Thesis (Honors)--College of William and Mary, 2008. / Includes bibliographical references (leaves 58-61). Also available via the World Wide Web.

The object of this thesis is the synthetic generation of possible future flows in the James River at Buchanan, Virginia, through the utilization of existing records of monthly precipitation and runoff. Twelve separate monthly regression models were chosen on the basis of the degree of correlation as indicated by the correlation coefficient. Random monthly precipitation totals were generated from the twelve separate distributions of historical monthly precipitation totals. The synthetic precipitations were used in the twelve monthly models to generate 5000years of artificial record. The 5000-year synthetic record was divided into fifty separate 100-year records for the purpose of analysis. The dependable flows were found for each of the fifty records for each of eight reservoir sizes. The ninety percent confidence interval and the dependable flow for each of eight reservoir sizes was found. The model had a negative bias of approximately thirteen percent. This bias appeared to be alleviated when the dependable flow was expressed as a percent of the average flow for the period in question. It appears that there is great variability in the estimated value of the dependable flow in the James River. / Master of Science

An on-site interview and mail survey questionnaire of anglers on the James River, Virginia, was conducted to compare the characteristics of anglers, estimate angler compliance and illegal harvest, and determine the factors related to angler compliance with a black bass slot length limit regulation of 280 to 356-mm (11 - 14 in) and a daily creel limit of five bass. Boat and bank anglers differed significantly in yearly tackle expenditures, travel distances, knowledge of existing regulations, and species preference. Angler compliance with the slot limit averaged nearly 85% for the entire river, while angler compliance with the creel limit was over 99%. The total illegal harvest of black bass averaged approximately 10% of the total bass harvested. Comparisons between known complying anglers and known non-complying anglers showed differences in daily bait expenditures and yearly tackle expenditures. Non-complying anglers had a yearly tackle expense that was one-half that of complying anglers, and a daily bait expense that was more than twice that of complying anglers. All other characteristics were similar. Comparisons between anglers who knew the regulations and those who did not showed differences in species preference and yearly tackle expenditures. For fishery managers, understanding the factors related to an angler's probability of complying will be an important criteria when establishing or changing fishing regulations. By understanding those factors that cannot be manipulated by managers and serve only as predictors of compliance (i. e., angling methods), and those factors that can be modified (i. e., regulation knowledge), managers should better comprehend angler behavior. / Master of Science

The tidal-fresh James River experiences recurring blooms of toxin-producing cyanobacteria, including Microcystis aeruginosa. However, cyanobacteria cell densities in the James are relatively low. Our purpose was to identify key factors suppressing cyanobacteria growth in the face of eutrophication. A mesocosm experiment was designed to test the effects of light, mixing and grazing on cyanobacteria abundance, with nutrients held constant. We predicted that toxic cyanobacteria would be most abundant under stagnant conditions, with enhanced light, with no bivalve grazers present. Abundances of indicator gene copies and phytoplankton counts supported this hypothesis. However, chlorophyll-a, phycocyanin, and the toxin microcystin were all found to be most abundant under mixed conditions with ambient light. Statistically, light and mixing were important in controlling toxic cyanobacteria abundance, with little to no effect observed for bivalve grazers. Our findings suggest that toxin production may be regulated by factors independent from those driving algal growth and cyanobacteria abundance.

This study examined the extent to which zooplankton in the James River Estuary (Virginia, USA) exploit the available algal-food resources. Zooplankton abundance, community composition and grazing rates were assessed at three locations which included a site with high algal production (near the VCU Rice Center) and two sites where algal production was lower. Grazing rates were measured by determining the rate of phytoplankton decline (as chlorophyll a) during 48-hour incubation experiments in the presence and absence of zooplankton. Significant differences in zooplankton abundance were observed among the three sites, with the greatest average zooplankton density (434 ± 69 ind/L) occurring at the phytoplankton maxima. There were no significant differences in zooplankton filtration or ingestion rates among the three sites. The amount of chlorophyll a consumed was low at all sites (< 5%), suggesting that only a small proportion of primary production was directly passed to higher trophic levels. Low grazing rates were attributed to poor food quality owing to the presence of non-algal particulate matter and a predominance of cyanobacteria comprising the phytoplankton community. These findings are consistent with prior studies showing that cyanobacteria are a poor quality food source for zooplankton and that non-algal particulates may interfere with grazing rates. Further, this study lends support to the hypothesis that food quality is an important determinant of trophic transfer efficiency in aquatic food webs.

Thesis (Honors)--College of William and Mary, 2008. / Includes bibliographical references (leaves 34-36). Also available via the World Wide Web.

Distribution of the James spinymussel (Pleurobema collina) and aspects of its life history were studied from June 1987 to October 1989. Field and laboratory observations were used to determine gravidity and glochidial release periods, fish host requirements, age class structure, growth characteristics, and juvenile survival. Stream surveys conducted at 243 sites in 20 counties revealed new populations of this species in three subdrainages (Catawba Creek, Pedlar River, and Mechums River), of the James River, greatly expanding its known range. Female P. collina were gravid from late May through early August 1988 and 1989 in Craig Creek, Virginia, and the South Fork Potts Creek, West Virginia. Glochidia were released from late June through early July in the South Fork Potts Creek, at mean water temperatures between 21 and 25 °C, and discharges between 0.013 and 0.050 m l/sec. Field observations and laboratory tests confirmed that cyprinids serve as fish hosts for P. collina glochidia. Glochidia of the James spinymussel were identified on the common shiner (Notropis cornutus), rosyside dace (Clinostomus funduloides), bluehead chub (Nocomis leptocephalus), pumpkinseed (Lepomis gibbosus), and fantail darter (Etheostoma flabellare) in the South Fork Potts Creek. Eleven fish families were tested for suitability as fish hosts in the laboratory, but only the following 7 species served as hosts: bluehead chub (N. leptocephalus), rosyside dace (C. funduloides), satinfin shiner (N. analostanus), rosefin shiner (N. ardens), central stoneroller (Campostoma anomalum), blacknose dace (Rhinichthys atratulus), and mountain redbelly dace (Phoxinus oreas). Juvenile P. collina, fed a mixture of three green algae species in chambers with and without silt, lived 50 days. Juveniles in silt grew significantly faster than those not in silt after 18 days. Age and growth characteristics of adults were obtained by thin-sectioning valves collected in muskrat middens in Dicks and Johns creeks, Virginia. Ages ranged between 3 and 19 yr, and a strong year class was identified at age 11. Mean annual mortality rate was calculated to be 9.8%. As predicted by the von Bertalanffy growth equation, P. collina reaches a maximum length of 74.4 mm, and annual growth increments decrease from 7.04 mm/yr (age 1) to 0.88 mm/yr (age 19). As judged by qualitative surveys, current populations of P. collina in Craig Creek, Johns Creek, and the South Fork Potts Creek appear to be self-sustaining. Populations in Catawba and Patterson creeks appear to be small and are probably in jeopardy of being extirpated. The status of the James spiny mussel in Dicks Creek, Rocky Run, and Pedlar and Mechums rivers is unknown since these streams were not extensively surveyed. / Master of Science

Entocytherid ostracods were collected on crayfishes inhabiting the James and York River basins of Virginia. Of the seventeen species encountered, only one (Donnaldsoncythere ardis) seems to be endemic. Ankylocythere ancyla, Dactylocythere banana, Dt. falcata, Dt. suteri, Donnaldsoncythere ardis, Dn. hiwasseensis, Dn. truncata, Entocythere sp. A, E. internotalus and Phymocythere phyma occur on the crayfishes Cambarus acuminatus, C. b. bartonii, C. longulus and Orconectes juvenilis in the streams of the Valley and Ridge Province. In the Coastal Plain where sluggish streams are encountered, Ankylocythere telmoecea and Ank. tiphophila are associated with Procambarus a. acutus. Cambarus acuminatus is also found in the Coastal Plain in moderately flowing streams and it is infested with Dactylocythere suteri and Donnaldsoncythere hiwasseensis. The primary burrowing crayfish of the Alleghany Mountains (Cambarus dubius) is host to Ascetocythere asceta and Dactylocythere chalaza whereas its ecological similar Cambarus d. diogenes of the Piedmont and Coastal Plain is the only host known with certainty for Dactylocythere jeanae, Okriocythere cheia and Ornithocythere waltonae. Ankylocythere tiphophila is associated with Fallicambarus uhleri, an inhabitant of swampy areas and marshes and may ocassionally construct simple burrows in the Coastal Plain. / Master of Science

M. S.

The bus route survey technique is a new on-site angler survey technique that was developed for small rivers, with remote access points and low angler use. The technique employs vehicle counts to collect angler effort information. Interviews are conducted at access points to collect user characteristic and catch data from arriving, mid-trip, or departing anglers. This technique was modified to sample total recreational use on 306 km of the James River from Glen Wilton to Richmond, Virginia. The river was spatially stratified into 6 areas, two urban areas (Areas 5 and 6), and four rural areas (Areas 1-4). The two-year study was conducted from March through November, in 1988 and 1989. In order to compare the bus route technique in a large riverine system, I conducted four 4-day intensive sampling days, two weekend and two week days, in Areas 1 and 4 during each year. During these periods a complete as possible access-point survey was conducted simultaneously with the bus route survey. Surveyors for both techniques collected effort, user characteristic, and catch data from several user groups. Aerial flights were also conducted to estimate effort during the 4-day intensive sampling periods. Effort estimates of the bus route and complete access-point surveys were similar in both areas, however aerial surveys collected 205 (29%) more hours of effort per sample because it included users accessing the river through undefined or private access points. Data collected on most user characteristics were not significantly different among methods. In three of four sampling periods catch was not significantly different between the bus route and complete access-point techniques, but in 1988, Area 4, catch was statistically higher for the complete access-point surveys. To solve this problem of underestimating case with the bus route survey more afternoon samples must be conducted to intercept departing anglers. In areas with more than 15 access points or driving time between access points is longer than half the survey day, the bus route can be extended over a two-day period, or a sub-sample of a number of access points can be surveyed. A 4-day intensive sampling period was conducted in 1989, Area 1 during the summer season to compare effort, user characteristics, and catch data between two-day, sub-sampling, and complete access-point surveys. Also, 26 sampling days were conducted in 1989, Area 1 during the summer season to compare effort, user characteristics, and catch between two-day and sub-sampling bus route techniques. No significant difference in effort, and certain (9) user characteristics, or angler catch data was detected between bus route modifications or the complete access-point survey. Also, no significant differences in effort, user characteristics (11), and angler catch variables (2) were detected between the two-day and sub-sampling methods that were conducted throughout the entire summer period. The bus route survey was designed to have equal daily probabilities. When unequal daily probabilities are used, the daily effort formula becomes complex. Daily effort, user characteristics, and catch data were compared from interviews conducted in morning and afternoon samples in 1989, Area 4 during the summer season. Results showed no statistical difference in effort although a mean of 72 (52%) more hours of effort were collected per afternoon sampling period. Most user characteristics were not significantly different, but a larger proportion of departing users were interviewed in the afternoon period (54%) then the morning period (22%). Because only two departing interviews in the early sampling period were anglers, catch estimates could not be compared between the two periods. If collecting catch data is an important survey objective, then more afternoon bus route sampling periods must be conducted. / Ph. D.