scholarly journals A GIS based approach to determine the changes of water hyacinth (Eichhornia crassipes) cover and it’s relation with Lesser Whistling Teal (Dendrocygna javanica) assemblage at Santragachi Wetland, West Bengal

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Masuma Begam ◽  
Sudin Pal ◽  
Niranjita Mitra ◽  
Asitava Chatterjee ◽  
Anirban Mukhopadhyay ◽  
...  
Keyword(s):  
Water Hyacinth ◽  
Eichhornia Crassipes ◽  
Bird Species ◽  
Open Water ◽  
Water Area ◽  
Google Earth ◽  
Open Water Area ◽  
Marked Decline ◽  
The Relationship ◽  
Migratory Waterbirds

The present investigation is conducted to study the year wise (2011 to 2018) changes of water hyacinth (Eichhornia crassipes) cover at Santragachi Lake a Wetland under National Wetland Conservation Programme of India. Further the relationship between water hyacinth cover and the most abundant migratory waterbirds of Satragachi, Lesser Whistling Teal (LWT; Dendrocygna javanica) is assessed because this bird species is fully depended on water hyacinth mat for their roosting. The study comprises of eight satellite images procured from Google earth (2011 to 2018) to explore this relationship. A marked decline in the number of LWT at Santragachi wetland is observed in the year of 2017 and 2018. It is very interesting fact that from 2017-2018, the water hyacinth mat of this wetland is almost cleared before winter and the result of cluster analysis supports this fact. Significant positive correlation is also observed within LWT number and water hyacinth cover area (r = 0.7481 at p< 0.05) along with the total perimeter (r = 0.8648 at p< 0.05) of the water hyacinth islands at Santragachi wetland. However, open water area is also needed for diving, swimming, food searching for the LWT and other waterbirds. Therefore, more study is needed to optimize the clearing operations, focused on optimizing shape and size of water hyacinth islands for proper management of the waterbirds habitat. 

Towards a Model of Regional Vessel Near-miss Collision Risk Assessment for Open Waters based on AIS Data

2019 ◽  
Vol 72 (06) ◽  
pp. 1449-1468 ◽  
Author(s):  
Weibin Zhang ◽  
Xinyu Feng ◽  
Yong Qi ◽  
Feng Shu ◽  
Yijin Zhang ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Safety Management ◽  
Open Water ◽  
Water Area ◽  
Assessment System ◽  
Near Miss ◽  
Collision Risk ◽  
Accurate Analysis ◽  
Open Water Area ◽  
Temporal Features

The absence of a regional, open water vessel collision risk assessment system endangers maritime traffic and hampers safety management. Most recent studies have analysed the risk of collision for a pair of vessels and propose micro-level risk models. This study proposes a new method that combines density complexity and a multi-vessel collision risk operator for assessing regional vessel collision risk. This regional model considers spatial and temporal features of vessel trajectory in an open water area and assesses multi-vessel near-miss collision risk through danger probabilities and possible consequences of collision risks via four types of possible relative striking positions. Finally, the clustering method of multi-vessel encountering risk, based on the proposed model, is used to identify high-risk collision areas, which allow reliable and accurate analysis to aid implementation of safety measures.

scholarly journals Regulation of Vegetation and Evapotranspiration by Water Level Fluctuation in Shallow Lakes

Water ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 2651
Author(s):  
Qiang Liu ◽  
Liqiao Liang ◽  
Xiaomin Yuan ◽  
Sirui Yan ◽  
Miao Li ◽  
...  
Keyword(s):  
Water Level ◽  
Open Water ◽  
Water Area ◽  
Water Level Fluctuation ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Water Evaporation ◽  
Level Fluctuation ◽  
Open Water Area ◽  
Annual Scale

Water level fluctuations play a critical role in regulating vegetation distribution, composition, cover and richness, which ultimately affect evapotranspiration. In this study, we first explore water level fluctuations and associated impacts on vegetation, after which we assess evapotranspiration (ET) under different water levels. The normalized difference vegetation index (NDVI) was used to estimate the fractional vegetation cover (Fv), while topography- and vegetation-based surface-energy partitioning algorithms (TVET model) and potential evaporation (Ev) were used to calculate ET and water evaporation (Ep). Results show that: (1) water levels were dramatically affected by the combined effect of ecological water transfer and climate change and exhibited significant decreasing trends with a slope of −0.011 m a−2; and (2) as predicted, there was a correlation between water level fluctuation at an annual scale with Phragmites australis (P. australis) cover and open-water area. Water levels also had a controlling effect on Fv values, an increase in annual water levels first increasing and then decreasing Fv. However, a negative correlation was found between Fv values and water levels during initial plant growth stages. (iii) ET, which varied under different water levels at an annual scale, showed different partition into transpiration from P. australis and evaporation from open-water area and soil with alterations between vegetation and open water. All findings indicated that water level fluctuations controlled biological and ecological processes, and their structural and functional characteristics. This study consequently recommends that specifically-focused ecological water regulations (e.g., duration, timing, frequency) should be enacted to maintain the integrity of wetland ecosystems for wetland restoration.

scholarly journals Autumn bacterioplankton of the open waters and coastal part of the Barents Sea

2021 ◽  
Vol 12 (3-2021) ◽  
pp. 36-45
Author(s):  
A.V. Vashchenko ◽  
Keyword(s):  
Coastal Waters ◽  
Barents Sea ◽  
Open Water ◽  
Bottom Layer ◽  
Water Area ◽  
Northeastern Part ◽  
Autumn Season ◽  
Open Water Area ◽  
The Barents Sea

The paper presents the results of microbiological studies carried out in the Motovsky Bay (2017) and the northeastern part of the Barents Sea (2020) in October. It was shown that, with comparable values of abundance, the biomass of bacterioplankton in open waters was slightly higher than in coastal waters. The quantity was 148–717 thousand cells/ml in Motovsky Bay and 170–957 thousand cells/ml in the open water area. The biomass was 7.26–29.07 mg/m3 in Motovsky Bay and 9.71–51.39 mg/m3 in the open water area. The maximum values were in the 0–50 m layer,the minimum – in the bottom layer in both areas. Those results supplement the existing understanding of bacterioplanktons development and distribution in the Barents Sea in the autumn season.

Changes in phytoplankton concentration now drive increased Arctic Ocean primary production

Science ◽  
2020 ◽  
Vol 369 (6500) ◽  
pp. 198-202 ◽  
Author(s):  
K. M. Lewis ◽  
G. L. van Dijken ◽  
K. R. Arrigo
Keyword(s):  
Sea Ice ◽  
Primary Production ◽  
Arctic Ocean ◽  
Open Water ◽  
Water Area ◽  
The Arctic ◽  
Carbon Export ◽  
Phytoplankton Primary Production ◽  
Open Water Area ◽  
The Arctic Ocean

Historically, sea ice loss in the Arctic Ocean has promoted increased phytoplankton primary production because of the greater open water area and a longer growing season. However, debate remains about whether primary production will continue to rise should sea ice decline further. Using an ocean color algorithm parameterized for the Arctic Ocean, we show that primary production increased by 57% between 1998 and 2018. Surprisingly, whereas increases were due to widespread sea ice loss during the first decade, the subsequent rise in primary production was driven primarily by increased phytoplankton biomass, which was likely sustained by an influx of new nutrients. This suggests a future Arctic Ocean that can support higher trophic-level production and additional carbon export.

Studying the bottom landscapes of Lake Ladoga with use of underwater vehicles

2020 ◽  
Author(s):  
Vladimir Anokhin ◽  
Dina Dudakova ◽  
Mikhael Dudakov
Keyword(s):  
Coastal Zone ◽  
High Efficiency ◽  
Open Water ◽  
Underwater Vehicles ◽  
Water Area ◽  
Gps Tracking ◽  
Lake Ladoga ◽  
Underwater Video ◽  
Open Water Area ◽  
First Time

&lt;p&gt;In 2019, the Institute of Limnology of the Russian Academy of Sciences (IL RAS) carried out geological and geomorphological studies of the bottom and shores of Lake Ladoga within the framework of the State project of the IL RAS No. 0154-2018-0003 / 5. The research included the study of the bottom landscapes of Lake Ladoga with help of a series of underwater vehicles Limnoscout, designed and assembled at the IL RAS.&lt;/p&gt;&lt;p&gt;Underwater photo and video of the bottom in the coastal zone was carried out by the Limnoscout-230 vehicle from a boat. Each video filming polygon &amp;#160;included 2 continuous video profiles of 1-2 km normal to the shore, and 1 connecting profile parallel to the shore of 200-400 m, in the deep part.&lt;/p&gt;&lt;p&gt;Underwater video filming of the bottom in the open water area of &amp;#8203;&amp;#8203;the lake was carried out by the Limnoscout-50 vehicle from the board of the r/v &amp;#8220;Poseidon&amp;#8221;, by point diving, in which the bottom was shot within a radius of 2-4 m from the dive point.&lt;/p&gt;&lt;p&gt;Maximal deep of studies was 117 m.&lt;/p&gt;&lt;p&gt;All underwater surveys were accompanied by echo-sounding surveys and GPS tracking.&lt;/p&gt;&lt;p&gt;In total, 24 underwater video filming&amp;#160; polygons in the coastal zone and 23 underwater video filming points in the open water area of &amp;#8203;&amp;#8203;the northern part of Lake Ladoga were worked out.&lt;/p&gt;&lt;p&gt;The collected extensive photo and video materials made it possible to make preliminary typology of the bottom landscapes of Lake Ladoga and evaluate their condition.&lt;/p&gt;&lt;p&gt;Several new important facts of the structure of the bottom of Lake Ladoga and biota distribution were discovered, in particular:&lt;/p&gt;&lt;p&gt;- For the first time on the bottom of Lake Ladoga, an invasive species of mollusk Dreissena polymorpha was discovered, which in other large lakes has a significant impact on ecosystems.&lt;/p&gt;&lt;p&gt;- For the first time at the bottom in the northern part of the lake, outlets of presumably Riphean sandstones were discovered, which significantly complements the geological picture of the area.&lt;/p&gt;&lt;p&gt;- For the first time at the bottom in the northeastern part of the lake an abnormally deep occurrence of coarse deposits was discovered, which is likely to be associated with the intense activity of glaciers.&lt;/p&gt;&lt;p&gt;The use of underwater photo and video in combination with traditional methods for studying the bottom landscapes of Lake Ladoga has shown the high efficiency of these methods. The studies will be continued.&lt;/p&gt;

scholarly journals Sea ice sensitivity to the parameterisation of open water area

2010 ◽  
Vol 3 (2) ◽  
pp. 3-9 ◽  
Author(s):  
Zeliang Wang ◽  
Youyu Lu ◽  
Daniel G Wright ◽  
Frederic Dupont
Keyword(s):  
Sea Ice ◽  
Open Water ◽  
Water Area ◽  
Open Water Area

scholarly journals MICROPLASTICS POLLUTION MONITORING IN BOTTOM SEDIMENTS OF THE SEVASTOPOL REGION RECREATION ZONES

2021 ◽  
pp. 91-101
Author(s):  
E.N. Sibirtsova ◽  
◽  
A.V. Temnykh ◽  
M.I. Silakov ◽  
◽  
...  
Keyword(s):  
Bottom Sediments ◽  
World Ocean ◽  
Open Water ◽  
Dry Weight ◽  
Water Area ◽  
Pollution Monitoring ◽  
Open Water Area ◽  
Water Edge ◽  
Order Of Magnitude ◽  
Frag Ments

A study of the concentration of microplastic pollution (MP) in the bottom sediments of the water areas adjoining recreation zones (RZ) of the Sevastopol region in 2018 - 2020 was carried out. An increase in MP was registered practically in all areas, the average values of MP concentration were 13.4 items•kg-1 dry weight. As for the shape of microplastics (MPs) particles, the maximum share was made up by frag-ments (50-83%), fibers were also numerous (33%). A significant increase in the concentration of MP on the 0-20 m section of the underwater coastal slope from the water edge was recorded in zones with an open water area and presence of a cliff. The revealed level of MP is comparable to that in the Mediterra-nean, Caspian, Baltic Seas, but an order of magnitude lower than in other regions of the World Ocean.

scholarly journals Overexploitation, Recovery, and Warming of the Barents Sea Ecosystem During 1950–2013

2021 ◽  
Vol 8 ◽  
Author(s):  
Torstein Pedersen ◽  
Nina Mikkelsen ◽  
Ulf Lindstrøm ◽  
Paul E. Renaud ◽  
Marcela C. Nascimento ◽  
...  
Keyword(s):  
Primary Production ◽  
Trophic Level ◽  
Barents Sea ◽  
Open Water ◽  
Water Area ◽  
Climatic Conditions ◽  
Ecosystem Dynamics ◽  
Ecosystem Structure ◽  
Open Water Area ◽  
The Barents Sea

The Barents Sea (BS) is a high-latitude shelf ecosystem with important fisheries, high and historically variable harvesting pressure, and ongoing high variability in climatic conditions. To quantify carbon flow pathways and assess if changes in harvesting intensity and climate variability have affected the BS ecosystem, we modeled the ecosystem for the period 1950–2013 using a highly trophically resolved mass-balanced food web model (Ecopath with Ecosim). Ecosim models were fitted to time series of biomasses and catches, and were forced by environmental variables and fisheries mortality. The effects on ecosystem dynamics by the drivers fishing mortality, primary production proxies related to open-water area and capelin-larvae mortality proxy, were evaluated. During the period 1970–1990, the ecosystem was in a phase of overexploitation with low top-predators’ biomasses and some trophic cascade effects and increases in prey stocks. Despite heavy exploitation of some groups, the basic ecosystem structure seems to have been preserved. After 1990, when the harvesting pressure was relaxed, most exploited boreal groups recovered with increased biomass, well-captured by the fitted Ecosim model. These biomass increases were likely driven by an increase in primary production resulting from warming and a decrease in ice-coverage. During the warm period that started about 1995, some unexploited Arctic groups decreased whereas krill and jellyfish groups increased. Only the latter trend was successfully predicted by the Ecosim model. The krill flow pathway was identified as especially important as it supplied both medium and high trophic level compartments, and this pathway became even more important after ca. 2000. The modeling results revealed complex interplay between fishery and variability of lower trophic level groups that differs between the boreal and arctic functional groups and has importance for ecosystem management.

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