Oceanography Commons^™

A Reproductive-Resting Stage In An Harpacticoid Copepod, And The Significance Of Genetically Based Differences Among Populations, D. J. Lonsdale, P. Weissman, Fred C. Dobbs

OES Faculty Publications

Dormancy is an important life-history strategy which allows copepods to increase their fitness by delaying growth and reproduction until harsh environmental conditions have ameliorated. For marine species, the primary strategies identified to date include the production of dormant eggs by shallow-water species, and copepodite overwintering in deep-water species. Herein, we describe a third strategy in which fertilized adult females enter a “reproductive-resting” stage during the late fall that allows them to overwinter and provide a first source of spring naupliar recruitment. This strategy has been observed in the estuarine copepod Coullana canadensis, but may also occur in other species. …

Plankton Transport Patterns And Residence Times Around A Tall Seamount: Simulation Results, Dorlisa Louise Hommel

OES Theses and Dissertations

A semi-spectral primitive equation circulation model was used to simulate flow over an isolated gaussian seamount. Model configuration was such that a Taylor Cap was generated in the flow over the seamount. Arrays of 100 drifters were released in the simulated flow fields at several depths (50, 100, 200, and 400 m) both upstream and over the seamount. For several experiments vertical behaviors were imposed on the drifters to simulate zooplankton migration patterns. The drifter simulations extended for three months. Drifter transport patterns were determined by the initial release position of the drifter relative to the Taylor Cap as well …

The Growth And Bioenergetics Of Callinectes Sapidus Larvae And The Effects Of Diet Quality On Larval Physiology, James J. Pletl

OES Theses and Dissertations

Food quality, especially ω3 polyunsaturated fatty acids (PUFA), can affect the physiology and metabolic efficiency of larvae of the blue crab, Callinectes sapidus. These affects may correlate with success in development and juvenile recruitment.

Larvae were exposed to two diets differing quantitatively in ω3 PUFA and respiration, excretion, growth, and feeding rates were measured for each larval stage and the megalopal stage. The energy partitioned to molts and specific dynamic action was also measured. T

he ω3 PUFA enriched diet resulted in a lower respiration rate when compared to the unsupplemented diet, but there was little differences in excretion …

Molecular And Physiological Responses Of Diatoms To Variable Levels Of Irradiance And Nitrogen Availability: Growth Of Skeletonema Costatum In Simulated Upwelling Conditions, G. Jason Smith, Richard C. Zimmerman, Randall S. Alberte

OES Faculty Publications

Molecular mechanisms that drive metabolic acclimation to environmental shifts have been poorly characterized in phytoplankton. In this laboratory study. the response of light- and N-limited Skeletonema costatum cells to an increase in light and NO₃ availability was examined. C assimilation was depressed relative to N assimilation early in enrichment, and the photosynthetic quotient (O₂: CO₂) increased, consistent with the shunting of reducing equivalents from CO₂ fixation to NO₃- reduction. The concomitant increase in dark respiration was consistent with the increased energetic demand associated with macromolecular synthesis. The accelerations of N-specific rates of …

Spiny Lobster Recruitment In South Florida: Quantitative Experiments And Management Implications, Mark J. Butler Iv, William F. Herrnkind

Biological Sciences Faculty Publications

Understanding recruitment and identifying factors critical to that process are imperative if adult spiny lobster Panulirus argus stocks are to be conserved and properly managed. The goal of our research has been to obtain ecological information linking inshore postlarval spiny lobster recruitment to later life stages, thereby providing the basic framework for assessing and predicting adult stock. Since 1983, we have investigated various aspects of spiny lobster recruitment including: postlarval time-to-metamorphosis, postlarval/juvenile habitat selection and selection cues, postlarval/juvenile crypticity and susceptibility to predation, juvenile food preference and emigration, juvenile sociality, and the effect of habitat degradation (i.e., siltration) on postlarval/juvenile …

Development And Evaluation Of Tracer Particles For Use In Microzooplankton Herbivory Studies, Mary Putt

OES Faculty Publications

Two methods of preparing algae for use as tracer particles in single species measurements of microzooplankton herbivory were evaluated. Algae were either heat-killed and labelled with 5-(4,6-dichlorotriazin-2-yl amino fluorescein) (DTAF) (Rublee & Gallegos 1989; Mar, Ecol. Prog. Ser. 51: 221-227) or stained with hydroethidine (HYD). Both DTAF and HYD-stained algae were readily visible within the digestive vacuoles of most microzooplankton collected in estuarine and coastal waters of Massachusetts (USA) and preserved with Lugol's iodine. However, DTAF was ineffective at staining several chromophytic algae and the heat-kill process reduced cell volume by ≥ 50% in several of the algae which were …

The Effects Of Two Polycyclic Aromatic Hydrocarbons Benzo[A]Pyrene And Naphthalene On Reproductive Success Embryological Development Larval Physiology And Mortality Of The Mud Crab Rhithropanopeus Harisii (Gould), Gregory V. White

OES Theses and Dissertations

Polycyclic aromatic hydrocarbons (PAHs) such as naphthalene (Nap) and benzo[a]pyrene (B[a]P) are common in the water column and sediments of estuarine and coastal areas. The mud crab Rhithropanopeus harrisii was exposed to varying concentrations of Nap or B[a]P to determine the effects on reproductive success, embryological development, larval physiology and mortality. Nap and B[a]P decreased hatching success and prolonged embryological development. Both pollutants produced high abnormality frequencies for egg exposed larvae. Molt frequency and respiratory rates of larvae from non-exposed eggs were more chronically affected by these pollutants than were egg exposed larvae. The EC₅₀ concentrations were determined for …

Fisheries Research Report No. 84 - The Marine Open Shelf Environment: Review Of Human Influences, D. A. Hancock

Fisheries Research Reports

For the purpose of this review, the marine environment has been classified into three physical zones - the littoral zone, the open-shelf environment and the coral reef. Since the boundaries are arbitrary, there will inevitably be some overlap, but for this review the subject matter will be related to the area between low water of ordinary spring tides and the edge of the continental shelf; i.e., to a depth varying to 200 metres.

Human influences may have a dual role in affecting the marine environment, firstly in a causative manner and secondly in providing a remedy, in which case the …

Fecundity Of Blue Crab, Callinectes Sapidus, In Chesapeake Bay: Biological, Statistical And Management Considerations, Michael H. Prager, John R. Mcconaugha, Cynthia M. Jones, Patrick J. Geer

OES Faculty Publications

Ovigerous blue crabs were collected from the mouth of Chesapeake Bay during the 1986 and 1987 spawning seasons. Mean carapace width was 14.7 cm; mean fecundity was 3.2×106 eggs. Fecundity was significantly related to carapace width, and did not vary significantly with developmental stage of the eggs. Mean fecundities were 2.6×106 eggs in 1986, and 4.0×106 eggs in 1987. An additive model with year and size effects described the observed fecundities reasonably well, was compact, and was easier to interpret than a multiplicative model. To fit a more general model without year effects, the authors took the mean of 1986 …

Estimates Of Spawning Stock Size Of Blue Crab, Callinectes Sapidus, In Chesapeake Bay, 1986-1987, Cynthia M. Jones, John R. Mcconaugha, Patrick J. Geer, Michael H. Prager

OES Faculty Publications

The 1986 spawning stock exhibited a single abundance peak, increasing from 1.0×105 individuals in early July to 9.3×106 in late July, maintaining high levels throughout the summer, and declining in the fall to 7.4×105 individuals. The 1987 spawning stock showed 2 peaks of abundance. The population reached the lesser peak, 1.0×106 individuals, in late July; the greater peak, 1.5×106, in late August. By late September, the population had declined to 6.5×105 individuals. The peak abundance of the 1987 female spawning stock was only 16% as great as the peak abundance in 1986; the 1987 spawning stock size in 1986. Variability …

The Temporal And Spatial Distribution Of Blue Crab Larvae On The Mid-Atlantic Bight Adjacent To The Chesapeake Bay, 1982-1983, Lyle Michael Varnell

OES Theses and Dissertations

Recruitment processes are important information for the management of commercially and recreationally exploited marine species. Recruitment processes of the Chesapeake Bay's most important commercial and recreational species, the blue crab, are unknown, due in part to the lack of knowledge of the processes directly preceeding recruitment.

The present study was undertaken to investigate and explain the movement and developmental patterns of blue crab larvae while offshore. Interannual and intraseasonal variations of these patterns were also examined.

Sampling occurred from May to November during 1982 and 1983. Larvae were collected at three depths (neuston layer (upper 10 cm), one meter and …

Picoplankton/Phytoplankton Dynamics In Hampton Roads, Virginia, Leslie E. Dorworth

OES Theses and Dissertations

The biomass distribution of the three main size components of the phytoplankton (net, nano, and picoplankton) was examined in the lower Chesapeake Bay. Work was done at two stations during the spring and neap tidal cycles when freshwater flow into the bay was at its seasonal minimum and maximum. Emphasis was placed on how the picoplankton ( < 2.0 μm, > 0.2 μm) reacted during the sampling period.

Picoplankton made up approximately 13% of the total biomass, during the observed time period, at the more oceanic station. The picoplankton fraction contributed up to 16% of the total biomass at the estuarine station. From this …

Population Variation In The Mitochondrial-Dna Of Two Marine Organisms: The Hard Shell Clam Mercenaria Spp. And The Killifish, Fundulus Heteroclitus, Bonnie Lynn Brown

OES Theses and Dissertations

The two major topics are covered in this dissertation: the integration of molecular genetic tools with applied aquacultural research and short-term evolutionary dynamics. The first study investigated the extent of geographic differentiation of native clam stocks along the U.S. east and Gulf coasts. Clam mitochondrial DNA (mtDNA) demonstrated size polymorphism (16.5-19.0 kb) and restriction site heteroplasmy. Size heteroplasmic individuals occurred at a frequencies of 0-89% in clam populations. Restriction site heteroplasmy occurred in 12% of the 317 individuals assayed. Results of the study indicated that although harbouring a wealth of genetic variation, clams from northern regions were similar and lacked …

Are Artificial "Witham" Surface Collectors Adequate Indicators Of Caribbean Spiny Lobster, Panulirus Argus, Recruitment?, Mark J. Butler Iv, William F. Herrnkind

Biological Sciences Faculty Publications

Understanding the local dynamics of Caribbean spiny lobster (Panulirus argus) postlarval influx, settlement, and recruitment may be essential for the responsible management of this important and heavily exploited resource. Most lobster recruitment research programs in the Caribbean employ derivations of the "Witham"-type surface collector to monitor postlarval (puerulus) lobster influx. However, the relevance of data obtained from surface collectors with respect to the estimation of actual puerulus influx, settlement, or recruitment to subsequent benthic juvenile stages remains untested. We investigated that relevance on regional (i.e., tens of kilometers) and local (i.e., tens of meters) scales by examining the …

Survival And Reproduction Of The Freshwater Grass Shrimp Palaemonetes Paludosus (Gibbes 1850) (Decapoda:Palaemonidae), In Saline Water, Brian Thomas Lowe

OES Theses and Dissertations

To determine the effects of salinity on adult and larval survival, egg deposition, egg hatching and metamorphosis, shrimp were held in the laboratory and exposed to treatment salinities ranging from O to 35 ppt. Tests on adult survival indicate a 96 hour LC-50 between 30 and 35 ppt. Longer term tests on adult survival showed high mortality in salinities greater than 15 ppt. Shrimp became ovigerous in salinities of O - 20 ppt with egg hatching and metamorphosis limited to O - 5 ppt. Starved- larvae hatched from field captured ovigerous females in O ppt were able to metamorphose in …

Consequences Of Thymidine Catabolism For Estimates Of Bacterial Production: An Example From A Coastal Marine Sediment, Kevin R. Carman, Fred C. Dobbs, James B. Guckert

OES Faculty Publications

Radioactively labeled thymidine (TdR) has been used extensively to measure bacterial production in aquatic environments, but critical assumptions of the TdR technique often have gone untested. In this study of a coastal marine sediment, the metabolic fate of methyl [³H]TdR and methyl [¹⁴C]TdR was at variance with the assumptions necessary for determining bacterial production. Only 2% of incorporated radioactivity was recovered in the DNA fraction of TCA-insoluble material following time-course incubations of l-300 min. At least the methyl group of TdR was extensively catabolized, as shown by copious production of ¹⁴C0₂. The temporal …

The Effects Of Siltation On Recruitment Of Spiny Lobsters, Panulirus Argus, William F. Herrnkind, Mark J. Butler, Richard A. Tankersley

Biological Sciences Faculty Publications

Fewer juvenile pinry lobsters were found in areas of the Florida Keys where their primary habitat was heavily silted as compared with similar, less silted habitat. Several hypotheses explaining this relationship were tested, and the time-to-metamorphosis was compared for settling pueruli within silted and nonsilted algae stands. Limited postlarval settlement and avoidance of silted algal habitats by juveniles, probably accounts for the paucity of young lobsters in heavily silted sites. In addition, although juvenile lobsters are nonselective predators, lower prey availability in silted algae probably promotes transciency which, in turn, causes increased mortality by predation while juveniles are exposed.

Evaluation Of Possible Reproductively Mediated Character Displacement In The Crayfishes, Orconectes Rusticus And O. Sanbornii, Mark J. Butler Iv

Biological Sciences Faculty Publications

Orconectes rusticus is replacing several species of crayfishes in north-central and northeastern North America, including O. sanbornii in Ohio. Recent evidence suggests that the species replacements may be driven by asymmetrical reproductive success favoring O. rusticus. Nonetheless, some sympatric associations appear locally persistent. Because crayfish demonstrate size assortative mating and there is a disparity in the sizes of the species, further divergence in the sizes of the species in sympatry could enhance reproductive isolation, ultimately providing a mechanism for character displacement. To test this hypothesis the size differentials between crayfish collected from allopatric and sympatric populations in east-central Ohio …

Molting In The Mature Female Blue Crab, Callinectes Sapidus, Rathbun, Kirk J. Havens

OES Theses and Dissertations

The present study examines the hypothesis that mature female blue crabs, Callinectes sapidus, do not have a terminal anecdysis. Induced molting via eyestalk ablation, size frequency distributions and gonad and limb regeneration indices from field collected animals are used as indicators of potential post maturity molts.

Eyestalk ablation of mature females resulted in ecdysis approximately 51 days after ablation, indicating a physiological ability if mature females to complete ecdysis. Analysis of size frequency distributions indicates two distinct shifts from smaller to larger females, one in early spring and a second in early fall. While migration of larger females into …

Phytoplankton Dynamics In The Very Low Salinity Region Of The James River Estuary, Virginia, U.S.A., Changho Moon

OES Theses and Dissertations

During summer and autumn discharge from the James River estuary, Virginia, was less than 120 _m³sec^-1. There was a peak phytoplankton biomass in the very low salinity region (defined as the location where surface salinity measured less than 0.5$ 0/00) and this peak represented five to ten times greater biomass than adjacent waters. The peak biomass occurred independent of the tidal state and the location of nutrient inputs. It disappeared during winter and spring, and nutrient limitation was not responsible for the low phytoplankton biomass, indicating there were physical, not chemical controlling factors.

The peak biomass …

Acceleration Of Nutrient Uptake By Phytoplankton In A Coastal Upwelling Ecosystem: A Modeling Analysis, Richard C. Zimmerman, James N. Kremer, Richard C. Dugdale

OES Faculty Publications

Studies of upwelling centers in the eastern Pacific suggest that maximum rates of nitrate uptake (light and nutrient saturated) increase, or shift-up, as newly upwelled water moves downstream. The rate of shift-up appears to be related to irradiance and the ambient concentration of limiting nutrient at the time of upwelling. A mathematical model was developed to evaluate effects of irradiance and initial nitrate concentration on temporal patterns of shift-up and subsequent time scales of nutrient utilization over a range of simulated upwelling conditions. When rates consistent with field studies were used, complete shift-up was possible only under certain conditions, and …

Is Growth Of Eelgrass Nitrogen Limited? A Numerical Simulation Of The Effects Of Light And Nitrogen On The Growth Dynamics Of Zostera Marina, Richard C. Zimmerman, Robert D. Smith, Randall S. Alberte

OES Faculty Publications

A numerical model of nitrogen uptake and growth was developed for the temperate seagrass Zostera marina L. Goals were to evaluate the relative effects of light and nitrogen availability on nitrogen uptake and partitioning between leaf and root tissue, and to estimate nitrogen concentrations in the sedment and water column required to saturate growth. Steady-state predictions are quite robust with respect to a range of parameter values justified by available data The calculations indicated that roots are probably more important in overall nitrogen acquisition in most light and nitrogen environments encountered in situ, but may contribute less than 50 …

A Histological Investigation Of The Larval Mandibular Organ In The Mud Crab Rhithropanopeus Harrisii (Gould) (Crustacea Decapoda Xanthidae), Lore Lynn Hantske

OES Theses and Dissertations

Mandibular organs of the mud crab, Rhithropanopeus harrisii (Gould) were histologically located and followed throughout the larval cycle to determine their role in metamorphosis. Specimens from each day of the four larval stages and the megalopa stage were embedded in paraffin, sectioned at 8 μm, stained and observed under the microscope for the mandibular organs. The organs were located in the mandibular area of second, third and fourth stage larvae. The organs were probably present in the first stage zoeae and in the megalopa stage, although the

techniques of the study were not sensitive enough to observe them. The …

Sediment Processing And Selective Feeding By Pectinaria Koreni (Polychaeta: Pectinariidae), Fred C. Dobbs, Teresa A. Scholly

OES Faculty Publications

Pectinaria (Lagis) koreni (Malmgren) is an abundant, deposit-feeding, infaunal inhabitant of shallow-water marine environments in northern Europe. Laboratory experiments were performed to quantify the polychaete's sediment processing in 2 distinct sediments, 1 fine-grained and high in combustibles, the other coarse-grained and low in combustibles. Gut passage time and time to pseudodefecation were predictable only in coarse-grained sediment. In both sediments, reworking rate increased with worm size and over time, although temporal patterns differed in the 2 sediments. The ratio of pseudodefecated sediment to defecated sediment did not differ significantly over time in either sediment, but the ratio was greater in …

In Situ Growth And Chemical Composition Of The Giant Kelp, Macrocystis Pyrifera: Response To Temporal Changes In Ambient Nutrient Availability, Richard C. Zimmerman, James N. Kremer

OES Faculty Publications

Temporal variations in growth of the giant kelp Macrocystis pyrifera were examined in relation to ambient nutrient availability and chemical composition of mature blades, the primary site of nutrient and carbohydrate storage in M. pyrifera. The effect of nutrient availability on growth was well approximated by a Monod rectangular hyperbola, with growth saturating at ambient nitrate concentra- tions between 1 and 2 FM. M. pyrlfera was unable to generate nutrient reserves that would last beyond 30 d. Nitrogen reserves were stored as free amino acids, and generally constituted about 10 % of total tissue nitrogen. Total nitrogen content was …

Deep Flow Variability In Central Drake Passage, John M. Klinck, Eileen E. Hofmann

CCPO Publications

A rotary empirical orthogonal function analysis of the currents measured in central Drake Passage during DRAKE 79 shows that the deep (2500 m) flow has the same spatial and temporal structure as the flow at 500 m, suggesting that current variability in this region penetrates to the bottom. However, comparison of the time amplitude of the corresponding modes indicates that the variability of the 2500 m flow resulting from north to south shifts in the location of the Polar Front lags that at 500 m by one to three days. This implies that the Polar Front slopes to the east …

Factors Regulating Settlement And Microhabitat Use By Spiny Lobsters Panulirus Argus, William F. Herrnkind, Mark J. Butler Iv

Biological Sciences Faculty Publications

Clumps of highly-branched red algae Laurencia spp. serve as important settling habitat for postlarval spiny lobsters Panulirus argus and as residence for early benthic-stage juveniles. Given choice between the 2 most abundant macrophytes in Florida Bay, Laurencia spp. and the seagrass Thalassia testudinum, postlarval and juvenile lobsters chose Laurencia spp. Postlarvae apparently use intricate algal architecture as a cue for settlement, whereas juveniles use both architecture and food abundance in selecting habitat. In tethering experiments, predation on juvenile lobsters was very high on open sand, much reduced in algal clumps and seagrass, and lowest in dense algal meadows. Predation …

Comparison Of An Improved Plankton Sampler To The Standard Conical Plankton Net, Ronald S. Schmidt

OES Theses and Dissertations

A comparison of field and tank tests between the standard conical plankton net and an improved version of a plankton sampler is presented. The improved sampler was shown to filter larger quantities of water than the standard net without having the filtration efficiency reduced below 85%. The improved sampler was also shown to capture an increased number of plankton per volume sampled, as a result of eliminating increased avoidance activity by zooplankton. It was not shown that. the improved sampler capture either larger maximum sizes of zooplankton or additional species.

Microbial Manganese Reduction By Enrichment Cultures From Coastal Marine Sediments, David J. Burdige, Kenneth H. Nealson

OES Faculty Publications

Manganese reduction was catalyzed by enrichment cultures of anaerobic bacteria obtained from coastal marine sediments. In the absence of oxygen, these enrichment cultures reduced manganates when grown on either lactate, succinate, or acetate in both sulfate-free and sulfate-containing artificial seawaters. Sodium azide as well as oxygen completely inhibited microbial manganese reduction by these enrichment cultures, whereas molybdate had no effect on them. The addition of nitrate to the medium slightly decreased the rate of Mn²⁺ production by these enrichment cultures. These findings are consistent with the hypothesis that the manganese-reducing organisms in these enrichment cultures use manganates as terminal …

The Effects Of X-Irradiation On The Metamorphosis And Budding Of Aurelia Aurita, Michael John Prokopchak

OES Theses and Dissertations

With the aid of the Aurelia Metamorphosis Test System, the acute or subtle morphological and behavioral effects of irradiation on the Norfolk Aurelia aurita were described and the sensitivity to X-irradiation of those organisms receiving thyroxine and those not receiving thyroxine was compared. Levels of radiation were 0 (control), 5,000, 10,000, 15,000, 20,000 and 40,000 rads. Morphology of the ephyrae, statolith and rhopalia numbers were recorded using the light microscope, Developmental abnormalities of the scyphistomae and ephyrae were recorded with the scanning electron microscope and light microscope. Two major findings from this investigation were the absence of rhopalia and statoliths …