• Penetrative convection in sediments

      Musgrave, David L. (1983-05)
    • The life history of the intertidal barnacle, Balanus balanoides (L.) in Port Valdez, Alaska

      Rucker, Tami Louise (1983-09)
      The life history of the boreo-arctic barnacle Batanus balanoides was examined at three study sites in Port Valdez. Ovarian tissue development began in early summer. Fertilized eggs, evident by September, were brooded throughout the winter. Larval release was synchronous with the spring phytoplankton bloom. Settlement was observed in April and continued until June. Maximal shell growth occurred immediately subsequent to assimilation of organic material from the spring bloom. Seasonal fluctuations in body weight were noted and reflect feeding, spermatogenesis, and energy transfer to other biological processes (i.e., shell growth and reproduction). Mortality, greater for juveniles than adults, resulted from seasonal stresses (lowered salinity and heightened sedimentation), spatial competition, predation, and pollutants (hydrocarbons). Once life-history events were confirmed for barnacles in Port Valdez, comparisons of trends observed at the three sites were possible. Differences between populations were evident and were attributed to the unique micro-habitats of the study sites.
    • Nitrogen utilization during spring phytoplankton bloom development in the southeast Bering Sea

      Sambrotto, Raymond Nicholas (1983-12)
      Interactions between a high latitude, continental shelf, spring phytoplankton bloom and water column physics and chemistry were studied using measured rates of nitrogen uptake. Peak bloom conditions commenced when the mixed layer shallowed and minimized respirational losses. Integrative light-mixing growth models were accurate during early bloom stages. An advection-diffusion model associated peak bloom nitrate uptake with pycnocline mixing rates of 2.1 m d * in an 18 m mixed layer. The accumulation of surface buoyancy was a reliable index of peak bloom temporal and spatial "patchiness" since mixing rates influenced both respirational losses and nutrient supply. Maximum nitrogen specific uptake rates (h r .- 1 ), unlike those of carbon, coincided with peak bloom conditions. Although species com positions among peak bloom periods were similar, particulate C/N ratios were not. Apparently, both intercellular factors and prevailing mixing conditions influence specific uptake rates and cell composition. A large proportion of new (nitrate) to total productivity was associated with the dominance of the early bloom forming diatoms in the mixed layer. In the absence of these net plankton the residual nanoplankton dominated community exhibited a greater dependence on regenerated nitrogen. Nitrate uptake averaged 700 mg-at m during the spring bloom and 1 g-at m-2 year-1 The yearly f factor was 0.40. Nitrogen uptake based carbon productivity was 188 g C m -2 year -1 A mass balance of the inorganic carbon system indicates that nitrate uptake alone cannot account for all the carbon leaving the surface layer. The correspondence between 1SN0~ uptake measurements and nitrate decreases suggests the diffusion of slope water into the middle shelf is slow. Large scale meteorological patterns may be responsible for the inter annual variability observed in production. Frequent May storm activity prolonged peak bloom periods, while calm conditions promoted extensive Chijl layers. The passage of atmospheric low pressure system s was also associated with the cross shelf "pumping" of water masses.
    • Reproductive and larval biology of northern shrimp, Pandalus borealis Kroyer, in relation to temperature

      Nunes, Pepsi (1984-05)
      The northern shrimp, Pandalus borealis Kr^yer, is an important fishery resource in Alaska. However, a drastic decline in the commercial catch since 1978 poses a serious problem for the fishery. This study examined the effects of temperature on reproduction and larval survival of P. borealis. These are factors though to be vital to the determination of year class strength. P. borealis was found to have narrow thermal requirements for egg production with moderate (6°C) to low (3°C) temperatures generally more favorable than high (9°C) temperatures. In contrast with egg production, larval survival was enhanced by higher (6 and 9°C) temperatures. This study provides useful information for management of the fishery by demonstrating that temperature can trigger flucuations in the commercial catch from 5-50% through its effects on rates or reproduction and larval survival, and thereby population size. In warm water areas averaging >6°C, temperature exerts its main influence on reproduction, causing fecundity to vary by as much as 50%. While in colder areas average <3°C, fecundity and larval survival can vary with temperature by as much as 20 and 40%, respectively. Use of the information derived here requires monitoring temperature in the major fishery areas to detect changes in abundance of ovigerous females, egg number and larval mortality. Changes in these parameters are valuable indicators of stock condition when combined with abundance surveys and fishing intensity estimates.
    • Nutritional and behavioral aspects of reproduction in walruses

      Gehnrich, Pauline Hayton (1984-09)
      Walruses (Odobenus rosmarus) at Marineland, California consumed food in increasing amounts as they grew larger out ate less per unit of body weight. Adult males consumed the most food in November - December, then fasted throughout the breeding season. Females apparently fasted during ovulation and birth. Females consumed 50% more energy while pregnant or lactating than when not pregnant or lactating. Male walruses spent more time displaying, and their displays were more stereotyped, during the breeding season. Females initiated and terminated interactions with the males during the breeding season, and those interactions were preceeded by displays. Females vocalized to the calf to initiate suckling bouts, reassure the calf, and to call the calf. Calves vocalized to initiate suckling bouts and indicate danger. When the calf was threatened, the female responded quickly by tusk strikes, kinesic tusk threats, vocal threats, or calling the calf. The calf tended to follow the female.
    • The role of stratification in the spring ice edge bloom in the Bering Sea: a numerical model

      Freed, Martin (1984-09)
      Marginal ice edge zones are unique frontal systems with air-ice-sea interfaces. Phytoplankton blooms which occur along the edge of some melting ice packs in the spring, appear to be related to melt water driven density stratification. In this thesis a numerical model of a marginal ice edge zone is constructed. The wind driven circulation and spring phytoplankton bloom at the Bering Sea ice edge are simulated as functions of air-ice-sea-biology interaction. It was found that as long as the ice was allowed to melt, blooms occur regardless of wind direction. However, because of the compactness dependent melt scheme invoked, the faster the ice advects out from the pack, the faster the water column stratifies. The speed and the area of the bloom depend on the rate and extent of stratification. The model data compare favorably with field data.
    • Heavy metals in the sediments of an arctic lagoon, northern Alaska

      Sweeney, Michael Devlin (1984-12)
      The total abundances of V, Cr, Mn, Fe, Co, Ni, Cu, and Zn in oxic, nearshore sediments of north arctic Alaska, are similar to those of corresponding pristine or pre-industrial-age sediments of many tropical-temperate regions, and thus do not reflect the unique weathering and depositional processes of the Arctic. Laboratory experiments on metal partitioning suggest that about 50% of the metal contents (<20% for V, Cr), which are bound predominantly in Fe oxides, may be mobilized into solution following the onset of reducing conditions at the sediment surface. A three-part extraction design would be effective in discriminating the three major associations of heavy metals in the sediments: easily leachable, Fe hydroxides, and refractory particles, and is recommended for use in monitoring the nearshore Beaufort Sea for future contamination by heavy metals.
    • Processes Controlling Radon-222 And Radium-226 On The Southeastern Bering Sea Shelf (Chemical Oceanography, Two-Dimensional Model, Continental, Gas-Exchange, Sediment Flux)

      Glover, David Mark (1985)
      An investigation was made into the use of ('222)Rn and ('226)Ra as tracers of air-sea gas exchange, water column mixing and sediment-water exchange on the southeastern Bering Sea shelf. Furthermore, a two-dimensional model was developed to unify these three processes into a coherent picture of ('222)Rn flux out of the sediments, through the water column and into the atmosphere. The best time period to average wind speeds when regressing them against gas transfer coefficients was found to be 3.3 days by a linear regression optimization, approximately the synoptic time scale of storms in the southeastern Bering Sea. A statistically significant relationship between averaged wind speed and transfer coefficients was found at the 80% confidence level. Gas transfer coefficients were found to be obscured in shallow waters by radon flux from the sediments. Two-dimensional mixing in these continental shelf waters rendered the traditional one-dimensional vertical mixing model of excess ('222)Rn unable to obtain reliable vertical eddy diffusivities. Exchange across the sediment-water interface was calculated from the deficiency of ('222)Rn measured in sediment cores, the standing crop of excess ('222)Rn in the overlying water column and the ('222)Rn production rate of sediment surface grab samples. The flux of radon out of the sediments was found to increase in the onshore direction. Biological irrigation appears to be the primary exchange mechanism between the sediment and water columns on this shelf. Distributions in the water column show finestructure reported previously as well as biological removal of ('226)Ra. A (chi)('2) hypersurface search found the optimal horizontal and vertical eddy diffusivities that explained the two-dimensional distribution of ('222)Rn provided from a kriging estimation exercise on the data measured in this study. This model was essentially a hybrid of a least squares surface fit and a numerical integration of the governing differential equation of ('222)Rn. When considered as a two-dimensional system in the cross-shelf direction, the rates of gas exchange, water column mixing and sediment-water exchange agree with each other to an acceptable degree.
    • A comparison of the food habits of juvenile Pacific cod and walleye pollock in the southeast Bering Sea

      Lee, Sang Suh (1985-05)
      The food habits of juvenile Pacific cod, Gadus macrocephalus, and walleye pollock, Theragra chalcogramma, collected in July and August in 1981 through 1983 in the eastern Bering Sea, were compared in relation to some morphological characteristics. The fishes' gill rakers were counted, the distances between gill rakers were measured, and the stomach tissue weight was measured. The stomach contents were analysed by occurrence, number and volume. It was found that the fishes' gill structures were related to size-selective predation in both fishes. Pollock utilized small zooplankton and cod large zooplankton. Food competition was expected when fishes are smaller than 40 mm TL as indicated by high values in proportional similarity. However, food competition decreases as the fishes grow and develop distinct size-selective predation habits. Prey composition in the stomachs reflected the regional differences of local oceanographic environments.
    • Body composition (carbon, nitrogen and calories) and energetics of immature walleye pollock, Theragra chalcogramma (Pallas), in the southeast Bering Sea

      Harris, Robert K. (1985-05)
      The body composition (carbon, nitrogen and calories) of Bering Sea and Resurrection Bay (Alaska) immature walleye pollock (9-360 g wet weight) were related to dry weight and Fulton's condition factor index by regression models. The condition factor was a better predictor of body composition than dry weight. As condition improved from a minimum starvation level of 0.42 to a maximum of 1.16, body caloric, percent carbon, and the carbon-nitrogen ratio increased, while percent nitrogen and percent ash decreased. The body composition measurements allowed energy budget terms (assimilation coefficient, growth, and metabolism) to be expressed in common units. The assimilation coefficient and growth terms were estimated from literature sources. Oxygen consumption measurements at 3-10°C yielded the metabolic term. The daily food requirement for 0-3 year old walleye pollock, at their annual average Bering Sea habitat temperature of 3.8°C, was 1.0 - 1.5% of the body weight.
    • Processes controlling radon-222 and radium-226 on the southeastern Bering Sea shelf

      Glover, David M. (1985-12)
      An investigation was made into the use of radon-222 and radium-226 as tracers of air-sea gas exchange, water column mixing and sediment-water exchange on the southeastern Bering Sea shelf. Further more, a two-dimensional model was developed to unity these three processes into a coherent picture of radon-222 flux out of the sediments, through the water column and into the atmosphere. The best time period to average wind speeds when regressing them against gas transfer coefficients was found to be 3.3 days by a linear regression optimization, approximately the synoptic time scale of storms in the southeastern Bering Sea. A statistically significant relationship between averaged wind speed and transfer coefficients was found at the 80% confidence level. Gas transfer coefficients were found to tie obscured in shallow waters by radon flux from the sediments. Two-dimensional mixing in these continental shelf waters rendered the traditional one-dimensional vertical mixing model of excess radon-222 unable to obtain reliable vertical eddy ditfusivities. Exchange across the sediment-water interface was calculated from the deficiency of radon-222 measured in sediment cores, the standing crop of excess radon-222 in the overlying water column and the radon-222 production rate of sediment surface grab samples. The flux of radon-222 out of the sediments was found to increase in the onshore direction. Biological irrigation appears to be the primary exchange mechanism between the sediment and water column s on this shelf. Distributions in the water column show fine structure reported previously as well as biological removal of radium-226. A chi-square hypersurface search found the optimal horizontal and vertical eddy diffusivities that explained the two-dimensional distribution of radon-222 provided from a kriging estimation exercise on the data measured in this study. This model was essentially a hybrid of a least squares surface fit and a numerical integration of the governing differential equation of radon-222. When considered as a two-dimensional system in the cross-shelf direction, the rates of gas exchange, water column mixing and sediment-water exchange agree with each other to an acceptable degree.
    • Breeding performance of kittiwakes and murres in relation to oceanographic and meteorologic conditions across the shelf of the southeastern Bering Sea

      Lloyd, Denby S. (1985-12)
      Contrary to expected results, black-legged and red-legged kittiwakes on St. George Island exhibited more variability in annual breeding performance than black-legged kittiwakes at Cape Peirce. Thick-billed and common murres at St. George also showed more annual variability than common murres at Cape Peirce. Kittiwakes at St. George exhibited improved breeding performance during years with colder water temperatures and lower summer wind speeds. Correlations between breeding performance in kittiwakes and murres and environmental conditions at Cape Peirce were inconclusive. A general decline in the annual breeding success of kittiwakes and murres at St. George between 1976 and 1984 coincided with reduced abundance of juvenile walleye pollock. Consistently low breeding success of kittiwakes and murres at Cape Peirce varied little among six years observed between 1970 and 1984. These results challenge previous considerations of pelagic food webs on the outer shelf as being more stable than those in the coastal domain.
    • Pelagic nitrogen cycle in an arctic lake

      Whalen, Stephen Charles (1986-05)
      A mass balance for nitrogen was developed for the water column of Toolik Lake and the isotope tracers 15N and 14C were used to examine the phytoplankton ecology with respect to dissolved in organic nitrogen (ammonium and nitrate). The nutrient budget showed an oligotrophic ecosystem with important flux terms few and small in magnitude. Nitrogen input was primarily from inflowing rivers and was dominated by the dissolved organic fraction. Ammonium release from sediment provided the only other major source of nitrogen to the lake water. Toolik acted as a nitrogen sink, trapping 18% of the annual input. Retention was almost exclusively (98%) as dissolved organic nitrogen. Tracer experiments suggested chronic nitrogen deficiency in the phytoplankton, but indigenous populations were well-adapted for utilizing characteristically low levels of nutrient. Phytoplankton showed a high affinity for both nitrate and ammonium as well as a lack of discrimination between the two forms of inorganic nutrient. The ambient concentration was the most important factor regulating uptake, with light and temperature of secondary importance. More than 66% of the dissolved in organic nitrogen supporting phytoplankton productivity was derived from local recycling, with the remainder from sediment efflux and riverine input. Dissolved organic nitrogen from inflowing waters probably provided an additional, important source of nutrient for the phytoplankton.
    • Effects of disturbance by clipping on two distinct forms of Zostera marina L.

      Roth, Joanna E. (1986-05)
      Biweekly clipping of leaves was used as a type of disturbance to compare the responses of eelgrass (Zostera marina) in shallow and deep water to those predicted from a terrestrial ecosystem succession model. All clipped plants had lower leaf growth rates than controls. Clipped plants decreased root-rhizome biomass in shallow water, but not in deep-water stands during 1981. During 1982 (better weather), shallow-water plants increased leaf carbon concentrations; deep-water plants decreased root-rhizome biomass. Root-rhizome to leaf ratios (high in shallow water and low in deep water) and weather conditions appeared important in determining the response to clipping. All plants had similar nitrogen content. These responses were typical of those reported for the tropical turtle grass, but were contrary to differences in plant growth strategies and nutrient use predicted from some terrestrial ecosystem studies of other higher vascular plants.
    • Benthic community development in Boca de Quadra, Alaska

      Winiecki, Carol Irene (1986-05)
      The purpose of this experiment was to find ways of evaluating the community development in Boca de Quadra, a fjord in southeast Alaska, after a severe physical disturbance. Containers of defaunated sediment were used near the head of the fjord to simulate the benthic habitat after such a disturbance. Important features of community development were described, potential indicator taxa were selected, and the extent of community development was examined. Seasonal variations tended to mask the developmental trends. However, samples collected during the same season, but representing various lengths of colonization, allowed developmental trends to be observed in faunal composition, numbers of taxa, density, biomass, and diversity. Maldanidae, Nematoda, Lumbrineris luti. Leitoscoloplos pugettensis, Pholoe minuta. and Spionidae are potential indicators of community maturity.