Research report : enhanced hydrographic survey for CPL discharge in Nueces Bay

The objectives of the enhanced hydrographic survey in Nueces were: A. to monitor the vertical and horizontal distributions of temperature and salinity, nutrients and plant pigments in the nearby area of the CPL cooling water discharge channel in Nueces Bay. B. to compare the distributions of the above parameters to those throughout other portions of Nueces Bay during freshwater release and non-release periodsFor Central Power and Light Company ... Corpus Christi, Texas ...November 1993Marine Scienc

Pan-Arctic distribution of bioavailable dissolved organic matter and linkages with productivity in ocean margins

Rapid environmental changes in the Arctic Ocean affect plankton productivity and the bioavailability of dissolved organic matter (DOM) that supports microbial food webs. We report concentrations of dissolved organic carbon (DOC) and yields of amino acids (indicators of labile DOM) in surface waters across major Arctic margins. Concentrations of DOC and bioavailability of DOM showed large pan-Arctic variability that corresponded to varying hydrological conditions and ecosystem productivity, respectively. Widespread hot spots of labile DOM were observed over productive inflow shelves (Chukchi and Barents Seas), in contrast to oligotrophic interior margins (Kara, Laptev, East Siberian, and Beaufort Seas). Amino acid yields in outflow gateways (Canadian Archipelago and Baffin Bay) indicated the prevalence of semilabile DOM in sea ice covered regions and sporadic production of labile DOM in ice-free waters. Comparing these observations with surface circulation patterns indicated varying shelf subsidies of bioavailable DOM to Arctic deep basins.Published version2019-07-3

Distribution, fluxes and biological utilization of inorganic nitrogen during a spring bloom in the New York Bight

The utilization of ammonium (NH4) and nitrate (NO3) by natural phytoplankton communities was measured during a Ceratium tripos-dominated spring bloom in the New York Bight…

Carbon Uptake Rates of Sea Ice Algae and Phytoplankton under Different Light Intensities in a Landfast Sea Ice Zone, Barrow, Alaska

To determine whether nitrogen or light exerts the most control for the rates of carbon production of ice algae and phytoplankton under the ice, nitrogen addition (NO3 or NH4) and light increment experiments were executed on the landfast sea ice of Barrow, Alaska, during the 2003 growing season by using a 13C-15N dual isotope tracer technique. The productivity of the bottom sea ice algae and phytoplankton at Barrow in 2003 was limited mainly by low light levels (approximately 0.3% of the surface irradiance) at the bottom under the snow-covered sea ice. The carbon and nitrate uptake rates of ice algae and phytoplankton increased as the incubation depth in the ice hole decreased and light intensity increased. In addition, under higher light conditions, the relative production of proteins of the bottom ice algae decreased, whereas the lipid proportion increased. The higher level of lipid synthesis of the ice algae might be significant to the nutrition of zooplankton and benthos because lipids are the most energy-dense biomolecules.Afin de déterminer si c’est l’azote ou la lumière qui exerce le plus grand contrôle sur les taux de production de carbone émanant des algues de glace et du phytoplancton sous la glace, des expériences consistant en l’ajout différentiel d’azote (NO3 ou NH4) et de lumière ont été effectuées sur la glace de mer côtière de Barrow, en Alaska, pendant la saison de croissance de 2003 grâce à une technique de traceurs d’isotopes mixtes de 13C-15N. La productivité des algues de glace de mer et de phytoplancton de fond à Barrow en 2003 a été surtout restreinte par les faibles taux de lumière (environ 0,3 % de l’éclairement de la surface) au fond, sous la glace de mer couverte de neige. Les taux d’absorption de carbone et d’azote chez les algues de glace et le phytoplancton augmentaient au fur et à mesure que la profondeur d’incubation du trou de glace diminuait et que l’intensité lumineuse s’intensifiait. De plus, lorsque les conditions de luminosité étaient plus grandes, la production relative de protéines des algues de glace de fond diminuait, tandis que la proportion de lipides grimpait. Le taux plus élevé de synthèse des lipides des algues de glace pourrait revêtir de l’importance dans la nutrition du zooplancton et du benthos parce que les lipides sont les biomolécules les plus denses en énergie

Seasonal Variations In Nutrient Concentrations and Speciation in the Chena River, Alaska

To better understand the seasonal controls on nutrient abundances, speciation, and fluxes in a watershed underlain by discontinuous permafrost, we collected water samples biweekly from the Chena River during 2005-2006 to measure inorganic and organic N, P, and Si in dissolved and particulate phases. Nitrate concentrations were low (8-14 mu M) during the winter and summer dry seasons but were elevated during the spring freshet (15-24 mu M). Ammonium varied from 8 to 13 mu M during the winter but dropped dramatically during the ice-open season to 0.1-3 mM. Phosphate was very low throughout the year (ranging from 0.03 to 0.3 mu M), reflecting the pristine condition of the watershed. Dissolved silica was high in the winter and reached its minimum during the spring freshet. DIN was the dominant species in the total N pool (60%), followed by DON (30%) and PN (10%). Most of the phosphorous was present in the particulate phase (74%), with phosphate and DOP only comprising 19% and 7%, respectively. Seasonal variations in nutrient concentrations and speciation were mostly controlled by the hydrological flow regime and biological activity in the river. Annual nutrient export fluxes from the Chena River during 2005-2006 were 51.1 x 10(6) mole-N, 1.4 x 10(6) mole-P, and 197 x 10(6) mole-Si, corresponding to an annual yield of 9.8 x 10(3) mol-N km(-2), 0.28 x 10(3) mol-P km(-2), and 37.9 x 10(3) mol-Si km(-2), respectively. Within the annual export fluxes, the spring freshet contributed about 18% of TN, 27% of TP, and 10% of Si, while the winter season contributed 11% of TN, 12% of TP, and 20% of Si. Continued climatic warming in northern watersheds will likely increase the export of nutrient species from watersheds

Community Metabolism and Nutrient Cycling in the Mississippi River Plume: Evidence for Intense Nitrification at Intermediate Salinities

Community respiration, net nutrient fluxes and heterotrophic bacterial production were investigated in the Mississippi River (USA) plume during May 1992 using dark bottle incubations of unfiltered water. Highest rates of community O2 consumption and dissolved inorganic carbon regeneration were observed at intermediate (10 to 27%0) plume salinities. Plume surface 02 consumption rates were 2- to 4-fold greater than rates reported previously during the summer and winter. Heterotrophic bacterial production ([3H]-leucine incorporation) was also highest at intermediate salinities and 2- to 4-fold greater than rates reported from other seasons. Net regeneration of NH4+ was observed in the 0 to l8%0 region of the plume while low rates of net NH4+ consumption were observed at 27%0. Net NO2- regeneration in the Mississippi River suggested the occurrence of nitrification m the fresh waters of the delta. Serendipitous observations of rapid NO3- regeneration at 18 and 27%0 indicated the development of intense nitrification at intermediate plume salinities. Nitrification accounted for 20 to \u3e50 % of the community 02 demand at 18 and 27%0. These data indicated that nitrification was an important component of the plume nitrogen cycle and contributed significantly to oxygen consumption in the plume

Brown Tide Symposium and Workshop : 15-16 July 1991

The 'brown tide' bloom of an aberrant Chrysophyte sp. phytoplankter occurred for more than 18 months and extended into both upper (cover map) and lower Laguna Madre, Texas. Great concern for the Laguna Madre ecosystem was shown during the brown tide event by local, state and regional groups, but little previous knowledge was available about this unusual phytoplankton bloom. Since field data had been collected by an ongoing UTMSI field program in the Laguna, it was felt that a workshop format meeting should be convened with national and international experts to discuss the data and results on brown tide and other unusual phytoplankton blooms. A relatively quick response was needed as planning for the workshop started in May 1991 for a meeting date in July, with support supplied by the Gulf of Mexico Program of U.S. Environmental Protection Agency (Grant No. X 006242-01-0), The Resource Protection Division of the Texas Parks and Wildlife Department and The University of Texas Marine Science Institute. This report includes the agenda, abstracts of presentations and summary of findings by the workshop participants. The participants also strongly agreed that long term research support was necessary to further understand the brown tide bloom and its effects. To that end, a resolution was drafted and unanimously approved by all the workshop participants.September 1991Marine Scienc

Modification of NO, PO, and NO/PO During Flow Across the Bering and Chukchi Shelves: Implications for Use as Arctic Water Mass Tracers

The NO and PO tracers (9[NO3-] + 02 and 135[PO4-] + 02, respectively,) and their derivative NO/PO have found increasing use in Arctic water mass analyses for identifying the specific basin or shelf areas from which surface waters originate, based upon assumed differences in Pacific- and Atlantic-derived content and basin-to-basin differences within the Arctic. Following shipboard sampling in June-September 1993 and May-June 1994, both north and south of Bering Strait, we have found evidence that Pacific-derived waters flowing north to Bering Strait do not necessarily have any unique NO, PO, or NO/PO identity that would permit unequivocal use as a water mass tracer. In particular, NO/PO ratios in the Bering Sea continental shelf (\u3c150 m) waters varied from 0.7 to 1.1, which encompasses ratios previously reported for Arctic continental shelf and Atlantic origin waters in the Arctic Ocean. The highest NO/PO ratios (~ 1) in the Bering Sea were observed to the southwest of St. Lawrence Island, close to where high nutrient waters are first upwelled onto the shelf, and seasonally early in the biological production cycle. By contrast, later in the summer, north of Bering Strait, at the depth of the Arctic Ocean nutrient maximum, the highest concentrations of silica (~60 μM) were associated with low NO/PO ratios (-0.7). Apparent increases in the proportions of sea ice melt in these waters, inferred from 180 and salinity regressions, were associated with lower NO/PO ratios. This pattern, the potential for sea-air exchange, and a significant relationship between decreases in nitrate/phosphate ratios and both NO/PO ratios and silica concentrations indicate that biological and physical processes north and south of Bering Strait affect the fidelity of these nutrient-based tracers. These results indicate the need for consideration of shelf-based processes before NO/PO ratios and other nutrient-based tracers can be successfully applied as Arctic circulation tracers. Copyright 1999 by the American Geophysical Union

The Northeast Pacific GLOBEC Program: Coastal Gulf of Alaska

(First Paragraph) The Gulf of Alaska (GOA) continental shelf encompasses approximately 370,000 km2, or about 13% of the U.S. continental shell and supports a rich and diverse marine ecosystem including some of the largest commercial fisheries in the U.S. Exclusive Economic Zone. Of particular economic importance is the salmon fishery, which was worth on the order of $170 million (landed value) in 2000 accrued from a catch of over 100 million fish. However, there is considerable variability on both interannual and longer time scales in harvest and recruitment success to this and other GOA fisheries. Of recent interest are compelling indications that abundances of salmon, other fish species, and zooplankton vary on decadal scales in association with North Pacific basin-scale climate changes (Beamish, 1995; Mantua et al., 1997; Roemmich and McGowan, 1995; Brodeur et al., 1996; Francis et al., 1998; Anderson and Piatt, 1999; Hollowed et al., 2001)