scholarly journals Growth rates across multiple temperatures and light intensities for seven strains of a marine Chaetoceros sp. isolated from Narragansett Bay March 2018. Growth was measured across six to seven temperatures and three light intensities for each strain

2019 ◽  
Author(s):  
David Hutchins
Keyword(s):  
Growth Rates ◽  
Narragansett Bay ◽  
Light Intensities

Growth Rates for Quahogs (Mercenaria mercenaria) in a Reduced Nitrogen Environment in Narragansett Bay, RI

2020 ◽  
Vol 27 (3) ◽  
pp. 534
Author(s):  
Sandra B. Robinson ◽  
Autumn Oczkowski ◽  
M. Conor McManus ◽  
Marnita Chintala ◽  
Suzanne Ayvazian
Keyword(s):  
Growth Rates ◽  
Mercenaria Mercenaria ◽  
Narragansett Bay ◽  
Reduced Nitrogen

scholarly journals Effects of light on the growth and photosynthesis of Egeria najas planchon

2003 ◽  
Vol 46 (2) ◽  
pp. 203-209 ◽  
Author(s):  
Washington Luiz Gomes Tavechio ◽  
Sidinei Magela Thomaz
Keyword(s):  
Root Growth ◽  
Growth Rates ◽  
Low Light ◽  
Light Requirement ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Light Compensation Point ◽  
Light Intensities ◽  
Light Requirements ◽  
Egeria Najas

Photosynthesis and growth of Egeria najas (Hydrocharitaceae) from a subtropical reservoir (Itaipu Reservoir, Brazil-Paraguay) were measured in response to low light intensities (0-124 µM m-2 s-1 PAR) in the laboratory. Photosynthesis approached saturation in the range of light intensities used and light compensation point was reached at ca. 6-22 µM m-2 s-1 PAR, indicating that this species had a low light requirement for growth. Light stimulated shoot and root relative growth rates (RGR) but it was not related to ratios between root:shoot RGR. Laboratory observations indicated that (i) both shoot and root growth were simultaneously stimulated by light and (ii) the low light requirements of E. najas may explain its incidence in the Itaipu Reservoir, where biogenic as well as abiogenic turbidity is high.

scholarly journals Interactive effects of seawater carbonate chemistry, light intensity and nutrient availability on physiology and calcification of the coccolithophore <i>Emiliania huxleyi</i>

2018 ◽  
Author(s):  
Yong Zhang ◽  
Feixue Fu ◽  
David A. Hutchins ◽  
Kunshan Gao
Keyword(s):  
Light Intensity ◽  
Growth Rates ◽  
Carbon Fixation ◽  
Inorganic Nitrogen ◽  
Emiliania Huxleyi ◽  
High Light ◽  
Interactive Effects ◽  
Nutrient Concentrations ◽  
Light Intensities ◽  
Co2 Levels

Abstract. Rising atmospheric carbonate dioxide (CO2) levels lead to increasing CO2 concentration and declining pH in seawater, as well as ocean warming. This enhances stratification and shoals the upper mixed layer (UML), hindering the transport of nutrients from deeper waters and exposing phytoplankton to increased light intensities. In the present study, we investigated combined impacts of CO2 levels (410 μatm (LC) and 925 μatm (HC)), light intensities (80–480 μmol photons m−2 s−1) and nutrient concentrations [101 μmol L−1 dissolved inorganic nitrogen (DIN) and 10.5 μmol L−1 dissolved inorganic phosphate (DIP) (HNHP); 8.8 μmol L−1 DIN and 10.5 μmol L−1 DIP (LN); 101 μmol L−1 DIN and 0.4 μmol L−1 DIP (LP)] on growth, photosynthesis and calcification of the coccolithophore Emiliania huxleyi. HC and LN synergistically decreased growth rates of E. huxleyi at all light intensities. High light intensities compensated for inhibition of LP on growth rates at LC, but exacerbated inhibition of LP at HC. These results indicate that the ability of E. huxleyi to compete for nitrate and phosphate may be reduced in future oceans with high CO2 and high light intensities. Low nutrient concentrations increased particulate inorganic carbon quotas and the sensitivity of maximum electron transport rates to light intensity. Light-use efficiencies for carbon fixation and calcification rates were significantly larger than that of growth. Our results suggest that interactive effects of multiple environmental factors on coccolithophores need to be considered when predicting their contributions to the biological carbon pump and feedbacks to climate change.

scholarly journals Comparison of Guekensia Demissa Populations Along a Nitrogen Loading Gradient in Narragansett Bay, RI

2013 ◽  
Author(s):  
Janis Hall
Keyword(s):  
Rhode Island ◽  
Growth Rates ◽  
Salt Marshes ◽  
Condition Index ◽  
Nitrogen Loading ◽  
Narragansett Bay ◽  
The Other ◽  
Nitrogen Levels ◽  
Ribbed Mussels ◽  
Ribbed Mussel

<p>Anthropogenic eutrophication of coastal estuaries impacts these vital ecosystems by increasing primary production, hypoxic conditions, pathogen concentration, and greenhouse gas emissions, all of which are leading to the degradation of shorelines, disease transmission, and hypoxia-related fish kills. Narragansett Bay is a prominent feature of Rhode Island, making up over 500 km of coastline and acting as a watershed for over 2,000 square meters of land in both Massachusetts and Rhode Island. This estuary is important to both the economy of the state of Rhode Island and its fringing ecosystems are necessary for a healthy shoreline. The beaches of Narragansett Bay revenue over $5 billion a year in tourism, stimulate more than 40,000 jobs, and are a source of many economically important marine organisms such as oysters, mussels, hard shell clams, finfish, and lobsters. The numerous fringing habitats of Narragansett Bay, including rocky intertidal zones, seagrasses, and estuarine marshes all play important roles for the coastline of Rhode Island, with salt marshes accounting for more than 600 ha of the shoreline.</p> <p>Salt marshes along Narragansett Bay serve many ecological roles including water quality maintenance, storm surge reduction, erosion control, and habitat and food to fish and wildlife. The ribbed mussel, Geukensia demissa is the biomass-dominant benthic invertebrate in coastal marshes and is a foundation species, providing habitats for other organisms. Ribbed mussels have also been found to be a useful indicator species of nitrogen levels within Narragansett Bay, exhibiting increases in nitrogen-loads with greater biomass, density, and growth rates, and the <strong>δ</strong>15N signatures of G. demissa tissues reflect anthropogenic-derived nitrogen. The purpose of my thesis was to compare ribbed mussel populations in some of the same salt marshes along the well-documented nitrogen-loading gradient, 14 years after the previous studies and following the installation of one phase of a two-part wastewater reduction program into the bay. In addition, my work is part of a larger effort to investigate changes in greenhouse gas emissions by plants, sediment microbiota, and gut microbiota in the ribbed mussels, in response nitrogen-loading and elevated temperatures. Characterizing the mussel populations is integral to understanding the effects of global change on the Narragansett Bay ecosystem.</p> <p>The density, biomass, condition index, and growth rates of ribbed mussels were all positively correlated with the nitrogen-loading gradient in Narragansett Bay. Fecundity did not follow the same pattern but was significantly greater in June at one of the marshes and was negatively correlated with shell length and condition index. These results suggest that although mussels reproduce continuously, gametogenesis and spawning may have occurred prior to sampling. Another unexpected outcome is that with greater food availability resulting from nitrogen-loading, there are both costs and benefits. At the marsh with the highest nitrogen levels, Apponaug, the recruitment, growth, and condition index of the mussels were all significantly greater than at the other two marshes, but the high density may have limited the size of the mussels or even contributed to higher rates of mortality through intraspecific competition. At the opposite end of the nitrogen-loading gradient, mussels at Fox Hill had the greatest average shell length, but the density, biomass, condition index, recruitment, and growth rates were significantly lower than the other two marshes, suggesting that this less perturbed marsh may still be nitrogen-limited despite the historical nitrogen-loading in Narragansett Bay.</p> <p>The results from this study are critical for documenting the variation among the ribbed mussel populations within differing nitrogen-loaded marshes, but will also be used as a benchmark for a longer-term study analyzing the historical responses of this species to changes in nutrient loads into Narragansett Bay.</p>

The impact of different intensities of green light on the bacteriochlorophyll homologue composition of the chlorobiaceae Prosthecochloris aestuarii and Chlorobium phaeobacteroides

Microbiology ◽  
2004 ◽  
Vol 150 (8) ◽  
pp. 2555-2564 ◽  
Author(s):  
Astrid Massé ◽  
Ruth L. Airs ◽  
Brendan J. Keely ◽  
Rutger de Wit
Keyword(s):  
Growth Rates ◽  
Green Light ◽  
Reducing Power ◽  
Side Chains ◽  
Straight Chain ◽  
Specific Content ◽  
Prosthecochloris Aestuarii ◽  
Light Intensities ◽  
Chlorobium Phaeobacteroides ◽  
The Impact

Members of the Chlorobiaceae and Chloroflexaceae are unique among the phototrophic micro-organisms in having a remarkably rich chlorophyll pigment diversity. The physiological regulation of this diversity and its ecological implications are still enigmatic. The bacteriochlorophyll composition of the chlorobiaceae Prosthecochloris aestuarii strain CE 2404 and Chlorobium phaeobacteroides strain UdG 6030 was therefore studied by both HPLC with photodiode array (PDA) detection and liquid chromatography-mass spectrometry (LC-MS). These strains were grown in liquid cultures under green light (480–615 nm) at different light intensities (0·2–55·7 μmol photons m−2 s−1), simulating the irradiance regime at different depths of the water column of deep lakes. The specific growth rates of Ptc. aestuarii under green light achieved a maximum of 0·06 h−1 at light intensities exceeding 6 μmol photons m−2 s−1, lower than the maximum observed under white light (approx. 0·1 h−1). The maximal growth rates of Chl. phaeobacteroides under green light were slightly higher (0·07 h−1) than observed for Ptc. aestuarii and were achieved at 3·5 and 4·3 μmol photons m−2 s−1. LC-MS/MS analysis of pigment extracts revealed most (>90 %) BChl c homologues of Ptc. aestuarii to be esterified with farnesol. The homologues differed in mass by multiples of 14 Da, reflecting different alkyl subsituents at positions C-8 and C-12 on the tetrapyrrole macrocycle. The relative proportions of the individual homologues varied only slightly among different light intensities. The specific content of BChl c was maximal at 3–5 μmol photons m−2 s−1 [400±150 nmol BChl c (mg protein)−1]. In the case of Chl. phaeobacteroides, the specific content of BChl e was maximal at 4·3 μmol photons m−2 s−1 [115 nmol BChl e (mg protein)−1], and this species was characterized by high carotenoid (isorenieratene) contents. The major BChl e forms were esterified with a range of isoprenoid and straight-chain alcohols. The major isoprenoid alcohols comprised mainly farnesol and to a lesser extent geranylgeraniol. The straight-chain alcohols included C15, C15 : 1, C16, C16 : 1 and C17. Interestingly, the proportion of straight alkyl chains over isoprenoid esterified side chains shifted markedly with increasing light intensity: the isoprenoid side chains dominated at low light intensities, while the straight-chain alkyl substituents dominated at higher light intensities. The authors propose that this phenomenon may be explained as a result of changing availability of reducing power, i.e. the highly reduced straight-chain alcohols have a higher biosynthetic demand for NADPH2 than the polyunsaturated isoprenoid with the same number of carbon atoms.

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