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Articles 1 - 12 of 12
Full-Text Articles in Physical Sciences and Mathematics
The Distribution Of Phytoplankton In Frontal Regions Of The Lower Chesapeake Bay, Richard V. Lacouture
The Distribution Of Phytoplankton In Frontal Regions Of The Lower Chesapeake Bay, Richard V. Lacouture
OES Theses and Dissertations
The spatial and temporal distribution of phytoplankton was measured in relation to frontal areas located in the entrance to the Chesapeake Bay. Phytoplankton biomass, taxonomy, and several physical parameters were measured on fifteen sampling cruises between September,1981 and February, 1983.
Several statistical tests revealed that phytoplankton biomass did not accumulate at the fronts and that generally the distribution of phytoplankton biomass was homogenous across the frontal region. The cell count data indicated that the community structure of the phytoplankton assemblage was usually very similar on both sides of the front. The data which was concerned with temporal variations in the …
The Effect Of Sea Nettle Abundance On The Food Chain Of The Lower Chesapeake Bay, Michael Glenn Kelly
The Effect Of Sea Nettle Abundance On The Food Chain Of The Lower Chesapeake Bay, Michael Glenn Kelly
OES Theses and Dissertations
The significance of sea nettle abundance on lower levels of the Chesapeake Bay food chain was examined in a field study and by the analysis of medusa gut contents. In the field study, the abundance of four levels of the food chain (Chlorophyll (a), copepods, the ctenophore Mnemiopsis leidyi, and the Schyphomedusa Chrysaora guinguecirrha) were monitored twice weekly at four stations from May 10 through September 30, 1982. The copepod standing stock declined sharply in late May when M. leidyi appeared, but rebounded a month later when C. guinguecirrha medusae reduced the ctenophore population. Despite the additional presence …
The Effect Of Polynuclear Aromatic Hydrocarbons On The Fecundity Of Acartia Tonsa (Calanoid Copepoda), Juanita Y. Grabarczyk
The Effect Of Polynuclear Aromatic Hydrocarbons On The Fecundity Of Acartia Tonsa (Calanoid Copepoda), Juanita Y. Grabarczyk
OES Theses and Dissertations
The concentrations of polynuclear aromatic hydrocarbons (PNAHs) were determined for several stations in the Elizabeth River. Thirteen PNAHs of the sixteen EPA priority pollutant PNAHs were present in the particulate fraction. The concentrations ranged from 10.0 ng/1 to 1000 ng/1. Ten of the sixteen EPA priority pollutant PNAH were present in the dissolved phase. Concentrations ranged from 2.0 ng/1 to 100 ng/1.
The environmental PNAHs concentrations were used to determine test concentrations. Bioassays were conducted to determine the effects of indigenous concentrations of seven predominant PNAHs (0.01 mg/1 to 2.4 mg/1 concentrations) on the fecundity of Acartia tonsa (calanoid Copepoda). …
Adaptations Of Dolphin Vision To The Oceanic Environment, Andre Rivamonte
Adaptations Of Dolphin Vision To The Oceanic Environment, Andre Rivamonte
OES Theses and Dissertations
The objective of this study has been to develop an hypothesis explaining comparable aerial and underwater visual acuity of the bottlenose dolphin, Tursiops truncatus. This objective was accomplished by integrating the findings of other dolphin researchers working in the fields of comparative psychology, histology and ophthalmology. Their combined results enabled the formulation of a schematic dolphin eye. It is proposed that a dolphin lens, similar to the spherical lens of teleost fish with a rigid core of uniformly high refractive index and a margin of radially decreasing refractive index, could function as a bifocal lens and compensate for the eye's …
A Model Of The Population Dynamics Of The Blue Crab In Chesapeake Bay, Betty Springer Hester
A Model Of The Population Dynamics Of The Blue Crab In Chesapeake Bay, Betty Springer Hester
OES Theses and Dissertations
This study has particular application to the blue crab fisheries in Chesapeake Bay, an economically important industry whose successful management has been hindered by relatively poor understanding of the population dynamics. Recent biological studies have indicated a systematic spawning behavior which seems designed for ejection of larvae seaward from the bay entrance where they spend their pre-metamorphosis stages in the neuston. A physical mechanism for retention of the larvae in sufficient proximity to the bay entrance for their return at the proper time which involves the action of wind stress in shallow waters is proposed. Since the supply of blue …
Simultaneous Functional Hermaphroditism In The Shrimp Hippolysmata Wurdemanni (Gibbes) (Decopoda: Caridea: Hippolytidae), Marie Hollister Bundy
Simultaneous Functional Hermaphroditism In The Shrimp Hippolysmata Wurdemanni (Gibbes) (Decopoda: Caridea: Hippolytidae), Marie Hollister Bundy
OES Theses and Dissertations
The caridean shrimp Hippolysmata wurdemanni Gibbes was studied from a histological and a behavioral basis and was found to be a protandric hermaphrodite which later adopts simultaneous functional hermaphroditism. When the animal reaches a certain size, the androgenic gland degenerates, the male secondary sexual characteristics are lost, and vitellogenesis occurs in the anterior portion of the gonad. The animals do not lose the ability to function as males as evidenced by the presence of mature sperm in the gonad and the gonadal lumen of gravid shrimp, and the ability of both members of an isolated pair of shrimp to repeatedly …
The Growth And Feeding Behavior Of Juvenile Spot, Leiostomus Xanthurus Lacepede, In The Nursery Region Of The James River, Virginia, John Thomas Mccambridge Jr.
The Growth And Feeding Behavior Of Juvenile Spot, Leiostomus Xanthurus Lacepede, In The Nursery Region Of The James River, Virginia, John Thomas Mccambridge Jr.
OES Theses and Dissertations
The in situ growth and feeding behavior of juvenile spot, Leiostomus xanthurus Lacepede, was investigated for populations in the nursery area of the James River, Virginia. Growth of juvenile spot was found to be fairly rapid (11.34 mm/month, standard length) during their first summer in the nursery grounds, but it levelled off in the autumn. The mean size of spot after the first year was calculated to be 195 mm total length. The weight-length relationship was log W = -5.018 + 3.246(log L), where W = wet weight in grams and L = standard length in millimeters.
Juvenile spot appeared …
The Effect Of Crowding On Growth Of The Cichlid Fish, Oreochromis Mossambicus, Bonnie A. Barrows
The Effect Of Crowding On Growth Of The Cichlid Fish, Oreochromis Mossambicus, Bonnie A. Barrows
OES Theses and Dissertations
It has been reported that the Java tilapia, Oreochromis mossambicus, displays hypersensitivity to a substance it produces when biomass levels in a flow-through culture system exceed 20 g/1, resulting in reduced growth and high mortality. Experiments on the growth of this species in small tanks were conducted in order to determine whether O. mossambicus produces a growth-inhibiting compound under crowded conditions. This species was successfully maintained at biomass levels of 38 g/1 and 57 g/1 with a total mortality of only 4.5%.
The Java tilapia can grow rapidly in small aquaria, as indicated by the data taken during Experiment …
Polychlorinated Biphenyl Levels In The Ocean Scallop (Placopecten Magellanicus) Gmelin From The Philadelphia Sewage Sludge Disposal Site, Guy Jeffrey Hall
Polychlorinated Biphenyl Levels In The Ocean Scallop (Placopecten Magellanicus) Gmelin From The Philadelphia Sewage Sludge Disposal Site, Guy Jeffrey Hall
OES Theses and Dissertations
Ocean Scallops (Placopecten magellanicus) were sampled from stations in and around the Philadelphia Disposal Site. Each sample was dissected and aliquots of adductor muscle and reproductive tissue were chemically extracted for Polychlorinated Biphenyls (PCBs). A perchlorinated procedure outlined by Diosady et al., 1972, Aromour, 1973 and Crist et al., 1977 was employed to increase detection levels and simplify quantitation of PCBs. PCB levels were reported in dry weight and lipid weight of both adductor muscle and reproductive tissue. Findings indicated residual levels or PCB/lipid weight increased as lipid levels decreased in both tissue types. Levels detected in all adductor muscle …
Input And Distribution Of Sewage Derived Sedimentary Material Adjacent To Chesapeake-Elizabeth Sewage Outfall, Virginia Beach, Virginia, Robert Carroll Brown
Input And Distribution Of Sewage Derived Sedimentary Material Adjacent To Chesapeake-Elizabeth Sewage Outfall, Virginia Beach, Virginia, Robert Carroll Brown
OES Theses and Dissertations
The concentrations of coprostanol and hydrocarbons were measured in the effluent from the Chesapeake-Elizabeth sewage treatment plant and surface sediments from the area surrounding the effluent discharge site. Most of the coprostanol (>84%) and hydrocarbons (>91%) were associated with particulates in the effluent. Some of these particles were incorporated into the sedimentary column within the study area, while some may have escaped from the area.
The study area is found to be a dynamic area where changes in the percentage and distribution of fine-grained sediments occur over periods of months. The movement of fine-grained sediments is an important …
Variability Of Atmospheric Hydrocarbon Concentrations And Deposition Rates, Charles Thomas Farmer
Variability Of Atmospheric Hydrocarbon Concentrations And Deposition Rates, Charles Thomas Farmer
OES Theses and Dissertations
The atmospheric hydrocarbon concentration was determined at various locations throughout Southeastern Virginia from July 1981 to February 1983. During this period the concentration ranged from 0.4 to 5.5 μg/m3 . From October 1982 to February 1983, WET and dry deposition samples were collected in conjunction with these air samples. Total hydrocarbon dry deposition rates ranged from deposition rates ranged from 4 to 189 μg/m2 /day, while WET 22 to 670 μg/m2 /day. Hydrocarbon concentrations found were within the ranges reported in the literature for wet, dry and atmospheric hydrocarbon concentrations.
Linear trend analysis revealed no correlation between …
A Study Of Increased Flow Off The Eastern Seaboard Of The United States Within Four Synoptic Flow Patterns During The Winter Months, John Dale Liechty
A Study Of Increased Flow Off The Eastern Seaboard Of The United States Within Four Synoptic Flow Patterns During The Winter Months, John Dale Liechty
OES Theses and Dissertations
A study of increased winds during the winter season off the United States Eastern Seaboard was made in each of four synoptic flow patterns: prefrontal; postfrontal; northeast; and southerly. Eight years of synoptic data for the months October through March from two pairs of stations were utilized. Each pair consisted of one land and one sea station; of the sea stations, Frying Pan Light was located in or near the warmer water of the Gulf Stream while Chesapeake Light was situated in colder, coastal water. Both land stations were situated in the vicinity of the coast.
A statistical analysis was …