Hydrozoans of southern Chesapeake Bay and its tributaries were studied from April 1965 until March 1968 to determine faunal diversity, seasonality and reproductive periodicities. Laboratory culture techniques were used in describing unknown or inadequately known stages in the life history of several species and as an aid in identification. A total of 55 species was identified, including 43 hydroids and 32 medusae. Of these, 22 hydroids and 15 medusae are reported in Chesapeake Bay for the first time. Two species earlier reported from the bay, Eudendrium carneum and Blackfordia virginica, were not found. Clytia paulensis and the hydroid of Proboscidactyla ornata are previously unreported in North America, and the hydroid of Amphinema dinema is recorded for the first time from the North American Atlantic coast. The southern range of Hybocodon prolifer, Obelia longissima and Opercularella pumila is extended, as is the northward range of Podocoryne minima, Clytia kincaidi and Phialucium carolinae. Both hydroids and hydromedusae show an affinity with the Carolinian Zoogeographic Province; 76% of the hydroids and 77% of the hydromedusae occur south of Cape Hatteras, while 59% of the hydroids and 35% of the hydromedusae occur north of Cape Cod. The hydroid of Dipurena strangulata and the older medusae of Bougainvillia rugosa and Lovenella gracilis are described for the first time. Partial life histories are described for four other species. The genus Calyptospadix Clarke, 1882 is placed in synonymy with Bimeria Wright, 1859. Hydroids are shown to be characteristically seasonal in occurrence due to the annual water temperature range, which varies from approximately 2 C to 28 C. During seasons of inactivity, laboratory-tested species, Ectopleura dumortieri, Bougainvillia rugosa and Eudendrium ramosum, remained in a dormant state in the stems, stolons, or both, until favorable temperatures returned. Field observations on other hydroid species indicated a similar phenomenon. Dormant stages are resistant to unfavorable temperatures and may have important implications on hydrozoan zoogeography. In nature, the temperature at which renewed growth commenced in spring for winter-dormant species was higher than that at which regression occurred in autumn, and the converse was true for summer-dormant species. This may be an adaptive mechanism insuring favorable conditions for growth once development has begun. Of 23 hydroids whose seasonality was studied in detail, 16 were ’’summer” species and 7 were ’’winter” species. Among the hydromedusae, seasonality was typically less prolonged, with a maximum diversity in late summer and early autumn and a minimum diversity in winter. Although undescribed species or endemics to the bay were not found, two unidentified hydroids, ’’Campanulina” sp. and coast and should not be ruled out as being new species, endemics or both, until more is known about their biology.

This dissertation is from the Joint Program Degree from the College of William & Mary and University of Virginia and awarded by the University of Virginia.

Idiopathic blindness is an environmental disease observed in the American lobster, Homarus americanus H. Milne Edwards, 1837. The only diagnostic assay for idiopathic blindness has been the histological assessment of the eye, which is a time consuming, invasive, and a delicate procedure. I investigated several tools, including the otolaryngoscope and enhanced counterstaining using Bouin’s fixative as alternative, rapid methods for the detection of idiopathic blindness in lobsters. I applied these new diagnostic techniques to toxicology studies to explore a possible lead on the etiology of this condition. Divalent manganese is a well-established neurotoxin released from sediments under hypoxic conditions. Previous studies have shown that the metal exhibits a high affinity for nervous tissue in the confamilial Norway lobster, Nephrops norvegicus. With this prior knowledge, an acute exposure study was designed to expose H. americanus to 0, 20, 80, 150, and 300 mg Mn L-1 (ppm) for 96 hrs. The objectives were to explore disparities in Mn accumulation within various tissues, and determine a non-lethal or sublethal exposure concentration to be used in a chronic exposure study. A positive correlation between Mn accumulation and exposure concentration was observed in all tissue types. The metal was shown to have a consistent pattern of affinity with respect to internal tissues: Hemolymph > optic nerve > brain > hepatopancreas = muscle. A chronic exposure study was designed to investigate the potential link between Mn exposure and idiopathic blindness. That study consisted of a seven week exposure to 150 ppm Mn, with regular assessment of the eyes of the animals using the otolaryngoscope, histological analysis as an endpoint, and comparisons of Mn in the tissues. Animals that molted in the chronic exposure study were found to have very high levels of Mn in their exoskeletons compared to those that had not molted. There was no apparent relationship between Mn exposure and blindness. Alternative theories concerning the etiology of this disease should be considered in future studies.

Microplastic contamination of aquatic environments has only recently caught the attention of scientists, regulators and the public. Microplastics are typically more recalcitrant than naturally occurring polymers and so have the potential to cause a range of issues, including increased exposure of marine life to chemical contaminants sorbed to or leached from microplastics, negative impacts due to ingestion of microplastics by biota, and the potential to carry and transport pathogenic and invasive species long distances. Bio-based, bio-degradable polymers have begun to gain market share as an alternative to traditional petrochemical-based plastics, but not much is known about their impacts in marine environments. The overall objective of this thesis was to improve our understanding of how bio-based microplastics compare to petrochemical-based plastics in the marine environment. This information could be used to evaluate the overall sustainability of bio-based polymers as replacements for petrochemical-based polymers. The first chapter of this work investigated the potential of four types of microplastics, polyethylene (PE), polyvinyl chloride (PVC) and two bio-based polymers, poly-3-hydroxybutyrate (PHB) and polylactic acid (PLA), to sorb hydrophobic organic contaminants (pyrene, PCB-153, and BDE-47) from the surrounding water column. It also examined how co-exposure to several of these contaminants influenced their sorption. The bio-based polymers used in this work, exhibited lower affinity for the organic contaminants investigated compared to the more widely used, petrochemical-derived microplastics. This may be due to several factors including hydrophobicity of the plastic surfaces and the chemical structure of each plastic. Further, competition between several co-exposed contaminants led to an overall decrease in chemical partitioning on polyethylene microplastics. The second chapter reported on the microbial composition of biofilm communities that form on bio-based (PHB and PLA) and petrochemical-based (PE and PVC) microplastics in comparison to a naturally occurring polymer, chitin. Microbial compositions of biofilms that formed on the different plastics were similar during the first and second week of growth, but chitin exhibited a distinct community from the microplastics. By the fourth week of growth, all substrates had a similar community composition. Diversity was generally higher on bio-based plastics. Genera harboring marine pathogens and hydrocarbon-degrading bacteria were identified on all substrates. This work has implications to policy surrounding marine debris issues, exploring the more nuanced differences between bio-based polymers and petrochemical polymers, introducing concerns over additive use in bio-based polymers, and reinforcing the need for “eco-cyclable” materials in single-use items.

Pteropods (pelagic snails) are ubiquitous zooplankton in the Southern Ocean and abundant along the Western Antarctic Peninsula (WAP), one of the most rapidly warming regions on the planet. They are important prey for higher trophic levels, grazers of phytoplankton, and contribute to particulate organic and inorganic carbon export. Pteropods are heralded as bioindicators of ecosystem health due to the vulnerability of their aragonitic shells under ocean acidification conditions, which could greatly affect their abundances in the future. Despite their importance within Antarctic food webs, few studies have analyzed the effects of climate change on pteropod physiology and biogeography in the Southern Ocean. I utilized zooplankton net tows and sediment trap samples collected as part of the Palmer Antarctica Long Term Ecological Research (PAL LTER) program to determine long-term changes in pteropod biogeography and phenology (life history). I also conducted shipboard experiments on PAL LTER research cruises to analyze the effects of shifting temperature and food conditions on pteropod metabolism. Lastly, to examine WAP pteropod feeding ecology, I utilized high-throughput sequencing techniques and analyzed pteropod gut contents at an unprecedented taxonomic resolution. Pteropod populations along the WAP from 1993-2017 either remained stable (shelled pteropods) or increased (non-shelled pteropods) and were most strongly controlled by La Niña conditions the year prior, which led to warmer, ice-free waters. There was a weak relationship between pteropod abundance and carbonate chemistry, and no detectable long-term trend in carbonate chemistry parameters (i.e., aragonite saturation), thus ocean acidification is not presently a factor influencing WAP pteropod abundance. More open-water areas the year prior also increased growth rates of the shelled pteropod, Limacina helicina antarctica, and caused earlier time of appearance in the PAL LTER sediment trap. There was considerable interannual variability in the time of appearance of a new pteropod cohort, which ranged from year day 22 to 255, but no long-term, directional change in time of appearance or growth rate. The effects of warming seawater temperatures and shifting food availability on L. h. antarctica metabolism revealed that highest respiration and usually highest excretion rates occurred under higher temperatures, but the effect of food concentration was more limited. The proportion of dissolved organic matter to total organic and inorganic dissolved constituents was high and the metabolic ratios of C, N, and P were all below the canonical Redfield ratio, which can directly affect phytoplankton growth and bacterial production in the WAP. Analysis of L. h. antarctica gut contents revealed its microbiome for the first time with Mollicutes bacteria the most abundant prokaryote. Pteropods were mainly herbivorous in summer, consuming predominantly diatoms but also supplementing their diet with microzooplankton such as ciliates. My dissertation shows that pteropods along the WAP are sensitive to changes in the environment from daily to interannual time scales. These insights into the metabolic and ecologic responses of pteropods to ocean variability increase our understanding of the role of zooplankton in biogeochemical cycles and help predict future responses to climate change.

Gelatinous zooplankton (GZ; cnidarians, ctenophores, and pelagic tunicates) periodically are the dominant members of the zooplankton throughout the majority of the world’s oceans. their unique body plans and life cycles allow them to rapidly take advantage of favorable environmental conditions, which has far-ranging consequences for food web dynamics and biogeochemical cycles. GZ populations have been speculated to respond to anthropogenic changes, but few long-term studies exist to test this hypothesis and even fewer have examined the consequent effects on carbon export. I analyzed two long-term time series in the Chesapeake Bay and one in the Sargasso Sea for annual and interannual changes in GZ populations and the environmental drivers of these changes. I also conducted mesocosm experiments in the Chesapeake Bay and developed a carbon flux model for the Sargasso Sea to evaluate the role that GZ play in vertical carbon flux in these two regions. In the Chesapeake Bay, summer populations of the dominant scyphozoan medusae, Chrysaora quinquecirrha, are positively correlated with spring salinity and negatively with dissolved oxygen concentrations. C. quinquecirrha biovolume has been decreasing from 1985-2011, reducing predation pressure on the ctenophore Mnemiopsis leidyi, with cascading effects on copepod abundances. This top-down control of the food web extends to changes in vertical carbon flux, with the presence of M. leidyi reducing copepod fecal pellet flux by 50%. In the Sargasso Sea, large salp blooms can completely dominate the zooplankton community, and both cyclonic mesoscale eddies and seasonal changes in primary production can regulate annual salp population dynamics. Long-term salp population trends are correlated with changes in decadal climate oscillations, and a long-term increase in the most abundant salp species, Thalia democratica, was observed from 1994-2011. During blooms, salps can graze more than 100% of the primary production, and rapidly export carbon to depth through sinking fecal pellets and carcasses, and through active transport via respiration at depth. This carbon export to 200 m (average of 2.3 mg C m-2 d-1) is equivalent to 11% of the measured sediment trap flux at the same depth, but salp fecal pellets and carcasses attenuate slowly and can be equivalent to > 100% of measured sediment trap carbon at 3200 m, representing a large export of carbon to the bathypelagic zone during salp blooms. GZ populations in both the Chesapeake Bay and Sargasso Sea are sensitive to seasonal changes in the environment on annual and interannual time scales. Long-term changes in GZ abundances could continue into the future, causing corresponding changes in carbon export.

As Earth’s climate changes, polar environments experience a disproportionate share of extreme shifts. Because the Ross Sea shelf has the highest annual productivity of any Antarctic continental shelf, this region is of particular interest when striving to characterize current and future changes in Antarctic systems. However, understanding of mesoscale variability of biogeochemical patterns in the Ross Sea and how this variability affects assemblage dynamics is incomplete. Furthermore, it is unknown how the Ross Sea may respond to projected warming, reduced summer sea ice concentrations, and shallower mixed layers during the next century. to investigate these dynamics and explore their consequences over the next century, high-resolution glider observations were analyzed and used in conjunction with a one-dimensional, data-assimilative biogeochemical-modeling framework. An analysis of glider observations from two latitudinal sections in the Ross Sea characterized mesoscale variability associated with the phytoplankton bloom and highlighted potential mechanisms driving change in the assemblage. In particular, an observed increase in the ratio of carbon to chlorophyll (C:Chl) suggested a marked transition from a phytoplankton assemblage dominated by Phaeocystis antarctica- to one dominated by diatoms. The expected control of phytoplankton variability by Modified Circumpolar Deep Water and mixed layer depth were shown to be insignificant relative to the effects of wind and sea surface temperature on the temporal/spatial scales measured by the glider. Additional glider measurements were used to force the Model of Ecosystem Dynamics, nutrient Utilisation, Sequestration and Acidification, which was adapted for use in the Ross Sea (MEDUSA-RS) to include both solitary and colonial forms of Phaeocystis antarctica. The impacts of climate-induced changes on Ross Sea phytoplankton were investigated with MEDUSA-RS using projections of physical drivers for mid- and late-21st century, and these experiments indicated increases of primary productivity and carbon export flux. Additional scenario experiments demonstrated that earlier availability of low light due to reduction of sea ice early in the growing season was the primary driver of simulated productivity increases over the next century; shallower mixed layer depths additionally contributed to changes of phytoplankton composition and export. Glider data were assimilated into MEDUSA-RS using the Marine Model Optimization Testbed (MarMOT) to optimize eight phytoplankton model parameters. Assimilation experiments that used different data subsets suggest that assimilating observations at the surface alone, as are typically available from remote-sensing platforms, may underestimate carbon export to depth and overestimate primary production. Experiments assimilating observations characteristic of a cruise-based sampling frequency produced a wide range of solutions, depending on which days were sampled, suggesting the potential for large errors in productivity and export. Finally, assimilating data from different spatial areas resulted in less variation of optimal solutions than assimilating data from different time periods in the bloom progression; these temporal differences are primarily driven by decreasing colonial P. antarctica growth rates, increasing colonial P. antarctica C:Chl, and faster sinking of colonies as the bloom progresses from the accumulation stage through dissipation. Overall, this dissertation research demonstrates the value of using bio-optical glider observations in conjunction with modeling to characterize phytoplankton dynamics in a remote marine ecosystem. High-resolution glider data are better able to resolve mesoscale physical-biological relationships, which are typically not discernible from lower frequency data, but it can be difficult to identify mechanistic relationships from in situ measurements alone. In addition, biogeochemical models can be used to extend insights gained by empirical observation, but application is often limited by the quantity and type of in situ data appropriate for evaluation and forcing. The use of gliders for facilitating development and operation of a lower trophic level model demonstrated the effectiveness of a synthetic approach that partly overcomes the individual limitations of these otherwise distinct approaches. Finally, the combination of these approaches is especially useful for gaining a better understanding of ecosystem dynamics in regions similar to the Ross Sea that are undergoing substantive climate-induced changes and where harsh conditions make other means of access difficult.

Morphology is described for larvae of Diploprion bifasciatus, Belonoperca chabanaudi, Jeboehlkia gladifer, and Grammistes sexlineatus of the serranid subfamily Epinephelinae. Known larvae of all epinephelines are compared. Larval epinephelines differ in patterns of pigmentation, head spination, sequence of fin formation and morphology of elongate (often spectacularly so!) dorsal-fin spines. Relationships among epinepheline genera are investigated based on phylogenetic analysis of larval and adult morphology. Five monophyletic tribes are cladistically delineated, and relationships among tribes and among genera of the tribe Grammistini are hypothesized. Generic composition of tribes differs from Johnson's (1983) classification only in the allocation of Jeboehlkia to the tribe Grammistini rather than the Liopropomini. Despite the presence of the ichthyotoxin grammistin in the Diploprionini and Grammistini, the latter is proposed to be the sister group of the Liopropomini. This hypothesis is based, in part, on previously unrecognized larval features. Larval morphology also provides convincing evidence of monophyly of the subfamily Epinephelinae, the clade comprising all epinepheline tribes except Niphonini, and the tribe Grammistini. Larval features provide the only evidence of a monophyletic Epinephelini and a monophyletic clade comprising the Diploprionini, Liopropomini and Grammistini; identification of larvae of more epinephelines is needed to test those hypotheses. Within the tribe Grammistini, Jeboehlkia gladifer is hypothesized to be the sister group of a natural assemblage comprising the former pseudogrammid genera (Aporops, Pseudogramma and Suttonia). The "soapfishes" (Grammistes, Grammistops, Pogonoperca and Rypticus) are not monophyletic, but form a series of sequential sister groups of Jeboehlkia, Aporops, Pseudogramma and Suttonia (the closest of these being Grammistops, followed by Rypticus, then Grammistes plus Pogonoperca). The absence in adult Jeboehlkia of several derived features shared by Grammistops, Aporops, Pseudogramma and Suttonia is incongruous with this hypothesis but may be attributable to paedomorphosis. The generic phylogeny of the Grammistini proposed herein emerges as the single most parsimonious hypothesis largely because of the method chosen for analyzing multistate characters. This study demonstrates that ontogeny is valuable in phylogenetic studies as a source of characters, means of assessing homology and aid to identifying heterochrony.

Squids are thought to have physiological and locomotive deficiencies that put them at a competitive disadvantage to fishes and exclude them from inshore, highly variable environments that are rich in nektonic fauna. However, brief squid Lolliguncula brevis may be a notable exception. Trawl surveys revealed that L. brevis, particularly juveniles <6 cm dorsal mantle length (DML), are abundant in the Chesapeake Bay, especially when salinity and water temperature are high, and tolerate a wide range of physical conditions relative to other cephalopods. L. brevis is also different from other cephalopods examined previously because its pattern of oxygen consumption as a function of velocity was found to be parabolic and thus similar to aerial flight, and its swimming costs were competitive with ecologically equivalent fishes. Power-speed curves derived from video footage of swimming squid and hydrodynamic force calculations also were parabolic in shape, with high costs both at low and high speeds because of power requirements for lift generation and overcoming drag, respectively. L. brevis employed various behaviors to increase swimming efficiency and compensate for negative buoyancy, such as swimming in various orientations (e.g., arms-first and tail-first), altering angles of attack of the mantle, arms, and funnel, and using fin activity. Fin motion, which could not be characterized exclusively as drag- or lift-based propulsion, was used over 50--95% of the sustained speed range and provided as much as 78% of the vertical and 55% of the horizontal thrust. Small squid (<3.0 cm DML) used different swimming strategies than larger squid possibly to maximize the benefits of toroidal induction, and aerobic efficiency curves indicated that squid 3--5 cm. DML are most efficient. Brief squid also may take advantage of unsteady phenomena, such as attached vortices, for added lift and thrust. Furthermore, an electromyographic study revealed that L. brevis uses different circular muscle layers for various speeds and like fish has muscular "gears", suggesting that there is specialization and efficient use of locomotive muscle in some cephalopods. Therefore, the presumption that squids are inescapably constrained by a second-rate propulsive system and physiological deficiencies is not applicable to L. brevis.

Water-flow is a vital component to the life histories of sessile marine invertebrates and essential to the structure and function of coral reefs. Recent studies have identified water-flow as an asset in the resistance to and recovery from short-term bleaching events of high irradiance and thermal increases. to determine whether the benefits of water-flow scale from the landscape level down to the flow patterns experienced over individual polyps and to quantify potential metabolic consequences, three studies were performed on Montastrea annularis (Ellis and Solander, 1786), using in situ heated bleaching flow-chambers during two saturation missions at the Aquarius underwater laboratory. The first study developed a single coral polyp sampling method and a low-volume protein extraction and quantification protocol. The second study determined and quantified position-effects (upstream and downstream) of enhanced water-flow rates on the organism's photobiology, expressed as Quantum Yield (QY), and within the same experimental set-up, a third study used the regulation and synthesis of the heat shock proteins 70 and 90 (hsp70 and hsp90) as biomarkers, thus allowing the quantification of potential affects of asymmetric flow pattern across the same six coral colonies. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting analysis were used to resolve as little as 87 pg of hsp70 per coral polyp. Relatively large amounts of total protein (x?»= 77 SD +/- 9 mug) were recoverable from single coral polyps. Montastrea annularis colonies developed and sustained significant spatially asymmetric patterns of QY across the entire coral surface, with the upstream side of the colonies exhibiting reduced QY. The mechanism producing this pattern is also unclear. We speculate that increased flow may lead to an up-regulation of photosynthesis by the entire colony through bicarbonate delivery accentuated by the Q10 effect. Local down-regulation of the photosynthetic response (decreased quantum yield) might then occur to keep tissue oxygen concentrations within tolerable limits. The same colonies also developed and sustained significant spatially asymmetric patterns of stress protein synthesis across the entire coral surface, with upstream sectors expressing more hsp70. The mechanism producing this pattern is unclear. We speculate that increased flow may lead to an initial up-regulation in the synthesis of hsps by the entire colony followed by a down-regulation in discrete areas of increased hydraulic stress or biochemical energy requirements. This study is the first to investigate asymmetric patterns of flow-modulated stress protein synthesis and photosynthetic regulation, within mounding and flat plate morphologies of M. annularis, during and following thermal stress and elevated water-flow. Evidence now exists that following sustained periods of increased flow, irradiance and thermal stress, a yet-to-be determined physiological threshold, if breached, can disrupt metabolic processes e.g., the regulation of molecular chaperons synthesis and/or regulate photosynthetic efficiency. Therefore we propose the existence of a water flow threshold (FTmax) that operates in concert with e.g. , temperature. The threshold is proposed to occur somewhere within the range of 3.0--45.0 cm s-1. Flow appears not only to accelerate the effects of the co-stressor temperature, but regulates through the direct effects of velocity, exactly where on the coral regulation of stress protein synthesis and photosynthetic efficiency occurs. Water flow might now be likened to an agent provocateur and posited to join the ranks of other bleaching conspirators such as solar radiation and oxygen toxicity, which act synergistically with temperature in lowering the threshold at which thermal anomalies stimulate coral stress.