon, sulfate, nitrate, ammonium and elemental carbon. The observed PM2.5 concentration is positively correlated with temperature but negatively-correlated with wind speed. The correlation between PM2.5 mass and wind direction at some locations indicates the impact of the emissions from hog facilities on PM2.5 formation. The modeled results overpredict the observed results in each case, where the nitrate concentrations had the largest percentage overprediction. The predicted total inorganic PM concentrations are overpredicted by 40-45% of the observed values under conditions with median initial total PM species concentrations, median RH and median temperature. The ambient conditions with high PM precursor concentrations, low temperature and high relative humidity favor the formation of the secondary PM. The model runs of the individual days at the three speciated sites showed overprediction for all species, where some predicted values of ammonium were within a factor of 2 of the observed concentrations.

Introduced species are a threat to native species conservation worldwide and can cause an overall reduction in biodiversity. In the Cape Horn Biosphere Reserve in southern Chile, introduced beaver and trout are highly successful invaders in the landscape and alter stream ecosystem function. Our research suggests introduced beaver create favorable feeding habitats for native puye (Galaxias maculatus) by increasing available macrobenthic biomass and creating ideal feeding conditions for puye. A negative effect of trout on puye was only detectable in favorable beaver-altered habitats where puye abundance was significantly reduced. A negative relationship between trout density and aquatic macrobenthic biomass suggests introduced trout reduce prey availability at the patch-scale. Our findings also show the presence of endangered Aplochiton spp. on Navarino and Hoste islands and the absence of brown trout completely from the southeast fringe of the Cape Horn Biosphere Reserve. Conservation measures be taken to prevent the spread of brown trout into the area in order to protect rare Aplochitons spp. These results emphasize the need for understanding introduced species distributions and their influence on native biota and stream ecology so conservation measures to preserve native species and the pristine status of the Cape Horn Biosphere Reserve can be implemented.

Long-term in situ measurements have been made on the mid-continental shelf in Onslow Bay, NC to determine the frequency and direction of bottom sediment movement and the processes responsible for bottom sediment motion. As part of the Coastal Ocean Research and Monitoring Program (CORMP) at the University of North Carolina at Wilmington, a quadrapod frame with a downward looking Pulse-Coherent Acoustic Doppler Profiler (PC-ADP) and an upward looking Acoustic Doppler Current Profiler (ADCP) has been maintained on the continental shelf at approximately 30 m depth since May of 2000. The instruments are moored 27 nautical miles off the coast of Wilmington, North Carolina in Onslow Bay, adjacent to a productive marine hardbottom. Simultaneous measurements of flow velocities from the surface to the seabed, along with acoustic backscatter measurements, have been obtained. Measurements of seabed elevation, temperature, conductivity, and pressure were also collected at the site. Bed stresses due to wave-current interactions are calculated using a bottom boundary layer model (Styles and Glenn, 2002). Wave-current interactions resulted in shear stresses at the sediment-water interface that exceeded the critical threshold for sediment movement over 50% of the time during a climatological average year. Sediment transport was been shown to occur during four different types of events at the site: 1) small to moderate northerly wind events 2) Gulf Stream Intrusion events 3) strong southerly wind events associated with the passage of frontal systems 4) the passage of tropical storm systems. Over the course of a year the total net suspended sediment flux at 1 mab was in the positive along-shelf direction (southwest) and in the negative across-shelf direction (onshore), where there was several times more net transport in the onshore direction than the along-shelf direction. Three mechanisms leading to significant sediment transport on the mid-continental shelf have been indentified: 1) wave-current interactions 2) subtidal currents associated with sustained wind-driven flows and the intrusion of Gulf Stream water on the shelf 3) infragravity waves. Subtidal currents played a key role in the sediment transport during all types of events. Wind driven subtidal currents were important in determining the magnitude and direction of sediment transport during storm events, while subtidal currents associated with a Gulf Stream intrusion event combined with fair-weather swell resulted in accretion at the site of 3 cm over a three week period. The results show that a moderate northeasterly wind event with sufficient duration to generate wind driven subtidal flows resulted in an order of magnitude more sediment transport (20,237 g cm^?2) than a similar northerly wind event and the southerly wind event without developed wind?driven flows. These two events resulted in similar amounts of sediment transport of 3,600 g cm^?2 and 3,061 g cm^?2, respectively. The passage of a hurricane resulted in an order of magnitude more sediment transport than the moderate northeasterly wind event, on the order of 240,000 g cm^?2. Shear velocities during the passage of Hurricane Isabel resulted in the largest bed shear stresses (~300 dynes cm^?2) on record. Field measurements in the bottom boundary layer were compared with the bblm generated current profiles during moderate wind events and Hurricane Isabel. In addition, the suspended sediment concentration profiles from the model were compared with the ABS profile measurements to verify shape and magnitude as the storms increased and waned. In general, there was good agreement between the measured and model derived current profiles, and between suspended sediment measurements and the model concentration profiles for both large and small-scale events that occurred at the site.

Groundwater and surface water samples were taken at 14 locations at a lowland rainforest site (La Selva Biological Station) in Costa Rica for the analysis of DIC, DOC, 14C, 13C, 36Cl, 18O, and other geochemical parameters. The data are consistent with the mixing of two endmember groundwaters. One is a local water having low Cl concentrations (<0.07 mM), low DIC (<3.0 mM), high 14C (>100 pmc), δ13C between -22? and -26?, and highly variable 36Cl/Cl ratios. This chemistry is consistent with locally recharged shallow groundwaters having short residence times in which the DIC originates from plant root respiration and atmospheric deposition is the only source of Cl. The other endmember is bedrock groundwater, representing interbasin groundwater flow (IGF) into La Selva and having relatively high Cl concentration (>0.9 mM), high DIC (about 14 mM), low 14C (<8 pmc), high δ13C (-3? to -5?), and a low and more consistent 36Cl/Cl ratio. This chemistry is consistent with the expectations for bedrock groundwater recharged on the flanks of Volcan Barva to the north of La Selva, with a majority of the DIC and Cl derived from magmatic degassing and dissolution of the volcanic rocks that make up the aquifer. A 14C age of 750 ? 4650 years before present was estimated for the bedrock groundwater endmember using NETPATH geochemical mass-balance modeling software, suggesting an average linear velocity of 3-20 m/yr for this groundwater; the actual age is probably closer to the upper limit, and velocity closer to the lower limit. The results of this study are consistent with prior work using major ion, 18O, and physical hydrologic data, suggesting that the conclusions about IGF and groundwater mixing at this site are correct. Also, new DIC data for bedrock groundwater and previous hydrologic data on bedrock groundwater inputs to the Arboleda watershed at La Selva suggest that IGF of bedrock groundwater is responsible for a large inorganic carbon flux into lowland watersheds (about 740 grams of carbon per m2 of watershed each year for the Arboleda).

This study was part of a larger, more comprehensive project assessing the effects of culvert designs on freshwater mussel habitat. Because many freshwater mussels depend on an obligate relationship with certain fish hosts to complete their life cycle as well as sole mechanism for dispersal, it is critical to identify obstacles to fish movement that, in turn, could negatively impact dispersal success of mussels. The primary goal of our study was to quantify the impact of four commonly used road crossings (bridge, arch culvert, box culvert, and pipe culvert) on stream fish abundance and diversity, as well as movement. We conducted a mark-recapture study in 16 streams located in the Piedmont region of the Cape Fear River Basin of North Carolina during the summer of 2004. Following electrofishing surveys, all fish were identified to species and measured to the nearest millimeter. Fish ¡Ü 30 mm total length (TL) were individually marked elastomer paint. These procedures were repeated four, eight, and 12 weeks after the initial sampling period. With the exception of species richness, all response variables: estimates of population size, species diversity, fish index of biotic integrity (FIBI), and Conditional Percent Movement (CPM) did not vary significantly with crossing type, position (upstream and downstream), or month. Downstream reaches of box culverts contained significantly higher species richness of stream fish than other crossing types. High diversity of stream fish downstream of box culverts may have been due to a scouring effect common below box and pipe culverts which results in pool formation and a possible change from benthic to pool fish species on a local level. The general lack of stream fish abundance and diversity responses to road crossings may be due to: the insensitivity of stream fish community variables (FIBI and diversity index) to anthropogenic effects, the overall resilience of fish communities, or the shifting baseline theory--fish communities having shifted to an impacted community prior to sampling. There were extremely low numbers of individuals that moved between stream reaches in the first study, therefore we conducted a second mark-recapture study using Passive Integrated Transponder (PIT) tags with remote antenna arrays on six streams, three streams with bridges and three streams with box culverts, during the summer of 2005. We surveyed each stream using electrofishing and marked all fish measuring ¡Ý 60 mm TL with an ISO PIT tag. Custom built antenna arrays, with weir nets to direct fish passage through the antenna loop, were installed in each stream either upstream or downstream of a given crossing and detected tagged fish continuously for 30 days. Estimates of mean percent movement of fish through box culverts (28.27% ¡À 12.24% SE) was almost half that of bridges (44.35% ¡À 8.77% SE); however, the percent tagged fish detected by the antenna for bridges and culverts showed no significant difference between the two crossing types. These results suggest that a larger study might detect a significant difference in fish movement through culverts as opposed to bridges. This application of PIT tags and remote antenna arrays proved a more effective and efficient use of research funding to assess stream fish movement through culverts and we recommend the antenna systems for further non-game fish research.

Ocean bottom seismic observations within the 9°50â N region of the East Pacific Rise indicate persistent, low-amplitude tremor activity throughout the October 2003 through February 2007 period of monitoring. These signals exhibit either mono- or polychromatic spectral characteristics, with a ~6 Hz fundamental frequency and up to two harmonics. Individual events cannot be correlated between nearby (<1 km) stations, implying the presence of multiple, small-amplitude sources positioned within the shallow crust. Tremor exhibits a semi-diurnal periodicity, with some stations recording activity during times of increasing tidal extension and others detecting tremor signals during times of increasing compression. The amplitude, duration, and rate of activity also correlate positively with fortnightly changes in the amplitude of the tides. These spatio-temporal patterns are consistent with tremor generation in response to tidally modulated fluid flow within a network of shallow cracks. Tremor energy flux is spatially and temporally heterogeneous; however, there are extended periods of greater and lesser activity that can be tracked across portions of the array. Despite their shallow crustal origin, changes in tremor amplitude and spectral character occur in the months prior to a major microearthquake swarm and inferred seafloor spreading event on 22 January 2006, with an increase in the degree of correlation between tremor activity and tidal strain observed in the weeks leading up to this event. After the spreading event, two eruption-surviving stations near the axis continue to show high rates of tremor activity; whereas, these signals are suppressed at the single station recovered from the near-axis flanks. This off-axis quiescence may result from the dike-induced closing of cracks, or perhaps from the emplacement of impermeable flows near the station.

This pilot project presents 14C groundwater ages in the Black Creek and Upper Cape Fear aquifers of the Coastal Plain of North Carolina, an evaluation of the relationship between He concentration and groundwater age, and 3H concentrations in groundwater. Groundwater samples were collected with a Bennett pump from 7 wells that lie along a trend roughly parallel to groundwater flow (at least, predevelopment groundwater flow). 14C, 13C, DIC, DOC, He, Ne, Ar, N2, O2, CO2, CH4, H2, 3H, S, Fe, Al, Mn, Si, Na+, K+, Ca2+, Mg2+, Cl-, SO4-, and NO3- were measured in all samples. Estimation of groundwater age involved inverse mass balance modeling with NETPATH to account for geochemical reactions (calcite dissolution, organic matter oxidation, and cation exchange) affecting 14C activity in groundwater, as well as a separate correction to account for loss of 14C by diffusion into contiguous aquitards. 14C groundwater ages were 580, 10700, 19100, and greater than 35300 years old at four wells in the Black Creek aquifer, and 15100, 26900, and 31100 years old at three wells in the Upper Cape Fear aquifer. These groundwater ages, together with falling heads, suggest that groundwater withdrawals in these aquifers represent a sort of ?mining.? He concentration in groundwater increased with 14C groundwater age with one exception (a sample very high in He concentration from the Upper Cape Fear where it directly overlies crystalline basement rocks). Groundwater from 6 of the wells had 3H concentrations that are consistent with the presence of young water, but it is uncertain whether the 3H in these wells is from relict drilling fluid, downward leakage along the well casings, or a more broadly distributed downward leakage.

This research has investigated the ability to model precipitation over East Africa using the RegCM regional climate model, and the ability of a stochastic model to predict Lake Victoria lake level one season in advance. The stochastic model was built using precipitation, sea surface temperatures and temperature, and provides detail about the steps used to develop the model. Precipitation modeling was carried out using RegCM and several convective schemes were compared to determine which performed best for East Africa. Additionally the microphysical scheme SUBEX was investigated thoroughly and several tuning parameter changes were made. Finally the precipitation from RegCM was split into 9 rainfall classifications which were then studied to determine how the regional climate model performed for representing rainfall events in the model, in terms of duration, intensity, and overall structure between all the event types.

The source to sink investigation of complex sedimentary systems necessitates chemical (stable isotope and elemental) and physical (modeling) analyses to elucidate temporal changes in volume and provenance of sediment supply. The stable isotopic composition of organic matter in continental margin sediments provides a useful, long-term record of environmental change. The Waipaoa River watershed, New Zealand, represents a system of interest due to its location on an active margin, very large sediment supply, and well known, relatively recent history of anthropogenic disturbance. Radiocarbon measurements of three continental shelf cores taken aboard the RV Marion Dufresne in January 2006 offshore from the river mouth suggest a record extending into the late Pleistocene, dating as far back as 14,000 years. Geographic information systems (GIS) modeling suggests large increases in erosion with reduction in landcover due to natural volcanic events and anthropogenic disturbances. Carbon and nitrogen isotope analyses of terrestrial sources including soil profiles, sedimentary rocks and riverine sediments from within the watershed suggest terrestrial processes such as shoreline progradation, hillslope erosion and gully incision, volcanic eruptions, and the capture of river tributaries are possibly influencing isotopic ratios and impacting the marine stratigraphic record. Unique isotopic signatures of soil profiles from disparate areas of the watershed could explain some isotopic variation seen in the cores as deviation in delivery volume from certain tributaries. Within the marine record in all three cores exists a distinct excursion of carbon isotopes to more positive values. Possible explanations for this include: 1) an increase in the flux of an isotopically heavy terrestrial fraction from the erosion of kerogen and 2) a decrease in the proportion of terrestrial organic matter due to dilution of river sediments with volcanic ash. Increasing nitrogen isotope values also within the excursion could suggest an increase in marine organic matter, however this could be the result of increased input of degraded refractory terrigenous organic matter or contributions of inorganic nitrogen.