Age, growth rates, and patterns of movement were studied in the Atlantic stingray, Dasyatis sabina, in the Indian River lagoon system in east central Florida. Age was estimated using the growth rings on the vertebral centrum and tretacycline marking. Tetracycline injections produced clear readable rings in all pups, but failed to be incorporated into the centra of adults. Females possess more centrum rings than males, but annual periodicity could not be verified. Growth rates were determined from aquarium held pups and adults and from tagged and recaptured animals. Males appeared to reach maturity in about two years, females in slightly less than three. Males and females probably reached mean size, 240 and 300 mm, respectively, in six to nine years. Movements of Dasyatis sabina were fairly restricted seasonally as well as annually; the majority (81%) of animals recaptured were taken at the release site. The general age and growth strategies for this species are consistent with those of most other elasmobranchs, characterized by rapid growth the first few years followed by slow adult growth.

The eastern oyster, Crassostrea virginica, once an integral part of the ecology and economy of Chesapeake Bay, has been severely depleted. Factors leading to the decline of the eastern oyster include over-harvesting, environmental degradation and disease pressure caused by the protozoans Haplosporidium nelsoni and Perkinsus marinus, known commonly as MSX and Dermo, respectively. Studies regarding the feasibility of introducing a nonnative oyster to the Bay were initiated, and field-based research on an Asian oyster, Crassostrea ariakensis, suggested that it might be a viable species for introduction. Research surrounding the proposed introduction has focused on recommendations such as those from the International Council for Exploration of the Seas, suggesting that the "ecological, genetic and disease relationships of the species in its natural range and environment" be examined. In order to assess the disease risks associated with C. ariakensis, a parasite survey of oysters collected from China, Japan and Korea was undertaken to examine the pathogens associated with C. ariakensis in its natural range. The protozoan parasites, Perkinsus olseni and a new Perkinsus sp., as well as multiple genetic strains of molluscan herpesvirus, were discovered using molecular diagnostic methods. Molluscan herpesvirus and Perkinsus spp. protozoans are known to cause mortality of many commercially important bivalve species. Characterization of the new Perkinsus sp. included a comprehensive analysis of three DNA loci along with histological examination of the Perkinsus sp. cells in preserved tissue sections. Challenge experiments were undertaken using P. olseni and the new Perkinsus sp. in order to assess the transmission risk of these exotic microbes to the eastern oyster and the hard clam, Mercenaria mercenaria. The laboratory experiments suggest that bivalve shellfish native to Chesapeake Bay may be susceptible to the alien Perkinsus spp. associated with C. ariakensis. In addition, C. ariakensis may acquire moderate to lethal infections of P. marinus under stressful conditions. In light of the proposed introduction of C. ariakensis, it appears that there is a great disease risk associated with this Asian oyster species with the potential to have a negative impact on the naive shellfish populations of Chesapeake Bay.

A size-selectivity curve was constructed to characterize the performance of the New Bedford style Atlantic sea scallop (Placopecten magellanicus) dredge when it is configured to meet the requirements of Amendment #10 to the Sea Scallop Fishery Management Plan. The curve was generated using the SELECT model on catch-at-length data, obtained by simultaneously towing a New Bedford style dredge and a non-selective National Marine Fisheries Service sea scallop survey dredge from commercial scallop vessels. Data were collected during three cruises in the Northwest Atlantic between 2005 and 2006. One cruise was completed in Georges Bank (Groundfish Closed Area II) and two cruises were completed in the mid-Atlantic (both in the Elephant Trunk Closed Area). The resulting selectivity curve for all cruises combined yielded a 50% retention length of 100.1 mm, a selection range of 23.6 mm and a relative efficiency value of 0.77. A length of 100.1 mm corresponds to an age of 4.6 years in Georges Bank and 5.8 years in the mid-Atlantic and a meat-weight of approximately 16 g. This implies that entry into the fishery is being delayed, potentially increasing yield-per-recruit and the population’s total reproductive output. The resultant selectivity curve can assist fisheries managers with stock assessments, mortality calculations and with the interpretation of catch data from government and industry-based surveys. Additionally, the curve can be used to evaluate the effect of future changes to sea scallop dredge design.

The Chesapeake Bay spawning stock of striped bass, Morone saxatilis, is considered one of the largest sources of juvenile production along the Atlantic coast and exhibits a high degree of interannual recruitment variability. Year class strength is judged by near-shore seine surveys that cover major tributaries of Chesapeake Bay and survey results are incorporated into annual stock assessments. In these surveys, the contribution of the Rappahannock River (Virginia) to total production is significant. In this system, abundance of juveniles is highest at a single seine site, suggesting that juvenile production may be related to habitat heterogeneity and food availability. To evaluate this possibility, we describe daily variability in prey consumption, prey composition, and prey selection of juvenile striped bass at the productive site (RK 89) and habitat-specific patterns in feeding along an estuarine gradient that included the productive site. I examined diets of juvenile striped bass collected in five 24-h seine surveys at RK 89 in 1983 and conducted seine hauls at four stations (RK 89, RK 81, RK 71 and RK 60) in 2004. During 24-hr sampling, more fish were caught at 1800 hours and 2100 hours than at other times. In 2004, significantly more fish were caught at RK 89 than at RK 60. Fish were significantly less full at 0300, 0600 and 0000 hours than at all other times. Prey with the highest Index of Relative Importance values were dipteran larvae, calanoid copepods and polychaetes, ranking 1-3 respectively in both years. Peak mean density of Bosmina, other cladocerans, calanoid copepods, and dipteran larvae occurred at RK 89. However, fish were fuller at RK 60 than at RK 89. YOY striped bass showed some indications of selective feeding. As young striped bass grow in the Rappahannock River, they gradually disperse from natal areas into heterogeneous nursery habitats downriver. This ontogeny is reflected in diets as smaller fishes upriver fed on many individuals of smaller plankton prey (especially calanoid copepods) and were less full than cohorts downriver that consumed fewer individuals of larger benthic prey (especially polychaetes).

No description available.

The Longnose Lancetfish, Alepisaurus ferox, is a pelagic marine fish that has a heterodont dentition, including large fangs on both the upper and lower jaws. Their diet is well documented and includes salps, hyperiid amphipods, pelagic polychaete worms, mesopelagic fishes, and cephalopods. However, the function of the heterodont dentition, the structure of the teeth, and replacement mode is largely unknown. We studied a series of A. ferox to describe their dentition and tooth replacement. All teeth are replaced extraosseously. Palatine and dentary fangs develop horizontally in the oral epithelium on the lingual surface of dentigerous bones. Developing fangs rotate into place and attach to the bone through a pedicel that forms at the base of each tooth on the lingual side of the dentigerous bone. We compare extraosseous horizontal tooth replacement and rotation of large fangs in A. ferox to examples of other teleosts rotation of fangs. Atlantic Cutlassfish, Trichiurus lepturus, have large, barbed premaxillary and dentary fangs and sharp, dagger-shaped teeth in their oral jaws. We used dry skeletons, histology, SEM, and micro-CT scanning to study T. lepturus to describe its dentition and tooth replacement. We identified and described three modes of intraosseous tooth replacement in T. lepturus depending on the location of the tooth in the jaw. Such distinct modes of tooth replacement in a teleostean species are unknown. We compared modes of replacement in T. lepturus to 20 species of scombroids to explore the phylogenetic distribution of these three replacement modes. Our study highlights the complexity and variability of intraosseous tooth replacement and that developmentally different tooth replacement processes can yield remarkably similar dentitions. We review literature on the comparative anatomy of Ocean Sunfishes (Molidae) and presents new findings based on our studies. We document similarities and differences among the three living genera, Ranzania, Masturus, and Mola using an organ system approach to examine: general body form and external anatomy; skeleton; integument; brain and sense organs; digestive organs; heart and circulation; respiratory system; excretory system; and endocrine organs. Molids have many anatomical specializations such as the formation of the clavus from dorsal- and anal-fin elements, enlarged gills with unusual skeletal supports, a heart with thick walls and more valves than other teleosts, ontogenetic loss of the swimbladder, enlarged kidneys and a well-developed urinary bladder, reduced otoliths, and a spinal cord contained completely within the braincase. Tagging studies on locomotion and diving behavior demonstrate that molids move efficiently over horizontal and vertical distances in the water column, and this new information helps to interpret the many unusual features of molid anatomy.

The ability of an upflow, denitrifying biofilter using a fermentation generated carbon source to treat the high nitrate concentrations typically seen in recirculating aquaculture systems was studied using a synthetic nitrate wastewater supplied at two nitrate loadings, 1.13 and 2.52 kg NO3-N/m3/day. A supplemental carbon source was provided primarily through the fermentation of fish food which generated volatile fatty acids (VFA) in the form of acetic, propionic, isobutyric, n-butyric, 2-methylbutyric, 3-methylbutyric, and n-valeric acids. Acetic and propionic acids were the predominant constituents generated, while lower concentrations of the longer carbon chain butyric and valeric acids were produced. The VFAs proved to be a viable carbon source for the denitrification process as indicated by the ability of the biofilm to assimilate all of the constituents generated. Carbon limiting the system resulted in an increase in effluent nitrite and incomplete nitrate removal. During the low nitrate loading condition, influent COD to NO₃-N ratios greater than 5 typically achieved high total nitrogen removals greater than 95%. This influent ratio corresponded with a COD to NOx -N consumption ratio of 4.62 ± 0.28 mg/L as COD per mg/L as N for complete nitrogen removal. Under the high nitrate loading condition, influent COD to NO₃-N ratios achieving high nitrogen removals showed great variability and did not correspond to a distinct value. The COD to NOx -N consumption ratios were often below stoichiometric values, which was attributed to the hydrolysis of influent fermentation solids captured within the column to generate a COD source not measured by filtered samples. The column biofilm kinetics were modeled using a half-order reaction rate and denitrification coefficients (k) of 0.70 ± 0.02 (mg NOx-N/L)1/2 / min and 1.18 ± 0.12 (NOx-N /L)1/2 / min were determined for the low and high nitrate loading phases, respectively. / Master of Science

Sonic-tagged flannelmouth suckers made long distance and local movements; 12.5% of fish moved ≥ 98 km downstream and 40% stayed within Glen Canyon. Motivation for long distance movements could be spawning or food related. A controlled flood of 1,274 m³/sec did not displace flannelmouth suckers downstream or interrupt spawning. The majority (62%) of fish moved into the impounded mouth of the Paria River. Spawning occurred as evidenced by capture of adults over spawning areas and collection of young-of-year (YOY) in spring and summer. From May-September 1996, YOY flannel mouth suckers were captured in the impounded mouth of the Paria River. Successful rearing of YOY fish was attributed to the presence of a warm, slackwater area in the mouth. Formation of this area is dependent upon antecedent Colorado and Paria river flows and their effect on sediment deposition in the mouth of the Paria River.

Through the implementation of in vivo feeding trials, the efficacy of three wheat gluten (WG) products, vital (Amytex®), hydrolysed (Merripro®) and soluble hydrolysed (Solpro®) wheat gluten as replacement of soy protein concentrate, and scFOS prebiotic (Profeed®) supplementation were analysed to assess their impacts on intestinal health and production of juvenile rainbow trout. Microbial community analysis in experiment one revealed a degree of diet based modulation with 7.5% and 15% inclusions of wheat gluten (WG) products. Bacterial species diversity was significantly reduced with 15% hydrolysed wheat gluten (HWG) inclusion compared to the plant protein control and 15% vital wheat gluten (VWG) treatments, with sequenced OTUs dominated by the phylum Firmicutes and possible promotion of probiotic species. No detrimental effects were observed on intestinal morphology. These findings led onto a longer duration feed trial with a more holistic, higher resolution approach. Experiment two revealed modulation of the allochthonous intestinal microbiota, with increased proportions of Enterococcus and Weissella in the 10% and 20% VWG treatments. Bacillus and Leuconostoc relative abundances were significantly increased with 10% HWG and soluble hydrolysed (Sol) wheat gluten inclusions. HSP 70 transcripts were significantly down-regulated in all WG treatments compared to the basal soy protein concentrate treatment (SPC) and increased intraepithelial leukocyte counts were observed with 10% VWG inclusion. Growth performance was unaffected by 10% dietary inclusions of WG, however, FCR’s were significantly improved in the 20% VWG treatment compared to the 10% HWG and Soluble treatments. This led to the investigation of increased inclusion levels of WG products in experiment three. All WG treatments in experiment three yielded significantly improved growth performance. Somatic indices were significantly increased with 30% blended WG inclusion compared to the SPC treatment. Modulation of allochthonous intestinal microbiota was observed to a lower degree than the previous experiments, with a dose response observed with increasing blended WG inclusion. In the final experiment two basal diets (SPC and 20% Blended) and two scFOS supplemented diets (SPC + FOS and 20% Blended + FOS) were investigated for the effect on growth performance, gut health and allochthonous microbial population. Growth performance was unaffected, however, modulation of the allochthonous microbial population was observed with an apparent synergistic effect of scFOS supplementation in WG diets. This synergistic trend was also observed in the transcription level expression of immune relevant genes. 20% WG inclusion with additional scFOS supplementation observed significant down regulation of the pro-inflammatory cytokine TNF-α, as well as HSP 70, CASP 3 and Glute ST compared to the 20% Blend treatment. The present research demonstrates dietary inclusions of WG products, solely or blended, at the expense of soy protein concentrate to modulate the allochthonous microbial population, potentially promoting probiotic species, whilst reducing the levels of intestinal stress in juvenile rainbow trout. Supplementation of the prebiotic scFOS modulated the microbial populations, enhancing the proportion of potential probiotic species, and combined with WG inclusions, reduce intestinal and oxidative stress and inflammation biomarkers, with no observed deleterious effects.

<p>The primary aim of the current study falls within the main framework of the Frontier Program (Pitcher 2005), namely to address aspects of &ldquo / Animal Husbandry&rdquo / . Within this research area, the determination of the effects of handling/grading and chemicals (anaesthetics) on the growth and survivorship of abalone are highlighted as key research areas and these are thus one of the focuses of this research.</p>