The striped mullet, Mugil cephalus, has supported a commercial fishery in North Carolina since the 1800s and today ranks in the top ten of commercially valuable fin- fisheries in the state worth over a million dollars annually. The species is a direct link between lower and higher trophic levels and thus serves an important role in the food web. Despite striped mullet?s biological and economic importance, basic life history data from North Carolina are limited and the stock status is unknown. Objectives of this study were to describe striped mullet growth, reproductive seasonality, size and age at maturity, and fecundity. Monthly samples of striped mullet were collected using both fishery independent and dependent sampling strategies throughout North Carolina. Sagittae otoliths were removed and sectioned for age and growth analyses. Gonads were fixed and histologically prepared for maturity indices and fecundity estimation. Length was highly variable within age classes. Regional growth differences within North Carolina were found as fish collected from the southern sampling regions were smaller at age and lived longer than fish from the northern regions. Growth models suggest growth rates in North Carolina were greater than other areas in the species? range. Based on the presence of recently post-spawned fish and gonadal development, striped mullet spawn between late September and December. The collection of a hydrated female less than 1 km from an inlet, coupled with the presence of post-ovulatory follicles from fish sampled within the estuary, provided evidence for near-shore spawning. Males matured at a smaller length (L50) than females, 283 mm and 324 mm fork length, respectively. Fecundity correlated well with fork length (r2=0.88) and body weight (r2=0.91), and ranged from 1193 to 2535 eggs per gram of eviscerated body weight. This study provides the first life history assessment of striped mullet reproduction and growth from North Carolina and shows differences in growth, maturity, spawning location, reproductive seasonality, and fecundity compared to other areas in the species? range.

As top predators, sharks have an important role in marine ecosystems in relation to populations of fish and invertebrates at lower trophic levels. Fishery management plans stress the need for an ecosystem approach, but few quantitative data on the foraging ecology of sharks have been published. Results from a literature review found that shark species close in taxonomic relation have high diet overlap. Stomach contents and catch data of early life stages of Atlantic sharpnose (<i>Rhizoprionodon terraenovae</i>), blacktip (<i>Carcharhinus limbatus</i>), finetooth (<i>Carcharhinus isodon</i>), and spinner sharks (<i>Carcharhinus brevipinna</i>) taken from fishery independent surveys in Apalachicola Bay, Florida, April-October 1999-2002 were examined to test for resource competition. All species are capable of taking teleost prey from birth, though Atlantic sharpnose and blacktip sharks show an ontogenetic shift in diet. Young-of-the-year Atlantic Sharpnose sharks feed mainly on shrimp, juveniles on sciaenids, and adults on clupeids. Young-of-the-year blacktip sharks feed mainly on sciaenids, whereas juveniles feed on clupeids. The primary prey of young-of-the-year and juvenile finetooth and spinner sharks is menhaden. Seven of ten size-selectivity tests showed neutral selection. Atlantic sharpnose and finetooth sharks consume relatively small-sized prey (over 60% <20% of their length) compared to teleost piscivores while blacktip sharks consume relatively larger prey (58% >20% of their length). Regardless of maturity state and species, diet overlap is high for species-life stage combinations that are similar in size; however, species-life stages did not show significant overlap in habitat use. One possible interpretation is that prey categories shared by similar-sized species are not limiting, but competition may exist for available habitat resources. More intensive monitoring is needed to fully understand temporal and spatial habitat use patterns among these early life stages. Quantifying the links among these sharks and the links between these sharks and resource species are critical for ecosystem modeling and a key step to a broader approach in fisheries management.

Eight Xenopus laevis claudin genes, Xcla1, Xcla4B, Xcla5, Xcla6, Xcla12, Xcla16, Xcla18 and Xcla19, were cloned and sequenced. Their normal mRNA expression was determined from cleavage stage to tadpole stage by whole mount in situ hybridization. The protein expression of Xcla5 was detected at the neural stage by whole mount immunostaining. Overexpression of Xcla5 by injection of synthetic mRNA into embryos caused morphological defects similar to those in embryos exposed to Bisphenol A (BPA). Altered patterns of claudin gene expression in the presence of BPA can be correlated with these developmental defects. The results suggest that claudins may play an important role in neural crest cell migration, epithelial-mesenchymal transition and ultimately organogenesis during embryonic development.

We used a system capable of simulating avian census conditions when birds are detected aurally to evaluate environmental effects on the detection process. We were interested in quantifying the effects of observers, species, and background noise on detection probability and maximum detection distance in two habitats (mixed pine/hardwood forest and deciduous forest) and two leaf conditions (leaves on and leaves off). We found significant effects of background noise, habitat, and leaf conditions on maximum detection distance. Maximum detection distance decreased on average by 36.61 m +- 5.44 with the addition of background noise, 29.52 m +- 6.25 with leaves on trees, and 35.68 m +- 5.58 between mixed pine/hardwood forest and deciduous forest. Average estimated detection probabilities varied greatly by factor combination and species, but in general they decreased with the addition of background noise, under leaf-on conditions, and in deciduous forest sites compared to mixed pine/hardwood sites. Average detection probabilities at 100 m ranged from 0 to 1 among species and under different environmental conditions. Average detection probability estimates never exceeded 0.19 for the Black-and-white Warbler (Mniotilta varia) at 100 m in deciduous forest. We found that a relative hearing index explained a maximum of 37% of the variation in observer detection probabilities. Interacting factors differed among species and were therefore difficult to predict. Environmental conditions can impart substantial bias in auditory point count data. We suggest estimating detection probability directly and incorporating this estimate in abundance estimates.

Many species of plants that produce fleshy fruits depend on birds for seed dispersal, and many of the birds that disperse seeds rely on fruits for a substantial proportion of their diets. From an ecological and evolutionary standpoint, it is important to understand why frugivorous birds feed in the particular plants they do. Intrinsic plant characteristics (e.g., crop size) influence the foraging patterns of birds; however, these factors cannot be fully understood outside the context of the communities within which birds and plants find themselves. Here I report on spatial patterns of bird use of fruiting plants in central Puerto Rico and its relationship to plant distributions and fruit abundance. From Feb.-Jun. 1998 I quantified frugivorous bird visitation to fruiting trees of Schefflera morototoni in a secondary forest-shade coffee plantation mosaic. Visitation rate was positively related to crop size and negatively related to conspecific fruit abundance within 30 m of focal plants. The presence or abundance of heterospecific bird-consumed fruits had mixed relationships with visitation: four species were positively related to visitation; one was negatively related. The fruit neighborhood explained most variation in visitation to focal trees, suggesting that such variables might help explain the high variability seen in other fruiting plant frugivore systems. In order to evaluate spatial dependency in tree distributions, fruiting, and frugivory over a range of tree species and spatial scales, I mapped bird-consumed fruiting plants on a 4.05 ha study grid in secondary wet forest and monitored fruiting and frugivory from Aug.-Nov. 1999. I focused analyses on four tree species: Dendropanax arboreus, Guarea guidonia, Miconia serrulata, and Schefflera morototoni. All of these were intraspecifically aggregated at scales < 80 m, but differed markedly in degree of crowding experienced by individuals. G. guidonia was the most, and M. serrulata the least crowded. Distributions of visited trees and autocorrelation in the number of frugivory observations at trees suggested that individuals of some species (e.g., S. morototoni) facilitated visitation to one another at small spatial scales (< ~30 m). Frugivory was positively correlated with fruit abundance on trees for all species; spatial variation in fruit abundance appeared to have reduced, and in some cases outweighed (e.g., M. serrulata), facilitative benefits of visited neighbors. Evidence of facilitation was especially weak for G. guidonia and may have reflected its particularly high density in the study area. Consideration of interspecific tree distributions showed S. morototoni to be aggregated with M. serrulata at scales > 69 m, and G. guidonia to be aggregated with D. arboreus at scales < 5 m. All other pairs were randomly or regularly distributed with respect to one another. Spatial patterns of fruiting and frugivory of M. serrulata appeared linked to the distribution of fruiting S. morototoni. Spatial patterns of frugivory also overlapped for other species and generally suggested facilitation at larger scales. Interspecific interactions were probably strongest at larger scales because of shifts in the relative abundances of conspecifics and heterospecifics at those scales. These findings highlight the potentially large size of plant neighborhoods with respect to use by avian frugivores and the dependence of neighborhood effects on local plant densities and crop sizes. From the perspective of birds, spatial patterns of frugivory suggested birds closely tracked fruit abundance. I observed few agonistic interactions between birds and found little evidence of their negatively influencing one another?s use of fruiting trees. Similarity in spatial patterns of frugivory between bird species, and positive cross-correlation in frugivory of different species at patch boundaries, suggested birds may have assisted one another (via calling) in locating new foraging patches. This could explain mixed-species flock formation.

In the year 2000, a reported 460 turtles were removed from North Carolina for commercial use. In 2002, the reported take of turtles soared to a staggering 23,311 turtles. A continuation of this trend could severely deplete the turtle populations of North Carolina in a short time. Therefore a moratorium on commercial turtle harvesting was instituted by the North Carolina General Assembly on July 1, 2003, effective until the NC Wildlife Resources Commission could determine rules and regulations for harvesting. It is crucial to know the level of harvest that populations can sustain, and, if a population is harvestable, which age groups are most sensitive to harvest. Regulations on reporting and validation of numbers, identifications, sizes, and sex of turtles will be crucial. I conducted a mark-recapture survey of freshwater turtles in six eastern Piedmont ponds: three of which had been harvested and three of which had no record of harvest. I tested for differences in sex ratios, size and age distributions, and population densities between the harvested and unharvested populations of Yellow-bellied Sliders (Trachemys scripta). Although no significant differences were found between the two types of populations, the amount of variance in the results does not allow any clear conclusions to be drawn. Severe weather impacts on habitat may have influenced sampling results. More research is required to determine the true effects turtle harvesting has on populations, including extensive stage-based simulation modeling and determination of metapopulations.

Three complete complementary DNAs encoding different forms of the yolk precursor protein, vitellogenin (Vtg), were cloned from a white perch (Morone americana) liver cDNA library. The two longest cDNAs encoded Vtgs with a complete suite of yolk protein domains and, based on comparisons with Vtg sequences from other species, they were categorized as VtgAa and VtgAb using nomenclature for multiple teleost Vtgs. The shorter cDNA encoded a Vtg that lacked a phosvitin (Pv) domain, had a shortened C-terminus, and was categorized as VtgC. Multiple distinct Vtg receptors (Vtgrs) with disparate affinities for binding the different types of complete Vtg ligands (Vtgs Aa and Ab) were discovered in the ovary of white perch. Ligand blots of ovarian membranes separated by non-denaturing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) using digoxigenin-labeled purified VtgAa and VtgAb resolved one large (200+kDa) receptor that binds primarily to VtgAa and two smaller receptors (116kDa and 110.5kDa) that bind primarily to VtgAb. Furthermore, in this species, the Pv-less Vtg (VtgC) does not bind to ovarian membranes in either ligand blotting or competitive binding assays. These findings provide the first evidence for a system of multiple Vtgrs involved in the specific uptake of dual complete type Vtgs and the lack of a receptor-mediated system for uptake of VtgC, thus providing for a new model of yolk protein deposition into teleost oocytes.

Fish population dynamics are partially determined by successful larval transport. Many fish in the southeast U.S. use estuaries as juvenile nursery habitat, but are spawned on the continental shelf. Favorable cross-shelf larval transport pathways for fall / winter-spawned species off North Carolina have been theorized to occur as a result of seasonal circulation patterns of currents and episodic onshore movement of water masses. As a result, hydrographic fronts which separate the water masses; including the outer-shelf front and mid-shelf front have been linked to cross-shelf larval transport for several species. The objective of this study was to determine whether fronts on the continental shelf off the southeast U.S. influence larval fish distribution and cross-shelf transport. Ichthyoplankton and hydrographic data were analyzed in concert to determine if the presence of fronts on the shelf influenced larval distribution patterns or mean distance from shore of larvae. In addition, ?average? larval distribution patterns for each species were compared with the results from when fronts were present. Results indicated larval fish were not aggregated at fronts, though abundance and size distribution patterns and mean distance from shore of several species-size classes analyzed were significantly different when the outer-shelf front, mid-shelf front, warm Gulf Stream filament front, or Hatteras front (i.e., intrusions of Virginia coastal water) were present on the shelf. Average cross-shelf distributions of several species were similar to previous studies which led to the conclusion that cross-shelf larval transport was predominately driven by seasonal circulation patterns; however, present results verify that episodic events, such as fronts modify seasonal transport pathways.

The spermatheca of the acridid Orthoptera Schistocerca americana and Dissosteira carolina both consist of a ductus seminalis and a receptaculum seminis that ends in two blind sacs called the apical and preapical diverticula. The diverticula of acridid grasshoppers show high morphological variation that might imply functional differences. A microscopic examination of the structure of the spermatheca surface of both species found the presence of numerous gland ductules, but a lack of acanthae typical of many acridids. A histological study of macromolecules in the spermatheca of mated females found large carbohydrate and protein secretions present in all chambers. The secretion was not present in virgin S. americana but was present in virgin D. carolina. These secretions are likely glycoproteins either secreted by female gland ductules or contributed from males. Lipids were limited to small droplets contained within epithelial cells lining the walls of the spermatheca of both mated and virgin females. Histological sections of the spermatheca were utilized to track the course of sperm bundles in the chambers at various intervals following copulation initiation. In S. americana sperm bundles are found primarily in the diverticula and appear to be degraded in the apical diverticulum. In D. carolina sperm bundles are seen in all chambers of the spermatheca except the ductus seminalis and maintain a constant distribution an hour into copulation. Implications of this study are discussed in relation to the function of acridid spermatheca and sperm organization.

After partial denervation of mature muscle, the remaining motoneurons grow terminal sprouts, which reinnervate denervated muscle fibers. In neonatal rat soleus muscle however, not only do the remaining motoneurons fail to reinnervate nearby muscle fibers, but they also display clear morphological and physiological evidence of terminal disruption. My ultimate aim is to attain a better understanding of this disruption by performing repeated in vivo observations of individually identified terminals in transgenic mice expressing fluorescent proteins in their motoneurons. For technical reasons, these in vivo imaging studies would ideally be conducted on CFP mouse sternomastoid (SM) muscle. I therefore tested whether neonatal partial denervation of CFP mouse SM muscle also causes terminal disruption. Two to five days after neonatal partial denervation, I fluorescently labeled nerve terminals and acetylcholine receptors (AChRs) to assess the effect on terminal morphology. Terminal disruption after partial denervation did not occur as extensively in CFP mouse SM muscle (a fast-twitch muscle) as it did in rat soleus muscle (a slow-twitch muscle). This relative absence of terminal disruption in CFP mouse SM suggested that the extent/occurrence of terminal disruption after neonatal partial denervation could depend on either the species being studied or muscle fiber type. To distinguish between these possibilities, I investigated terminal disruption after partial denervation of rat SM muscle. In both soleus and sternomastoid muscles of rats, neonatal partial denervation resulted in disruption of about half of the terminals, whereas in SM muscles from CFP mice only 8% of terminals showed evidence of disruption. Therefore, it appears that the nature of terminal disruption that takes place after partial denervation of neonatal muscles is not related to muscle fiber type but may be species-specific.