Browsing by Author "Forward, Richard B"

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    Barnacle cement: a polymerization model based on evolutionary concepts.
    (2009-11) Dickinson, Gary H.
    The tenacity by which barnacles adhere has sparked a long history of scientific investigation into their adhesive mechanisms. To adhere, barnacles utilize proteinaceous cement that rapidly polymerizes and forms adhesive bonds underwater, and is insoluble once polymerized. Although progress has been made towards understanding the chemical properties of cement proteins, the biochemical mechanisms of cement polymerization remain largely unknown. In this dissertation, I used evolutionary concepts to elucidate barnacle cement polymerization. Well-studied biological phenomena (blood coagulation in vertebrates and invertebrates) were used as models to generate hypotheses on proteins/biochemical mechanisms involved in cement polymerization. These model systems are under similar selective pressures to cement polymerization (life or death situations) and show similar chemical characteristics (soluble protein that quickly/efficiently coagulates). I describe a novel method for collection of unpolymerized cement. Multiple, independent techniques (AFM, FTIR, chemical staining for peroxidase and tandem mass spectroscopy) support the validity of the collection technique. Identification of a large number of proteins besides ‘barnacle cement proteins’ with mass spectrometry, andobservations of hemocytes in unpolymerized cement inspired the hypothesis that barnacle cement is hemolymph. A striking biochemical resemblance was shown between barnacle cement polymerization and vertebrate blood coagulation. Clotted fibrin and polymerized cement were shown to be structurally similar (mesh of fibrous protein) but biochemically distinct. Heparin, trypsin inhibitor and Ca2+ chelators impeded cement polymerization, suggesting trypsin and Ca2+ involvement in polymerization. The presence/activity of a cement trypsin-like serine protease was verified and shown homologous to bovine pancreatic trypsin. Protease activity may activate cement structural precursors, allowing loose assembly with other structural proteins and surface rearrangement. Tandem mass spectrometry and Western blotting revealed a homologous protein to human coagulation factor XIII (fibrin stabilizing factor: transglutaminase that covalently cross-links fibrin monomers). Transglutaminase activity was verified and may covalently cross-link assembled cement monomers. Similar to other protein coagulation systems, heritable defects occur during cement polymerization. High plasma protein concentration combined with sub-optimal enzyme, and/or cofactor concentrations and sub-optimal physical/muscular parameters (associated with hemolymph release) results in improperly cured cement in certain individuals when polymerization occurs in contact with low surface energy silicone and its associated leached molecules.
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    Estuarine Ingress of the Blue Crab Callinectes Sapidus
    (2008-04-21) Ogburn, Matthew Bryan
    This dissertation investigated ingress of postlarval blue crabs Callinectes sapidus to the Newport River estuary, North Carolina, USA. Data from C. similis, Menippe mercenaria, Pachygrapsus transversus, and Arenaeus cribrarius are included in some chapters for comparison. Changes in tolerance to low salinity were examined by: 1) exposing postlarvae (megalopae) collected in coastal and estuarine areas to a range of salinities and 2) determining the cue that stimulates acclimation of coastal megalopae to low salinities, the time to acclimation, and the decrease in salinity necessary for acclimation. Coastal megalopae were less tolerant to salinities of 5 and 10 than megalopae from the estuary. Coastal megalopae became acclimated to low salinities within 12 h when salinity was reduced from 35 to 31. Spatial patterns in abundance during ingress were investigated simultaneously in coastal and estuarine areas. Coastal distributions were determined using nighttime surface plankton tows at slack water after ebb tide and slack water after flood tide on four nights; two each during spring and neap tides. Estuarine distributions were determined using nightly settlement on 'hog's hair' collectors. C. sapidus megalopae were most abundant at the coast east of Beaufort Inlet, but settlement was restricted to western channels of the estuary. Species-specific patterns in abundance were maintained during two spring/neap cycles, possibly due to interactions between larval behavior and physical forcing. Biophysical mechanisms of estuarine ingress were investigated by comparing nightly abundance in coastal and estuarine areas with environmental variables. Comparisons were made using cross-correlation and cross-fourier analyses. High estuarine abundances were associated with wind-driven estuarine inflow and nighttime flood tides. The seasonal pattern of estuarine ingress was strongly associated with the seasonal pattern of alongshore wind stress, suggesting that inter-annual variations in atmospheric forcing may determine the yearly abundance of megalopae arriving in estuarine nursery habitats. The effect of sampling interval on annual megalopal abundance estimates was determined using an 11-year dataset of nightly settlement. Variability in abundance estimates increased with increasing sampling interval. Switching from a one day to two day sampling interval resulted in a 20 % decrease in the likelihood of detecting a significant correlation between annual abundance and CPUE in the North Carolina blue crab pot fishery.
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    Evaluation of Public Participation and Outreach Methods for the North Carolina Coastal Habitat Protection Plan
    (2004) Kelly, Leah F.
    Public participation has become an important component to many decision-making processes. It has many benefits, both for the participant as well as the decision-maker. It provides education and raises public awareness on important issues. It can reduce conflict between competing interest groups. It increases the willingness to accept programs to which participation is contributed. As part of the Fisheries Reform Act of 1997, the North Carolina Division of Marine Fisheries (DMF) is developing an integrated approach to coastal management. The North Carolina Coastal Habitat Protection Plan (CHPP) will be the first attempt at regulatory co-management of commercially important coastal fish habitats. Within the scope of this project, DMF has included a public participation aspect to the writing and researching process. To increase the level of cooperation and support to this new management approach, DMF and the North Carolina Coastal Federation began an outreach campaign that started with the distribution of educational materials and resulted in the execution of 10 public meetings. I conducted a survey of participants who attended the ten public meetings. I assessed the representation of participating interest groups, the distribution tactics of the publications, and the effectiveness of the educational portion of the meetings. I also evaluated the respondents’ satisfaction with the level of knowledge gained from the outreach materials and the meetings. Anticipated future involvement in the process was an indicator of the success of the campaign. The results of this project indicate that the meetings and public outreach campaign succeeded in many ways. They provided education for the participating citizens, and they increased interest for future involvement in environmental issues. However, representation of target populations, such as fishermen and developers, did not meet the expressed goals of NCCF and DMF. Distribution tactics and outreach procedures should be reanalyzed to further increase the interest of the CHPP process for broader involvement of interest groups. As this is an ongoing process, it is important to see how public participation benefits citizens so that the decision-makers can work to maintain, or increase citizens’ level of interest in the CHPP process.
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    Larval Release Rhythms and Larval Behavior of Palinurid Lobsters: a Comparative Study
    (2007-11-28) Ziegler, Tracy Ann
    This dissertation investigated larval release and larval behavior of the Caribbean spiny lobster Panulirus argus and the spotted spiny lobster P. guttatus. These species were examined under laboratory conditions to determine the phase relationship between larval release and natural environmental cycles. P. argus displayed a nocturnal tidal rhythm, while P. guttatus displayed a circadian rhythm in larval release. P. argus releases larvae near the time of nocturnal high slack water, while P. guttatus released larvae near the time of sunrise. The role of 'pumping pheromones' in controlling larval release behaviors was tested by measuring the pumping response of ovigerous P. argus to (1) hatch water, (2) homogenized-embryo water, (3) embryo-conditioned water, and (4) water containing homogenized-egg cases. Lobsters with late-stage embryos displayed increased pleopod pumping with increased concentration of hatch water. Water individually conditioned with homogenized late-stage embryos, intact late-stage embryos, and homogenized egg-cases induced pumping activity in females with late-stage embryos, indicating the presence of a chemical cue. I quantified pumping responses upon exposure to synthetic peptides to determine if they mimicked pheromones that induce larval release behaviors. Pumping behavior was evoked by oligopeptides with a basic amino acid at the carboxy-terminus, preceded by several neutral amino acids. Carboxyl-terminal arginine peptides serve as pheromone mimics. I investigated whether these peptides originate from the action of trypsin-like enzymes by conducting a bioassay measuring pumping activity of ovigerous P. argus subjected to increasing concentrations of trypsin, trypsin inhibitor, and a combination of the two. Pumping activity increased with increasing concentrations of trypsin and trypsin inhibitor, while behaviors ceased when ovigerous females were subjected to a complex of the two. Pheromones are generated by trypsin-like enzymes assisting in the degradation of the egg membranes at the time of hatching. Vertical swimming behaviors of stage-I phyllosoma larvae of P. argus and P. guttatus were observed under laboratory conditions. P. argus larvae displayed a pattern of twilight vertical migration, while P. guttatus larvae displayed nocturnal diel vertical migration (DVM). Rhythms persisted for 5-6 cycles under constant conditions, indicating that an endogenous rhythm in activity plays a proximate role in DVM for both species.
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    THE IMPACT OF THE EUROPEAN GREEN CRAB (CARCINUS MAENAS) ON THE RESTORATION OF THE OLYMPIA OYSTER (OSTREA LURIDA) IN TOMALES BAY, CALIFORNIA
    (2004) Snyder, Caitlin
    The introduced European green crab, Carcinus maenas, poses a potential risk to the restoration of the native Olympia oyster, Ostrea lurida, in Tomales Bay, California. The green crab is a voracious predator, and has negatively impacted shellfish in both its native and invaded environments. The Olympia oyster population in Tomales Bay is low due to pollution, predation, and past overharvesting. A collaborative restoration project began in 1999 to try and reinstate the Olympia oyster to Tomales Bay by placing artificial reefs at several locations in the Bay. I investigated the potential impacts of the European green crab on the Olympia oyster during July and August 2003. At four field sites in Tomales Bay, I trapped green crabs at both potential and established oyster reef restoration areas. I conducted laboratory feeding experiments of C. maenas on O. lurida to get an idea of whether or not the crabs would consume the oyster, and whether different sizes of crabs showed a preference for varying sizes of oyster. Initial trapping results suggest higher green crab population numbers at rocky habitats as opposed to mud flats. In addition, the trapping data suggest it may be possible to trap out the green crabs from the reef areas. The feeding experiments indicate that the green crabs do consume the Olympia oysters, and that the number of oysters consumed decreased as oyster size increased.