Seasonal Development of Ice Algae and its Prediction from Environmental Factors near Resolute, N.W.T., Canada

1989 ◽  
Vol 46 (10) ◽  
pp. 1793-1804 ◽  
Author(s):  
Harold E. Welch ◽  
Martin A. Bergmann
Keyword(s):  
Algal Biomass ◽  
Algal Growth ◽  
Dry Weight ◽  
Seasonal Development ◽  
Detectable Effect ◽  
Distribution Data ◽  
First Year ◽  
Ice Algae ◽  
Doubling Times ◽  
Snow Thickness

Development of ice algae growing at the bottom of first-year congelation sea ice near Resolute, N.W.T. (75°N) was studied 1984–86. Ice algae moved downwards 1.5 cm∙d−1 as the ice thickened. Biomass increased logarithmically with doubling times on the order of 4–8 d, reaching over 150 mg chlorophyll a∙m−2 in 1985 and over 300 mg∙m−2 in 1986. Algal development was synchronous up to 120 km from the main study site. Snow cover controlled algal growth indirectly by its effect on light. Algal biomass was predictable from snow thickness and date, or snow thickness and light equally well (overall r2 = 0.77 for 1985 and 1986 combined). Ice-associated amphipods were correlated with reduced ice algal biomass, but Si and NO3 concentrations and tidal cycle had little or no detectable effect. Snow depth frequency distribution data are given. Peak ice algal biomass under low snow in 1986 was equal to 0.5 t dry weight and 4.7 kg Si∙ha−1.

Seasonal Development of Ice Algae Near Chesterfield Inlet, N.W.T., Canada

1991 ◽  
Vol 48 (12) ◽  
pp. 2395-2402 ◽  
Author(s):  
H. E. Welch ◽  
M. A. Bergmann ◽  
T. D. Siferd ◽  
P. S. Amarualik
Keyword(s):  
Shallow Water ◽  
Deep Water ◽  
Snow Depth ◽  
Algal Biomass ◽  
The Arctic ◽  
Seasonal Development ◽  
Northwest Coast ◽  
Detectable Effect ◽  
First Year ◽  
Hudson Bay

Ice algal chlorophyll a, (Chl), an estimator of biomass, was measured throughout the growing season (March–May) near Chesterfield Inlet on the northwest coast of Hudson Bay (63°30′N). The log10 transformation of Chl per square metre was a negative linear function of snow depth at any given date and location. Maximum biomass reached about 170 mg Chl∙m−2 over deep water but only one tenth as much over shallow water. This smaller standing crop was correlated with lower concentrations of nitrate in shallow water, postulated to result from nitrogen uptake by kelp. Ice-associated amphipods were abundant but had little detectable effect on the development of ice algal biomass. Ice algal Chl over deep water was predicted closely by the model developed for Resolute at 75°N, relating Chl to overlying snow depth and cumulative surface light. It appears that, where nutrients are adequate, ice algal biomass below first-year sea ice can be predicted for much of the Arctic from two variables, cumulative surface light and snow depth.

Bacterial dynamics in first year sea ice and underlying seawater of Saroma-ko Lagoon (Sea of Okhotsk, Japan) and Resolute Passage (High Canadian Arctic): Inhibitory effects of ice algae on bacterial dynamics

2000 ◽  
Vol 46 (7) ◽  
pp. 623-632 ◽  
Author(s):  
Patrick Monfort ◽  
Serge Demers ◽  
Maurice Levasseur
Keyword(s):  
Sea Ice ◽  
Algal Biomass ◽  
Bacterial Abundance ◽  
Canadian Arctic ◽  
Total Cell ◽  
First Year ◽  
Ice Algae ◽  
Inhibitory Effects ◽  
Bacterial Dynamics ◽  
Culturable Fraction

The seasonal development of bacterial abundance in first year bottom ice and underlying seawater were studied at Saroma-ko Lagoon in Hokkaido, Japan, and at Resolute Passage in the High Canadian Arctic during the algal bloom in spring 1992. The aim of this study was to evaluate whether the high algal concentrations reached during the bloom of ice algae have inhibitory effects on bacterial dynamics. Bacterial abundance (measured as total cell count and colony-forming units CFU) increased with the increase of the algal biomass up to 500 µg Chla·L-1in both locations. Culturable fraction (measured as the percentage of CFU counts versus the total cell counts) was between 7% and 22% at Saroma-ko, and approximately 0.08% at Resolute Passage. When algal biomass exceeded 500 µg of Chla·L-1, both bacterial abundance and culturable fraction decreased significantly. There was a maximum threshold of algal biomass (between 500 and 800 µg of Chla·L-1) after which bacterial dynamics become negatively coupled to the algal biomass. These results suggest that bactericidal and/or bacteriostatic compounds from these extremely high algal concentrations could explain the decrease in bacterial abundance and culturability in bottom ice observed after the ice algae bloom.Key words: bacteria, culturability, algae, inhibitory effects, sea ice, Arctic.

scholarly journals Algal-biomass Production from Chlorella sp. Using Hot and Cold Water Infusions of Poultry Droppings

2019 ◽  
pp. 1-9
Author(s):  
E. Effiong ◽  
O. K. Agwa ◽  
G. O. Abu
Keyword(s):  
Algal Biomass ◽  
Cold Water ◽  
Algal Growth ◽  
Dry Weight ◽  
Hot Water ◽  
Biodiesel Production ◽  
Crude Fibre ◽  
Physicochemical Composition ◽  
Chlorella Sp ◽  
Poultry Droppings

Background: Microbial biomass is a valuable resource to the development of sustainable energy. However, the challenge of having an effective media for energy production have adversely affected biotechnological development. This study was aimed at comparing algal biomass produced by Chlorella sp. using hot and cold water extracts of poultry droppings. Methodology: Fifteen grams (15 g) of poultry droppings was infused into 500 mL (cold and hot water) and allowed to stand for 48 h prior. Algal growth was monitored by cell dry weight and optical density readings taken at 620 nm using a spectrophotometer. Results: Physicochemical composition of the poultry droppings for cold water infusion revealed the following: pH, 6.7; conductivity, 3404.1 µs/cm; phosphate, 25.3 ppm; nitrate,1.88 ppm; phosphate, 25.3 ppm; Mg2+, 27.20 ppm; TOC, 38.03 ppm and COD, 53.8 ppm after 48 h. Whereas, the values obtained for hot extractions were: pH, 6.28; conductivity, 3.82 µs/cm; nitrate, 1.24 ppm; phosphate, 28.0 ppm; Mg2+, 19.85 ppm; TOC, 64.03 ppm and COD, 553.3 ppm. The proximate composition of extract revealed crude fibre, 17.69%, ash content, 24.16%; crude fibre, 22.7%; crude protein, 21.02%; crude fat, 3.19% and crude carbohydrate 23.02%. Microflora obtained from the biostability test revealed the presence of Proteus sp, Vibrio sp. and Salmonella sp. in cold extract while hot extract had Bacillus sp. and Serratia sp. The Chlorella sp. was identified using colonial and microscopic features. Biomass yield of 3.1 g/L and 2.8 g/l wet weight of Chlorella biomass was recorded for the cold and hot aqueous extracts of the poultry droppings respectively. Conclusion: This study revealed that hot poultry droppings extract (PDE) could offer a better feedstock for biodiesel production.

Comparison of Ascat Estimated Snow Thickness on First-Year Sea Ice in the Canadian Arctic with Modeled and Passive Microwave Data

2020 ◽  
Author(s):  
John J. Yackel ◽  
Torsten Geldsetzer ◽  
Mallik Mahmud ◽  
Rory Armstrong ◽  
Vishnu Nandan ◽  
...  
Keyword(s):  
Sea Ice ◽  
Canadian Arctic ◽  
Passive Microwave ◽  
First Year ◽  
Snow Thickness ◽  
Microwave Data

Development and application of a simple procedure for toxicity testing using immobilized algae

1996 ◽  
Vol 33 (6) ◽  
pp. 129-138 ◽  
Author(s):  
Mohammad I. Abdel-Hamid
Keyword(s):  
Simple Procedure ◽  
Algal Growth ◽  
Toxicity Testing ◽  
Dry Weight ◽  
Toxicity Assessment ◽  
Response Curves ◽  
Response Parameter ◽  
Test Alga ◽  
Almost All ◽  
Immobilized Algae

A simple microplate technique was adopted for toxicity assessment of a number of pesticides including six herbicides (Atrazine, Dichloroprop, Glyphosphate, Chlorsulfuron, MCPA, and Simazine), an insecticide (Dimethoate) and a fungicide (Propiconazol). Growth response of free and immobilized cultures of the green chlorococcal algae Selenastrum capricornumtum to different treatments of these pesticides was tested and compared. The biotests were carried out under conditions optimal for the growth of the test alga. Algal growth was exposed in terms of dry weight, and was employed as the toxicity-response parameter. Dose-response curves were used to calculate the toxicity of the tested compounds in terms of EC50. Based on EC50 values, the responses of both immobilized and free cultures were quite similar for almost all the treatments. The technique facilitated the visual detection of the lowest toxic concentration giving no detectable algal growth (EC100). The technique is quite simple, rapid, practical, accurate, and space saving. It suggested that batteries of immobilized algae could replace free cultures in studies of toxicity testing.

scholarly journals Albedo of Young and First-Year Antarctic Sea Ice

1990 ◽  
Vol 14 ◽  
pp. 331 ◽  
Author(s):  
Richard Brandt ◽  
Ian Allison ◽  
Stephen Warren
Keyword(s):  
Sea Ice ◽  
Radiation Flux ◽  
Open Water ◽  
First Year ◽  
Spectral Measurements ◽  
Antarctic Sea Ice ◽  
Antarctic Expedition ◽  
Downward Radiation ◽  
Radiation Measurements ◽  
Snow Thickness

Reflection of solar radiation was studied in the seasonal sea-ice zone off East Antarctica on a cruise of the Australian Antarctic Expedition, October-December 1988. Spectral and total albedos were measured for grease ice, nilas, young grey ice, grey-white ice, snow-covered ice, and open water. Spectral measurements covered the region 400–1000 nm wavelength. For ice too thin to support our weight, the radiometers were mounted at the end of a 1.5 m rod extended out the door of a helicopter or from a basket hung from the ship's crane, using a positioning and leveling rack. Corrections had to be applied to the downward radiation flux because the helicopter or the crane was in the field of view of the cosine-collector. The fractional coverage of each of the ice types (and open water) was estimated hourly for the region near the ship, as well as the thickness of each ice type, and the snow thickness. Observations were carried out continuously during the four weeks the ship was in the ice, supplemented by occasional helicopter surveys covering larger areas. These observations, together with the radiation measurements, make possible the computation of area-average albedo for the East Antarctic sea-ice zone in spring.

scholarly journals Short-term Recurring Drought Affects Growth and Photosynthetic Capacity of Four Conifer Species

2013 ◽  
Vol 31 (1) ◽  
pp. 39-42
Author(s):  
Joshua R. Pool ◽  
Jason J. Griffin ◽  
Cheryl R. Boyer ◽  
Stuart L. Warren
Keyword(s):  
Root Growth ◽  
Great Plains ◽  
Growth Index ◽  
Dry Weight ◽  
Detectable Effect ◽  
Severe Drought ◽  
Short Term ◽  
Southern Great Plains ◽  
Reduced Height ◽  
Tree Survival

The Midwest and southern Great Plains are known for historic and severe droughts. More common, however, are short-term recurring drought events that can limit tree survival. The pressure of environmental stress combined with numerous diseases and pests are decimating existing Pinus L. spp. (pine) plantings and driving the effort to identify alternative species. Four species of conifer were subjected to recurring moderate or severe drought to observe the effects on growth and photosynthesis. Species evaluated were: Abies nordmanniana (Nordmann fir), Cupressus arizonica (Arizona cypress), Picea engelmannii (Engelmann spruce), and Thuja × ‘Green Giant’ (‘Green Giant’ arborvitae). Recurring drought reduced height and growth index of T. × ‘Green Giant’. However, photosynthesis and root growth were unaffected by drought treatments. In contrast, reduced Pnet was the only detectable effect of recurring drought in P. engelmannii. Growth of A. nordmanniana was not affected by drought. When subjected to drought, C. arizonica reduced shoot dry weight, while maintaining photosynthesis and root growth. Overall, C. arizonica was able to maintain growth of roots and shoots as well as maintain photosynthesis which may be an advantage in the harsh climate of the Midwest and southern Great Plains.

scholarly journals Infection with intracellular parasite Amoeboaphelidium protococcarum induces shifts in associated bacterial communities in microalgae cultures

2021 ◽  
Vol 33 (5) ◽  
pp. 2863-2873
Author(s):  
Anna-Lena Höger ◽  
Carola Griehl ◽  
Matthias Noll
Keyword(s):  
Bacterial Communities ◽  
Large Scale ◽  
Algal Growth ◽  
Dry Weight ◽  
Illumina Miseq ◽  
Culture Conditions ◽  
Rrna Gene ◽  
Scale Production ◽  
Market Demand ◽  
Freshwater Microalgae

AbstractIn recent years microalgae products have developed increasing market demand, but sustainable industrial production is still challenged by biological stability of large-scale production plants. Yet the relationships between algal hosts, associated microbiomes, and contaminants in photobioreactors remains widely understudied. The aim of this study was to investigate the temporal development of microbiomes of four freshwater microalgae species Scenedesmus vacuolatus, Desmodesmus quadricauda, Chlorella sorokiniana, and Botryococcus braunii, in presence and absence of the zoosporic parasite Amoeboaphelidium protococcarum. To compare the effects of sterile and nonsterile culture conditions, infection experiments were performed in sterile laboratory (sterile) and simulated industrial conditions (open). Algal growth (dry weight, optical density, and nutrient consumption) was observed for 21 days, and samples of the associated microbiome were collected for bacterial 16S rRNA gene Illumina MiSeq sequencing. Infection patterns of A. protococcarum were algae species-specific, irrespectively of culture conditions. Bacterial community analysis demonstrated distinct and stable bacterial communities for each algae species, which were mostly dominated by α- and γ-Proteobacteria. Upon aphelid parasitosis, bacterial diversity increased, and community compositions diverged algae-specific over time. Moreover, bacterial functional traits shifted to detoxification, degradation, and cellulolysis once algae were infected. This study provides a first insight into the close connection between algae, associated bacterial microbiomes and appearing contaminants in photobioreactor systems.

A Hybrid Evaluation-Optimization Trial to Evaluate an Intervention Targeting the Intersection of Alcohol and Sex in College Students and Simultaneously Test an Additional Component Aimed at Preventing Sexual Violence

2021 ◽  
Author(s):  
Amanda E Tanner ◽  
Kate M Guastaferro ◽  
Kelly L Rulison ◽  
David L Wyrick ◽  
Jeffrey J Milroy ◽  
...  
Keyword(s):  
College Students ◽  
Sexual Violence ◽  
Sexual Behaviors ◽  
Detectable Effect ◽  
First Year ◽  
Behavioral Strategies ◽  
Single Experiment ◽  
First Year College ◽  
First Year College Students

Abstract Background Using the multiphase optimization strategy (MOST), we previously developed and optimized an online behavioral intervention, itMatters, aimed at reducing the risk of sexually transmitted infections (STI) among first-year college students by targeting the intersection of alcohol use and sexual behaviors. Purpose We had two goals: (a) to evaluate the optimized itMatters intervention and (b) to determine whether the candidate sexual violence prevention (SVP) component (included at the request of participating universities) had a detectable effect and therefore should be added to create a new version of itMatters. We also describe the hybrid evaluation-optimization trial we conducted to accomplish these two goals in a single experiment. Methods First year college students (N = 3,098) at four universities in the USA were individually randomized in a hybrid evaluation-optimization 2 × 2 factorial trial. Data were analyzed using regression models, with pre-test outcome variables included as covariates in the models. Analyses were conducted separately with (a) immediate post-test scores and (b) 60-day follow-up scores as outcome variables. Results Experimental results indicated a significant effect of itMatters on targeted proximal outcomes (norms) and on one distal behavioral outcome (binge drinking). There were no significant effects on other behavioral outcomes, including the intersection of alcohol and sexual behaviors. In addition, there were mixed results (positive short-term effect; no effect at 60-day follow-up) of the SVP component on targeted proximal outcomes (students’ self-efficacy to reduce/prevent sexual violence and perceived effectiveness of protective behavioral strategies). Conclusions The hybrid evaluation-optimization trial enabled us to evaluate the individual and combined effectiveness of the optimized itMatters intervention and the SVP component in a single experiment, conserving resources and providing greatly improved efficiency. Trial Registration NCT04095065.

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