TEM observations of holotrich nematocysts in catch tentacles of the sea anemone Haliplanella luciae reveal that capsule wall formation occurs by means of a self-assembly of proteins from a Golgi-derived pool within the capsule interior. Wall growth results from precipitation of material onto the wall, as indicated by an increase in wall thickness throughout development. Wall maturation is characterized by wall thinning. Such thinning was reversed by performic acid treatment, suggesting that disulfide bond formation within the wall causes thinning. Nematocyst thread walls stain with the sulfur stain, alcian blue, both before and after performic acid treatment, while capsule walls are stained only after such treatment, suggesting that the thread has "free" sulfur groups that are absent from the capsule. / Occurring simultaneous with wall development, is a Golgi-deposition of calcium into the developing nematocyst, as evidenced by potassium pyroantimonate deposits in the Golgi and nematocyst interior that were removed by EGTA. Tube inversion is accompanied by an apparent increase in antimonate concentration within the nematocyst, along with an increase in fluids in the cytoplasm, suggesting that a dehydration of nematocyst contents occurs at the time of tube inversion. / The mature nematocyst moves to the cell surface (in preparation for discharge) by apparent microtubule disassembly between the capsule and dense bodies located at the cell surface. / Nematocyst discharge begins with the opening of the capsule tip apical flaps. The flaps are sealed by subunit-lined seams that separate upon discharge, suggesting that the subunits hold the flaps together. / The everted thread is lined on both sides by subunits that might bind together to hold the uneverted thread in its folded configuration. Thread eversion could follow subunit uncoupling. / Nematocyst discharge is accompanied by a calcium-mediated contraction of supporting cell microfilament bundles. Such contraction causes the capsule to become recessed beneath these bundles, possibly anchoring the capsule in the tentacle. Because extracellular fibrous network connections occur between the cnidocyte cell surface and the supporting cell stereocilia, it was proposed that supporting cell contraction (which changes supporting cell shape) might initiate nematocyst discharge. / Source: Dissertation Abstracts International, Volume: 44-10, Section: B, page: 3013. / Thesis (Ph.D.)--The Florida State University, 1983.

Atya innocous occurs in permanent and temporary freshwater streams in Panama. Its microhabitat distribution depends in part on the presence of congeners. The propodus and dactylus of each cheliped of A. innocous bear about 300 setae modified for specific functions in food collection. These setae may be divided into three basic types: chemoreceptors, scrapers, and filtering setae. The latter two types also function as mechanoreceptors. The cheliped setae are probably extended by hemocoelic pressure, producing an efficient filtering fan. Mechanosensory and chemosensory bipolar neurons innervate the cheliped setae, presumably providing the shrimp with the ability to detect current velocity, particulate load and food sources. The external morphology and ultrastructure of these sensilla are described. / The peropods are also used to groom body parts and brooded embryos. Super-8 cine films show the role mouthparts play in grooming. The third maxillipeds groom the antennae and antennules of the prawn, with the distal endite of the second maxillipeds freeing lodged debris from pereopods one and two. The pectinate comb of the fifth pereopod grooms the dorsal surface of the abdomen and pleopods. / Electron microscopy showed pores leading to unicellular glands within the epidermis. Three gland types were observed and their respective functions described. / Adaptations for a lotic habitat seem to have dominated atyid evolution. With the exception of lake species, most atyid shrimp have a wide array of morphological modifications for life in running water. / The mouthparts, mandibles and foregut of Atya innocous and another atyid Potimirim glabra are compared to test the hypothesis that these structures are related to diet. Potimirim glabra inhabits quiet pools scraping periphyton from leaf surfaces and decaying organic detritus. The feeding appendages of both species are modified for handling fine food. The mandible of these shirmp have a strong incisor and molar process but are not utilized for crushing large food items. The primitive nature of the mandibles and foregut suggest the placement of the family Atyidae at the base of the caridean evolutionary tree. / Source: Dissertation Abstracts International, Volume: 43-12, Section: B, page: 3877. / Thesis (Ph.D.)--The Florida State University, 1982.

The research outlined in this dissertation represents a study towards the examination of the presence of mitochondrial arginine kinase (AK) activity in horseshoe crab (Limulus polyphemus) hearts and its possible physiological significance. The existence of such a mitochondrial bound AK was hinted at by the residual enzymatic activity in the mitochondrial pellet and the ability of arginine to stimulate state 3 respiration in the presence of ATP. The presence of a mitochondrial bound AK (AKm) in L. polyphemus hearts was confirmed by sucrose-density centrifugation and solubilization experiments. Between 1.5 and 2% of total cytoplasmic AK activity appeared to be associated with the mitochondria. Cellulose acetate electrophoresis revealed the existence of two populations of AKm--a 'fast' electrophoretic form (AKmf), migrating identically to cytoplasmic AK (AKc), and a 'slow' electrophoretic form (AKms). Both forms were present in a 1:1 ratio. The 'fast' form was easily extractable while AKms showed hydrophobic characteristics, only extractable with detergents. SDS-PAGE electrophoresis of these isoenzymes following purification showed the molecular weight subunit of both AKc and AKmf to be virtually the same (39-40 kD), but that of AKms being slightly higher (43.5 kD). The peptide maps of AKc and AKmf were identical, whereas that of AKms displayed some unique peptide fragments. AKmf is therefore thought to be a similar protein as AKc while AKmf may contain, however, an additional hydrophobic sequence for insertion and anchoring into the inner membrane of the mitochondrion. / Kinetic and thermodynamic experiments in the presence and absence of oxidative phosphorylation (OP) showed no difference in the kinetic parameters or movement of the mass action ratio, respectively. These results thus do not suggest effective functional coupling between OP (e.g. the adenosine nucleotide translocator) and the AKm reaction. These experiments exclude the possibility that there is preferential access of the AKm enzyme(s) for the product of respiration (ATP). A study comparing the efficacy of bound mitochondrial AK versus a soluble source of ADP showed that mitochondrial associated AK might be advantageous by minimizing the diffusion of ADP. / Source: Dissertation Abstracts International, Volume: 51-03, Section: B, page: 1077. / Major Professor: William Ross Ellington. / Thesis (Ph.D.)--The Florida State University, 1990.

Sea urchin U1 genes coding for the major embryonic U1 RNA are in the tandemly repeated units. The U1 repeat unit in L. variegatus is variable in size from 1.2 to 1.4 Kb while that in S. purpuratus has a homogenous size of 1.1 Kb. Two types of U1 repeats have been isolated from L. variegatus. They are conserved in the 5$\sp\prime$ flanking region for 500 bp, but vary in the 3$\sp\prime$ flanking sequence immediately after the CAAAGAAAGAAAA sequence necessary for 3$\sp\prime$ end formation. The tandemly repeated U1 cluster of S. purpuratus ends just 3$\sp\prime$ to the U1 coding region. / The sea urchin U1 gene is transcribed by RNA polymerase II in isolated nuclei, but it can be transcribed by RNA polymerase III in sea urchin nuclear extracts. Two assays were used for testing promoter function, a microinjection assay for testing the expression of U1 genes in vivo and a DNA-dependent nuclear extract for testing expression in vitro. At least 200 nucleotides, but no more than 345 nucleotides, 5$\sp\prime$ to the gene are required for the expression of U1 gene in vivo. Two of the four highly conserved regions between L. variegatus and S. purpuratus U1 5$\sp\prime$ flanking region are in these 142 nucleotides. In contrast, none of the 5$\sp\prime$ flanking region, but rather an internal promoter region is required for the synthesis of U1 RNA by RNA polymerase III in vitro. The internal promoter region contains a tRNA A-box consensus sequence and an 11-bp region with identical sequence to one of the highly conserved regions. These data suggest that the four highly conserved regions in the 5$\sp\prime$ flanking sequence are important for the expression of the sea urchin U1 gene. / Source: Dissertation Abstracts International, Volume: 50-12, Section: B, page: 5480. / Major Professor: William F. Marzluff, Jr. / Thesis (Ph.D.)--The Florida State University, 1989.

Although many researchers have examined the phenomenon of intertidal zonation and its structuring processes in rocky habitats, similar studies concerning soft-bottom habitats are relatively uncommon. The bivalve assemblage of Polymesoda caroliniana (Corbiculidae) and Rangia cuneata (Mactridae), common in the shallow subtidal and intertidal zones of the mesohaline-oligohaline regions of southeastern United States estuaries, allows some analogies to previously studied rocky intertidal communities in that the adults of these bivalves are large (20-70 mm in shell length), and move very little, making the populations relatively easy to census and manipulate. I conducted field surveys and manipulative experiments on populations of R. cuneata and P. caroliniana between 1982 and 1984 in the Ochlockonee-Sopchoppy estuary of northwestern Florida. The emphasis of the research was description of the vertical distribution of members of each species, and analysis of factors controlling these distributions, including recruitment, physiological factors, disturbance, and potential competitive effects. Results indicate that R. cuneata is a subtidal inhabitant whose upper bound is controlled by physical factors, including physiological tolerances to such factors, and probably a lack of sufficient time for feeding and respiration. Recruitment of R. cuneata is highly variable, and results in populations dominated by single age classes. P. caroliniana is shown to be an intertidal inhabitant. The lower bound of the P. caroliniana population is determined, in an ecological sense, by larval settlement, but in an evolutionary time frame is probably controlled by biological factors such as predation and disturbance by predators and bioturbators. P. caroliniana seems to recruit regularly, but juvenile mortality is high, so recruitment to the adult population is low. No competitive effects between adult P. caroliniana and R. cuneata were found. / Source: Dissertation Abstracts International, Volume: 49-03, Section: B, page: 0601. / Major Professor: William Heard. / Thesis (Ph.D.)--The Florida State University, 1987.

by Wong Cheung-on, Li, Yun-hoi. / Title also in Chinese. / Summary in Chinese. / Thesis (M.B.A.)--Chinese University of Hong Kong, 1980. / Bibliography: leaves 164-165.

This research investigates the policy response to the 2007-2010 sanitary crisis in the Chilean salmon industry, the second largest producer and exporter of salmon in the world. This industry is an emblematic case of the possible consequences of employing an intensive natural resource model for development. The research draws upon the two literatures on policy learning and policy change, and crisis and disaster management, and upon the system failure to explain the causes and consequences of the sanitary crisis in the industry. The thesis employs the qualitative method of case study and utilises primary and secondary sources of data and information. The main argument of the research is that the process of policy learning during and following catastrophic events is very different from the process of the policy learning during normal times. The main findings are, firstly, in the case of the Chilean salmon industry, the sanitary crisis disrupted the industry governance processes, including the regulatory framework of the industry, opening a window for radical institutional change. Secondly, potentially radical measures were part of a set of policies that emerged as initial responses, after which a set of more incremental policy responses were developed and applied. Moreover, the sanitary crisis was not transient nor episodic but was enduring, persistent and dynamic. Thirdly, the policy responses to the sanitary crisis destabilised the consensus in the Chilean industry causing conflict and ambiguity over policy responses. The thesis contributes to the policy learning and policy change literature in the context of catastrophic events by extending the view this literature offers on dramatic events such as crises, by considering them as dynamic and persistent situations, analysing their potential as precipitators of radical policy change, and providing a means for considering the timing and processes by which this radical policy change may occur and be directed toward better social outcomes.

The sandbar shark, Carcharhinus plumbeus, is the most abundant large coastal shark in the temperate and tropical waters of the northwest Atlantic Ocean. The Chesapeake Bay, Virginia and adjacent waters serve as a nursery ground for C. plumbeus as well as many other fauna. Characterizing the diet of a higher trophic level predator such as the sandbar shark sheds light on a small portion of the temporally and spatially complex food web in the Bay. This study describes the diet of the sandbar shark, highlighting differences in diet within various portions of the nursery area, as well as ontogenetic changes in diet. Stomach samples were obtained in 2001 and 2002 from 232 sharks caught in gillnets or by longline gear. Historical data from the Virginia Institute of Marine Science (VIMS) Shark Ecology program were also analyzed. Ontogenetic changes in diet were evident, with crustacean prey decreasing in importance and frequency with increasing shark size, and elasmobranch prey importance and frequency increasing with increasing shark size. While previous research in Chincoteague Bay, VA showed the blue crab, Callinectes sapidus, as the dominant crustacean in sandbar shark diet, the mantis shrimp, Squilla empusa, dominated the crustacean portion of the diet in this study. Differences in diet were mainly attributable to location of shark capture. Small juveniles (< 80 cm precaudal length) in the lower Chesapeake Bay ate significantly more fishes, whereas Eastern Shore juveniles ate more crustaceans. The type of crustacean consumed varied within areas of the Eastern Shore, with more portunid crabs consumed in waters near Wachapreague and more mantis shrimp consumed near Sand Shoal Inlet. This study was not able to detect any change in diet over time due to insufficient sample sizes and the effect of location.

The lower Chesapeake Bay and adjacent coastal waters serve as the primary summer nursery areas for juvenile sandbar sharks (Carcharhinus plumbeus) in the Northwest Atlantic Ocean. The large population of juvenile sandbar sharks in this ecosystem benefits from increased food availability that fuels rapid growth and from limited exposure to large shark predators. Juvenile growth and survival is the most critical life history stage for sandbar sharks, and juvenile nursery grounds will continue to play an important role in the slow recovery of this stock from severe population declines due to overfishing. The goal of this study was to assess the possible impacts of juvenile sandbar sharks as apex predators on the lower Chesapeake Bay ecosystem and to evaluate the energetic benefits of using this nursery. The bioenergetics model was used as a tool to predict energy consumption rates of individual sandbar sharks based on their energetic demands: metabolism, growth, and loss of waste. Metabolic rate is the largest and most variable component of the energy budget, particularly for species such as the sandbar shark that must swim continuously to ventilate their gills. The standard (basal) and routine metabolic rates of juvenile sandbar sharks were measured in two laboratory respirometry systems, using oxygen consumption rate as a proxy for metabolic rate. These data span the entire range of body sizes and water temperatures characteristic of the Chesapeake Bay population. Standard metabolic rates of sandbar sharks were similar to values obtained for related shark species by extrapolation of power-performance curves. The effects of body size and temperature on standard metabolic rate were similar to previous results for elasmobranchs and teleost fishes. In fifteen sharks, routine metabolic rate while swimming averaged 1.8 times the standard metabolic rate when the sharks were immobilized. Data obtained from the literature support the theory that limited gill surface areas and narrow metabolic scopes of many elasmobranchs help to explain their slow growth rates, since growth has the lowest rank of the multiple metabolic demands placed on the oxygen delivery system. These new metabolic rate data were then combined with other species-specific data to construct a bioenergetics model for juvenile sandbar sharks for the time they spend in Chesapeake Bay each summer. This model predicted higher daily rations than previous estimates for this species that were based on simple bioenergetics models or stomach contents and gastric evacuation rate models. However, the predicted rations agree with reconstructed meal sizes of juvenile sandbar sharks and are comparable to those of ecologically similar shark species. When extrapolated from individuals to the population level, the model predicted a negligible effect of predation by juvenile sandbar sharks on the lower Chesapeake Bay ecosystem; the consumption rate of juvenile sandbar sharks pales in comparison to other carnivorous fishes and to humans, the true apex predators in the system.

Only a miniscule fraction of the world’s largest volume of living space, the ocean’s mid-water biome, has ever been sampled. As part of the International Census of Marine Life field project Mid-Atlantic Ridge Ecosystems (MAR-ECO), a discrete-depth trawling survey was conducted in 2009 aboard the NOAA ship Henry B. Bigelow to examine the pelagic faunal assemblage structure and distribution over the Charlie-Gibbs Fracture Zone (CGFZ) of the northern Mid-Atlantic Ridge. This is the first MAR-ECO project aimed specifically at describing diel vertical migration as a distributional phenomenon. Discrete-depth sampling from 0-3000 m was conducted during both day and night in similar locations using a Norwegian “Krill” trawl with five codends that were opened and closed via a pre-programmed timer. Seventy-five species of fish were collected, with a maximum diversity and biomass observed between depths of 700-1900 m. An incremental gradient in sea surface temperature and underlying watermasses, from northwest of the CGFZ zone to the southeast, was mirrored by a similar gradient in ichthyofaunal diversity. Using multivariate analyses, eight deep-pelagic fish assemblages were identified, with depth as the overwhelming discriminatory variable. Strong diel vertical migration (DVM) of the mesopelagic fauna was a prevalent feature of the study area, though the numerically dominant fish, Cyclothone microdon (Gonostomatidae), exhibited a broad (0-3000 m) vertical distribution and did not appear to migrate on a diel basis. In all, 3 patterns of vertical distribution were observed in the study area: a) DVM of mesopelagic, and possibly bathypelagic, taxa; b) broad vertical distribution spanning meso- and bathypelagic depths; and c) discrete vertical distribution patterns. Overall species composition and rank order of abundance of fish species agreed with two previous expeditions to the CGFZ (1982-83 and 2004), suggesting some stability in the ichthyofaunal composition of the study area, at least in the summer. Frequent captures of putative bathypelagic fishes, shrimps, and squid in the epipelagic zone (0-200 m) were confirmed. The results of this expedition reveal distributional patterns unlike those previously reported for open ocean ecosystems, with the implication of increased transfer efficiency of surface production to great depths in the mid-North Atlantic.