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Articles 31 - 56 of 56
Full-Text Articles in Oceanography and Atmospheric Sciences and Meteorology
Iron Limitation Of A Springtime Bacterial And Phytoplankton Community In The Ross Sea: Implications For Vitamin B12 Nutrition, Erin M. Bertrand, Mak A. Saito, Peter A. Lee, Robert B. Dunbar, Peter N. Sedwick, Giacomo R. Ditullio
Iron Limitation Of A Springtime Bacterial And Phytoplankton Community In The Ross Sea: Implications For Vitamin B12 Nutrition, Erin M. Bertrand, Mak A. Saito, Peter A. Lee, Robert B. Dunbar, Peter N. Sedwick, Giacomo R. Ditullio
OES Faculty Publications
The Ross Sea is home to some of the largest phytoplankton blooms in the Southern Ocean. Primary production in this system has previously been shown to be iron limited in the summer and periodically iron and vitamin B-12 colimited. In this study, we examined trace metal limitation of biological activity in the Ross Sea in the austral spring and considered possible implications for vitamin B-12 nutrition. Bottle incubation experiments demonstrated that iron limited phytoplankton growth in the austral spring while B-12, cobalt, and zinc did not. This is the first demonstration of iron limitation in a Phaeocystis antarctica-dominated, early …
Early Season Depletion Of Dissolved Iron In The Ross Sea Polynya: Implications For Iron Dynamics On The Antarctic Continental Shelf, Peter N. Sedwick, C. M. Marsay, B. M. Sohst, A. M. Aguilar-Islas, M. C. Lohan, M. C. Long, K. R. Arrigo, R. B. Dunbar, M. A. Saito, W. O. Smith, G. R. Ditullio
Early Season Depletion Of Dissolved Iron In The Ross Sea Polynya: Implications For Iron Dynamics On The Antarctic Continental Shelf, Peter N. Sedwick, C. M. Marsay, B. M. Sohst, A. M. Aguilar-Islas, M. C. Lohan, M. C. Long, K. R. Arrigo, R. B. Dunbar, M. A. Saito, W. O. Smith, G. R. Ditullio
OES Faculty Publications
The Ross Sea polynya is among the most productive regions in the Southern Ocean and may constitute a significant oceanic CO2sink. Based on results from several field studies, this region has been considered seasonally iron limited, whereby a "winter reserve" of dissolved iron (dFe) is progressively depleted during the growing season to low concentrations (~ 0.1 nM) that limit phytoplankton growth in the austral summer (December-February). Here we report new iron data for the Ross Sea polynya during austral summer 2005-2006 (27 December-22 January) and the following austral spring 2006 (16 November-3 December). The summer 2005-2006 data show …
On The Fractional Solubillity Of Copper In Marine Aerosols: Toxicity Of Aeolian Copper Revisited, Edward R. Sholkovitz, Peter N. Sedwick, Thomas M. Church
On The Fractional Solubillity Of Copper In Marine Aerosols: Toxicity Of Aeolian Copper Revisited, Edward R. Sholkovitz, Peter N. Sedwick, Thomas M. Church
OES Faculty Publications
Paytan et al. (2009) argue that the atmospheric deposition of aerosols lead to copper concentrations that are potentially toxic to marine phytoplankton in a large area of tropical and subtropical North Atlantic Ocean. A key assumption in their model is that all marine aerosols (mineral dust and anthropogenic particles) have a high (40%) fractional solubility of copper. Our data show that the fractional solubility of copper for Saharan dust over the Sargasso Sea and Bermuda is significantly lower (1-7%). In contrast, anthropogenic aerosols with non-Saharan sources have significantly higher values (10-100%). Hence, the potential Cu toxicity in the tropical and …
Peptide Hydrolysis And The Uptake Of Dipeptides By Phytoplankton, Margaret R. Mulholland, Cindy Lee
Peptide Hydrolysis And The Uptake Of Dipeptides By Phytoplankton, Margaret R. Mulholland, Cindy Lee
OES Faculty Publications
Rates of peptide hydrolysis (using the fluorescent substrate, lucifer yellow anhydride-labeled tetra-alanine) and dipeptide uptake (using dually labeled, 15N and 13C, dialanine) were measured in phytoplankton cultures and in natural populations during algal blooms dominated by one or two taxa. During most sampling events, both peptide hydrolysis and dipeptide uptake were greatest in the size fraction containing the dominant phytoplankter, suggesting that phytoplankton contribute substantially to or may even dominate observed extracellular peptide hydrolysis and dipeptide uptake in the environment. These are the first data suggesting that dipeptides may be taken up directly by phytoplankton and this may …
Co2 Sensitivity Of Southern Ocean Phytoplankton, Philippe D. Tortell, Christopher D. Payne, Yingyu Li, Scarlett Trimborn, Bjorn Rost, Walker O. Smith, Christina Riesselman, Robert B. Dunbar, Peter Sedwick, Giacomo R. Ditullio
Co2 Sensitivity Of Southern Ocean Phytoplankton, Philippe D. Tortell, Christopher D. Payne, Yingyu Li, Scarlett Trimborn, Bjorn Rost, Walker O. Smith, Christina Riesselman, Robert B. Dunbar, Peter Sedwick, Giacomo R. Ditullio
OES Faculty Publications
The Southern Ocean exerts a strong impact on marine biogeochemical cycles and global air-sea CO2 fluxes. Over the coming century, large increases in surface ocean CO2 levels, combined with increased upper water column temps. and stratification, are expected to diminish Southern Ocean CO2 uptake. These effects could be significantly modulated by concomitant CO2-dependent changes in the region's biol. carbon pump. Here we show that CO2 concentrations affect the physiology, growth and species composition. of phytoplankton assemblages in the Ross Sea, Antarctica. Field results from in situ sampling and ship-board incubation experiments demonstrate that inorganic …
Ship Ballast Tanks: How Microbes Travel The World, Fred C. Dobbs
Ship Ballast Tanks: How Microbes Travel The World, Fred C. Dobbs
OES Faculty Publications
As the international shipping fleet travels the oceans, it carries with it hidden cargoes of microbes. Fred C. Dobbs explores the hazards posed and what can be done to counteract them.
Simulations Of Phytoplankton Species And Carbon Production In The Equatorial Pacific Ocean 1. Model Configuration And Ecosystem Dynamics, Baris Salihoglu, Eileen E. Hofmann
Simulations Of Phytoplankton Species And Carbon Production In The Equatorial Pacific Ocean 1. Model Configuration And Ecosystem Dynamics, Baris Salihoglu, Eileen E. Hofmann
OES Faculty Publications
The primary objective of this research is to investigate phytoplankton community response to variations in physical forcing and biological processes in the Cold Tongue region of the equatorial Pacific Ocean at 0N, 140W. This research objective was addressed using a one-dimensional multicomponent lower trophic level ecosystem model that includes detailed algal physiology, such as spectrally-dependent photosynthetic processes and iron limitation on algal growth. The ecosystem model is forced by a one-year (1992) time series of spectrally-dependent light, temperature, and water column mixing obtained from a Tropical Atmosphere-Ocean (TAO) Array mooring. Autotrophic growth is represented by five algal groups, which have …
Grazing Impacts Of Diverse Zooplankton Taxa On Thin Layers, Alexander Bochdansky
Grazing Impacts Of Diverse Zooplankton Taxa On Thin Layers, Alexander Bochdansky
OES Faculty Publications
The US Navy needs to know how distributions and abundances of light-scattering and sound-scattering organisms in the ocean vary in space and time, particularly in the vertical dimension. Recent field observations have shown that many biological properties may vary substantially over small e.g. centimeter scales, commonly referred to as thin layers e.g. Cowles et al. 1998, 1999, Hanson Donaghay 1998, Holliday et al. 1999, Dekshenieks et al. 2001, Alldredge et al. 2002, Rines et al. 2002. Our previous ONR-funded research has allowed us to begin to understand how zooplankton interact with thin layers and how they can take advantage of …
Red And Black Tides: Quantitative Analysis Of Water-Leaving Radiance And Perceived Color For Phytoplankton, Colored Dissolved Organic Matter, And Suspended Sediments, Heidi M. Dierssen, Raphael M. Kudela, John P. Ryan, Richard C. Zimmerman
Red And Black Tides: Quantitative Analysis Of Water-Leaving Radiance And Perceived Color For Phytoplankton, Colored Dissolved Organic Matter, And Suspended Sediments, Heidi M. Dierssen, Raphael M. Kudela, John P. Ryan, Richard C. Zimmerman
OES Faculty Publications
Using field measurements and quantitative modeling, we demonstrate that red coloration of the sea surface is not associated with any particular group of phytoplankton and is strongly dependent on the physiology of the human visual system. Red or brown surface waters can be produced by high concentrations of most types of algae, colored dissolved organic matter, or suspended sediment. Even though light reflected by red tides commonly peaks in the yellow spectral region (570–580 nm), human color perception requires consideration of the entire spectrum of light relative to receptors within the human eye. The color shift from green to red …
Evaluating The Biogeochemical Cycle Of Selenium In San Francisco Bay Through Modeling, Shannon L. Meseck, Gregory A. Cutter
Evaluating The Biogeochemical Cycle Of Selenium In San Francisco Bay Through Modeling, Shannon L. Meseck, Gregory A. Cutter
OES Faculty Publications
A biogeochemical model was developed to simulate salinity, total suspended material, phytoplankton biomass, dissolved selenium concentrations (selenite, selenate, and organic selenide), and particulate selenium concentrations (selenite + selenate, elemental selenium, and organic selenide) in the San Francisco Bay estuary. Model-generated estuarine profiles of total dissolved selenium reproduced observed estuarine profiles at a confidence interval of 91- 99% for 8 different years under various environmental conditions. The model accurately reproduced the observed dissolved speciation at confidence intervals of 81-98% for selenite, 72-91% for selenate, and 60-96% for organic selenide. For particulate selenium, model-simulated estuarine profiles duplicated the observed behavior of total …
A Unique Seasonal Pattern In Phytoplankton Biomass In Low-Latitude Waters In The South China Sea, Chun-Mao Tseng, George T. F. Wong, I.-I. Lin, C.-R. Wu, K.-K. Liu
A Unique Seasonal Pattern In Phytoplankton Biomass In Low-Latitude Waters In The South China Sea, Chun-Mao Tseng, George T. F. Wong, I.-I. Lin, C.-R. Wu, K.-K. Liu
OES Faculty Publications
A distinctive seasonal pattern in phytoplankton biomass was observed at the South East Asian Time series Study (SEATS) station (18°N, 116°E) in the northern South China Sea (SCS). Surface chlorophyll-a, depth integrated chlorophyll-a and primary production were elevated to 0.3 mg/m3, ~35 mg/m2 and 300 mg-C/m2/d, respectively, in the winter but stayed low, at 0.1 mg/m3, ~15 mg/m2 and 110 mg-C/m2/d as commonly found in other low latitude waters, in the rest of the year. Concomitantly, soluble reactive phosphate and nitrate+nitrite in the mixed layer also became …
Relevant Scales In Zooplankton Ecology: Distribution, Feeding, And Reproduction Of The Copepod Acartia Hudsonica In Response To Thin Layers Of The Diatom Skeletonema Costatum, Alexander B. Bochdansky, Stephen M. Bollens
Relevant Scales In Zooplankton Ecology: Distribution, Feeding, And Reproduction Of The Copepod Acartia Hudsonica In Response To Thin Layers Of The Diatom Skeletonema Costatum, Alexander B. Bochdansky, Stephen M. Bollens
OES Faculty Publications
We investigated the interaction of the copepod Acartia hudsonica in relation to thin layers of the diatom Skeletonema costatum. Thin layers have recently received much attention, since they are common and persistent features in the water column, often overlooked by traditional sampling methods. Their frequent abundance in coastal oceans and the high biomass associated with them has led to the assumption that they are important grazing sites of calanoid copepods. We employed 2-m tall tower tanks that allowed us to simulate thin layers. Three variables representative of three time scales were considered: the distribution of copepods in the tanks …
Peptide Hydrolysis, Amino Acid Oxidation, And Nitrogen Uptake In Communities Seasonally Dominated By Aureococcus Anophagefferens, Margaret R. Mulholland, Christopher J. Gobler, Cindy Lee
Peptide Hydrolysis, Amino Acid Oxidation, And Nitrogen Uptake In Communities Seasonally Dominated By Aureococcus Anophagefferens, Margaret R. Mulholland, Christopher J. Gobler, Cindy Lee
OES Faculty Publications
Elevated levels of dissolved organic nitrogen (DON) and dissolved inorganic nitrogen (DIN) are among the factors implicated in the initiation of algal blooms. However, the degree to which phytoplankton augment their autotrophic metabolism with heterotrophic uptake of organic carbon that is associated with DON is unknown. We evaluated the relative importance of peptide hydrolysis, amino acid oxidation, and amino acid uptake over a seasonal cycle in an embayment on Long Island, New York, that had high concentrations of dissolved organic matter (DOM) and a bloom of the brown tide pelagophyte, Aureococcus anophagefferens. Amino acids were a significant component (up …
Uptake Of Dissolved Organic Selenides By Marine Phytoplankton, Stephen B. Baines, Nicholas S. Fisher, Martina A. Doblin, Gregory A. Cutter
Uptake Of Dissolved Organic Selenides By Marine Phytoplankton, Stephen B. Baines, Nicholas S. Fisher, Martina A. Doblin, Gregory A. Cutter
OES Faculty Publications
Se is present in multiple oxidation states in nature, each of which has unique chemical and biological reactivities. As a consequence, the rate of Se incorporation into food webs or its role as either a limiting nutrient or a toxic substance is a function of complex biogeochemistry. In particular, little is understood about the accumulation of dissolved organic selenides by phyto- or bacterioplankton. We assessed the bioavailability of dissolved organic selenides to marine and estuarine phytoplankton by presenting various algal species with filtered lysates of the diatom, Thalassiosira pseudonana, grown on media amended with radiolabeled selenite (75Se[IV]). …
Control Of Phytoplankton Growth By Iron And Silicic Acid Availability In The Subantarctic Ocean: Experimental Results From The Saz Project, D. A. Hutchins, Peter N. Sedwick, G. R. Ditullio, P. W. Boyd, B. Queguiner, F. B. Griffiths, C. Crossley
Control Of Phytoplankton Growth By Iron And Silicic Acid Availability In The Subantarctic Ocean: Experimental Results From The Saz Project, D. A. Hutchins, Peter N. Sedwick, G. R. Ditullio, P. W. Boyd, B. Queguiner, F. B. Griffiths, C. Crossley
OES Faculty Publications
Subantarctic Southern Ocean surface waters in the austral summer and autumn are characterized by high concentrations of nitrate and phosphate but low concentrations of dissolved iron (Fe, similar to0.05 nM) and silicic acid (Si, <1 muM). During the Subantarctic Zone AU9706 cruise in March 1998 we investigated the relative importance of Fe and Si in controlling phytoplankton growth and species composition at a station within the subantarctic water mass (46.8degreesS, 142degreesE) using shipboard bottle incubation experiments. Treatments included unamended controls; 1.9 nM added iron (+Fe); 9 muM added silicic acid (+Si); and 1.9 nM addediron plus 9 muM added silicic acid (+Fe+Si). We followed a detailed set of biological and biogeochemical parameters over 8 days. Fe added alone clearly increased community growth rates and nitrate drawdown and altered algal community composition relative to control treatments. Surprisingly, small, lightly silicified pennate diatoms grew when Fe was added either with or without Si, despite the extremely low ambient silicic acid concentrations. Pigment analyses suggest that lightly silicified chrysophytes (type 4 haptophytes) may have preferentially responded to Si added either with or without Fe. However, for many of the parameters measured the +Fe+Si treatments showed large increases relative to both the +Fe and +Si treatments. Our results suggest that iron is the proximate limiting nutrient for chlorophyll production, photosynthetic efficiency, nitrate drawdown, and diatom growth, but that Si also exerts considerable control over algal growth and species composition. Both nutrients together are needed to elicit a maximum growth response, suggesting that both Fe and Si play important roles in structuring the subantarctic phytoplankton community.
Control Of Phytoplankton Growth By Iron Supply And Irradiance In The Subantarctic Southern Ocean: Experimental Results From The Saz Project, P. W. Boyd, A. C. Crossley, G. R. Ditullio, F. B. Griffiths, D. A. Hutchins, B. Queguiner, Peter N. Sedwick, T. W. Trull
Control Of Phytoplankton Growth By Iron Supply And Irradiance In The Subantarctic Southern Ocean: Experimental Results From The Saz Project, P. W. Boyd, A. C. Crossley, G. R. Ditullio, F. B. Griffiths, D. A. Hutchins, B. Queguiner, Peter N. Sedwick, T. W. Trull
OES Faculty Publications
The influence of irradiance and Fe supply on phytoplankton processes was studied, north (47°S, 142°E) and south (54°S, 142°E) of the Subantarctic Front in austral autumn (March 1998). At both sites, resident cells exhibited nutrient stress (Fv/Fm 0 at 47°S and 9% I0 at 54°S because of MLDs of 40 (47°S) and 90 m (54°S), when these stations were occupied. The greater MLD at 54°S is reflected by tenfold higher cellular chlorophyll a levels in the resident phytoplankton. In the 47°S experiment, chlorophyll a levels increased to >1 μg/L-1 only in the high-Fe treatments, regardless …
Iron And Manganese In The Ross Sea, Antarctica: Seasonal Iron Limitation In Antarctic Shelf Waters, Peter N. Sedwick, Giacomo R. Ditullio, Denis J. Mackey
Iron And Manganese In The Ross Sea, Antarctica: Seasonal Iron Limitation In Antarctic Shelf Waters, Peter N. Sedwick, Giacomo R. Ditullio, Denis J. Mackey
OES Faculty Publications
Dissolved iron and manganese and total dissolvable iron were measured in water column samples from the Polynya Region of the southern Ross Sea in cruises in Nov.-Dec. 1994 (spring 1994) and Dec. 1995 to Jan. 1996 (summer 1995). Iron and manganese addition bottle incubation experiments were also performed on these cruises to assess the nutritional sufficiency of ambient iron and manganese concentrations for phytoplankton growth. Generally high dissolved iron concentrations (>0.5 nM) and relatively complex iron and manganese vertical profiles were obtained in spring 1994 vs. summer 1995. Dissolved iron concentrations in the upper water column averaged 1.0 nM …
Intraspecific Variation In The Selenium Requirement Of Different Geographic Strains Of The Toxic Dinoflagellate Gymnodinium Catenatum, Martina A. Doblin, Susan I. Blackburn, Gustaaf M. Hallegraeff
Intraspecific Variation In The Selenium Requirement Of Different Geographic Strains Of The Toxic Dinoflagellate Gymnodinium Catenatum, Martina A. Doblin, Susan I. Blackburn, Gustaaf M. Hallegraeff
OES Faculty Publications
The requirement for selenium (IV) was assessed in five strains of the toxic dinoflagellate Gymnodinium catenatum Graham, representing three populations from Tasmania (Australia), as well as one each from Japan and Spain. Strains were grown in nutrient-enriched sea water medium with 10-9 M selenium added as selenite (H2SeO3), or with no added selenium, and monitored for growth and cell yield. Strains exhibited different selenium (Se) requirements, as evidenced by (i) a decrease in exponential growth rate (10-20%) and cell yield (up to 80%) (Japanese strain); (ii) a decrease in cell yield only (Tasmania Derwent Estuary …
Resource Allocation And Sucrose Mobilization In Light Limited Eelgrass Zostera Marina, Teresa Alcoverro, Richard C. Zimmerman, Donald G. Kohrs, Randall S. Alberte
Resource Allocation And Sucrose Mobilization In Light Limited Eelgrass Zostera Marina, Teresa Alcoverro, Richard C. Zimmerman, Donald G. Kohrs, Randall S. Alberte
OES Faculty Publications
This study evaluated the ability of Zostera marina L. (eelgrass) to balance the daily photosynthetic deficit by mobilization of carbon reserves stored in below-ground tissues during a period of extreme winter light limitation. A quantitative understanding of the mobilization process and its limitations is essential to the development of robust models predicting minimum light levels required to maintain healthy seagrass populations. Plants were grown in running seawater tanks under 2 light regimes. One treatment was provided with 2 h irradiance-saturated photosynthesis (Hsat) to produce severe Light Limitation, while control plants were grown under 7 h Hsat, …
Absorption Efficiencies And Biochemical Fractionation Of Assimilated Compounds In The Cold Water Appendicularian Oikopleura Vanhoeffeni, Alexander B. Bochdansky, Don Deibel, Richard B. Rivkin
Absorption Efficiencies And Biochemical Fractionation Of Assimilated Compounds In The Cold Water Appendicularian Oikopleura Vanhoeffeni, Alexander B. Bochdansky, Don Deibel, Richard B. Rivkin
OES Faculty Publications
Using Ge-68:C-14 dual-labeling, we investigated the absorption efficiency of diatom carbon for the cold water appendicularian Oikopleura vanhoeffeni. The absorption efficiency of bulk carbon (mean = 67%) was not influenced by body size or ingestion rate. For the first time for a pelagic tunicate, food and feces were fractionated into their major biochemical constituents (i.e., low-molecular-weight compounds, lipid, protein, and polysaccharide), allowing calculation of absorption efficiencies for each fraction. Low-molecular-weight compounds and proteins were preferentially absorbed over lipids and polysaccharides. However, predicted C:N ratios of the fecal pellets of O. vanhoeffeni were in the lower range of C:N ratios …
Regulation Of Algal Blooms In Antarctic Shelf Waters By The Release Of Iron From Melting Sea Ice, Peter N. Sedwick, Giacomo R. Ditullio
Regulation Of Algal Blooms In Antarctic Shelf Waters By The Release Of Iron From Melting Sea Ice, Peter N. Sedwick, Giacomo R. Ditullio
OES Faculty Publications
During summer 1995-96, we measured iron in the water column and conducted iron-enrichment bottle-incubation experiments at a station in the central Ross Sea (76°30'S, 170°40'W), first, in the presence of melting sea ice, and 17 days later, in ice-free conditions. We observed a striking temporal change in mixed-layer dissolved iron concentrations at this station, from 0.72-2.3 nM with sea ice present, to 0.16-0.17 nM in ice-free conditions. These changes were accompanied doubling of algal (diatom) biomass. Our incubation experiments suggest that conditions were iron-replete in the presence of sea ice, and iron-deficient in the absence of sea ice. We surmise …
Benthic Microalgal Production At Stellwagen Bank, Massachusetts Bay, Usa, Lawrence B. Cahoon, Guy R. Beretich Jr., Carrie J. Thomas, Amy M. Mcdonald
Benthic Microalgal Production At Stellwagen Bank, Massachusetts Bay, Usa, Lawrence B. Cahoon, Guy R. Beretich Jr., Carrie J. Thomas, Amy M. Mcdonald
OES Faculty Publications
Benthic microalgal chlorophyll a and production were measured at 3 sites at Stellwagen Bank, a cold temperate continental shelf habitat in Massachusetts Bay, USA, during August 1991. Benthic microalgal chlorophyll a averaged 39.8 Mg M-2, vs average integrated phytoplankton chlorophyll a of 25.9 mg m-2. Gross benthic microalgal production, measured by oxygen exchange in clear and opaque benthic chambers, averaged 20.9 mg C m-2 h-1. This production was supported by average daily light fluxes to the bottom that never exceeded 1 % of surface incident radiation and were as low as 4.7 μE …
Molecular And Physiological Responses Of Diatoms To Variable Levels Of Irradiance And Nitrogen Availability: Growth Of Skeletonema Costatum In Simulated Upwelling Conditions, G. Jason Smith, Richard C. Zimmerman, Randall S. Alberte
Molecular And Physiological Responses Of Diatoms To Variable Levels Of Irradiance And Nitrogen Availability: Growth Of Skeletonema Costatum In Simulated Upwelling Conditions, G. Jason Smith, Richard C. Zimmerman, Randall S. Alberte
OES Faculty Publications
Molecular mechanisms that drive metabolic acclimation to environmental shifts have been poorly characterized in phytoplankton. In this laboratory study. the response of light- and N-limited Skeletonema costatum cells to an increase in light and NO3 availability was examined. C assimilation was depressed relative to N assimilation early in enrichment, and the photosynthetic quotient (O2: CO2) increased, consistent with the shunting of reducing equivalents from CO2 fixation to NO3- reduction. The concomitant increase in dark respiration was consistent with the increased energetic demand associated with macromolecular synthesis. The accelerations of N-specific rates of …
Development And Evaluation Of Tracer Particles For Use In Microzooplankton Herbivory Studies, Mary Putt
Development And Evaluation Of Tracer Particles For Use In Microzooplankton Herbivory Studies, Mary Putt
OES Faculty Publications
Two methods of preparing algae for use as tracer particles in single species measurements of microzooplankton herbivory were evaluated. Algae were either heat-killed and labelled with 5-(4,6-dichlorotriazin-2-yl amino fluorescein) (DTAF) (Rublee & Gallegos 1989; Mar, Ecol. Prog. Ser. 51: 221-227) or stained with hydroethidine (HYD). Both DTAF and HYD-stained algae were readily visible within the digestive vacuoles of most microzooplankton collected in estuarine and coastal waters of Massachusetts (USA) and preserved with Lugol's iodine. However, DTAF was ineffective at staining several chromophytic algae and the heat-kill process reduced cell volume by ≥ 50% in several of the algae which were …
Acceleration Of Nutrient Uptake By Phytoplankton In A Coastal Upwelling Ecosystem: A Modeling Analysis, Richard C. Zimmerman, James N. Kremer, Richard C. Dugdale
Acceleration Of Nutrient Uptake By Phytoplankton In A Coastal Upwelling Ecosystem: A Modeling Analysis, Richard C. Zimmerman, James N. Kremer, Richard C. Dugdale
OES Faculty Publications
Studies of upwelling centers in the eastern Pacific suggest that maximum rates of nitrate uptake (light and nutrient saturated) increase, or shift-up, as newly upwelled water moves downstream. The rate of shift-up appears to be related to irradiance and the ambient concentration of limiting nutrient at the time of upwelling. A mathematical model was developed to evaluate effects of irradiance and initial nitrate concentration on temporal patterns of shift-up and subsequent time scales of nutrient utilization over a range of simulated upwelling conditions. When rates consistent with field studies were used, complete shift-up was possible only under certain conditions, and …
Changes In The Lower Chesapeake Bay Food-Chain In Presence Of The Sea Nettle Chrysaora-Quinquecirrha (Scyphomedusa), David Feigenbaum, Michael Kelly
Changes In The Lower Chesapeake Bay Food-Chain In Presence Of The Sea Nettle Chrysaora-Quinquecirrha (Scyphomedusa), David Feigenbaum, Michael Kelly
OES Faculty Publications
The abundance of 4 levels of the lower Chesapeake Bay food chain (Chlorophyll a, herbivores, ctenophore Mnemiopsis leidyi, and Scyphomedusa Chrysaora quinquecirrha) were monitored twice weekly at 4 stations from May 10 through Sep 30, 1982 in the Lafayette and Elizabeth Rivers (Virginia). The herbivore standing stock, largely copepods, declined sharply in late May when M. Jeidyi appeared, but rebounded a month later when C. quinquecirrha medusae reduced the ctenophore population. Despite the additional presence of Aurelia aurita (Scyphomedusa) from Jul onward, herbivore abundance remained at moderate levels until the end of the study period. Phytoplankton abundance fluctuated …