scholarly journals Transition from a Mixotroph/Heterotroph Protist Community During the Dark Winter to a Photoautotrophic Spring Community in Arctic Surface Waters

2021 ◽  
Author(s):  
Claudia Sabine Bruhn ◽  
Nina Lundholm ◽  
Per Juel Hansen ◽  
Sylke Wohlrab ◽  
Uwe John
Keyword(s):  
Water Column ◽  
Surface Waters ◽  
Spring Bloom ◽  
Transition Period ◽  
Abiotic Factors ◽  
Spectral Composition ◽  
Day Length ◽  
Winter Period ◽  
Initial Increase ◽  
Arctic Surface

Abstract Unicellular plankton communities (protists) are the basis of the marine food web. The spring bloom is especially important, because of its high biomass. However, it is poorly described how the protist community structure in Arctic surface waters develops from winter to spring. We show that mixotrophy and parasitism are the prominent trophic modes in the dark winter period. The transition period was characterized by a high relative abundance of mixotrophic dinoflagellates, while centric diatoms and the haptophyte Phaeocystis pouchetii dominated the successive phototrophic spring bloom event. Our observations indicate the presence of a characteristic winter community and a community shift from winter to spring, and not just a dormant spring community waiting for better circumstances. The spring bloom initiation commenced while sea ice was still obstructing the light penetration into the water column. The initiation coincided with a change in day length and spectral composition of the light, rather than with an increased light intensity. The initial increase in fluorescence, and therefore photosynthetic activity, was detected relatively deep in the water column, at ~55 m depth. This suggests that water column stratification and a complex interplay of abiotic factors eventually promote the spring bloom initiation.

scholarly journals Radiocesium in the Taiwan Strait and the Kuroshio east of Taiwan from 2018 to 2019

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wei-Jen Huang ◽  
Ming-Ta Lee ◽  
Kuei-Chen Huang ◽  
Kai-Jung Kao ◽  
Ming-An Lee ◽  
...  
Keyword(s):  
Water Column ◽  
Surface Waters ◽  
Half Life ◽  
North Pacific Ocean ◽  
Taiwan Strait ◽  
Depth Range ◽  
Near Surface ◽  
Activity Concentrations ◽  
The Taiwan Strait ◽  
The Kuroshio

AbstractThe release of anthropogenic radiocesium to the North Pacific Ocean (NPO) has occurred in the past 60 years. Factors controlling 137Cs (half-life, 30.2 year) and 134Cs (half-life, 2.06 year) activity concentrations in the Kuroshio east of Taiwan and the Taiwan Strait (latitude 20° N–27° N, longitude 116° E–123° E) remain unclear. This study collected seawater samples throughout this region and analyzed 134Cs and 137Cs activity concentrations between 2018 and 2019. A principal component analysis (PCA) was performed to analyze the controlling factors of radiocesium. Results of all 134Cs activity concentrations were below the detection limit (0.5 Bq m−3). Analyses of water column 137Cs profiles revealed a primary concentration peak (2.1–2.2 Bq m−3) at a depth range of 200–400 m (potential density σθ: 25.3 to 26.1 kg m−3). The PCA result suggests that this primary peak was related to density layers in the water column. A secondary 137Cs peak (1.90 Bq m−3) was observed in the near-surface waters (σθ = 18.8 to 21.4 kg m−3) and was possibly related to upwelling and river-to-sea mixing on the shelf. In the Taiwan Strait, 137Cs activity concentrations in the near-surface waters were higher in the summer than in the winter. We suggest that upwelling facilitates the vertical transport of 137Cs at the shelf break of the western NPO.

scholarly journals Relative importance of the bacteria Brucella, Salmonella, Staphylococcus and other indicator bacteria in some mountain farm waters in West-Cameroon (Central Africa) and the potential role of some environmental factors

2020 ◽  
Vol 8 (2) ◽  
pp. 081-084
Author(s):  
Pierrette Ngo Bahebeck ◽  
Mireille Ebiane Nougang ◽  
Paul Alain Nana ◽  
Claire Stéphane Metsopkeng ◽  
Antoine Tamsa Arfao ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Surface Waters ◽  
Brucella Abortus ◽  
Physicochemical Parameters ◽  
Potential Role ◽  
Abiotic Factors ◽  
Central Africa ◽  
Mountainous Regions ◽  
Brucella Suis

A bacteriological and physicochemical study was conducted in the waters of farms in mountainous regions of Cameroon. The different water samples were collected during two campaigns in December 2018 and February 2019. Ten stations representing the drinking water supply points in our study area were identified. The results showed that these waters contained both pathogenic and commensal fecal bacteria. The highest abundances reached 10x103 CFU/100mL for Salmonella sp., 72x103 CFU/100mL for Staphylococcus aureus, 102x103 CFU/100mL for Brucella suis and 40x103 CFU/100mL for Brucella abortus. These abundances were subject to space-time fluctuations. Water contamination by tweezers was not general and was present only in surface waters (rivers and ponds). The water in the ponds, rivers and wells analyzed were all basic, with low mineralization on average. The dissolved oxygen ranged from 37.5 to 70.6%, nitrate from 3.7 to 19.8 mg/L and iron from 0.01 to 3.5 mg/L. Most of the physicochemical parameters were relatively stable during the two campaigns. The degree of correlation between the physicochemical parameters and the abundance dynamics of the isolated bacteria was heterogeneous. This was clearly more pronounced with Salmonella sp. and Brucella suis. This would be due to the fraction of metabolically active cells present when the bacteria are exposed to unfavorable conditions. Correlations with the abiotic factors were less marked with Staphylococcus aureus and Brucella abortus; this would be due to their tolerance to environmental stresses.

scholarly journals Impact of ocean acidification and elevated temperatures on early juveniles of the polar shelled pteropod <i>Limacina helicina</i>: mortality, shell degradation, and shell growth

2010 ◽  
Vol 7 (6) ◽  
pp. 8177-8214 ◽  
Author(s):  
S. Lischka ◽  
J. Büdenbender ◽  
T. Boxhammer ◽  
U. Riebesell
Keyword(s):  
Ocean Acidification ◽  
Surface Waters ◽  
Elevated Temperatures ◽  
Shell Growth ◽  
Shell Diameter ◽  
Partial Pressures ◽  
Limacina Helicina ◽  
Different Temperatures ◽  
Arctic Surface

Abstract. Due to their aragonitic shell thecosome pteropods may be particularly vulnerable to ocean acidification driven by anthropogenic CO2 emissions. This applies specifically to species inhabiting Arctic surface waters that are projected to become locally undersaturated with respect to aragonite as early as 2016. This study investigated the effects of rising pCO2 partial pressures and elevated temperature on pre-winter juveniles of the polar pteropod Limacina helicina. After a 29 days experiment in September/October 2009 at three different temperatures and under pCO2 scenarios projected for this century, mortality, shell degradation, shell diameter and shell increment were investigated. Temperature and pCO2 had a significant effect on mortality, but temperature was the overriding factor. Shell diameter, shell increment and shell degradation were significantly impacted by pCO2 but not by temperature. Mortality was 46% higher at 8 °C compared to 3 °C (in situ), and 14% higher at 1100 μatm CO2 as compared to 230 μatm CO2. Shell diameter and increment were reduced by 10% and 12% at 1100 μatm CO2 as compared to 230 μatm CO2, respectively, and shell degradation was 41% higher at elevated compared to ambient pCO2 partial pressures. We conclude that pre-winter juveniles will be negatively affected by both rising temperature and pCO2 which may result in a possible abundance decline of the overwintering population, the basis for next year's reproduction.

scholarly journals Dispersal of invasive species by drifting

2011 ◽  
Vol 57 (6) ◽  
pp. 818-827 ◽  
Author(s):  
M.C. Van Riel ◽  
G. Van Der Velde ◽  
A. Bij De Vaate
Keyword(s):  
Invasive Species ◽  
Water Column ◽  
Aquatic Organisms ◽  
Aquatic Macroinvertebrates ◽  
Winter Period ◽  
River Rhine ◽  
Summer Period ◽  
Diel Patterns ◽  
Dispersal Mechanism ◽  
Dispersal Vectors

Abstract Drifting can be an effective way for aquatic organisms to disperse and colonise new areas. Increasing connectivity between European large rivers facilitates invasion by drifting aquatic macroinvertebrates. The present study shows that high abundances of invasive species drift in the headstream of the river Rhine. Dikerogammarus villosus and Chelicorophium curvispinum represented up to 90% of the total of drifting macroinvertebrates. Drift activity shows seasonal and diel patterns. Most species started drifting in spring and were most abundant in the water column during the summer period. Drift activity was very low during the winter period. Diel patterns were apparent; most species, including D. villosus, drifted during the night. Drifting macroinvertebrates colonised stony substrate directly from the water column. D. villosus generally colonised the substrate at night, while higher numbers of C. curvispinum colonised the substrate during the day. It is very likely that drifting functions as a dispersal mechanism for crustacean invaders. Once waterways are connected, these species are no longer necessarily dependent on dispersal vectors other than drift for extending their distribution range.

scholarly journals Biotic vs. abiotic forcing on plankton assemblages varies with season and size class in a large temperate estuary

2020 ◽  
Vol 42 (2) ◽  
pp. 221-237 ◽  
Author(s):  
Gretchen Rollwagen-Bollens ◽  
Stephen Bollens ◽  
Eric Dexter ◽  
Jeffery Cordell
Keyword(s):  
Community Dynamics ◽  
Abiotic Factors ◽  
River Estuary ◽  
Multiple Time Scales ◽  
Nutrient Concentrations ◽  
Winter Period ◽  
Zooplankton Abundance ◽  
Multiple Time ◽  
P Availability ◽  
Lower Estuary

Abstract Large river estuaries experience multiple anthropogenic stressors. Understanding plankton community dynamics in these estuaries provides insights into the patterns of natural variability and effects of human activity. We undertook a 2-year study in the Columbia River Estuary to assess the potential impacts of abiotic and biotic factors on planktonic community structure over multiple time scales. We measured microplankton and zooplankton abundance, biomass and composition monthly, concurrent with measurements of chlorophyll a, nutrient concentrations, temperature and salinity, from a dock in the lower estuary. We then statistically assessed the associations among the abundances of planktonic groups and environmental and biological factors. During the late spring high flow period of both years, the lower estuary was dominated by freshwater and low salinity-adapted planktonic taxa, and zooplankton grazers were more strongly associated with the autotroph-dominated microplankton assemblage than abiotic factors. During the early winter period of higher salinity and lower flow, nutrient (P) availability exerted a strong influence on microplankton taxa, while only temperature and upwelling strength were associated with the zooplankton assemblage. Our results indicate that the relative influence of biotic (grazers) and abiotic (salinity, flow, nutrients and upwelling) factors varies seasonally and inter-annually, and among different size classes in the estuarine food web.

Seasonal and Water Column Trends of the Relative Role of Nitrate and Nitrite as *OH Sources in Surface Waters

2007 ◽  
Vol 97 (8) ◽  
pp. 699-711 ◽  
Author(s):  
Davide Vione ◽  
Claudio Minero ◽  
Valter Maurino ◽  
Ezio Pelizzetti
Keyword(s):  
Water Column ◽  
Surface Waters ◽  
Relative Role ◽  
Nitrate And Nitrite

scholarly journals Effect of sea‐ice melt on inherent optical properties and vertical distribution of solar radiant heating in Arctic surface waters

2015 ◽  
Vol 120 (10) ◽  
pp. 7028-7039 ◽  
Author(s):  
Mats A. Granskog ◽  
Alexey K. Pavlov ◽  
Sławomir Sagan ◽  
Piotr Kowalczuk ◽  
Anna Raczkowska ◽  
...  
Keyword(s):  
Optical Properties ◽  
Sea Ice ◽  
Vertical Distribution ◽  
Surface Waters ◽  
Radiant Heating ◽  
Ice Melt ◽  
Inherent Optical Properties ◽  
Arctic Surface

scholarly journals The Use of Water Plants in Biomonitoring And Phytoremediation of Waters Polluted with Heavy Metals

2013 ◽  
Vol 20 (2) ◽  
pp. 353-370 ◽  
Author(s):  
Paweł Krems ◽  
Małgorzata Rajfur ◽  
Maria Wacławek ◽  
Andrzej Kłos
Keyword(s):  
Heavy Metals ◽  
Surface Waters ◽  
Abiotic Factors ◽  
Defence Mechanisms ◽  
Water Plants ◽  
Polluted Waters

Abstract The publication is a synthetic review of many years of research on the possibility of using water plants (macrophytes) to assess pollution of surface waters and the possibility of using the biomass in phytoremediation processes. The results of the research of kinetics and equilibria of heavy metals sorption and desorption conditions were presented in order to repeatedly use the biomass, as well as the research on the influence of abiotic factors on sorption processes. Defence mechanisms of macrophytes, which enable them to vegetate in considerably polluted waters, have been discussed. The results presented herein and carried out in many countries demonstrate that macrophytes can be successfully used in the biomonitoring of water environments and phytoremediation of waters and sewage; however, validation of these procedures requires more detailed research of the mechanisms, which accompany them.

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