Physical Sciences and Mathematics Commons^™

Atlantic Surfclam (Spisula Solidissima) Population Demographics And Distribution Along The Middle Atlantic Bight, Mauricio González Díaz

OES Theses and Dissertations

The Atlantic surfclam (Spisula solidissima) is a long-lived benthic biomass dominant organism that occurs on the Middle Atlantic Bight (MAB) continental shelf between 10 m and 50 m. Trends in Atlantic surfclam population specific growth and mortality rates were analyzed using four decades of age and length observations obtained from NOAA stock surveys from the 1980s to 2010s in six regions distributed along the MAB. Atlantic surfclam specific growth rates and asymptotic lengths were estimated from the age and length observations using the von Bertalanffy growth model. The analysis showed that the Atlantic surfclam median asymptotic length in …

Phytoplankton Community Response To Upwelling Events: Distribution And Abundance Investigated Using Genomic Methods, Sveinn V. Einarsson

OES Theses and Dissertations

Upwelling events are known to support blooms of phytoplankton, important primary producers at the base of the oceanic food web. Phytoplankton community structure changes in response to upwelling support higher trophic level growth and increased efficiency of carbon export from the euphotic zone. While these events occur globally, this study examined upwelling in coastal regions, where alongshore winds can drive Ekman transport and upwelling of deeper waters. The two upwelling regimes examined were the California Current System and the Alaskan Beaufort Sea. In the California Current System, the relative diatom community composition was examined using 18S sequencing to determine how …

Global Conservation Status Of Croaker And Drum (Family: Sciaenidae) And Role Of The Maw Trade, Claire E. Gorman

Biological Sciences Theses & Dissertations

Understanding threats and drivers of extinction risk is critical to conserving marine biodiversity. Although marine bony fishes are some of the most diverse and abundant vertebrates in the world, overexploitation is the major threat to these taxa. Species in the family Sciaenidae are important marine resources in many parts of the world, supporting small- and large-scale fisheries for consumption and the international maw (dried swimbladder) trade. Sciaenids exhibit a diverse array of life history characteristics, such as high fecundity, large body size, formation of spawning aggregations, and longevity. Some characteristics increase their susceptibility to anthropogenic stressors. Despite being ecologically and …

Nutrient Controls Over Cyanobacterial Synthesis Of The Neurotoxin Β-N-Methylamino-L-Alanine (Bmaa) And Its Potential Accumulation In The Blue Crab (Callinectes Sapidus), Madeline M. Hummel

OES Theses and Dissertations

Cyanobacteria are known to produce a variety of toxins that negatively impact both aquatic and terrestrial organisms. One putative neurotoxic compound is the non-protein amino acid β-N-methylamino-L-alanine (BMAA), which has epidemiological linkages to the development of several human neurological diseases. Three cyanobacterial species thought to produce BMAA —Microcystis aeruginosa, Synechococcus bacillaris, and Nostoc sp. —were grown in nutrient replete cultures to examine its synthesis and cellular distribution over a growth cycle. Production of BMAA was also examined in nutrient (nitrogen and phosphorus) deplete cultures of Microcystis aeruginosa. In addition, natural assemblages of phytoplankton dominated by …

Sponge Community Biocomplexity, Competition, And Functional Significance In Hard-Bottom Habitats Of The Florida Keys, Fl (Usa), Marla Maxine Valentine

Biological Sciences Theses & Dissertations

Sponges can have powerful effects on ecosystem processes in shallow, tropical marine ecosystems and are an integral component of the bentho-pelagic cycle of nutrients, via filtering of dissolved and particulate organic matter from the water column. The diversity of marine communities is thought to play a determining role in intensity of ecosystem processes; thus the loss of taxa alters community function and by extension ecosystem processes. Coastal sponge populations worldwide are increasingly exposed to declining water quality that in several regions has resulted in mass sponge mortalities and reduced sponge diversity. In the Florida Keys (Florida, USA), for example, frequent …

Life History And Management Methods For Blueline Tilefish (Caulolatilus Microps) From The United States Mid-Atlantic Region, Michael A. Schmidtke

OES Theses and Dissertations

Blueline tilefish (Caulolatilus microps) have recently undergone an increase in landings from waters off the US Mid-Atlantic region (Virginia-Massachusetts). Currently, life history characteristics of blueline tilefish in this area are undescribed. Additionally, appropriate indices of population abundance are not available for this region, necessitating the use of data-limited management methods to set restrictions for harvest of blueline tilefish in this area. This dissertation describes growth and reproductive characteristics of blueline tilefish caught off the coast of Virginia and explores improvements of data-limited management methods that have been applied to blueline tilefish in the US Mid-Atlantic. Blueline tilefish from …

Determining Critical Internesting And Foraging Habitats For The Conservation Of Sea Turtles In Gabon, Africa Using Satellite Tracking And Stable Isotope Analysis, Tiffany M. Dawson

Biological Sciences Theses & Dissertations

Understanding the horizontal and vertical habitat of olive ridley sea turtles (Lepidochelys olivacea), a threatened species, is critical for determining regions of protection that may effectively reduce bycatch, the largest threat to this species. Satellite transmitters were used to determine the movement and dive behavior of 21 female olive ridley turtles tagged in Pongara National Park, Gabon during the 2012, 2013, and 2015 nesting seasons. A switching state space model was used to filter the tracking data and categorize the internesting and post-nesting movements. Gridded utilization distribution (UD) home range analysis of tracking data revealed that the entire core habitat …

Hotspots, Extinction Risk And Conservation Priorities Of Greater Caribbean And Gulf Of Mexico Marine Bony Shorefishes, Christi Linardich

Biological Sciences Theses & Dissertations

Understanding the status of species is important for allocation of resources to redress biodiversity loss. Regional organizations tasked with managing threats to the 1,360 marine bony shorefishes of the Caribbean and Gulf of Mexico would benefit from a delineation of conservation priorities. However, prior to this study, conservation status was known for only one quarter of these shorefishes. Extinction risk assessment under IUCN Red List Criteria is a widely-used, objective method to communicate species-specific conservation needs. Data were collated on each species’ distribution, population, habitats and threats and experts at three Red List workshops assigned a global level extinction risk …

Regional Extinction Risk And Conservation Priorities For Persian Gulf Marine Bony Fishes, Jack Ryan Buchanan

Biological Sciences Theses & Dissertations

Around the world, protected areas are the primary conservation measure used to combat biodiversity loss; however, these are often established without comprehensive species-specific information, leading to placement in areas that often do not address the processes that threaten biodiversity. To address this, International Union for Conservation of Nature Red List assessments are being utilized to determine species-specific threats and population status at the global and sub-global levels. This study examines the regional extinction risk for all known marine bony fishes of the Persian Gulf. About 8.3% of the 471 marine bony fishes assessed are at elevated risk of regional extinction. …

Predation Thresholds In Marine Microbial Communities Applied To Environments With Low Prey Abundances, Bonnie Bailey

OES Theses and Dissertations

Prokaryotes (Bacteria and Archaea) comprise the largest component of biomass in the world's oceans. Their abundances are controlled by resource availability, viral infections and protist grazing. Many pico- and nano-eukaryotic predators grow almost as quickly as their prey, and greatly increase in numbers as soon as their prey do, leading in tum to depletion in prokaryotes. It is still unclear however, as to what extent microbial predators are able to feed in low prey environments, most prominently in the largest biome on Earth, the deep sea (below l 000 m depth). It has been hypothesized that in low prey environments, …

Benthic And Planktonic Microalgal Community Structure And Primary Productivity In Lower Chesapeake Bay, Matthew Reginald Semcheski

Biological Sciences Theses & Dissertations

Microalgal populations are trophically important to a variety of micro- and macroheterotrophs in marine and estuarine systems. In Chesapeake Bay, microalgae facilitate the survival and development of ecologically and economically relevant fauna, including shellfish and finfish populations. While regarded as significant components of coastal environments, microphytobenthic communities are historically understudied. In Chesapeake Bay, the importance of phytoplankton to the ecosystem is understood, but the contribution of microphytobenthos remains unclear. This project surveys intertidal microphytobenthic communities, in relation to phytoplankton communities, around lower Chesapeake Bay describing the taxonomic makeup of these populations, coupled with quantification of cell abundance, biomass, and primary …

Determination Of The Ecological Condition Of Benthic Communities Affected By Polycyclic Aromatic Hydrocarbons In The Elizabeth River, Chesapeake Bay, Usa, Adam M. Webb

Biological Sciences Theses & Dissertations

The Southern Branch of the Elizabeth River, a tributary of Chesapeake Bay, has historically been polluted with hydrocarbon based industrial by-products. My study compared benthic community condition from two locations in the Southern Branch: the subtidal region near Money Point, historically affected by pollution of polycyclic aromatic hydrocarbons (PAHs), to a subtidal region near Blows Creek on the opposite shore that is putatively designated as unimpacted by P AH contamination. Samples from both study sites in the Southern Branch were compared to the benthic community condition of samples from the same habitat type designations collected as part of the Chesapeake …

The Impact Of Multiple Nursery Areas On The Population Structure Of Atlantic Menhaden, Brevooria Tyrannus, Kristen A. Anstead

OES Theses and Dissertations

Understanding the population structure and patterns of connectivity in marine fishes is essential when making predictions about a species' resiliency and persistence in an increasingly changing environment. The Atlantic Menhaden Brevoortia tyrannus is a clupeid that plays a critical role in the marine food web and supports one of the largest fisheries on the US East Coast. In addition to a decrease in overall numbers and spawning stock biomass, recruitment levels have remained low since the 1990s. Menhaden use numerous estuaries along the Atlantic coast for juvenile development before recruiting to the adult population and the contribution of each of …

Response Of Natural Estuarine Algal Communities To Nitrogen Additions, Christopher Schweitzer

OES Theses and Dissertations

Coastal eutrophication resulting from nutrient over-enrichment plagues coastal waterways worldwide. In addition to dissolved inorganic N, many marine microbes, including phytoplankton, have the capacity to use certain dissolved organic nitrogen (DON) compounds. However, while we know that many specific DON compounds are labile, the bulk of the DON pool in nature is uncharacterized. The bioavailability of DON to estuarine microbes currently remains unclear.

It is becoming evident that natural phytoplankton assemblages in estuarine waters are capable of using both inorganic and organic N compounds for growth, both of which are present in anthropogenic point and non-point source discharges. Methods for …

Environmental And Physiological Influences On Productivity And Carbon Isotope Discrimination In Eelgrass (Zostera Marina L.), Meredith Leigh Mcpherson

OES Theses and Dissertations

A short-term longitudinal study was used to examine the relations of achievement motivation, general motivation, interest, and self-regulatory predictors to cognitive strategy use and academic performance. A total of 102 college undergraduates enrolled in their first college-level introductory psychology course completed an Achieving Tendency Scale of achievement motivation, the Motivated Strategies For Learning Questionnaire, and an Interest Profile in psychology during the first two weeks of the semester. At midterm they completed the Study Activity Survey of cognitive strategy use. At the end of the semester exam grades, total points earned in the course, and grade point average were obtained. …

Assessing Movement Of Fish Through Spectral Analysis Of Otolith Life History Scans, Renee Reilly Hoover

OES Theses and Dissertations

The ability to accurately measure movement timing across environmental gradients is fundamental for testing hypotheses in marine ecology that deal with ingress, egress, and migration of fish. Timing and patterns of movement have been estimated using life-history scans of the chemical signatures encoded in fish otoliths (ear stones). I provide a quantitative approach to examining life history scan data using spectral analysis, which retrospectively measures the movement timing for individual fish. Sagittal otoliths from juvenile Atlantic croaker (Micropogonias undulates) and adult black sea bass (Centropristis striata) were sampled using laser ablation inductively coupled plasma mass spectrometry …

Circulation Of The Western Antarctic Peninsula: Implications For Biological Production, Maria Andrea Piñones Valenzuela

OES Theses and Dissertations

The western Antarctic Peninsula (wAP) continental shelf is characterized by large persistent populations of Antarctic krill ( Enphausia superba) and by regions of enhanced concentrations of marine mammals and other predators (hot spots). This study focused on understanding the role of ocean circulation in providing retention/connectivity of wAP Antarctic krill populations and in maintaining biological hot spot regions. Numerical Lagrangian particle tracking simulations obtained from the Regional Ocean Modeling System (ROMS) configured for the wAP region provided quantitative estimates of retention, immigration and emigration from the wAP continental shelf. Additional simulations with a one-dimensional temperature-dependent growth model for krill …

Population Dynamics Of Sheepshead (Archosargus Probatocephalus; Walbaum 1792) In The Chesapeake Bay Region: A Comparison To Other Areas And An Assessment Of Their Current Status, Joseph Charles Ballenger

OES Theses and Dissertations

Sheepshead recently have seen an increase in fishing pressure in Virginian waters of the Chesapeake Bay. This increase in fishing pressure has led to demands to install effective management measures to protect the fishery. However, no study regarding the population dynamics, and thus potential yield, of sheepshead has been conducted north of Cape Hatteras. We addressed the need for information regarding the population dynamics of Chesapeake Bay sheepshead by investigating their age distribution, growth rate and reproductive biology. We used this information to construct yield-per-recruit models, which local management agencies may use in the formation of scientifically based management measures. …

Evaluating Methods For Optimizing Classification Success From Otolith Tracers For Spotted Seatrout (Cynoscion Nebulosus) In The Chesapeake Bay, Stacy Kavita Beharry

OES Theses and Dissertations

Identifying the natal sources of fish is an important step in understanding its population dynamics. Adult recruits are often sourced from multiple nursery areas, with good quality locations contributing disproportionately more fish to the adult stock. Because population persistence is strongly influenced by nursery habitat, methods that correctly identify the source of recruits are necessary for effective management. Within the last decade, otolith chemistry signatures have been increasingly used as a natural marker to delineate fish from a mixture of nursery sources. Despite the widespread use of otolith trace element and stable isotope ratios as habitat markers, the statistical approaches …

A Test Of The Area Of Refuge Hypothesis In Indo-Pacific Marine Biogeography, Jonnell C. Sanciangco

Biological Sciences Theses & Dissertations

Many hypotheses have been proposed to explain the marine biogeographic patterns of species richness of the Indo-Pacific. One of these hypotheses suggests that available habitat area is the main predictor of species richness. This is the basis for the area of refuge hypothesis that attempts to explain the global maxima of species richness found in the Coral Triangle, the area encompassing mostly the Philippines, Indonesia, and Malaysia. This species-area effect also has habitat heterogeneity as a potential component. The purpose of this study is to test the effects of habitat availability predictors, such as shallow water area and coastline length …

Impacts Of The Spotted Spiny Lobster (Panulirus Guttatus) On The Long-Spined Sea Urchin (Diadema Antillarum) And Patch Reef Communities In The Florida Keys, Meredith D. Kintzing

Biological Sciences Theses & Dissertations

Caribbean coral reefs have undergone a phase shift from a system dominated by corals to one where algae are pervasive. This shift was precipitated by the loss of herbivores, including the mass mortality of the long spined sea urchin (Diadema antillarum), coupled with disease and the recruitment failure of hermatypic corals. Diadema populations have recovered in some areas of the Caribbean, but are still below historical levels in the Florida Keys, likely due to low larval supply coupled with predation on juveniles. Lobsters are sea urchin predators in other systems and the spotted spiny lobster (Panulirus guttatus …

Changing Fecundity And Reproductive Output In Females Of A Chesapeake Bay Population Of Blue Crab, Callinectes Sapidus, Shannon L. Wells

OES Theses and Dissertations

The Chesapeake Bay blue crab, Callinectes sapidus, is an important species both ecologically and as a fishery. Fishery dependent and independent data indicate that the population declined abruptly in the mid-1990s and has remained low. Previous work prior to the decline in population abundance found a significant relationship between size and fecundity for mature females. As with many heavily fished populations, this population has experienced a reduction in the size at maturity. The objectives of this study were to reassess the fecundity of the population, determine the lipid and protein energy allocated for reproduction, and to examine the concentrations …

A Bio-Optical Model For Syringodium Filiforme Canopies, Margaret A. Stoughton

OES Theses and Dissertations

Seagrasses are significant ecological and biogeochemical agents in shallow water ecosystems throughout the world. In many regions, seagrass meadows occupy a sufficient fraction of the coastal zone, and generate optical signatures that can be observed from space. Bio-optical models of light absorption and scattering by submerged plant canopies for certain species such as Thalassia testudinum and Zostera marina have successfully modeled the plane irradiance distribution and photosynthesis within the submerged canopies. Syringodium filiforme differs &om T. testudinttm and Z marina, in leaf morphology and canopy architecture. The objective of this study was to develop a radiative transfer model that …

Limb Regeneration After Multiple Autotomy And Coxae Removal In The Blue Crab Callinectes Sapidus, Jennifer Ambler

OES Theses and Dissertations

This study investigated limb regeneration in the juvenile blue crab, Callinectes sapidus, specifically the role of the coxa and pedal nerve innervation of the regenerative limb bud over time. The coxa is a leg segment that has been defined as the source of positional, cellular, and neuronal information needed for limb regeneration in brachyuran crabs. This study indicates that removal of coxae under regenerative and non-regenerative conditions did not deter limb regeneration. The coxa is not the exclusive location of limb regenerative information since limbs re-grew with normal positional and functional arrangement in 86% of crabs showing regeneration at removal …

Interactions Between Phytoplankton And Bacteria In The Uptake Of Organic Compounds, Andrea Michel Rocha

OES Theses and Dissertations

The most common methods for estimating bacterial productivity are [³H]-leucine and [³H]-thymidine incorporation. Uptake of these compounds has been attributed primarily to bacteria; however, because dissolved organic nitrogen may be an important N source for some phytoplankton, the use of these compounds to estimate bacterial productivity needs to be reexamined. In order to ascertain whether phytoplankton could compete with bacteria on relevant timescales and thereby bias bacterial productivity estimates in estuaries, I examined the ability of cultured phytoplankton and size-fractionated natural populations to take up leucine and thymidine in systems seasonally dominated by phytoplankton mixotrophs. In …

Characterization Of Β-Lactam Resistant Pandemic Serotypes Of Vibrio Cholerae Isolated From Ships' Ballast Tanks And Coastal Waters, Amanda Lynn Goodrich

OES Theses and Dissertations

Vibrio cholerae serotypes 01 and 0139 are responsible for world-wide epidemics of cholera. These pandemic causing strains must possess genes that encode for the cholera toxin (CTX) and toxin co-regulated pili (TCP) in order to infect their hosts. In this study, 284 isolates of Vibrio cholerae from ballast and coastal waters were serotyped, with 11 % testing positive for serotype 01 and 21 % testing positive for serotype 0139. PCR assays were used to detect the presence of ctxA and tcpA genes in all positive isolates, none of which contained ctxA while 2% of the isolates contained tcpA. The 01 …

Age Validation And Reproductive Biology Of Bluefish, Pomatomus Saltatrix, Along The East Coast Of United States, Eric Robillard

OES Theses and Dissertations

I describe a new preparation technique that increases readability of otoliths, along with criteria for the interpretation of otolith microstructure of bluefish, Pomatomus saltatrix, collected from Florida to New York during 2001-2003 (n = 2652). I validated annulus formation in otoliths for ages 1 to 8 using marginal increment analysis and thus extended validation by four years to include the preponderance of age classes in the catch. Although otoliths are typically superior for ageing, bluefish are routinely aged with scales; thus a side-by-side comparison of otoliths versus scales is necessary before otoliths can supplant scales. When compared, precision …

Relating Water And Otolith Chemistry In Chesapeake Bay, And Their Potential To Identify Essential Seagrass Habitats For Juveniles Of An Estuarine-Dependent Fish, Spotted Seatrout (Cynoscion Nebulosus), Emmanis Dorval

Biological Sciences Theses & Dissertations

A quantitative understanding of habitat use of estuarine-dependent fishes is critical to the conservation of their most essential habitats. Because recruitment and fitness may be influenced by the quality of juvenile habitats, developing methods to quantify habitat-specific survivorship is pivotal to such understanding. An initial step to quantify survivorship is to validate the habitat-specific natural tags contained in otoliths. To this aim I investigated the variability in the chemistry of surface waters and otoliths of juvenile spotted seatrout, Cynoscion nebulosus, in five seagrass habitats of Chesapeake Bay, namely: Potomac, Rappahannock, York, Island, and Eastern Shore. I measured Mg, Ca, …

The Implications Of The Target-Area Hypothesis On The Population Dynamics Of The Spotted Spiny Lobster, Panulirus Guttatus, Denice N. Robertson

Biological Sciences Theses & Dissertations

The target-area hypothesis, based on the theory of island biogeography, predicts that larger islands are more effective at intercepting passive immigrants. Most marine invertebrates have meroplanktonic larvae and open population dynamics, so immigration to populations in isolated benthic habitats is primarily by pelagic larval recruits. Thus, recruitment to isolated habitat “islands” may be more continuous and predictable on large islands than on small ones. Consequently, populations on large islands should not only be larger than those on small islands, but should also have more evenly distributed size structures. These differences in size structure among populations in isolated habitats of differing …

Stomach Content Analysis Of Stranded Bottlenose Dolphins, Tursiops Truncatus, In Virginia, 1987-1996, John Mcgurk

Biological Sciences Theses & Dissertations

I examined the stomach contents from 94 bottlenose dolphins, Tursiops truncatus, that were stranded along the Virginia coastline from 1987 through 1996. Samples from 1987 through 1991 were obtained from the National Museum of Natural History (NMNH) and samples from 1992 through 1996 were collected by the Virginia Marine Science Museum (VMSM) Stranding Team. Prey species were identified using fish otoliths and cephalopod beaks.

The dolphins examined fed on 23 species of fish and one genus of cephalopods. The primary prey species was Atlantic croaker (Micropogonias undulatus); secondary species were weakfish (Cynoscion regalia), spot (Leiostomus xanthurus), silver perch (Bairdiella chrysoura), …