scholarly journals Density and nitrifying potential of indigenous bacterial community in mangrove and seagrass in the north of Vietnam

2020 ◽  
Vol 20 (4) ◽  
pp. 437-445
Author(s):  
Le Thanh Huyen ◽  
Dao Thi Anh Tuyet ◽  
Le Minh Hiep ◽  
Nguyen Tien Dat ◽  
Ha Thi Binh ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Average Density ◽  
Nitrifying Bacteria ◽  
Seagrass Beds ◽  
The North ◽  
Indigenous Microorganism ◽  
Dry Seasons ◽  
Quang Ninh ◽  
Sampling Times ◽  
Dry And Rainy Seasons

Density and nitrification potential of indigenous microorganism in mangroves (Tien Yen - Quang Ninh and Bang La - Hai Phong) and seagrass (Ha Coi, Dam Ha - Quang Ninh and Tam Giang - Thua Thien Hue) in the north of Vietnam were evaluated through 4 sampling times in the dry and rainy seasons in the years of 2017-2019. The analytical results showed that the average density of nitrifying bacteria was 4.6 ± 1.8 × 102 MPN/ml, in which the density in mangroves tended to be higher than that in the seagrass beds (P < 0.05) in both the rainy and dry seasons. The average nitrifying rate was 2.7 ± 0.6 µgN/g wet soil/hour, in which the rate in mangroves tended to be higher than that in seagrass beds in the rainy season (P < 0.05). Nitrifying density and rate are not only correlated with substrate concentration but also with other environmental factors such as P-PO4, BOD5, total phosphate in sediment and total bacterial density.

scholarly journals Density and de-nitrifying potential of indigenous bacterial assemblage in mangrove and seagrass in the North of Vietnam

2021 ◽  
Vol 21 (2) ◽  
pp. 223-232
Author(s):  
Huyen Le Thanh ◽  
Anh Tuyet Dao Thi ◽  
Hiep Le Minh ◽  
Dat Nguyen Tien ◽  
Binh Ha Thi ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Nitrifying Bacteria ◽  
Seagrass Beds ◽  
Bacterial Assemblage ◽  
The North ◽  
Mangrove Ecosystems ◽  
Sulfur Oxidizing ◽  
Dry Seasons ◽  
Quang Ninh ◽  
Sampling Times

This study assessed the density and de-nitrification potential of indigenous microorganisms in mangroves and seagrass beds in northern Vietnam through two mangrove ecosystems in Tien Yen - Quang Ninh and Bang La - Hai Phong and three seagrass beds in Ha Coi and Dam Ha - Quang Ninh and Tam Giang - Thua Thien Hue. The analysis results of 4 sampling times in rainy and dry seasons during 2017–2019 showed that the density of de-nitrifying bacteria ranged from (1.0 × 102)–(4.6 × 103) MPN/mL, averaging 1.1 ± 0.3 × 103 MPN/mL. The density in mangroves was higher than that in seagrass (a = 0.05). De-nitrification rates ranged from 0.0 µgN/wet to 69.0 µgN/wet soil g/hour, averaging 18.4 ± 7.4 µgN/wet soil g/hour. The rate at the experiments added 0.5 mgN/L in seagrass was higher than that in the mangrove. The density and rate of de-nitrification were significantly correlated with many environmental factors, especially density of sulfur-oxidizing bacteria, the density of nitrifying bacteria, pH, Eh, Nts, N-NH4, P- PO4 and BOD5.

scholarly journals Suspended sediment distribution under varied currents in the largest river-connected lake of China

2017 ◽  
Vol 18 (3) ◽  
pp. 994-1004 ◽  
Author(s):  
Hua Wang ◽  
Yijun Zhao ◽  
Fengnian Zhou ◽  
Huaiyu Yan ◽  
Yanqing Deng ◽  
...  
Keyword(s):  
Flow Pattern ◽  
Suspended Sediment ◽  
Flow Patterns ◽  
Field Investigation ◽  
Gravity Flow ◽  
Shear Stresses ◽  
Sediment Distribution ◽  
Back Flow ◽  
The North ◽  
Dry Seasons

Abstract Poyang Lake was selected as the research area. Based on laboratory experiment, field investigation and numerical simulation, the spatial distributions of suspended sediment (SS) under the gravity-flow, jacking-flow and back-flow patterns were quantitatively analysed. An annular flume experiment was conducted to determine the critical starting shear stresses of the sediments in the flood and dry seasons. By numerical experiment, the SS transport under different flow patterns was explored. Several results stand out. (1) The critical starting shear stresses of the sediments in the flood and dry seasons were 0.35 N·m−2 and 0.29 N·m−2, respectively. (2) Due to the strongest flow disturbance and scouring effect, SS under the gravity-flow pattern was characterized by the highest loads. The lowest SS was observed during the jacking-flow pattern, which could be attributed to the lowest water level gap between the lake and external rivers. The loads ranged from 0.053 kg·m−3 to 0.068 kg·m−3. (3) Under the back-flow pattern, SS in the north lake was evidently influenced by the Yangtze River, and the mean value was approximately 0.12 kg·m−3. With the gradually weakened back-flow impact, the SS load was decreased from the north to the middle of the lake.

Investigation on Eutrophication Level for Gucheng Lake by the Model of Butterfly Catastrophe

2013 ◽  
Vol 726-731 ◽  
pp. 2051-2056
Author(s):  
Hua Wang ◽  
Yi Yi Zhou ◽  
Feng Qiang Ji
Keyword(s):  
Fuzzy Membership ◽  
Ecological Indicator ◽  
Pollution Load ◽  
The South ◽  
Flood Season ◽  
The North ◽  
Gucheng Lake ◽  
Dry Seasons ◽  
Membership Value ◽  
Water Eutrophication

Based on the field measured results in the typical periods of flood season and dry season of Gucheng Lake, the present eutrophication levels of the lake were investigated by the Model of Butterfly Catastrophe, in which series of the environmental factors were considered including the ecological indicator of chlorophylla, the nutrient indicator of total nitrogen and total phosphorus, and the physical index of water transparency. The results showed that: the water eutrophication levels of Gucheng Lake were mal-distributed in space and time; the lake eutrophication tendency in flood seasons were more obvious than that in dry seasons; the eutrophication levels in the south part of the lake were relatively lower than that in the north and the average comprehensive mutation of fuzzy membership value in the south was about 0.3006 in the dry seasons. Due to the increased pollution load and the hydrodynamic conditions, the eutrophication degree in the estuary areas were higher and the fuzzy membership value was close to 0.235, achieving the medium eutrophication level.

Bacterial Community Profiling of Plastic Litter in the Belgian Part of the North Sea

2015 ◽  
Vol 49 (16) ◽  
pp. 9629-9638 ◽  
Author(s):  
Caroline A. De Tender ◽  
Lisa I. Devriese ◽  
Annelies Haegeman ◽  
Sara Maes ◽  
Tom Ruttink ◽  
...  
Keyword(s):  
Bacterial Community ◽  
North Sea ◽  
The North ◽  
Community Profiling ◽  
The North Sea

Woodeaton

1917 ◽  
Vol 7 ◽  
pp. 98-119 ◽  
Author(s):  
M. V. Taylor
Keyword(s):  
Sea Level ◽  
The South ◽  
North East ◽  
The North ◽  
Dry Seasons ◽  
The Village

Woodeaton is a small Oxfordshire parish, four miles north-east of the centre of Oxford city and a little west of the wide marshy level of the ‘Plain of Otmoor.’ It stands on a low, detached and rounded hill, 315 feet above sea level, and 120 feet above Otmoor. In old days it must have been difficult of access, for Otmoor spreads away to the east of it; low pastures along the river Cherwell close it in on the north and west, while south-westwards, too, the land is low-lying and marshy. Even to the south-east a marshy hollow separates it from the wooded slopes of Beckley and Elsfield, once part of Shotover Forest. However, the well-known Roman road which connects Dorchester (Oxon.) with Alchester, and which passes along the foot of Shotover, and traverses the village of Beckley and the plain of Otmoor, runs within two miles of Woodeaton; in dry seasons it may have helped those who wished to get to the spot.

Crue éclair de juillet 1996 dans la région du Saguenay (Québec). 2. Impacts sur les sédiments et le biote de la baie des Ha! Ha! et du fjord du Saguenay

1999 ◽  
Vol 56 (11) ◽  
pp. 2136-2147 ◽  
Author(s):  
Émilien Pelletier ◽  
Bruno Deflandre ◽  
Christian Nozais ◽  
Guglielmo Tita ◽  
Gaston Desrosiers ◽  
...  
Keyword(s):  
Flash Flood ◽  
Biological Indicators ◽  
Average Density ◽  
Benthic Habitat ◽  
Sediment Layer ◽  
Pioneer Species ◽  
The North ◽  
Geological Processes ◽  
Saguenay Fjord ◽  
Interstitial Waters

Several million tons of sediments and various debris were transported to the north arm of the Saguenay Fjord and the Baie des Ha! Ha! following the torrential rains and accompanying flash flood of July 1996 in the Saguenay region (Québec). The flood deposits covered the indigenous sediments and buried the benthic community. The objective of this work is to determine the best chemical and biological indicators of the changes that occurred in the benthic habitat of the fjord. The new sediment layer is poor in organic matter but rich in detrital carbonates and contains low mercury and lead concentrations reflecting the absence of industrial contamination. Ongoing geological processes leading to the re-establishment of steady-state conditions were evidenced by measurements of porosity, redox potential (Eh), and salinity of interstitial waters taken a few weeks and a few months after the events. The meiofauna were severely affected with a massive reduction of the average density of organisms relative to values recorded before the flood, but recolonisation was already in progress 1 year after the flood. Important losses of macrobenthic species were recorded in 1997 relative to 1996. However, the abundance and the diversity of the polycheate taxa were higher in 1997, indicating a recolonisation of the new sediment layer by pioneer species.

scholarly journals Zooplankton biomass of reservoirs in different trophic conditions in the State of São Paulo, Brazil

2006 ◽  
Vol 66 (1b) ◽  
pp. 337-350 ◽  
Author(s):  
S. Sendacz ◽  
S. Caleffi ◽  
J. Santos-Soares
Keyword(s):  
Sao Paulo ◽  
Zooplankton Biomass ◽  
Dry Season ◽  
The State ◽  
Numerical Density ◽  
Calanoid Copepods ◽  
Trophic Conditions ◽  
Density Data ◽  
Dry Seasons ◽  
Dry And Rainy Seasons

This paper reports on a study involving an estimate of the biomass of rotifers, cladocerans, and cyclopoid and calanoid copepods found in reservoirs in different trophic conditions, comparing and relating numerical density data and pointing out differences between the dry and rainy seasons. In terms of numerical densities, both reservoirs were dominated by rotifers, although cladocerans represented a higher biomass in the oligotrophic environment in both seasons. In the eutrophic environment, higher biomass values were found for cyclopoids during the dry season and for cladocerans during the rainy one. Different biomass patterns were observed relating to both the trophic conditions and the rainy and dry seasons.

Occurrence of the grasshopper pest Zonocerus variegatus (L.) (Orthoptera: Pyrgomorphidae) in south-western Nigeria in relation to the wet and dry seasons

1980 ◽  
Vol 70 (4) ◽  
pp. 621-633 ◽  
Author(s):  
W. W. Page
Keyword(s):  
Dry Season ◽  
Seasonal Abundance ◽  
Secondary Peak ◽  
Rapid Decline ◽  
Arid Zones ◽  
Zonocerus Variegatus ◽  
Wet Season ◽  
The North ◽  
Dry Seasons ◽  
Peak Abundance

AbstractAn investigation into the seasonal abundance of Zonocerus variegatus (L.) around Ibadan, Nigeria, showed that hatching occurs between October and March and peak abundance is in late November. Adults occur almost throughout the year. Oviposition takes place between March and October or possibly November, with a peak in April. Eggs laid in March and April hatch in October and November after a diapause, while those laid from June onwards do not appear to enter diapause. Thus eggs laid in June and July hatch at the same time as those laid in March and April. Parasitism by the sargophagid fly Blaesoxipha filipjevi (Rod.) during March and April results in a rapid decline in adult numbers which may be followed by a secondary peak in adult numbers when nymphs, which are present at the same time and are rarely parasitised, reach adult stage. Oviposition resulting from such a peak does not produce a secondary peak in hatching as this coincides with hatching from earlier layings. The fungus Entomophthora grylli plays an important role in controlling the abundance of nymphs and adults during the dry season despite the intermittent nature of the attacks. During the wet season, the fungus is able to germinate and disperse more readily, thus keeping the numbers of the insects low. It is concluded that there is one generation of Z. variegatus a year, with a peak in population coinciding with the dry season (November-March). It is suggested from the results that the grasshopper may have originated in the semi-arid zones of the north.

scholarly journals Aerial Rivers and Lakes: Looking at Large-Scale Moisture Transport and Its Relation to Amazonia and to Subtropical Rainfall in South America

2012 ◽  
Vol 25 (2) ◽  
pp. 543-556 ◽  
Author(s):  
Josefina Moraes Arraut ◽  
Carlos Nobre ◽  
Henrique M. J. Barbosa ◽  
Guillermo Obregon ◽  
José Marengo
Keyword(s):  
South America ◽  
Moisture Transport ◽  
Large Scale ◽  
Precipitable Water ◽  
Trade Wind ◽  
Strong Increase ◽  
The North ◽  
The Andes ◽  
Dry Seasons ◽  
Southern Amazonia

Abstract This is an observational study of the large-scale moisture transport over South America, with some analyses on its relation to subtropical rainfall. The concept of aerial rivers is proposed as a framework: it is an analogy between the main pathways of moisture flow in the atmosphere and surface rivers. Opposite to surface rivers, aerial rivers gain (lose) water through evaporation (precipitation). The magnitude of the vertically integrated moisture transport is discharge, and precipitable water is like the mass of the liquid column—multiplied by an equivalent speed it gives discharge. Trade wind flow into Amazonia, and the north/northwesterly flow to the subtropics, east of the Andes, are aerial rivers. Aerial lakes are the sections of a moisture pathway where the flow slows down and broadens, because of diffluence, and becomes deeper, with higher precipitable water. This is the case over Amazonia, downstream of the trade wind confluence. In the dry season, moisture from the aerial lake is transported northeastward, but weaker flow over southern Amazonia heads southward toward the subtropics. Southern Amazonia appears as a source of moisture to this flow. Aerial river discharge to the subtropics is comparable to that of the Amazon River. The variations of the amount of moisture coming from Amazonia have an important effect over the variability of discharge. Correlations between the flow from Amazonia and subtropical rainfall are not strong. However, some months within the set of dry seasons observed showed a strong increase (decrease) occurring together with an important increase (decrease) in subtropical rainfall.

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