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

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.

Autumn bacterioplankton of the open waters and coastal part of 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.

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

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.

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

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.

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

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.

Lake Chad hydrological cycle under current climate change

&lt;p&gt;In a near future, the Sahara and Sahelian regions could experience more rainfall than today as a result of climate change. Wetter conditions in the hottest and driest place of the planet today raise the question of whether the near future might hold in store environmental transformations, particularly in view of the growing human-induced climate, land-use and land-cover changes. Reflecting an enhancement of the global hydrological cycle under warmer conditions, some experiments provide support for the notion of a strengthening of the monsoon in the future and more rainfall in central Sahel and Sahara. However, some remote forcing could counterbalance the decadal trend. Modeling experiments suggest that the freshwater discharge coming from Greenland melting could significantly impact the sea surface temperature of North Atlantic and induce a decrease in Sahel rainfall for the next decades, remaining left open the question how Sahara will be in a warmer climate?&lt;/p&gt;&lt;p&gt;By chance, Lake Chad, located at the southern edge of the Sahara, is recognized for being the best site in Africa for deciphering hydrological and climate change. After being ranked at the world&amp;#8217;s sixth largest inland water body with an open water area of 25,000 km&lt;sup&gt;2&lt;/sup&gt; in the 1960s, it shrunk dramatically at the beginning of the 1970s and reached less than 2000 km&lt;sup&gt;2&lt;/sup&gt; during the 1980s, decreasing by more 90% in area. Because it provides food and water to 50 millions of people, it becomes crucial to observe precisely its hydrological cycle during the last 20 years.&lt;/p&gt;&lt;p&gt;Here by using a new multi-satellite approach combined with ground-based observations, we show that Lake Chad extent has remained stable during the last two decades, slightly increasing at 14,000 km&lt;sup&gt;2&lt;/sup&gt;. We extend further this reconstruction by adding new data from the hydrological year 2019-2020, which is considered at an extreme in precipitation recorded over the Sahel. Moreover, since the 2000s, groundwater which contributes to 70% of Lake Chad&amp;#8217;s annual water storage, is increasing due to water supply provide by its two main tributaries draining a catchment area 610,000 km&lt;sup&gt;2&lt;/sup&gt; wide. Because the current climate change seems to be characterize by a higher interannual variability affecting from year to year the amount of precipitation during the rainy season and increasing the vulnerability of the economy of the region mainly based of agropastoral activities, we investigate the yearly cycle and see how it is impacted the hydrological cycle of Lake Chad and changed over time.&lt;/p&gt;

Summer valley-floor snowfall in Taylor Valley, Antarctica from 1995–2017

In polar, coastal areas like Taylor Valley, snowfall is predicted to increase under warming conditions as reduced sea ice increases open water area and evaporation potential, thereby creating conditions that would facilitate precipitation. Taylor Valley is a mosaic of glaciers, valley-bottom ice-covered lakes, ephemeral streams and dark, rocky soils. Ecosystems are both light- and nutrient-limited and rely on seasonally available liquid water. Although Taylor Valley receives minimal snowfall annually, light snow cover during summer months reduces radiation for primary productivity and slows melting by increasing the local albedo. Snowfall has been measured at four sites in Taylor Valley since 1995. Daily photographs at the Lake Hoare station in the central portion of the valley record snow cover since 2007 and augment the automated precipitation measurements. Here, we focus on valley-floor snowfall due to its effect on ecosystems in the valley-bottom lakes and streams. Precipitation increased by 3 mm water equivalent (w.e.) a−1 from 1995 to 2009, then decreased by 1 mm w.e. a−1 through 2017. Since 2009, annual snowfall in Taylor Valley ranges from 1 to 30 mm w.e. High snowfall during the Spring near the coast is indicative of high summer snowfall at the more inland Lake Bonney station (r2 = 0.66; p < 0.05). In contrast, the average fraction of days with snow on the ground tripled at Lake Hoare after 2011, primarily during Spring and Fall. Fall snow persistence at Lake Hoare has been increasing by ~ 1 day per year since the start of the record in 2007, although Spring snow cover exhibits no trend. In agreement with previous studies, regression analysis revealed no correlation of snow cover or snowfall with sea ice extent or mean temperatures. Strong seasonality and interannual variability underscores the complexity of precipitation and snow persistence controls in Taylor Valley. In regions where snow cover contributes more to the radiation budget than the hydrologic budget, photographs are the most reliable method for monitoring precipitation. The results of this study highlight the importance of continued monitoring of precipitation throughout Taylor Valley. The establishment of coastal and inland snow cover monitoring stations would augment point observations of snow cover and add spatial complexity to our present understanding of the expected hydrologic and ecosystem response to climate change in Taylor Valley.

Changes in phytoplankton concentration now drive increased Arctic Ocean primary production

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

&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;

Response of Zooplankton Indices to Anthropogenic Pressure in the Catchment of Field Ponds

As methods for assessing the environmental conditions in ponds are still not well developed, I studied zooplankton to identify a response of community indices to abiotic, biotic, and habitat type in two types of ponds differing in the level of human stress. Ponds of low human alterations (LowHI) harbored generally richer communities and a higher share littoral zooplankton, whose occurrence was associated with higher water transparency and complex macrophyte habitat, particularly the presence of hornworts and charoids. In high human-impact ponds (HighHI) planktonic communities prevailed. Their distribution was mainly related to the open water area and fish presence. Anthropogenic disturbance was also reflected in the frequency of rare species, which were associated with LowHI ponds. Higher diversity of zooplankton increased the chance for rare species to occur. Despite the fact that the majority of rare species are littoral-associated, they had no prevalence towards a certain ecological type of plants, which suggests that any kind of plant cover, even macrophytes typical for eutrophic waters (e.g., Ceratophyllum demersum) will create a valuable habitat for conservation purposes. Thus, it is postulated that a complex and dense cover of submerged macrophytes ought to be maintained in order to improve the ecological value of small water bodies.