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Effects of micro-nutrients and major nutrients on the growth and species composition of natural phytoplankton populationsFrey, Bruce E. 28 April 1977 (has links)
Large-volume (20-liter) bioassays were carried out in order to
assess the effects of major nutrients and micro-nutrients on
natural phytoplankton populations in water collected from a site
close to the mouth of Yaquina Bay, Oregon. Seven long-term
experiments were conducted during the years 1975-1976. A stripping
technique employing activated carbon was used to reduce the trace
metal and dissolved organic load of a portion of the water. Various
combinations of major nutrients (nitrate, phosphate, and silicate)
and micro-nutrients (trace metals and vitamins) were added to both
the carbon-stripped and the non-carbon-stripped water in order to
assess the effects of various nutrient substances on the growth
rate, biomass yield, and species composition of the phytoplankton
populations which developed from small natural inocula.
The major nutrients and the micro-nutrients appear to have
fundamentally different effects on the species composition and
population growth characteristics of the phytoplankton. The
micro-nutrients had marked systematic effects on the species composition
of the phytoplankton populations which developed in the
experimental vessels, while the major nutrients had minimal effects
on species composition. The micro-nutrients appeared essential for
the achievement of maximal population growth rates and minimal lags,
while the major nutrients had no effect on growth rates or lags.
Both the major nutrients and micro-nutrients had significant
effects on the final biomass yields. There were seasonal variations
in the control of final biomass yields by major nutrients and micro-nutrients. / Graduation date: 1977
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Species specific phytoplankton production rates during a spring diatom bloom in Yaquina Bay, OregonMcMurray, Gregory R., 1925- 21 September 1976 (has links)
A simplified autoradiographic method for estimating species-specific
phytoplankton production rates in mixed natural communities
was evaluated in the laboratory and employed in the field. Laboratory
experiments were designed to test the reliability and variability of
the simplified method. Assays of ¹⁴C uptake by liquid scintillation
spectrometry were used to evaluate assays by autoradiographic silver
grain counts. Linear relationships between the two assays were found
for varying activities within a species. With corrections for
radiation geometry and self-absorption, a linear relationship was
obtained for species from 400 to 50,000 μm³ in cell volume. The
coefficient of variation for microscopic grain counting at densities
from 10 to 70 grains per 100 μm² was 4% of the mean. Counts of
replicate autoradiographs from individual incubations yielded
coefficients of variation of 7 and 14% for grain densities of 11 and
30 per 100 μm², respectively. The frequency distribution of grains
deposited over different cells of a species with varying photosynthetic
activities is indicative of the physiological state of the alga.
Samples from five depths at one station in Yaquina Bay, Oregon
were incubated in situ with ¹⁴C, daily from 2 April to 7 May 1974.
Phytoplankton biomass during the spring bloom reached 7106 μm³ cell
volume l⁻¹ and integral production reached 172 mgC m⁻² hr⁻¹. Total
community carbon uptake increased with biomass during the study but
species-specific uptake decreased as ambient nitrate + nitrite levels
decreased. Species-specific production rates were estimated for 22
consecutive days: 16 April to 7 May 1974. Three taxa, Chaetoceros
debilis Cleve, Thalassiosira decipiens (Grun.) Jorg., and unidentified
flagellates were responsible for over 65% of the community biomass
and over 85% of the primary production after 20 April 1974, Carbon-specific
uptake rates were calculated for 20 species. Maximum carbon-specific
uptake rates (expressed as the percent of the estimated cell
carbon content assimilated per hour) for six abundant diatom species
ranged from 111 to 158%, but average activity over the study period
for 20 species was much lower. Carbon-specific uptake rates (% cell
C hr⁻¹) averaged over all samples for the three dominant taxa were:
Chaetoceros debilis, 22%; Thalassiosira decipiens, 21%; and
flagellates, 54%. Flagellates were always two to three times more
productive than the dominant diatoms on a carbon specific basis.
Photosynthesis:biomass ratios (P/B) of the three dominant taxa
decreased proportionately during the study The percent of total
biomass and percent of total carbon uptake contributed by the three
dominant taxa were proportional over the period studied. Average
daily carbon-specific uptake rates demonstrate that Thalassiosira
decipiens succeeded Chaetoceros debilis due to a change in their
relative production rates. / Graduation date: 1977
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Phytoplankton of an ice-edge bloom in the Ross Sea, with special reference to the elemental composition of Antarctic diatomsCarbonell, Maria Consuelo 09 April 1985 (has links)
A phytoplankton bloom dominated by the pennate diatom Nitzschia
curta (Van Heurck) Hasle was observed during January-February 1983 at
a receding ice-edge in the Western Ross Sea, Antarctica. The core of
the bloom was found between 100-150 Km from the ice-edge. Nitzschia
curta cell densities up to 22 x 10⁶ cells/1 were observed. The nanoplankton
contributed to 18% (average) of the total biomass. The contribution
of another pennate diatom, Nitzschia closterium (Ehrenberg)
W. Smith, was significant in two offshore stations (22% and 90%).
Other diatom species, dinoflagellates and other phytoplankton groups
were very few in number. A wind-driven upwelling event occurred along
the ice-edge. The presence of off-shore species (e.g. Nitzschia
kerguelensis) close to the ice suggests the existence of an eddy
circulation.
Results of elemental composition experiments with 10 Antarctic
diatoms showed that the C:Si:N ratio for Antarctic diatoms, when compared
to the Redfield-Richards ratio for diatoms of other environments,
have less carbon and more silicon per unit nitrogen. Comparison of
laboratory results with the field data confirms the anomalous elemental
composition of the major bloom species observed in the Ross Sea.
Blooms like the one observed in this study seem to be restricted
to the Western part of the Ross Sea and appear to be produced in inshore
waters late in the austral summer. / Graduation date: 1985
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Transformations of carotenoids in the oceanic water column /Repeta, Daniel James. January 1982 (has links)
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Science, 1982. / Supervised by Robert B. Gagosian (W.H.O.I.). Vita. Includes bibliographies.
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Transformations of carotenoids in the oceanic water column /Repeta, Daniel James. January 1982 (has links)
Thesis (Ph. D.)--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1982. / Includes bibliographical references.
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Spatial and temporal variation in greenhouse gas emissions from two open water prairie wetlandsPhipps, Kimberly Jennette 19 October 2006
Prairie wetlands provide valuable habitat for waterfowl and wildlife and buffer the impacts of upland land uses. Their contribution to Canadas greenhouse gas inventory is poorly understood. The purpose of this study was to compare the spatial and temporal variation in nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) emissions from Pond 1 at the St. Denis Wildlife Management Area, Saskatchewan and the Deep Crop Wetland (DCW) at the Manitoba Zero Tillage Research Association farm, Manitoba. Nitrous oxide flux was low on all measurements days: at Pond 1 flux ranged from -1.47 to 6.01 ng N2O-N m-2 s-1 in 2004 and -6.98 to 5.74 ng N2O-N m-2 s-1 in 2005 and flux from the DCW never exceeded 2.50 ng N2O-N m-2 s-1 in 2005. Methane flux from Pond 1 was substantially higher in 2005 (-469.10 to 3776.08 µmol CH4 m-2 d-1) than in 2004 (-251.55 to 191.55 µmol CH4 m-2 d-1). This increase in methane from Pond 1 followed a major increase in water volume in 2005 after snowmelt. Methane flux in 2005 from the open water and riparian sampling points at the DCW ranged from -13.64 to 110.47 µmol CH4 m-2 d-1 and -4.51 to 40.23 µmol CH4 m-2 d-1, respectively. Carbon dioxide flux from Pond 1 and the DCW in 2005 were very similar: open water flux ranged from -96.42 to 95.42 mmol CO2 m-2 d-1 at Pond 1 and 3.21 to 38.94 mmol CO2 m-2 d-1 at the DCW. Despite the similarity in CO2 flux, the DCW had 10- to 15-fold higher levels of macrophytes, phytoplankton and metaphyton biomass and similar levels of periphyton to Pond 1 in 2005. These biomass differences were not, however, reflected in the CO2 or CH4 flux. Pond 1 and the DCW were net sources for greenhouse gases but contributed less greenhouse gas than reports from other aquatic systems.
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Bio-optical Modeling of Aquatic Photosynthesis in the Laurentian Great LakesSilsbe, Gregory 17 May 2010 (has links)
The methodology of phytoplankton production measurements in the Laurentian Great Lakes and other freshwater lakes has remained largely unchanged in the past 40 years. In most studies photosynthesis from a single water sample is measured across an in vitro light gradient usually using an artificial light source then extrapolating to the in situ environment. These traditional methods are laborious, thus limiting the amount of observations in space and time, and may not accurately represent in situ photosynthesis. Active chl a fluorescence, intrinsically linked to photosynthesis, can be measured in situ and instantaneously. Various bio-optical models that scale these fluorescence measurements to phytoplankton production are gaining widespread attention in the marine environment but have not been extensively tested in freshwater ecosystems.
The methodology and efficacy of the various bio-optical models are tested in this thesis using a large dataset of active fluorescence profiles and ancillary water chemistry parameters against synchronously derived in vitro phytoplankton production collected across mixing, trophic and taxonomic gradients in Lake Erie. From this analysis, the most common bio-optical model parameterization yields photosynthetic rates that are largely incongruent with in vitro measurements. Bio-optical models are largely a function of two parameters, the absorption spectrum of photosystem II (aPSII) and the photochemical efficiency of PSII (fPSII). In Lake Erie fPSII is relatively constrained suggesting that even nutrient limited phytoplankton achieve balanced growth by adjusting the supply of energy through changes in light harvesting (aPSII) to match the demand for photosynthetic energy. This thesis goes on to demonstrate the success of bio-optical models depends largely on the formulation of aPSII. Alternative methods to derive aPSII, largely ignored in published bio-optical models, are reviewed, formulated, and when incorporated into a bio-optical model and compared to synchronous in vitro production measurements, this novel bio-optical model outperforms all other comparative studies performed across a taxonomic gradient.
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Effects of Nutrients, Photoinhibition & Photoacclimation on Photosystem II Function of Freshwater Phytoplankton CommunitiesHarrison, Joel January 2011 (has links)
Electron flow through Photosystem II (PSII) is essential to all life on Earth. The efficiency of this process in freshwater phytoplankton can be depressed by nutrient limitation, ultraviolet radiation (UVR), and excessive photosynthetically active radiation (PAR). The effects of nutrients and radiation on PSII function of natural communities were assessed using changes in the variable fluorescence of PSII (PSII VF), as determined by a pulse amplitude modulation (PAM) fluorometer. The net susceptibility to photoinhibition of PSII depends upon the sensitivity of the assemblage to photodamage and the efficiency of recovery. Damage and recovery rates were quantified by fitting changes in FV:FM during experimental spectral exposures to the model of Kok (1956). Phytoplankton from deep chlorophyll maxima were found to exhibit much higher photosynthetic impairment under UVR exposure than epilimnetic communities in two lakes, due to differences in both damage and recovery rates. In six temperate lakes of the Dorset-Haliburton region, the susceptibility to UVR-induced photoinhibition of PSII was found to be a function of the water transparency (dissolved organic carbon content) of the systems from which the plankton were isolated, with no obvious taxonomic pattern to the responses. Nutrient (nitrogen & phosphorus) supplementation of communities from the Dorset Lakes and from Lake Ontario did not have strong effects on PSII VF, and did not alter the response of Lake Ontario phytoplankton to spectral irradiance. Diurnal changes in FV:FM of Lake Ontario phytoplankton were modeled and average values for the upper half of the water column showed reasonable agreement with observed data; however it is suggested that the addition of a model to simulate vertical mixing could improve the depth-specific accuracy of the predictions. It is concluded that the light history (photoacclimation status) of phytoplankton is the major determinant of the sensitivity of PSII to UVR, and that the nutrient status and taxonomic composition of phytoplankton communities have a comparatively minor influence.
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Spatial and temporal variation in greenhouse gas emissions from two open water prairie wetlandsPhipps, Kimberly Jennette 19 October 2006 (has links)
Prairie wetlands provide valuable habitat for waterfowl and wildlife and buffer the impacts of upland land uses. Their contribution to Canadas greenhouse gas inventory is poorly understood. The purpose of this study was to compare the spatial and temporal variation in nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) emissions from Pond 1 at the St. Denis Wildlife Management Area, Saskatchewan and the Deep Crop Wetland (DCW) at the Manitoba Zero Tillage Research Association farm, Manitoba. Nitrous oxide flux was low on all measurements days: at Pond 1 flux ranged from -1.47 to 6.01 ng N2O-N m-2 s-1 in 2004 and -6.98 to 5.74 ng N2O-N m-2 s-1 in 2005 and flux from the DCW never exceeded 2.50 ng N2O-N m-2 s-1 in 2005. Methane flux from Pond 1 was substantially higher in 2005 (-469.10 to 3776.08 µmol CH4 m-2 d-1) than in 2004 (-251.55 to 191.55 µmol CH4 m-2 d-1). This increase in methane from Pond 1 followed a major increase in water volume in 2005 after snowmelt. Methane flux in 2005 from the open water and riparian sampling points at the DCW ranged from -13.64 to 110.47 µmol CH4 m-2 d-1 and -4.51 to 40.23 µmol CH4 m-2 d-1, respectively. Carbon dioxide flux from Pond 1 and the DCW in 2005 were very similar: open water flux ranged from -96.42 to 95.42 mmol CO2 m-2 d-1 at Pond 1 and 3.21 to 38.94 mmol CO2 m-2 d-1 at the DCW. Despite the similarity in CO2 flux, the DCW had 10- to 15-fold higher levels of macrophytes, phytoplankton and metaphyton biomass and similar levels of periphyton to Pond 1 in 2005. These biomass differences were not, however, reflected in the CO2 or CH4 flux. Pond 1 and the DCW were net sources for greenhouse gases but contributed less greenhouse gas than reports from other aquatic systems.
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Bloom dynamics and population genetics of marine phytoplankton : community, species and population aspects /Härnström, Karolina. January 2009 (has links) (PDF)
Diss. (sammanfattning) Göteborg : Göteborgs universitet, 2009. / Härtill 6 uppsatser.
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