MEES Theses and Dissertations

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Production and energetics of Atlantic menhaden in Chesapeake Bay
(1993) Rippetoe, Thomas Hunt; Brandt, Stephen B.; Marine-Estuarine-Environmental Sciences Program; Biology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)
Laboratory experiments were conducted to examine the effects of temperature and prey type on maximum consumption, absorption efficiency and gastric evacuation rates of age 0 Atlantic menhaden Brevoortia tyrannus. Maximum consumption reached a peak or asymptote between 25 and 29°C. Temperature had no effect on absorption efficiency, but gastric evacuations rates increased with increasing temperatures. Artemia sp. nauplii were absorbed more efficiently than the diatom Ditylum brightwelli. Prey type had no effect on gastric evacuation rates at temperatures below 25°C but D. brightwelli was evacuated faster than Artemia sp. nauplii at 28°C. Field estimates of daily ration based on stomach content analyses for age 0 menhaden were 5.5% of dry body weight (3.6% wet weight) in June and 3.6% of dry body weight (3.0% wet weight) in August. Most prey in menhaden stomachs were dinoflagellates, diatoms and a mixture of amorphic phytoplankton and detritus. Less than 1% of total biomass in menhaden stomachs was copepods. A diurnal feeding periodicity was apparent with peaks in stomach contents occurring around dusk. A bioenergetics model was developed for age 0 menhaden in mid-Chesapeake Bay. The model incorporated temperature and weight-specific parameters for consumption and respiration and site-specific parameters for growth, diet, energy density of predator and prey and water temperatures. Model estimates of population consumption and production were sensitive to assumptions about annual mortality rates. Daily population consumption peaked in September which coincided with the second annual peak in primary productivity typical of mid-Chesapeake Bay. Daily production peaked from mid-August through September. Model results showed that in 1990 menhaden population consumption would have removed <5% of primary production in mid-Chesapeake Bay from June through October.
Understanding Maternal Effects as a Recruitment Mechanism in Lake Michigan Yellow Perch (Perca flavescens)
(2000) Heyer, Christopher James; Miller, Thomas J.; Biology; Marine - Estuarine - Environmental Sciences Program; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)
Changes that have occurred in the abundance and trait distribution of adult Lake Michigan yellow perch (Perca flavescens) suggest that maternal effects on larval traits may be substantially influencing the recruitment of this heavily exploited species. Maternal effects on yellow perch larvae at hatching and through 32 days post hatch (dph) were investigated in ten maternal lines to test the null hypotheses of no effect of maternal condition on offspring condition at hatching, no persistence of maternal effects under conditions of starvation and high food availability, and no difference in offspring survival under conditions of starvation and high food availability. Maternal effects were detectable at hatching and likely result in differences among females in size, age, gonadal somatic index, and egg production. Maternal effects at hatching were expressed by differences in larval total length, yolk volume, dry weight, and DNA quantity. Maternal effects persisted under conditions of starvation to 6 dph, after which point virtually all larvae had perished. Maternal effects resulted in a twofold difference in resistance to starvation among the maternal lines. Larvae that exhibited the lowest resistance to starvation were long with small yolk volumes, while those exhibiting the highest resistance to starvation were short with large yolk volumes. Under high food availability maternal effects persisted to 32 dph, and resulted in threefold differences in survival among the maternal lines. No clear mechanism was identified to account for these survival differences. The observed maternal effects in Lake Michigan yellow perch may have substantial implications on recruitment.
Removal of Wastewater Nitrogen and Phosphorus by an Oligohaline Marsh
(2003-10-15) Traband, Jason John; Fisher, Thomas R; Cornwell, Jeffery C; Stevenson, J C; Stribling, Judith M; Marine-Estuarine-Environmental Sciences
Wetlands potentially contribute to water quality improvement. The objective of this thesis was to determine the role of wastewater processing by oligohaline Council Creek marsh (0.16 km2), which receives wastewater from Easton, MD. Tidal flushing, nutrient distributions, plant uptake, and sediment burial were examined as removal mechanisms. This marsh seems to be little affected by, and has a small impact on wastewater. Wastewater flow can raise mean water levels by 3 cm in addition to seasonal changes of 30 cm induced by thermal expansion and contraction of seawater. During the ~3 d flushing time of water, nutrients passing through the marsh experienced small transformations compared with 2575% dilution of wastewater in the marsh by Choptank River water, during summer high sea level stands. During the growing season, marsh plants intercepted 3044% N and 1117% P, while sediment burial appeared to remove 27% N and 6% P, annually.
The Effects of Spraying Deltamethrin Against Tsetse Flies on Insectivorous Birds in the Okavango Delta, Botswana
(2003-10-22) Pendleton, Frank N; Baldwin, Andrew H; Marine-Estuarine-Environmental Sciences
I investigated the effects of spraying deltamethrin for tsetse fly control on bird populations in the Okavango Delta, Botswana. Because deltamethrin has low toxicity to vertebrates, effects on birds would have been indirect and caused by reductions in insect food supplies, not by poisoning. The northern half of the Delta was sprayed in 2001 and the southern half in 2002. I monitored resident bird populations at four sites (two in each spray block), using point counts. Birds were classified by diet as insectivorous or non-insect-dependent in order to check for declines in insectivorous. Sections of the 2002 spray block burned before the spraying started. In the 2001 spray block, there were no declines of insectivorous birds, and varied results for non-insect-dependent birds. In the 2002 spray block, the Chitabe site showed declines in insectivorous forest birds, which were not strongly correlated with the spraying, and Nxaraxa showed no such declines.
Bioaccumulation of Polychlorinated Biphenyls in the Delaware River Estuary
(2003-11-03) Toaspern, Megan; Baker, Joel E; Secor, David H; Rowe, Chris; Marine-Estuarine-Environmental Sciences
Composite collections of channel catfish (Ictalurus punctatus), white perch (Morone americana), their prey items (forage fish and epibenthos), and surficial sediment were collected in the Delaware River estuary in Fall 2001 and Spring 2002 to quantify polychlorinated biphenyl (PCB) accumulation and to examine the mechanisms of bioaccumulation and trophic transfer. Samples were collected from four zones in a section of the Delaware River from Trenton, NJ to Liston Point, DE, and analyzed for lipid content and the hydrophobic organic contaminants PCBs. Our results indicate PCB levels and congener distributions in biota reflect spatial and temporal trends in ambient PCB concentrations. PCB congener patterns vary among sampling zones, with higher homologue groups enriched in lower zones. Demersal species have similar congener accumulation patterns. The presence of highly chlorinated congeners in lower zones does not reflect commercial Aroclor mixtures, indicating a possible point source of PCB contamination in the region downstream of Philadelphia, Pennsylvania. The relationships between total PCB levels in biota and those in water and sediment was constant over the study area based on bioaccumulation parameters. Ambient water quality criteria calculated for the Delaware River with estuarine-specific values derived from this study indicates a major reduction in PCB point and non-point loadings is necessary to reduce PCB contamination in fish, thereby meeting acceptable risk levels for human consumption.
Toxins and Toxicity from the Cosmopolitan, Bloom-Forming Dinoflagellate Karlodinium micrum
(2003-11-25) Deeds, Jonathan; Place, Allen R; Terlizzi, Daniel E; Reimschuessel, Renate; Stoecker, Diane K; Marine-Estuarine-Environmental Sciences
Karlodinium micrum (Leadbeater and Dodge) Taylor was first described in the United States during an investigation into the cause of repeated fish kills at an estuarine aquaculture facility located on a tributary of the Chesapeake Bay, MD, USA. As part of that investigation we described toxins in this species for the first time. Named karlotoxins (KmTx), these compounds possess hemolytic, cytotoxic, and anti-fungal properties. However, the primary harmful effect associated with blooms of this organism is ichthyotoxicity. Karlotoxins are lethal to fish through damage to gill epithelia. This research focused on two of these toxins, KmTx 1 (1338 Da.) and KmTx 2 (1344 Da.) These two toxins have been the main toxins, in terms of amount and potency, in all US isolates tested to date. Using a range of mammalian cell types, the mode of KmTx 2 cytotoxicity was shown to be non-selective permeabilization of cell membranes to a range of small ions and molecules resulting in cell death through osmotic lysis. Membrane sterol composition appears to play a role in the sensitivity of different species to KmTx's membrane disrupting effects. This sterol specificity also appears to be responsible for the apparent immunity of K. micrum from its own toxins. We have described various karlotoxins in K. micrum isolates and bloom samples from US east coast estuaries from Maryland to Florida. Among US east coast isolates, a geographic strain variation appears to exist in that KmTx 1 has only been found in Maryland isolates while KmTx 2 has been found in all other isolates tested from North Carolina, South Carolina, and Florida. Recently, a KmTx 2-like compound (1342 Da.) has been isolated from bloom samples from Western Australia, being the first confirmation of karlotoxin production outside of the United States. This work confirms the association between blooms of K. micrum and fish kills that has been observed in temperate estuaries around the world for over half a century. It also lays the foundation for future studies to determine the ecological function of toxin production in this species and the consequences of this production both on K. micrum's environment and ours.
EASTERN OYSTER (CRASSOSTREA VIRGINICA) GROWTH AND EPIFAUNAL COMMUNITY DEVELOPMENT ON BARS OF VARYING OYSTER DENSITY IN CHESAPEAKE BAY
(2003-11-26) Harris, Charles Stewart; Paynter, Kennedy; Christman, Mary C.; Goldsborough, William; Marine-Estuarine-Environmental Sciences
The eastern oyster, Crassostrea virginica, is a gregarious, reef-forming organism. Oyster populations that once dominated the Chesapeake estuary have declined significantly and interest has recently arisen to restore the economic and ecological benefits of native oyster populations. Understanding the ecological importance of oysters and oyster reefs is critical to the restoration of the estuary's ecosystem as a whole. Oyster densities on most Maryland reefs are very low, however, natural reefs formed in other areas are comprised of high densities of oysters. In order to maximize the effectiveness of oyster restoration, it is important to determine how oyster density may affect oyster growth, parasite prevalence and the formation of reef habitat utilized by the benthic community. In the fall of 1999, twelve 0.2-acre experimental plots were constructed in the Patuxent River, a tributary of the Chesapeake Bay, by placing fossil oyster shell on a barren natural oyster bar. The plots were assigned one of four treatments, zero, 124, 247, 494 oysters/m^2, in a completely randomized design. Oyster growth was 0.117 (± 0.0037 SEM) mm/day for the 2000 season and slowed to 0.067 (± 0.0061) mm/day in 2001. Throughout the study, oyster growth was independent of the density of oysters observed. Colonization of the oyster reefs with fouling organisms was correlated to the density of oysters.
A MEMETIC/PARTICIPATORY APPROACH FOR CHANGING SOCIAL BEHAVIORS AND PROMOTING ENVIRONMENTAL STEWARDSHIP IN JALISCO, MEXICO
(2003-12-04) Robles Diaz de Leon, Luisa Fernanda; Kangas, Patrick; Marine-Estuarine-Environmental Sciences
This dissertation addressed the issue of sustainable development at the level of individual behaviors. Environmental perceptions were obtained from people living around the biosphere reserve Chamela-Cuixmala in Jalisco, Mexico. Several environmental issues were identified by the people, such as garbage and grey water on the streets, burning plastics, and the lack of usage of recreational areas. All these issues could be addressed with a change in behavior by the villagers. Familiarization activities were conducted to gain people's trust in order to conduct a community forum. These activities included giving talks to school children and organizing workshops. Four different methodologies were generated using memetics and participation to test which would ameliorate those environmental issues identified by the people through a change in behavior. The methodologies were 1) Memes; 2) Participation and Memes; 3) Participation; 4) Neither Participation nor Memes. A meme is an idea expressed within a linguistic structure or architecture that provides it with self-disseminating and self-protecting characteristics within and among the minds of individuals congruent with their values, beliefs and filters. Four villages were chosen as the treatments, and one as the control, for a total of five experimental villages. A different behavior was addressed in each treatment village (garbage, grey-water, burning plastics, recreation.) A nonequivalent control-group design was established. A pretest was conducted in all five villages; the methodologies were tested in the four treatment villages; a posttest was conducted on the five villages. The pretest and posttest consisted in measuring sensory specific indicators which are manifestations of behavior that can either be seen, smelled, touched, heard or tasted. Statistically significant differences in behavior from the control were found for two of the methodologies 1) Memes (p=0.0403) and 2) Participation and Memes (p=0.0064). For the methodologies of 3) Participation alone and 4) Neither, the differences were not significant (p=0.8827, p=0.5627 respectively). When using memes, people's behavior improved when compared to the control. Participation alone did not generate a significant difference. Participation aided in the generation of the memes. Memetics is a tool that can be used to establish a linkage between human behavior and ecological health.
Effects of Environmental Factors on Distribution and Asexual Reproduction of the Invasive Hydrozoan, Moerisia lyonsi
(2003-12-10) Ma, Xiping; Kennedy, Victor S; Miller, Thomas J; Purcell, Jennifer E; Marine-Estuarine-Environmental Sciences
The effects of temperature, salinity, food and predation on the invasive hydrozoan, Moerisia lyonsi, were studied in the laboratory to understand its cross-oceanic distribution patterns and the quantitative relationships between the asexual reproduction of polyp and medusa buds. Polyp mortality occurred only at some treatments of salinities 35-40. Polyps reproduced asexually at salinities 1-40 at 20-29°C, but not at 10°C. The highest asexual reproduction rates occurred at salinities 5-20 without significant difference among salinities. The scyphomedusa, Chrysaora quinquecirrha, was found to prey heavily on the medusae of M. lyonsi and may have restricted its distributions in estuaries. The initiation and proportion of medusa bud production was more responsive to environmental changes than that of polyp bud production. Unfavorable conditions enhanced polyp bud production, while favorable conditions enhanced medusa bud production. The adaptive reproduction processes of M. lyonsi and the significance to survival and dispersal of the populations are discussed.
THE EFFECTS OF SUBMERGED AQUATIC VEGETATION AS HABITAT ON THE SURVIVORSHIP OF CLAMS: FIELD SURVEYS IN ST. MARY'S RIVER, MARYLAND AND LABORATORY PREDATION EXPERIMENTS
(2003-12-22) Reid, Carolyn Cristine; Mihursky, Joseph A; Breitburg, Denise L; Marine-Estuarine-Environmental Sciences
Submerged aquatic vegetation is a complex habitat that may strongly affect the survivorship of associated animal species. Location with reference to SAV and seasonal changes have been suggested as important factors influencing species' survivorship. A field study examining natural abundances during spring and summer was conducted to examine the SAV effect on clam survivorship in St. Mary's River, a Chesapeake Bay tributary. Data revealed that SAV biomass affected clam abundances in summer, but not spring. Crab pots caught significantly greater numbers of Callinectes sapidus (blue crab) outside grass beds than inside SAV, contrary to published studies. Greater predation pressure on clams in lower SAV biomass may be causing differences in clam abundance. Experiments investigating C. sapidus predation on Mya arenaria (soft-shell clam) in different SAV densities indicated that SAV presence significantly reduced predation. Habitat studies tracking behavior revealed crabs spent more time in vegetation but consumed more clams outside SAV.
Morphology in Urbanized Streams of the Puget Sound Lowland Region
(2004) Boyle, Pamela; Prestegaard, Karen; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
The purpose of this research is to evaluate the effects of urbanization on channel morphology. Three hypotheses are tested: 1) Channel morphology measured from one cross section is not similar to reach-averaged values, 2) Channel shear stress ratios and erosivity increase with urbanization, and 3) Channel morphological complexity decreases with urbanization increases. Results indicate that single cross-section data do not adequately describe channel morphology. Shear stress and bed mobility did not increase with urbanization, perhaps due to the presence of large bed grain sizes that adjust to increases in flow. Similarly, channel complexity did not decrease with increased urbanization. These data indicate that channel changes resulting from urbanization are influenced by sediment supply as well as discharge, and that this should be taken into consideration in restoration design.
MORPHOLOGY IN URBANIZED STREAMS OF THE PUGET SOUND LOWLAND REGION
(2004) Boyle, Pamela Roxana; Prestegaard, Karen; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Increased runoff from urbanization may result in erosion to the stream channel and banks, leading to channel incision, bed changes, loss of instream debris and habitat, and an overall reduction of heterogeneity and channel complexity. These impacts are especially evident in low gradient, gravel-bed, meandering streams - the major type of stream in the Puget Sound Lowland region. The failure of many stream restoration projects is due to a lack of understanding of how morphological features of a stream respond to hydrological changes. Single cross-section methods (instead of reach-level) are generally used and may not adequately portray the complexity, or variation, of the stream channel and bed. Three main hypotheses in this thesis are: 1) a single cross-section taken within a reach does not adequately describe a stream compared to a mean value calculated from several measurements; 2) urban streams with more urbanized drainage areas have higher shear stresses, and thus move larger bed particles and have higher reach mobility; and 3) urban channels have less channel complexity than non-urban channels. Results showed that a single cross-section may not adequately describe the morphological variables of a stream reach; however, this method may be appropriate for calculating reach shear stress. In addition, shear stress and mobility were not found to increase with increasing urbanization. Furthermore, complexity was not found to decrease with increasing urbanization. These two latter results indicate that urbanization (or percent imperviousness) alone cannot be used as a variable to investigate changes in stream morphology and hydraulics. In fact, a measure of sediment supply could be considered an additional independent variable by which to study urbanization impacts to streams. Substrate distributions from this thesis also support this finding.
Identification, life history, and ecology of peritrich ciliates as epibionts on calanoid copepods in the Chesapeake Bay
(2004-02-10) Utz, Laura Roberta Pinto; Small, Eugene B.; Marine-Estuarine-Environmental Sciences
Epibiotic relationships are a widespread phenomenon in marine, estuarine and freshwater environments, and include diverse epibiont organisms such as bacteria, protists, rotifers, and barnacles. Despite its wide occurrence, epibiosis is still poorly known regarding its consequences, advantages, and disadvantages for host and epibiont. Most studies performed about epibiotic communities have focused on the epibionts' effects on host fitness, with few studies emphasizing on the epibiont itself. The present work investigates species composition, spatial and temporal fluctuations, and aspects of the life cycle and attachment preferences of Peritrich epibionts on calanoid copepods in Chesapeake Bay, USA. Two species of Peritrich ciliates (Zoothamnium intermedium Precht, 1935, and Epistylis sp.) were identified to live as epibionts on the two most abundant copepod species (Acartia tonsa and Eurytemora affinis) during spring and summer months in Chesapeake Bay. Infestation prevalence was not significantly correlated with environmental variables or phytoplankton abundance, but displayed a trend following host abundance. Investigation of the life cycle of Z. intermedium suggested that it is an obligate epibiont, being unable to attach to non-living substrates in the laboratory or in the field. Formation of free-swimming stages (telotrochs) occurs as a result of binary fission, as observed for other peritrichs, and is also triggered by death or molt of the crustacean host. Attachment success of dispersal stages decreased as telotroch age increased, suggesting that colonization rates in nature may be strongly dependent on intense production of telotrochs by the epibiont ciliates. Laboratory experiments demonstrated that Z. intermedium colonizes equally adult and copepodite stages of A. tonsa and E. affinis. The epibiont is also able to colonize barnacle nauplii and a harpacticoid copepod, when these were the only living host available, but fails to colonize non-crustacean hosts, such as the rotifer Brachionus calyciflorus or polychaete larvae. When the epibiont could choose between adults of A. tonsa and alternate hosts from the zooplankton community, it always colonized preferentially its primary host, with only a few telotrochs attaching to other crustaceans (barnacle nauplii and harpacticoid copepod), and to rotifer eggs, suggesting that specific cues may be involved in host selection by this epibiotic species.
ASSESSMENT OF MANGROVE AND SALT MARSH MESOCOSM FUNCTIONAL VALUE USING PERIWINKLE SNAILS, LITTORARIA ANGULIFERA AND LITTORARIA IRRORATA, AS AN INDICATOR
(2004-04-01) Swartwood, Stacy Lyn; Kangas, Patrick C; Marine-Estuarine-Environmental Sciences
Although much research has been conducted on restoration techniques, questions about the functional value of restored and constructed ecosystems remain. Gastropods are a particularly useful indicator organism because they play a vital role at the detrital interface. This study addresses the question of whether the age structure, population density, and distribution of Littoraria angulifera in the Smithsonian Institution's Florida Everglades mesocosm in Washington, DC is analogous to that of wild populations. The second phase investigates these same factors, in populations of Littoraria irrorata at a reference site on Slaughter Creek and six mesocosm replicates at Horn Point Laboratory in Cambridge, Maryland. Neither the mangrove nor the salt marsh mesocosms were able to support healthy, reproducing populations of periwinkle snails. Salinity, humidity, territory requirements, habitat complexity, precipitation, photoperiod, and tidal variation were identified as potential causal factors for mortality and the absence of evidence of juvenile recruitment to mesocosm populations.
The Influence of Landscape Position on Coastal Marsh Loss
(2004-04-29) Rogers, Andrew Stephen; Kearney, Michael S.; Marine-Estuarine-Environmental Sciences
Coastal marshes are considered as important features of the landscape that are at risk of loss. Accurately assessing their prospects for survival is difficult in view of the wide possible causes of loss, the large areas involved and that most research is done on relatively small parcels. This project examined the probability of conversion of marsh surface parcels to open water as a function of distance from roadways across marshes, tidal creeks, and upland areas, and the distance upstream, and the size of a marsh parcel. These are understood to be stand-ins for hydrology, elevation and other factors that are more difficult to measure. The study area was divided into a MidAtlantic coastal region and a large bays region comprising the Chesapeake and Delaware Bays. A semi-automated system was developed for measuring the extent and severity of coastal marsh loss using Thematic Mapper (TM) data. The data derived from the TM analysis were used to develop algorithms to examine the impacts of the five factors listed above. The factors were examined individually using ordinary least squares (OLS) regression, and collectively using logistic regression. The OLS regression revealed that distance from uplands and distance from the nearest tidal creek were highly correlated with marsh loss in both areas. For the Atlantic Coast, however, the loss was negatively related to distance from tidal creeks, the opposite of what was expected. Distance upstream was negatively correlated with marsh loss as predicted. The relationship between distance from roads and marsh loss indicated that marshes are healthier near roads than farther away. The relationship between parcel size and marsh loss was non-linear, with small and large marshes having a lower probability of degradation than mid-sized marshes. The logistic regression model is useful for identifying areas with higher probabilities of conversion to open water. Sea level rise (SLR), tidal range, easting and northing were examined for use with the logistic models. SLR and tidal range added no information to the bay areas, but sea level rise was weakly negatively correlated with marsh loss on the Atlantic Coast and tidal range was weakly positively related.
An Environmental Economic Assessment of the Impacts of Recreational SCUBA diving on Coral Reef Systems in Hurghada, The Red Sea, Egypt
(2004-05-11) Serour, Ramy Khaled; Kangas, Patrick C.; Marine-Estuarine-Environmental Sciences
During visits to coral reef locations, divers support the economy by spending money on goods and services provided by local businesses. However, divers also impact the reef during their visits, causing stress. This study presents estimates of rates of damage to corals and assesses patterns of dive behavior on selected sites. I also present an economic analysis of diving activities in the region and propose an estimate of diver "carrying capacity", using an emergy-based approach. While diving tourism generates revenues in the order $5-8.3 million annually, divers inflict damage to the coral reef at a rate of ~1250 potentially damaging contacts a day at the most heavily used sites. As a result, I suggest that these sites should be subject to 13,000-14,000 dives per year. This study aims to provide valuable information for the development of management plans to regulate diving operations and reduce reef degradation in the region.
F-TYPE LECTINS: BIOCHEMICAL, GENETIC, AND TOPOLOGICAL CHARACTERIZATION OF A NOVEL LECTIN FAMILY IN LOWER VERTEBRATES
(2004-05-12) Odom-Crespo, Eric William; Vasta, Gerardo R; Marine-Estuarine-Environmental Sciences
In vertebrates, immunoglobulins have long been considered the primary means for recognition of potential pathogens since they are the product of an adaptive immune system capable of generating and selecting for the most efficient antibody when adequately primed. However, initiating a naive system requires signals from cells that employ invariant receptors rather than antibodies. These innate receptors appear to recognize repetitive polymers commonly found only in microbes. Frequently, these receptors are lectins specific for polysaccharides ubiquitous of the microbial surface. Lectins in the blood or lymph are widespread among metazoans while antibodies are a vertebrate innovation suggesting that lectins may be evolutionarily their functional precursors. Even in primitive jawed vertebrates, there is a complete adaptive immune system, but it is relatively inefficient in comparison to mammals. Therefore, lectins might have a prominent immune function in lower vertebrates comparable to antibodies. To test this, a teleost was surveyed for humoral and hepatic lectins. A fucose-specific lectin of 32 kDa (FBP32) was initially purified from the palmetto bass and upon sequencing indicated it was unlike other reported lectins. The primary structure is characterized by a tandem polypeptide motif (FBPL) with partial homology to a long pentraxin from a frog. An inflammatory challenge of bass to test if FBP32 behaved like a mammalian pentraxin indicated that the FBP32 transcript level increases, but protein levels appear constitutive. An extensive search using both molecular cloning and gene database queries revealed that FBP32 is a member of a diverse protein family reflecting varying concatenations of the FBPL and even present in a cell surface receptor, but of sporadic phylogenetic distribution most notably being absent in mammals. Analysis of FBP32s genic structure reveals that it is flanked by phase 1 introns, which may explain the domains ability to concatenate and shuffle to form mosaic proteins. In collaboration with experts, the tertiary structure of an FBPL including its fucose-binding site was elucidated revealing a novel lectin fold, the F-type lectin fold (FTL), that is shared by unrelated proteins. Characterization of FBPLs demonstrates that the study of mammals alone may not reveal the full extent of immune system innovation.
GROWTH OF EASTERN OYSTER, CRASSOSTREA VIRGINICA, IN CHESAPEAKE BAY
(2004-05-14) Coakley, Jessica; Miller, Thomas J; Marine-Estuarine-Environmental Sciences
I applied modern techniques of modal analysis to track size modes in Eastern oyster, Crassostrea virginica, populations longitudinally through time, from which I inferred age-classes to establish size-at-age relationships for individual oyster bars and across Maryland's Chesapeake Bay. Average shell lengths of putative age-0 through age-5 oysters range from 22.93 (6.67, n=194) mm to 84.46 (8.27, n=4) mm. Growth rates declined with age-class from a mean of 28.97mm/yr to 0.85mm/yr, and the maximum and minimum individual growth rates were 0.78 and 53.0 mm/yr, respectively. I estimated von Bertalanffy growth parameters across all sites as L90.85mm, k=0.55, and to=-0.51. On average, I estimated oysters take 3 years to reach a marketable size within Chesapeake Bay. As an alternative to modal length frequency analysis, annuli in chondrophore sections of known-age oysters in Chesapeake were examined. It was determined that annuli formation was unrelated to chronological age.
RECRUITMENT RESPONSES OF BENTHIC INFAUNA TO MANIPULATED SEDIMENT GEOCHEMICAL PROPERTIES IN NATURAL FLOWS
(2004-05-18) Engstrom, Steven John; Marinelli, Roberta L; Marine-Estuarine-Environmental Sciences
Recent studies have shown that local variation in sediment geochemistry can have significant effects on settlement rates of benthic invertebrates. For example, elevated porewater ammonium concentrations in soft-sediment benthic systems may result in decreased recruitment rates of settling larvae. Recruitment responses of the benthic polychaete Arenicola cristata and the bivalve Mercenaria mercenaria to varying ammonium concentrations were measured in realistic flow environments. Experiments made novel use of ammonium-spiked polyacrylamide gels placed beneath field-collected sediment, which produced predictable porewater ammonium concentrations. Post-larval arenicolids and Mercenaria were allowed to settle in an annular flume containing sediment treatments with varying ammonium concentrations. Porewater ammonium data indicated successful manipulation of geochemical properties without contamination of overlying water. In Mercenaria trials, recruit retention was low. For Arenicola trials, significant retention differences were observed as a function of ammonium concentration, and indicate that ammonium plays a significant role in determining recruitment patterns and hence juvenile abundance.
THE POPULATION STRUCTURE OF VIBRIO CHOLERAE IN CHESAPEAKE BAY
(2004-06-03) Choopun, Nipa; Colwell, Rita R; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
The population structure of V. cholerae in Chesapeake Bay, United States, was analyzed and a simple procedure that employed only two biochemical tests in an abbreviated identification scheme, i.e., arginine dihydrolase and esculin hydrolysis, was developed. After enrichment in alkaline peptone water and selective plating on thiosulfate-citrate-bile salts-sucrose agar, all of the sucrose fermenting colonies identified by the two tests were confirmed as V. cholerae by the polymerase chain reaction. A non-redundant collection of 224 V. cholerae strains collected from 1998 through 2000 from Chesapeake Bay was analyzed for phenotype, genotype, and genomic fingerprint. A long-range enterobacterial repetitive intergenic consensus (ERIC) PCR method that was developed for this study provided fingerprint patterns that proved useful in assessing relatedness among the strains. Cluster analysis was done using three different methods and revealed three well separated, primary clusters: Cluster A, consisting of the majority of the isolates, including the toxigenic type strain for the species and luminescent strains of V. cholerae; a smaller Cluster B, with the noteworthy characteristic of low toxR gene homology; and Cluster M, consisting exclusively of V. mimicus. Another primary cluster, Cluster C, was also identified as a single clone of a sucrose-negative, luminescent, toxR-negative strain. Because V. mimicus formed a separate cluster with similar distance values as demonstrated by V. cholerae Cluster B, using both ERIC fingerprinting and DNA-DNA hybridization, and had phenotypic and genotypic traits and 16S rDNA sequences similar to V. cholerae, it is concluded that all of the primary clusters observed in this study, including V. mimicus, belong to a single species, V. cholerae. V. mimicus was judged to be the highest risk group of the non-toxigenic isolates, in terms of susceptibility to CTX-phi and possession of the heat-stable enterotoxin gene (stn). Approximately 11% of the V. cholerae strains that lacked the toxin-coregulated pili (TCP) and 50% of the V. mimicus strains were found to be susceptible to CTX-phi. In addition to the V. cholerae strains in the toxigenic subcluster, luminescent V. cholerae strains represented the next highest risk, since 14% of the luminescent strains were susceptible to CTX-phi and 33% were stn positive.