scholarly journals Dynamics and Distribution of Marine Synechococcus Abundance and Genotypes during Seasonal Hypoxia in a Coastal Marine Ranch

2021 ◽  
Vol 9 (5) ◽  
pp. 549
Author(s):  
Guihao Li ◽  
Qinqin Song ◽  
Pengfei Zheng ◽  
Xiaoli Zhang ◽  
Songbao Zou ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Abiotic Factors ◽  
23S Rrna ◽  
Polymorphism Analysis ◽  
Coastal Zones ◽  
Internal Transcribed Spacer Region ◽  
Cell Abundance ◽  
Coastal Marine ◽  
Bottom Waters ◽  
Seasonal Hypoxia

Marine Synechococcus are an ecologically important picocyanobacterial group widely distributed in various oceanic environments. Little is known about the dynamics and distribution of Synechococcus abundance and genotypes during seasonal hypoxia in coastal zones. In this study, an investigation was conducted in a coastal marine ranch along two transects in Muping, Yantai, where hypoxic events (defined here as the dissolved oxygen concentration <3 mg L−1) occurred in the summer of 2015. The hypoxia occurred in the bottom waters from late July and persisted until late August. It was confined at nearshore stations of the two transects, one running across a coastal ranch and the other one outside. During this survey, cell abundance of Synechococcus was determined with flow cytometry, showing great variations ranging from 1 × 104 to 3.0 × 105 cells mL−1, and a bloom of Synechococcus occurred when stratification disappeared and hypoxia faded out outside the ranch. Regression analysis indicated that dissolved oxygen, pH, and inorganic nutrients were the most important abiotic factors in explaining the variation in Synechococcus cell abundance. Diverse genotypes (mostly belonged to the sub-clusters 5.1 and 5.2) were detected using clone library sequencing and terminal restriction fragment length polymorphism analysis of the 16S–23S rRNA internal transcribed spacer region. The richness of genotypes was significantly related to salinity, temperature, silicate, and pH, but not dissolved oxygen. Two environmental factors, temperature and salinity, collectively explained 17% of the variation in Synechococcus genotype assemblage. With the changes in population composition in diverse genotypes, the Synechococcus assemblages survived in the coastal hypoxia event and thrived when hypoxia faded out.

Methods for studying dissolved oxygen levels in coastal and estuarine waters receiving combined sewer overflows

1995 ◽  
Vol 32 (2) ◽  
pp. 95-103
Author(s):  
José A. Revilla ◽  
Kalin N. Koev ◽  
Rafael Díaz ◽  
César Álvarez ◽  
Antonio Roldán
Keyword(s):  
Dissolved Oxygen ◽  
Coastal Waters ◽  
Computational Cost ◽  
Oxygen Deficit ◽  
Alternative Methods ◽  
Coastal Zones ◽  
Combined Sewer Overflows ◽  
Sewer Systems ◽  
Combined Sewer ◽  
High Computational Cost

One factor in determining the transport capacity of coastal interceptors in Combined Sewer Systems (CSS) is the reduction of Dissolved Oxygen (DO) in coastal waters originating from the overflows. The study of the evolution of DO in coastal zones is complex. The high computational cost of using mathematical models discriminates against the required probabilistic analysis being undertaken. Alternative methods, based on such mathematical modelling, employed in a limited number of cases, are therefore needed. In this paper two alternative methods are presented for the study of oxygen deficit resulting from overflows of CSS. In the first, statistical analyses focus on the causes of the deficit (the volume discharged). The second concentrates on the effects (the concentrations of oxygen in the sea). Both methods have been applied in a study of the coastal interceptor at Pasajes Estuary (Guipúzcoa, Spain) with similar results.

scholarly journals Drivers, mechanisms and long-term variability of seasonal hypoxia on the Black Sea northwestern shelf – is there any recovery after eutrophication?

2013 ◽  
Vol 10 (6) ◽  
pp. 3943-3962 ◽  
Author(s):  
A. Capet ◽  
J.-M. Beckers ◽  
M. Grégoire
Keyword(s):  
Organic Matter ◽  
Spatial Distribution ◽  
Interannual Variability ◽  
Black Sea ◽  
Sea Surface ◽  
The Black Sea ◽  
Northwestern Shelf ◽  
Bottom Waters ◽  
Seasonal Hypoxia ◽  
Bottom Hypoxia

Abstract. The Black Sea northwestern shelf (NWS) is a shallow eutrophic area in which the seasonal stratification of the water column isolates the bottom waters from the atmosphere. This prevents ventilation from counterbalancing the large consumption of oxygen due to respiration in the bottom waters and in the sediments, and sets the stage for the development of seasonal hypoxia. A three-dimensional (3-D) coupled physical–biogeochemical model is used to investigate the dynamics of bottom hypoxia in the Black Sea NWS, first at seasonal and then at interannual scales (1981–2009), and to differentiate its driving factors (climatic versus eutrophication). Model skills are evaluated by a quantitative comparison of the model results to 14 123 in situ oxygen measurements available in the NOAA World Ocean and the Black Sea Commission databases, using different error metrics. This validation exercise shows that the model is able to represent the seasonal and interannual variability of the oxygen concentration and of the occurrence of hypoxia, as well as the spatial distribution of oxygen-depleted waters. During the period 1981–2009, each year exhibits seasonal bottom hypoxia at the end of summer. This phenomenon essentially covers the northern part of the NWS – which receives large inputs of nutrients from the Danube, Dniester and Dnieper rivers – and extends, during the years of severe hypoxia, towards the Romanian bay of Constanta. An index H which merges the aspects of the spatial and temporal extension of the hypoxic event is proposed to quantify, for each year, the intensity of hypoxia as an environmental stressor. In order to explain the interannual variability of H and to disentangle its drivers, we analyze the long time series of model results by means of a stepwise multiple linear regression. This statistical model gives a general relationship that links the intensity of hypoxia to eutrophication and climate-related variables. A total of 82% of the interannual variability of H is explained by the combination of four predictors: the annual riverine nitrate load (N), the sea surface temperature in the month preceding stratification (Ts), the amount of semi-labile organic matter accumulated in the sediments (C) and the sea surface temperature during late summer (Tf). Partial regression indicates that the climatic impact on hypoxia is almost as important as that of eutrophication. Accumulation of organic matter in the sediments introduces an important inertia in the recovery process after eutrophication, with a typical timescale of 9.3 yr. Seasonal fluctuations and the heterogeneous spatial distribution complicate the monitoring of bottom hypoxia, leading to contradictory conclusions when the interpretation is done from different sets of data. In particular, it appears that the recovery reported in the literature after 1995 was overestimated due to the use of observations concentrated in areas and months not typically affected by hypoxia. This stresses the urgent need for a dedicated monitoring effort in the Black Sea NWS focused on the areas and months concerned by recurrent hypoxic events.

scholarly journals Oxygen depletion in subarctic peatland thaw lakes

2017 ◽  
Vol 3 (2) ◽  
pp. 406-428 ◽  
Author(s):  
Bethany N. Deshpande ◽  
Frédéric Maps ◽  
Alex Matveev ◽  
Warwick F. Vincent
Keyword(s):  
Dissolved Oxygen ◽  
Ice Cover ◽  
Oxygen Depletion ◽  
Freshwater Ecosystems ◽  
In Situ Sensors ◽  
Modelling Studies ◽  
Bottom Waters ◽  
Bacterial Decomposition ◽  
Permafrost Thawing ◽  
Thaw Lakes

Permafrost thawing and erosion results in the enrichment of northern lakes by soil organic matter. These allochthonous inputs favour bacterial decomposition and may cause the draw-down of dissolved oxygen to anoxic conditions that promote methanogenesis. Our objective in the present study was to determine the seasonal variations in dissolved oxygen in a set of permafrost peatland lakes in subarctic Quebec, Canada, and to relate these changes to metabolic rates, ice cover, and mixing. The lakes had high dissolved organic carbon concentrations, and their surface waters in summer had greenhouse gas concentrations that were up to one (CO2) to three (CH4) orders of magnitude above air-equilibrium values, indicating their strongly heterotrophic character. Consistent with these observations, the peatland lakes had elevated rates of bacterial production and oxygen consumption. Continuous measurements of oxygen by in situ sensors and of ice cover by automated field cameras showed that the lakes became fully anoxic shortly after freeze-up. The waters were partially re-oxygenated by mixing events in spring and fall, but in one lake, the bottom waters remained anoxic throughout the year. These observations provide a foundation for subsequent biogeochemical and modelling studies of peatland thaw lakes as an abundant class of Arctic freshwater ecosystems.

scholarly journals Molecular Taxonomy of the Trichophyton rubrum Complex

2000 ◽  
Vol 38 (9) ◽  
pp. 3329-3336 ◽  
Author(s):  
Y. Gräser ◽  
A. F. A. Kuijpers ◽  
W. Presber ◽  
G. S. de Hoog
Keyword(s):  
Length Polymorphism ◽  
Fragment Length ◽  
Internal Transcribed Spacer ◽  
Fragment Length Polymorphism ◽  
Trichophyton Rubrum ◽  
Molecular Taxonomy ◽  
Polymorphism Analysis ◽  
Internal Transcribed Spacer Region ◽  
Trichophyton Soudanense ◽  
Ribosomal Operon

The validity of taxa around Trichophyton rubrum was evaluated by a combination of phenetic and molecular methods. Morphological and physiological features were compared to results of sequencing of the internal transcribed spacer region of the ribosomal operon, PCR fingerprinting, and amplified fragment length polymorphism analysis. The 15 species and varieties investigated (Trichophyton circonvolutum, Trichophyton fischeri,Trichophyton fluviomuniense, Trichophyton glabrum, Trichophyton gourvilii, Trichophyton kanei, Trichophyton kuryangei, Trichophyton megninii, Trichophyton pedis, Trichophyton raubitschekii, Trichophyton rodhaini,Trichophyton rubrum var. nigricans,Trichophyton soudanense, Trichophyton violaceumvar. indicum, and Trichophyton yaoundei) were reclassified or synonymized as T. rubrum or T. violaceum.

Effet de certains paramètres physico-chimiques sur les relations prédateurs–proies dans les populations de copépodes cyclopoïdes des mares temporaires d'eau douce

1986 ◽  
Vol 64 (1) ◽  
pp. 8-11
Author(s):  
Louise Vallières ◽  
Antoine Aubin
Keyword(s):  
Organic Matter ◽  
Body Size ◽  
Dissolved Oxygen ◽  
Water Temperature ◽  
Feeding Ecology ◽  
Mineral Content ◽  
Abiotic Factors ◽  
Size Class ◽  
Regression Analyses ◽  
Physical And Chemical

Copepod populations of three temporary freshwater pools (Alnus unit, Carex unit, and Molinia unit) were studied using a standard approach (species versus abiotic factors) and a holistic one (body size and feeding ecology). Multiple regression analyses of data indicate that the physical and chemical features of water (temperature, pH, dissolved oxygen, mineral content, and depth) explain 62 to 98% of the variability of carnivorous copepods, while the abundance of their prey accounts for much less. No size class of prey seems to be preferred. The abundance of decaying organic matter, typical of such pools, would result in an overabundance of prey. Predators would then be under the control of nonalimentary factors.

scholarly journals The effect of pulverising aeration on changes in the oxygen and nitrogen concentrations in water of Lake Starzyc

2015 ◽  
Vol 25 (1) ◽  
pp. 31-36 ◽  
Author(s):  
Piotr Wesołowski ◽  
Adam Brysiewicz
Keyword(s):  
Dissolved Oxygen ◽  
Nitrate Nitrogen ◽  
Ecological Status ◽  
Ammonium Nitrogen ◽  
Abiotic Conditions ◽  
The Third ◽  
Long Period ◽  
Nitrogen Concentrations ◽  
Bottom Waters ◽  
Restoration Measures

Abstract Due to poor ecological status of Lake Starzyc, lake restoration measures were undertaken in 2003 to improve aerobic conditions of near-bottom waters and to decrease phosphorus concentrations. To do this, a wind-driven pulverising aerator was installed in the lake. The aim of this study was to analyse variability of oxygen and nitrogen concentrations in lake water near the aerator in the third year of its operation and later on in the three-year-long period of the years 2008–2010. It was found that concentrations of ammonium-nitrogen, nitrate-nitrogen and dissolved oxygen near the aerator did not differ from those in sites 4 and 5, which evidenced similar abiotic conditions in analysed waters. Higher concentrations of dissolved oxygen and lower concentrations of nitrate-nitrogen were found in the years 2008–2010 than in 2005.

Russulaceous ectomycorrhizae of Abies lasiocarpa and Picea engelmannii

1997 ◽  
Vol 75 (11) ◽  
pp. 1843-1850 ◽  
Author(s):  
G. Kernaghan ◽  
R. S. Currah ◽  
R. J. Bayer
Keyword(s):  
Internal Transcribed Spacer ◽  
Fragment Length Polymorphism ◽  
Picea Engelmannii ◽  
Polymorphism Analysis ◽  
Abies Lasiocarpa ◽  
Tree Line ◽  
Chain Reaction ◽  
Internal Transcribed Spacer Region ◽  
Lactarius Deliciosus ◽  
Polymerase Chain

During a 3-year study of the ectomycorrhizal fungi of subalpine forests in the Front Ranges of the Canadian Rockies, species of Russula and Lactarius were conspicuous mycobionts of both erect and krummholz forms of Abies lasiocarpa (Hook.) Nutt. and Picea engelmannii Parry. Morphological identifications of Russulaceous mycorrhizae were confirmed by comparing polymerase chain reaction amplified ribosomal DNA (internal transcribed spacer region) with that of sporocarp tissue. Restriction fragment length polymorphism analysis using AluI, HhaI, HinfI, and RsaI gave a distinctive profile for each of 14 Russulaceous sporocarps and facilitated the identification of five mycorrhizae. Mantles formed by Lactarii (Lactarius alnicola, Lactarins caespitosus, and Lactarius deliciosus var. areolatus) exhibit characteristic laticifers and pigments comparable to the associated sporocarp. Those formed by species of Russula (R. brevipes and R. silvicola) bear distinctive cystidia or sulphovanillin-reactive cells. Key words: ITS, Lactarius, RFLP, Russula, subalpine, tree line.

scholarly journals Prevalence of Lyme Disease Borrelia spp. in Ticks from Migratory Birds on the Japanese Mainland

2000 ◽  
Vol 66 (3) ◽  
pp. 982-986 ◽  
Author(s):  
Fubito Ishiguro ◽  
Nobuhiro Takada ◽  
Toshiyuki Masuzawa ◽  
Takako Fukui
Keyword(s):  
Lyme Disease ◽  
Migratory Birds ◽  
Intergenic Spacer ◽  
23S Rrna ◽  
Polymorphism Analysis ◽  
Ixodes Persulcatus ◽  
Haemaphysalis Longicornis ◽  
Borrelia Garinii ◽  
Haemaphysalis Flava ◽  
Large Animals

ABSTRACT Borrelia sp. prevalence in ticks on migratory birds was surveyed in central Japan. In autumn, a total of 1,733 birds representing 40 species were examined for ticks. A total of 361 ticks were obtained from 173 birds of 15 species, and these ticks were immature Haemaphysalis flava (94.4%), Haemaphysalis longicornis, Ixodes columnae, Ixodes persulcatus, Ixodes turdus, and an unidentifiedIxodes species. Of these, 27 juveniles of H. flava on Turdus pallidus, Turdus cardis, or Emberiza spodocephala, 2 juveniles of I. persulcatus on T. pallidus, and 1 female H. flava molted from a T. pallidus-derived nymph were positive for the presence of Borrelia by Barbour-Stoenner-Kelly culture passages. In spring, a total of 16 ticks obtained from 102 birds of 21 species were negative for the spirochete. Isolates from 15 ticks were characterized by 5S-23S rRNA intergenic spacer restriction fragment length polymorphism analysis; all isolates were identified as Borrelia garinii with pattern B/B′ based on the previous patterning. According to the intergenic spacer sequences, 2 of 15 isolates, strains Fi14f and Fi24f, were highly similar to B. garinii strains 935T of Korea and ChY13p of Inner Mongolia, China, respectively. These findings indicate that Lyme disease-causing B. garinii may have been introduced to Japan by migratory birds from northeastern China via Korea. Additionally, a case of transstadial transmission of B. garinii from nymph to adult H. flava suggests that the infected H. flava may transmit Borrelia to large animals.

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