Thesis (Ph. D.)--Ohio State University, 2003. / Title from first page of PDF file. Document formatted into pages; contains xvii, 147 p.: ill. Includes abstract and vita. Advisor: David H. Bromwich, Dept. of Geography. Includes bibliographical references (p. 140-147).

Thesis (M.A. in National Security Affairs)--Naval Postgraduate School, June 2003. / Thesis advisor(s): David S. Yost, Mikhail Tsypkin. Includes bibliographical references. Also available online.

The Atlantic salmon (Salmo salar) has two developmental processes which are clearly seasonal; smoltification is restricted to the spring and maturation to late autumn. In the farming industry the seasonality of juvenile production is primarily responsible for the seasonal production in market-sized fish. Both smoltification and maturation appear to be controlled by mechanisms timed by photoperiod. This thesis investigates the effects of photoperiod on smoltification and maturation. The performance of both out-of-season eggs and particularly smolts are closely examined and the possible application of photoperiod techniques in the industry discussed. Both potential SI and S2 parr were subjected to natural photoperiods or a range of artificial photoperiods under constant and ambient temperature conditions. S I and S2 smolts reared under natural photoperiods were transferred to sea water during April and May. A 2-3 month period of short days followed by a period of long days was observed to advance smoltification; 0+ and 1+ smolts were transferred to sea during December (4 month advance) and October (6 month advance), respectively. A 12 month seasonal photocycle delayed by 3 months delayed smoltification by 2 months. Out-of-season smolts were produced in January, March, April, May, June, July, October, November and December. All groups of out-of-season smolts exhibited the same growth potential as natural smolts. The different transfer date of out-of-season smolts therefore resulted in different harvest periods compared to natural smolts. The age at maturity of out-of-season smolts was positively related to the length of the seawater growing period prior to the completion of maturation. Out-of-season smolts exhibited increased maturation in association with an increased size (compared to natural smolts) for a particular time of year. These large maturing fish were generally harvested as superior salmon prior to flesh deterioration. Mortality during the first month in sea water was significantly higher in a number of out-of-season smolt groups compared to natural smolts. This was considered to be related to site-specfic environmental conditions rather than the smoltification process. Smoltification was also examined under constant photoperiods and a 4 week period of short daylengths. Dissociation and suppression of certain aspects of smoltification were observed. The different aspects of smoltification: the development of bimodality, hypoosmoregulatory ability, decrease in condition and smolt coloration appeared to be controlled by different independent mechanisms. The development of bimodality, hypoosmoregulatory ability and possibly coloration appeared to be controlled by independent endogenous rhythms. The decrease in condition factor, associated with the parr-smolt transformation required a period of short day length greater than 2 months followed by a period of long daylength. Smoltification and maturation were examined in salmon retained in constant 1DOC borehole water. Smolts held in fresh water grew steadily and matured producing eggs and sperm both in- and out-of-season. There was, however, a period of increased mortality after smoltification and egg quality was reduced especially in fish subjected to photoperiod manipulation. The salmon responded to photoperiodic manipulation. Abrupt changes in photoperiod advanced spawning by 12 weeks and a reciprocal seasonal photoperiod (6 month out of phase with a natural photoperiod) advanced spawning by 22 weeks. The maturation process in the Atlantic salmon would appear to be controlled by similar mechanisms to those described for the rainbow trout. Freshwater holding conditions appeared to decrease the age at maturity and reduce egg quality. The progeny of freshwater broodstock (FI generation) successfully completed smoltification and seawater transfer. Photoperiodic manipulation can be used to produce out-of-season smolts and eggs. Through the use of photoperiod, farms could increase and target production. This could remove the seasonality from the production cycle and help stabilise the pricing structure for market salmon.

Many studies in animals and humans have demonstrated that exposure topolychlorinated biphenyls (PCBs) can interfere with the normal function of the thyroid system. In this study, Atlantic croaker (Micropogonias undulatus) were exposed to a PCB mixture (Aroclor 1254) or one of three individual congeners (ortho-PCB 153, ortho-PCB 47 or planar PCB 77) in the diet for 30 days to investigate the effects of PCBs on thyroidal status. Thyroid hormones, thyroxine (T4) and triiodothyronine (T3) were extracted from plasma samples and measured with an enzyme-linked immunosorbent assay. Both male and female croaker exposed to the PCB mixture Aroclor 1254 (0.2 and 1.0 mg/kg body wt/day) had decreased plasma levels of total T3 when compared to the parallel control groups, but the effects on total T4 levels were inconsistent. Exposure to PCB 153 (0.1 and 1.0 mg/kg body wt /day) significantly lowered both T4 and T3, while PCB 47 at the same doses had no effect on thyroid hormone levels. Fish exposed to PCB 77 had no effect on T4 or T3 levels except an increase in T4 levels at the highest dose employed (0.1 mg/kg body weight/day). However, this dose of PCB 77 caused partial loss of appetite and may be too high to be relevant for the effects observed after exposure to Aroclor 1254 considering the fact that it constitutes only 0.31% of the PCB mixture. The results of the present study demonstrate that exposure to synthetic endocrine disrupting chemicals, such as PCBs at the higher end of environmentally realistic concentrations can have profound effects on the thyroidal status of Atlantic croaker. The ability of Aroclor 1254, as well as ortho-PCB 153, to consistently disrupt the natural homeostasis of the thyroid system in croaker is an important finding that contributes to a better understanding of PCB endocrine toxicity in teleosts.

The goal of this research was to examine the role of the novel membrane progestin receptor alpha (mPR[alpha]) in the stimulation of sperm hypermotility by the progestin 17,20[beta],21-trihydroxy-4-pregnen-3-one (20[beta]-S) in two teleosts; the Atlantic croaker (Micropogonias undulatus) and the southern flounder (Platylicthys lethigstomata). In croaker, the expression, localization and hormonal regulation of mPR[alpha] in testis and sperm were investigated, as were the intracellular signaling pathways activated by 20[beta]-S and mPR[alpha] to induce croaker sperm hypermotility. In flounder, stimulation of sperm hypermotility by 20[beta]-S and binding of this steroid to flounder sperm membranes were examined. Finally, expression of mPR[alpha] was investigated in flounder testes and the expression and localization of this receptor in flounder testis and sperm was examined. In croaker sperm, mPR[alpha] was expressed on the plasma membrane and localized to the midpiece. Expression of mPR[alpha] was also shown to be associated with high sperm motility and regulated by gonadotropin. The signaling pathways activated by 20[beta]-S in croaker sperm were shown to involve activation of olfactory G-proteins (Golf). Subsequent activation of membrane adenylyl cyclases was also demonstrated and shown to be necessary for 20[beta]-S-stimulated cAMP production and 20[beta]-S-induction of sperm hypermotility. Furthermore, co-immunoprecipitation studies show mPR[alpha] and Golf physically associate with one another, establishing mPR[alpha] as the mediator of 20[beta]-S actions in croaker sperm. Finally, evidence was obtained for progestin-stimulation of sperm hypermotility and the presence of mPR[alpha] on sperm membranes in another marine teleost species belonging to a different family, the southern flounder. In addition, mPR[alpha] was shown to be expressed on flounder sperm membranes and also localized to the sperm midpiece. Results from the following studies support the hypothesis that mPR[alpha] is the mediator of 20[beta]S-stimulated sperm hypermotility in croaker and is a likely intermediary in southern flounder. Furthermore, these data provide a plausible mechanism by which 20[beta]-S and mPR[alpha] stimulate croaker sperm hypermotility. In addition, these results provide the first evidence of hormonal activation of Golf proteins for any species. Finally, mPR[alpha]-mediated mechanisms to increase sperm motility are suggested to be evolutionarily conserved in teleosts since they also likely exist in a non-sciaenid species, the southern flounder.

The Atlantic halibut (Hippoglossus hippoglossus) was selected as a new aquaculture candidate towards diversification from salmonid culture. The species was chosen because of its high market value and perceived good growth in the cold waters of the target farming regions. Extensive and collaborative research efforts formed the basis for the culture of this benthic marine species. Broodstock populations were established from a limited number of wild individuals due to the high costs involved in their capture. First generation hatchery reared offspring are now being selected as replacements but with no knowledge of a broodstock replacement strategy to manage this valuable genetic resource and to maximize the potential of this species the industry runs the risk of genetic degradation with the associated problems of inbreeding depression. This thesis investigates the processes involved with developing a genetic management strategy, using genetic profile technology, based on a population in Scotland at Otter Ferry Seafish Ltd. The level of genetic variability of 70 individuals in the parental population and 802 of their offspring (F1) in two year classes (1995 and 1998) was assessed at 7 microsatellite loci. The parental population which was comprised of three different stocks was genetically diverse, however, when compared with their offspring, substantial reductions in genetic variation, as judged by allelic diversity, were observed. The parentage of these F1 individuals was determined by exclusion principles and 91% of all the offspring genotyped were unambiguously assigned to a single parental pair. The assignment revealed that only half of the parents succeeded in contributing to the F1 generation. This problem was compounded by the fact that the family sizes were highly skewed such that the entire population consisted of a small number of large families resulting in an unacceptably low effective population size of 8.11. The inbreeding coefficient in the F1 generation was 6.16% however this differed markedly between the 1995 (7.74%) and 1998 (10.64%) year classes. The repeatability of reproductive performance defined by five performance traits reflecting quantity and quality of eggs, frequency of stripping events and viability was assessed by REML using data collected over three spawning seasons from 239 F1 females. The phenotypic correlations obtained between quality and quantity traits were low in magnitude and the study showed that with the exception of seasonal activity, all traits studied improved with age. There was also an effect of photoperiod in that fish kept under a 4 month-delayed regime did not perform as well as the fish under a one-month extended regime. Of all five traits, only volume of eggs collected was repeatable (r=0.37±0.07). This suggests that it is the only reproductive character influenced by the fish and all other traits, especially those pertaining to egg quality are determined by management practices. The heritability of body weight at four stages in the growout phase of production was estimated by REML using data from 486 F1 individuals. These animals were reared in two different sites, a land based tank and a sea cage. Significant effects of site, sex and grade were observed and by the end of the trial the average weight of fish in land based system was higher by 2 kg. Females were over 3 kg heavier than males and this difference was attributed to precocious maturation while fish in the smaller grade were consistently though decreasingly lighter than their larger counterparts. Heritabilities, derived from sire, dam and combined estimates ranged from 0.09 to 0.53 with wide confidence intervals. The poor precision of the estimates was due to the highly imbalanced family structure and the small number of offspring studied. Values varied depending on the age of fish and the source of variance used to estimate them. Heritabilities increased with age and although sire estimates were higher than dam estimates these differences were tested and the results obtained consistent with the conclusion that they represent nothing more than chance. The results suggested that selection for increased body weight in the halibut was likely to be successful. Based on the findings of the study a genetic management strategy for the Atlantic halibut was proposed structured on controlling the rate of inbreeding and a theory of domestication. The need to introduce additional individuals into the population was strongly recommended.

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This work represents an analysis of the spatial and temporal variability of nitrate deposition and preservation recorded in multiple ice core and snow pit records from the Greenland ice sheet. The primary objective of this research was to develop improved estimates of variability in the preserved ice core record of nitrate to aid in the interpretation of paleoatmospheric concentrations of reactive nitrogen compounds. Three separate works are presented, each focusing on a unique component of variability. The first is a study related to the direct preservation of nitrate over a single year. The second and third topics are related to analysis of ice core records collected during NASA's Program for Arctic Regional Climate Assessment (PARCA) which was initiated in 1993 and continued through 2002.The first study of preservation demonstrated that nitrate, despite possible post-depositional cycling and alteration, was well preserved throughout the year, such that the total flux measured in a snow pit taken to represent the previous year, was representative of snow surface concentrations during the past year. The small difference in preserved concentrations from observed surface snow concentrations gives evidence of only 7% post-depositional loss at this site (mean annual accumulation ~23 g cm-2 yr-1). Results from these studies indicate that at this site accumulation is the most significant process affecting preservation of nitrate in the firn.In the second study, the temporal variability of preserved nitrate was evaluated through time series analysis and correlation studies with available paleoclimate proxy records. Six Greenland ice cores covering the period 1794-1995 show correlated co-variability of nitrate concentration for periods greater than ten years and a ~60% increase in average concentration during the last 75 years. The changes in concentration yield ~30% higher nitrate flux (2.5 to 3.2 g m-2 a-1) and ~11% greater variability during 1895-1994 period versus the prior 100 years. Nitrate trends in the cores during the last 100 years are also correlated with global nitrate emissions, with an average r-value of 0.93 for the six cores.The last study focused on spatial variability of nitrate, and the relation of deposition to components of the earth system including temperature and accumulation. The objective of the study was to assess the contribution of spatial (latitude, longitude, and elevation) and climate (accumulation and temperature) components to the preserved record. Furthermore, the study evaluated the influence of anthropogenic activities on the spatial distribution of nitrate of the Greenland ice sheet. Large scale spatial variability exists as a result of accumulation gradients, with concentration 5% greater in the northern plateau, yet flux over the northern plateau is 30% lower than the dry snow zone as a whole. While spatially, flux appears to be more dependent on accumulation, preservation of flux shows increasing dependence on concentration with increasing accumulation. The relationship between concentration and accumulation is non-linear, showing less dependence in the low accumulation regions versus high accumulation regions. Accumulation alone is insufficient to account for the observed variability in nitrate flux in the low accumulation regions, and evidence supports an additional component to a transfer function model for nitrate that includes photochemistry, temperature, and possibly sublimation. In high accumulation regions, evidence points to a dilution effect, with concentration decreases resulting from increased accumulation. Flux estimates over the ice sheet are compared with a GEOS-CHEM model estimate of reactive nitrogen vertical fluxes showing the model captures a significant component of the variability in the southern portion of the ice sheet, but under-represents the flux and variability in the northern half of the ice sheet by a factor of 4.

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The Arctic Oscillation (AO) and the North Atlantic Oscillation (NAO) are the most pronounced modes of extratropical atmospheric wintertime variability in the Northern Hemisphere. This thesis investigates different aspects of the AO and NAO on the in traseasonal and seasonal time scales. First, the question of how the differences between the AO and NAO are influenced by the choice of the definitions of the NAO and to what extent the AO and NAO differ from each other is investigated using the daily NCEP/NCAR reanalysis data spanning 51 boreal winters. One AO index and four different NAO indices are used in this study. It is found that the AO and NAO are quite similar to each other when both are defined using pattern-based indices, while some notable differences are observed between them when the NAO is defined using a station/gridpoint-based index. Then the predictability of the AO and NAO is examined using a simple general circulation model (SGCM). Numerical experiments are performed to determine the sensitivity of the setup processes of the AO and NAO to the details of the initial conditions. The predictive skills for the AO and NAO are compared to each other. Finally, the potential role of tropical Pacific forcing in driving the seasonal variability of the AO is explored using both observations and the SGCM. The results indicate that a negative thermal forcing over the western tropical Pacific and a positive forcing north of the equatorial mid-Pacific play important roles in producing an AO-like atmospheric response.