Absorption properties of phytoplankton in the Lower Estuary and Gulf of St. Lawrence (Canada)

2008 ◽  
Vol 65 (8) ◽  
pp. 1721-1737 ◽  
Author(s):  
Suzanne Roy ◽  
Frédérick Blouin ◽  
André Jacques ◽  
Jean-Claude Therriault
Keyword(s):  
Spring Bloom ◽  
Size Structure ◽  
Particulate Material ◽  
Dominant Factor ◽  
Pigment Composition ◽  
Ocean Colour ◽  
Absorption Properties ◽  
Ultraviolet Range ◽  
Before And After ◽  
Phytoplankton Absorption

Models of ocean colour rely on information about phytoplankton absorption, which varies according to community composition and photoacclimation. Here we show that pigment packaging, which is strongly determined by the size structure of local algal populations, represents a dominant factor in the Estuary and Gulf of St. Lawrence, accounting for ~50%–80% of the reduction in phytoplankton absorption at 440 nm during the spring bloom periods and for 24%–48% before and after the blooms. This is consistent with the importance of diatoms in this environment. Comparison between three methods of estimating packaging gave average values within less than 20% of each other during the blooms. Changes in pigment composition, which also affect phytoplankton absorption, were more important outside bloom periods (particularly in the Gulf), although this influence was relatively modest (11%–13%). This was accompanied by an increase in photoprotective pigments and an absorption peak in the ultraviolet range (~330 nm). Regional variations in phytoplankton absorption reflected bloom conditions, whereas detrital particulate material was highest in the upstream Saguenay region (often more than 60% of the absorption of total particulate material at 440 nm (ap(440))) and was at least 20%–30% elsewhere. This information is a first step towards the development of regional models of ocean colour.

scholarly journals Relationships between phytoplankton light absorption, pigment composition and size structure in offshore areas of the Mediterranean Sea

2011 ◽  
Vol 2 (2) ◽  
pp. 107 ◽  
Author(s):  
Emanuele Organelli ◽  
Caterina Nuccio ◽  
Chiara Melillo ◽  
Luca Massi
Keyword(s):  
Mediterranean Sea ◽  
Cell Size ◽  
Size Structure ◽  
Taxonomic Composition ◽  
Small Range ◽  
Pigment Composition ◽  
Absorption Coefficients ◽  
Phytoplankton Assemblages ◽  
Phytoplankton Absorption ◽  
The Mediterranean

Phytoplankton absorption is mainly determined by pigment composition and packaging into the cell, in turn affected by pigment concentration and cell size and shape. The variations of the chlorophyll-specific absorption coefficients at two selected wavelengths (443 nm and 675 nm) were analysed for offshore areas of the Mediterranean Sea (Alboran, Algerian, Tyrrhenian, Ionian Basins and Sardinia Channel) investigated in autumn 2006, 2007 and 2008. The spatial distribution of Tchl a, accessory pigments, size structure and taxonomic composition of phytoplankton assemblages was diversified among the areas, characterized by higher contribution of photoprotective pigments in oligotrophic surface waters, while accessory chlorophylls increased in deeper layers and where microphytoplankton dominated. (443) values decreased from the oligotrophic waters to the more mesotrophic ones where microphytoplankton prevailed, while for (675) a small range of variation was observed. The differentiation of (443) was explained by the variations in the phytoplankton assemblage mean cell size, that consequently can be assumed as the main factor determining package effect. Comparison with previous parameterizations supported the existence of a Mediterranean differentiation for which the use of global models might determine inaccuracy for predicting phytoplankton absorption coefficients and thus refining ecological models.

Muskellunge Management: Fifty Years of Cooperation Among Anglers, Scientists, and Fisheries Biologists

2017 ◽  
Keyword(s):  
Size Structure ◽  
Population Decline ◽  
Round Goby ◽  
Management Plan ◽  
Neogobius Melanostomus ◽  
Before And After ◽  
Catch Rates ◽  
Survival Studies ◽  
St Lawrence River

<em>Abstract</em>.— Long-term research indicates a significant and ongoing decline within the upper St. Lawrence River Muskellunge <em>Esox masquinongy </em>population. Index surveys show a sharp reduction in catch of both spawning adults and age-0 Muskellunge, and catch rates by anglers have similarly declined while harvest remains low. Other changes associated with population decline include presence of fewer female adult Muskellunge and a change in adult Muskellunge size structure (increase in proportion of fish <1,016 mm) in addition to more large individuals greater than 1,372 mm. A significant adult die-off occurred from 2005 to 2008 (103 adults recovered in U.S. and Canadian waters) concomitant with an outbreak of viral hemorrhagic septicemia (VHS). These population changes were also temporally correlated with detection and proliferation of invasive Round Goby <em>Neogobius melanostomus</em>, a known VHS virus (VHSV) reservoir, egg predator, and competitor with native fishes. Comparisons of index netting before and after VHSV and Round Goby invasions suggest a direct link to the decline, but because these are correlations, we can only explore these effects. To examine the viability of Muskellunge nursery sites, we repeated survival studies conducted in the early 1990s with experimental releases of advanced fry at four locations during 2013–2015. Findings indicate contribution to age-0 populations, but catches poststocking (wild and stocked) were lower compared to the 1990s. We review information regarding potential stressors, including VHSV and Round Goby invasion, and conclude that their combined effects have created significant uncertainty and challenges to sustainable management of the Muskellunge population. In response, the St. Lawrence River Muskellunge management plan should be updated with a focus on restoration of the declining Muskellunge stock. Recommended actions target advancing conservation and restoration of critical habitat, restoring lost subpopulations, and reducing mortality associated with angling (e.g., from handling and harvest).

scholarly journals Study of Blended Waste Organic Extracts in Wastewater Treatment

2019 ◽  
Vol 31 (5) ◽  
pp. 1013-1016
Author(s):  
J.B. Veeramalini ◽  
B. Bharathiraja ◽  
S. Raghu Vinayak ◽  
R. Vignesh ◽  
S.K. Raghul
Keyword(s):  
Wastewater Treatment ◽  
Microbial Growth ◽  
Cost Effective ◽  
Particulate Material ◽  
Composite Fibre ◽  
Treatment Processes ◽  
Organic Extracts ◽  
Before And After ◽  
Micro Organisms

In present work, water treatment processes is carried out by an affordable, readily usable and non-chemical method. This study involved the process of water may reduce the concentration of particulate matter that includes suspended particles, micro organisms, a range of dissolved and particulate material derived from the surfaces. The substances used in this work were coarsely blended with each other and a special composite fibre filter was made. Several processes variables of quality of waste are also measured before and after the treatment. Results show that the water quality has been enriched in several ways such as reduction in the dissolved solids, pH has been controlled, deodorization and prevention of microbial growth. Hence use of this work has been utilized as a “Homemaker Model” and act as an alternative method for wastewater treatment in a cost effective way.

scholarly journals Harvesting peatland black spruce: Impacts on advance growth and site disturbance

1997 ◽  
Vol 73 (2) ◽  
pp. 249-255 ◽  
Author(s):  
Marc R. MacDonell ◽  
Arthur Groot
Keyword(s):  
Key Words ◽  
Picea Mariana ◽  
Size Structure ◽  
Black Spruce ◽  
Before And After ◽  
Harvesting Systems ◽  
Tree Length ◽  
Site Disturbance ◽  
Tree Harvesting

A project was established in the Lake Abitibi Model Forest to study the effects of several harvesting systems on advance growth protection and site disturbance. Tree-length and cut-to-length harvesting systems were compared to a full-tree system on peatland black spruce (Picea mariana (Mill.) B.S.P.) sites. The impacts of the various harvesting systems were compared by summarizing the structural and mensurational properties of the stands before and after harvest, by evaluating damage to residual trees, and by assessing site disturbance. The tree-length and full-tree systems, which were compared in winter harvesting, produced similar results. The cut-to-length system was compared to the full-tree system in both winter and summer harvesting, and protected substantially more advance growth, especially in the summer. Additionally, the cut-to-length system produced less damage to residual trees and lesser amounts of site disturbance. All harvesting systems resulted in or maintained residual stands with an uneven-size structure. Key words: black spruce, advanced regweneration, tree harvesting, systems

scholarly journals Variability in specific-absorption properties and their use in a semi-analytical ocean colour algorithm for MERIS in North Sea and Western English Channel Coastal Waters

2012 ◽  
Vol 118 ◽  
pp. 320-338 ◽  
Author(s):  
Gavin H. Tilstone ◽  
Steef W.M. Peters ◽  
Hendrik Jan van der Woerd ◽  
Marieke A. Eleveld ◽  
Kevin Ruddick ◽  
...  
Keyword(s):  
North Sea ◽  
Coastal Waters ◽  
English Channel ◽  
Ocean Colour ◽  
Absorption Properties ◽  
Specific Absorption

scholarly journals Sex-specific Changes in Walleye Abundance, Size Structure and Harvest Following Implementation of Regulation to Protect Broodstock

2015 ◽  
Vol 6 (2) ◽  
pp. 448-455 ◽  
Author(s):  
Keith D. Koupal ◽  
Jordan D. Katt ◽  
Casey W. Schoenebeck ◽  
Brad E. Eifert
Keyword(s):  
Relative Abundance ◽  
Size Structure ◽  
The State ◽  
Minimum Length ◽  
Sander Vitreus ◽  
Data Sets ◽  
Total Catch ◽  
Before And After ◽  
Existing Data

Abstract The popularity of walleye Sander vitreus fishing has resulted in the development of specialized regulations that are designed to protect these fisheries. In the case of Sherman Reservoir, Sherman County, Nebraska, the walleye population provides a sportfishing opportunity and serves as broodstock for the state. In 2009, for the primary purpose of protecting female broodstock, the regulation changed from a harvest limit of four walleye with 457-mm minimum length to allowing a reduced harvest limit of two walleye within a harvest slot (381–508 mm) and one walleye more than 711 mm. This study examined existing data sets to assess the percentage of spawning walleye protected with each regulation, sex-specific differences in relative abundance and size structure during broodstock collection and angler effort, total catch, and harvest of walleye. The new regulation has increased protection of female walleye by more than 90%, but decreased protection of male walleye by more than 60%. The relative abundance of female walleye caught per net during broodstock collection has more than doubled since the regulation was changed, but the size structure of female walleye collected during broodstock operations was similar. Correspondingly, the relative abundance of male walleye has declined since changing the regulation, but size structure remained similar. Effort and total catch of walleye by anglers were similar before and after the regulation was enacted, but harvest has increased by 130%. This regulation appears to protect female broodstock walleye, but it makes male walleye more vulnerable to angler harvest.

scholarly journals Analysis of the Factors Affecting Fine Dust Concentration Before and After COVID-19

2021 ◽  
Vol 21 (6) ◽  
pp. 395-402
Author(s):  
Woo-Chul Choi ◽  
Kyu-Soo Cheong
Keyword(s):  
Comparative Analysis ◽  
Wind Direction ◽  
Air Pollutants ◽  
Dominant Factor ◽  
Fine Dust ◽  
Factors Affecting ◽  
Before And After ◽  
Containment Policy ◽  
The Relationship ◽  
Dust Reduction

This study conducted a comparative analysis of the factors affecting the concentration of fine dust before and after COVID-19. Of these, the dominant factor was CO, and the influence between variables increased even after COVID-19. In the case of PM10, the influence of wind direction and wind speed variables decreased, which is thought to be due to the reduction of westerly-based foreign air pollutants following China’s containment policy. Comparative analysis by season showed that the influence of temperature and humidity was higher in winter. In spring, the influence of wind direction and speed decreased with changes in the westerly wind and the influence of China’s containment policy. In summer and autumn, when the concentration of fine dust is relatively low, the influence of CO after COVID-19 was rather high, indicating that continuous CO management is necessary. Considering the relationship between these air pollutants and the meteorological environment, it is judged that fine dust reduction measures should be implemented.

scholarly journals Адаптация золь-гель технологии наноструктурированного оксида цинка для целей гибкой электроники

2019 ◽  
Vol 89 (12) ◽  
pp. 1917
Author(s):  
И.А. Аверин ◽  
И.А. Пронин ◽  
Н.Д. Якушова ◽  
А.А. Карманов ◽  
Е.А. Алимова ◽  
...  
Keyword(s):  
Sol Gel ◽  
Spectroscopic Studies ◽  
Temperature Treatment ◽  
Photochemical Reactions ◽  
Qualitative Composition ◽  
Low Temperature Treatment ◽  
Zinc Oxide Films ◽  
Film Forming ◽  
Ultraviolet Range ◽  
Before And After

Abstract The possibility of replacing classical sol-gel operation methods of high-temperature annealing by photo-annealing using ultraviolet-range radiation has been analyzed. A technique for synthesizing hierarchically organized zinc oxide films using sol-gel technology based on the parallel combination of low-temperature treatment and UV photo-annealing is proposed. Spectroscopic studies of the qualitative composition of the film-forming sol and nanomaterials based on it, obtained on various types of substrates, have been carried out before and after initiation of photochemical reactions.

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