Water Mass Characteristics Research Articles

Characteristics of water masses and bio-optical properties of the Bering Sea shelf during 2007–2009

Characteristics of water masses and bio-optical properties of the Bering Sea shelf during 2007–2009

DISTRIBUTION OF SALINITY AND TEMPERATURE IN MUSI ESTUARY: USING VERTICAL SALINITY GRADIENT FOR ESTUARY CLASSIFICATION ZONE

Musi estuary is the mouth of the Telang and Musi rivers directly adjacent to the Bangka Strait. During flood (ebb) we see the distribution of salinity increases (decreases) which is known through the vertical distribution using CTD. The TS diagram is used to see the water mass characteristics the study area. Data-Interpolating Variational Analysis (DIVA) method is used to interpolate and visualize data from vertical and spatial temperature, salinity and density data. The classification of the Musi estuary zone is identified based on the value of the distribution of salinity, which considers the exchange of circulating salinity at flood and ebb. The density of the water mass is significantly affected by the proven graded salinity. While the temperature distribution does not change significantly with depth, the spatial distribution indicates that the temperature in the estuary is lower than in the upstream and ocean areas. The spatial distribution of salinity indicates that high salinity enters the estuary towards the river further at flood than at ebb. Salinity distribution ranges from 0.5 to 30 psu and temperatures between 29 and 33 oC from horizontal and vertical sections. The pattern of salinity distribution in the Musi river estuary was identified, consisting of three zones representing salinity conditions in the study area, namely the Polyhaline, Mesohaline, and Olygohaline zones.

Characterization of water masses around the southern Ryukyu Islands based on isotopic compositions

We investigated the water-mass structure on the Okinawa Trough and Pacific sides of the southern Ryukyu Island Arc (Yonaguni, Iriomote, and Ishigaki subareas) using the Nd isotope composition (143Nd/144Nd ratios; expressed as εNd values) of benthic foraminiferal tests in surface sediments, which reflect bottom-water composition, along with hydrogen and oxygen isotope compositions (δD and δ18O values, respectively) and physical properties (temperature and salinity) of seawater. The Okinawa Trough side has lower εNd values than the Pacific side due to continental/island material inputs characterized by relatively low εNd values. Moreover, within the Okinawa Trough, other processes control the Nd behavior of seawater and primarily affect the Yonaguni and Iriomote subareas, as follows. (1) Surface and subsurface waters are influenced by Taiwanese river discharge combined with temporospatial variations in oceanographic conditions including Kuroshio Current meandering. (2) Intermediate water is characterized by low εNd values (down to − 8.2), possibly attributable to sediment plumes and turbiditic fluxes. (3) The εNd values of bottom water indicate upwelling and vertical mixing, with composition therefore being similar to those of intermediate water. The εNd profiles are better defined on the Pacific side. High εNd values occur in surface and subsurface (< 300 m depth, potential density < 25.0 kg m−3) waters, and low values (down to − 7.0) occur in subsurface–core-intermediate water (400–600 m depth, 26–27 kg m−3). εNd values increase slightly to − 4.0 below 750 m depth and remain constant down to about 2000 m depth, below which deep water shows a slight decrease in εNd values. Intermediate and bottom/deep waters are distinguished from upper layers by their lower δD and δ18O values.

Biogeochemical Characteristics of Western Tropical Atlantic Ocean Water Masses

Water masses are commonly identified according to their conservative parameters. However, there are also studies that use non-conservative parameters, together with the conservative ones, to refine the water masses identification. The aim of this study was to analyze the chemical properties of the water masses in the western tropical Atlantic Ocean (WTAO) according to their inorganic nutrient concentration: nitrate-NO3–, phosphate-PO43–, and silicic acid-Si(OH)4, to set a regional descriptive framework of the water column in view of future comparative studies. We collected full-depth water column samples from 18 oceanographic stations from a latitudinal transect along 38°W, from 02°S to 15°N during the PIRATA-BR XVII and XVIII campaigns, in November 2017 and 2018. We have also used the regional data available from GLODAPv.2 data product to improve the water masses characterization. Six water masses were identified in the region based on their values of potential temperature, salinity, potential density, and neutral density observed in the study area according to the CTD-O2 data: Tropical Surface Water (TSW); South and North Atlantic Central Water (SACW and NACW, respectively); Antarctic Intermediate Water (AAIW); North Atlantic Deep Water (NADW); and Antarctic Bottom Water (AABW). Regarding the nutrient content within each water mass, our results showed that TSW corresponds to a surface oligotrophic water; NACW and SACW have intermediate nutrient concentration values between TSW and AAIW; AAIW showed the highest concentration of phosphate-PO43– (~ 1.35 µmol kg–1) and nitrate-NO3– (~30 µmol kg–1); AABW, on the other hand, was the water mass with the highest silicic acid-Si(OH)4 concentration (~ 80 µmol kg–1), as well as high nitrate-NO3– (~ 25 µmol kg–1) and phosphate-PO43– (~ 1.80 µmol kg–1) concentrations. Additionally, the water column between 300 and 650 m displays an increase in phosphate-PO43– concentrations north of 5oN, associated to a low dissolved oxygen area coupled to the North Equatorial Under Current (NEUC). Long-term, sustained hydrographic and ocean biogeochemistry observations are key to understand how climate change is affecting the ocean, and this study is a contribution to that.

Watermass characteristics and circulation near 110°E in the southeast Indian Ocean

We present a description of the large-scale physical oceanography of the southeast Indian Ocean to provide context for this special issue, revisiting 110°E as part of the Second International Indian Ocean Expedition. Full watermass properties and circulation are introduced based on the hydrographic observations, as well as underway systems and satellite sea surface height measurements. The 110°E line provides a window into the global meridional overturning circulation and the shallow overturning of the Indian Ocean. Measurements of change along this line provide valuable insight into the pulse of the climate system. The full depth hydrographic transects of 1963 and 2019 will provide invaluable calibration points for investigation of climate variability using the diverse observations that contribute to the Indian and global ocean observing systems.

Representative range of acoustic point source measurements in the Chukchi Sea

The use of stationary, active acoustics provides an effective approach to characterize and monitor temporal variability in the abundance and behavior of pelagic organisms, especially in seasonally ice-covered waters of high latitude marine ecosystems. However, point measurements from stationary echosounders are limited in their spatial coverage. A quantification of the spatial area represented by point measurements (i.e., representative range) is required to ensure effective biological characterization and monitoring. Here, concurrent mobile and stationary active acoustic data collected during summers of 2015 and 2017 are used to assess the representative range of fish and zooplankton density measurements from the Chukchi Ecosystem Observatory located at Hanna Shoal, Northeast Chukchi Sea. Six methods used to calculate representative ranges of backscatter means and variances resulted in representative ranges between approximately 0.3 and 86 km, depending on the year and calculation method. Such relatively large representative ranges reflect the tight bio-physical associations and large characteristic environmental length scales of the NE Chukchi Sea. Between years, up to 10-fold variations in representative ranges were attributed to interannual changes in water mass characteristics and associated species assemblages. Differences of 1–2 orders of magnitude in our calculated ranges among methods are attributed to differences in the rationale and associated assumptions of each approach. The choice of method and resulting representative range depends on monitoring goals: detection of change, mapping of spatial distributions, characterization of spatial variance, or interpolation of temporal variability over space. Our comparison of stationary acoustic to mobile surveys extends the understanding of spatiotemporal variability of marine organism distributions in the NE Chukchi Sea and informs cost-effective design of observing systems to monitor and predict impacts of environmental change.

The Spatio-Temporal Variation of Isothermal Water Mass in Jiaozhou Bay

According to the survey materials of the waters of Jiaozhou in April and August 1981, the author determined the variation range of temperature, location, and the variation process of isothermal water mass in the waters of Jiaozhou Bay. The results showed that in April, high-temperature water masses were formed in the coastal waters of Jiaozhou Bay from the northeast to the northwest, and the water temperature reached 12.82–13.70°C, where the length of the interval of seawater temperature change was 0.88°C. In August, the high-temperature water masses were formed in the coastal waters of Jiaozhou Bay from the northwest to the north with the high temperature within 27.32–27.37°C, where the length of the interval was 0.05°C. In April and August, the high-temperature water masses were formed in the northern coastal waters where the depth was 1.00–5.00 m. The heat of high-temperature water masses was sourced from solar radiation energy. In August and in the coastal waters near the estuary of Haibo River, high-temperature water masses were formed, with a high water temperature of 28.00–30.90°C. The high temperature of the Haibo River provided heat to the waters of Jiaozhou Bay. In April, a circular low-temperature water mass was formed in the central waters of the bay, and the water temperature reached a low temperature of 7.52–8.51°C, which indicated that the central waters of the bay still maintained the uniform low temperature in winter and formed a low-temperature water mass. Therefore, the innovation of this paper is to put forward the spatio-temporal variation of the isothermal water mass in Jiaozhou Bay, established the block diagram of temperature changes in the waters of Jiaozhou Bay in April and August, and further elaborated the characteristics of isothermal water masses. (1) At the same time change, both the high-temperature water mass and the low-temperature water mass have stability. (2) In different time changes, whether it is a high-temperature water mass with a relatively higher water temperature or a high-temperature water mass with a very high water temperature, the water mass is stable.

Ocean Ventilation Controls the Contrasting Anthropogenic CO2 Uptake Rates Between the Western and Eastern South Atlantic Ocean Basins

AbstractThe South Atlantic Ocean is an important region for anthropogenic CO2 (Canth) uptake and storage in the world ocean, yet is less studied. Here, after an extensive sensitivity test and method comparison, we applied an extended multiple linear regression method with six characteristic water masses to estimate Canth change or increase (ΔCanth) between 1980s and 2010s in the South Atlantic Ocean using two meridional transects (A16S and A13.5) and one zonal transect (A10). Over a period of about 25 years, the basin‐wide ΔCanth was 3.86 ± 0.14 Pg C decade−1. The two basins flanking the Mid‐Atlantic Ridge had different meridional patterns of ΔCanth, yielding an average depth‐integrated ΔCanth in the top 2000 m of 0.91 ± 0.25 mol m−2 yr−1 along A16S on the west and 0.57 ± 0.22 mol m−2 yr−1 along A13.5 on the east. The west‐east basin ΔCanth contrasts were most prominent in the tropical region (0–20°S) in the Surface Water (SW), approximately from equator to 35°S in the Subantarctic Mode Water (Subantarctic Mode Water (SAMW)), and all latitudes in the Antarctic Intermediate Water (AAIW). Less ΔCanth in the eastern basin than the western basin was caused by weaker ventilation driven by SAMW and AAIW formation and subduction and stronger Antarctic Bottom Water (AABW) formation in the former than the latter. In addition to the spatial heterogeneity, Canth increase rates accelerated from the 1990s to the 2000s, consistent with the overall increase in air‐sea CO2 exchange in the South Atlantic Ocean.

Simulation and Statistical Analysis on the Transport Process of Salt Water Mass from the North Branch in the Yangtze River Estuary

Based on the analysis of measured data, a two-dimensional hydrodynamic Salinity Transport Model in the Yangtze River estuary is established by using Mike21 model. This model is used to study the average daily distribution and changing patterns of the saline water mass in the South Branch that are from the North Branch while only the saltwater intrusion from the North Branch is considered. It determines the intrusion process of saline water mass from the North Branch and the area that are affected by saline water intrusion. In addition, through the research of salt water mass core moving down and salinity variation in the south branch channel, the flow pattern and mechanism of salt water mass in the south branch channel are revealed. The saltwater intrusion from the North Branch has a great impact on the vertical, horizontal and vertical salinity fields of the Yangtze River estuary. The variation trend of statistical variance, deviation and standard deviation of the half month time series of salinity at each point along the route is basically the same, showing a gradual decreasing trend towards the downstream. Those show that the salinity dispersion is larger in the upstream estuary and lower outside the estuary. Combined with the salinity kurtosis and skewness, the deviation degree and direction of the salinity distribution at each point along the route can be judged, which can reflect the comprehensive process of runoff, tidal current and topography. Therefore, the kurtosis and skewness statistics can effectively describe the law of transport and dynamic characteristics of intrusion saline water masses in the Yangtze River Estuary.

Habitat of Argentine squid (Illex argentinus) paralarvae in the southwestern Atlantic

Illex argentinus is one of Argentina’s most important commercial species and sustains one of the most important cephalopod fisheries worldwide. Catches, and presumably population abundances, show strong interannual fluctuations, probably forced by processes which occur during the species’ early life history. However, knowledge of paralarvae ecology and the influence of the environment on larval survival are fragmentary and limited. In this work, we describe the habitat of I. argentinus paralarvae caught in 4 research cruises between 34° and 42°S, taking into account information on seasonal transport of paralarvae by currents, chlorophyll a concentrations, characteristics of water masses and water column structure. Argentine squid paralarvae habitat is environmentally complex. Paralarvae occur in the plankton when the biological production in the area is relatively low but offshore transport is at a minimum, thus decreasing the chances of the paralarvae being exported to places unsuitable for survival. We discuss how the synchronization of the squid reproductive cycle relates to these environmental events and may improve paralarvae survival and recruitment.

Features of the Distribution of Chlorophyll-a Concentration along the Western Coast of the Novaya Zemlya Archipelago in Spring

In spring 2016, the thermohaline characteristics of water masses and the distribution of chlorophyll-a concentration in the pelagic zone of the eastern part of the Barents Sea were studied. For the first time, in the conditions of an abnormally warm year and the absence of ice cover, a complex of hydrobiological works was carried out on a section crossing the Barents Sea from south to north along the western coast of the Novaya Zemlya archipelago. High concentrations of chlorophyll-a &gt; 1 ˂ 6 mg/m3 at all stations of the transect indicate a stage of spring bloom in the successional cycle of microalgae. Significant differences in the content of chlorophyll-a in waters of various origins were revealed. The highest concentrations of chlorophyll-a corresponded to Arctic surface water (5.56 mg/m3). Slightly lower values were observed in the transformed Atlantic waters of the Novozemelskoe and Kolguevo–Pechorskoe currents (3.53 ± 0.97–3.71 ± 1.04 mg/m3), and the lowest was in the Barents waters (1.24 ± 0.84–1.45 ± 1.13 mg/m3).

Water mass characteristics in the Makassar Strait and Flores Sea in August-September 2015

Makassar Strait is one of the main entrance points for Indonesian Throughflow (ITF), which carries water from the North Pacific through Flores Sea. ITF has a crucial role as a branch of the thermohaline circulation system in controlling the Indonesian marine ecosystem as well as regional climate variability. This research aims to describe the structure and stratification of water mass and the distribution parameters of chemical physics in the area of Makassar Strait up to Flores Sea at the month of August-September 2015 as much as 8 casts of data CTD is obtained from the result of expedition STOKAS BRKP-KKP using research vessel Baruna Jaya VIII. Research results indicate that the origin of the water mass from the North Pacific is still dominant in the thermocline layer (NPSW) also in the intermediate (NPIW). On average the depth of mixed water layers 60m (± 12.59) with temperature variation between 25.62 – 27.65 C, the average depth of thermocline 130m (±43.65) with temperatures between 18.29 °C – 21.88 °C. Temperature, pH, and dissolved oxygen distribution tends to be higher in the northern region. Fluorescence distribution in the south is higher than the northern region due to inputs from the Makassar upwelling.

2021년 봄 남해 수괴 분포와 식물플랑크톤 군집의 공간분포 특성

봄 한국 남해 수괴 및 식물플랑크톤 군집의 공간분포를 파악하기 위해 2021년 4월 15개 정점의 표층과 엽록소 a 최댓 층(CML)을 대상으로 현장조사를 실시하였다. 결과, 봄 남해의 수괴는 고염수 특성인 쓰시마난류가 지배하였고, 일부에서 한국 고유연안수가 관찰되었지만, 저염 특성의 중국 대륙연안수는 관찰되지 않았다. 엽록소 a 농도는 0.20-2.53 μgL<SUP>-1</SUP> 범위에서 0.86±0.58 μgL<SUP>-1</SUP>로 변화하여, 연안수에서 1.0 μgL<SUP>-1</SUP> 이상 높았고, 쓰시마난류에서 0.5 μg L<SUP>-1</SUP> 이하로 낮았다. 식물플랑크톤 종 조성은 43속 74종으로 규조류가 68.4%, 와편모조류가 28.4%, 그리고 규질편모조류 및 유글레나조류가 각 1.6%를 보였다. 표층 현존량은 1.4-150.8 cells mL<SUP>-1</SUP> 범위에서 41.1±57.1 cells mL<SUP>-1</SUP>로, 연안부에서 100 cells mL<SUP>-1</SUP> 이상 높고, 쓰시마난류에서 5-20 cells mL<SUP>-1</SUP> 이하로 낮았다. 그리고 표층의 연안 전선 및 일부 해역에서 유기물 점액질이 높게 관찰되었다. 표층 10% 이상 우점율의 우점종은 Pseudo-nitzschia delicatissima, Leptocylindrus danicus, Chaetoceros socialis 및 Nitzschia sp./small size 등이며, CML은 L. danicus가 우점율 54.6%로 최우점종, Karenia sp. cf. mikimotoi가 우점율 12.9%로 차우점하였다. 상관분석 및 주성분 분석에서 봄 남해 식물플랑크톤 군집은 연안수에서 군집다양성이 높았지만, 쓰시마난류에서 낮은 특성으로 수괴의 영향에 따라 특성을 달리하는 것으로 나타났다.

Retraction Note: Precipitation anomaly in rainy season based on high resolution SAR and regulation of blood glucose in aerobic exercise for adolescents

This paper contains a large number of radar data information, analyzes the radar scattering characteristics of water masses in different imaging areas, such as quiet open area, wave area, agricultural area, and compares with the application of high-resolution SAR image extraction algorithm. We also use the data analysis of the data center to explore the evolution characteristics of the high-level and low-level atmospheric circulation and water vapor transport field before and after the beginning and end of the rainy season precipitation anomaly in Southwest China. Then, the low-frequency evolution characteristics of the precipitation anomaly series in the rainy season in Southwest China are analyzed, and eight phases are divided according to the 20–60 day intraseasonal oscillation of precipitation, which provides convenience for the transportation of low-frequency water and air. Thirdly, the method is applied to aerobic exercise. However, people with low blood glucose regulation are generally overweight, and drug treatment itself cannot change their health. Exercise has always been the most effective way of muscle strength training. If aerobic exercise and resistance exercise are combined, it can be combined exercise training. If the sequence and duration are long enough, excess sugar in the body can be burned. Training resistance can be used to improve muscle function and maintain strength. Therefore, the process of aerobic exercise is very important for people with poor blood glucose regulation, and it can also provide more meaningful and targeted concept development for the treatment of diabetes. In order to promote the development and application of SAR map, this paper studies the relationship between abnormal precipitation in rainy season and blood glucose regulation of teenagers during aerobic exercise, and applies it to the study of SAR map.

Influence of river water expansion on the spatial distribution of chlorophyll-a in the Kara Sea

In August-September 2013, the thermohaline characteristics of water masses and the concentration of chlorophyll-a were studied in the Kara Sea. Expansion of surface desalinated water to the north, according to the central type, influenced the spatial distribution of chlorophyll. Beyond the boundary of the Stock Front, the average pigment concentration in the surface layer was 0.45±0.16 mg/m3. In the area affected by the surface desalinated layer, most of the chlorophyll (0 m – 1.04±0.27 mg/m3, 5 m – 0.97±0.27 mg/m3, 10 m – 0.69±0.36 mg/m3) was localized within this layer (10-17 m). High concentrations were observed in the bays of the Kara Sea. The maximum concentration of chlorophyll-a in the surface layer of the Ob Bay was 4.22 mg/m3, in the Yenisei Bay – 3.22 mg/m3.

Impact of climate variability of the Western Tropical Pacific on maximum salinity water in the South China Sea

Salinity observations in the Vietnamese upwelling area in June 2016 indicated a significant increase in the salinity of the maximum salinity water (MSW). The source of MSW inflow into the South China Sea (SCS) is a mixture of the Western North Pacific Central Water and the North Pacific Equatorial Water. Although the East Asian winter monsoon is correlated with both the El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO), the mean salinity of MSW is only spuriously lag correlated to the PDO, but highly correlated to all tropical climate modes (except El Niño Modoki) with a time lag up to 7 months. Composite analyses indicate that the modulation of ENSO by a PDO in a positive phase results in optimal inflow conditions. A comparison of two post-El Niño years with different PDO polarity (negative in 2003 and positive in 2016) shows that the dominant driver is the variability in outgoing long-wave radiation (OLR) and in zonal wind in the tropics. In 2003, enhanced convective activity over the West Pacific warm pool resulted in a cyclonic circulation. In 2016, convective activity was weak and an anticyclonic circulation was intensified, which transported the saltier North Pacific Equatorial Water into the SCS. This observed increase in the salinity of MSW requires a modification of the previous definitions of characteristic water masses, which is presented here. The question of whether or not the increase in MSW salinity is a transient phenomenon cannot be answered. It might be possible that the increase in salinity is related to global warming.

Optical Properties and Biochemical Indices of Marine Particles in the Open Mediterranean Sea: The R/V Maria S. Merian Cruise, March 2018

A rich data set on particulate matter optical properties and parameters (beam attenuation coefficient, volume concentration, particle size and PSD slope), accompanied by measurements of biochemical indices (particulate organic carbon, particulate nitrogen and their stable isotopic composition) was obtained from the surface to deep waters across the Mediterranean Sea, in March-April 2018. A decrease of beam attenuation coefficients, total particle volume concentrations, particulate organic carbon and nitrogen concentrations was noted towards the eastern Mediterranean Sea (EMed) in comparison to the western Mediterranean Sea (WMed). LISST-derived optical properties were significantly correlated with water mass characteristics. Overall, the most turbid water mass identified in the Mediterranean Sea was the Surface Atlantic water (AW), and the most transparent was the Transitional Mediterranean Water (TMW) in the Cretan Sea, whereas a general decrease in particulate matter concentration is observed from the WMed towards the EMed. Relatively depleted δ13C-POC values in the particle pool of the open Mediterranean Sea can be attributed to contribution from terrestrial inputs, mainly via atmospheric deposition. Throughout the entire water column, a significant positive correlation between particle beam attenuation coefficient and particulate organic carbon concentration is observed in the open Mediterranean Sea. Such relationship suggests the predominance of organic particles with biogenic origin. POC concentration and particle median diameter D50 are significantly and negatively correlated both in the WMed and the EMed Sea, confirming that small particles are POC-rich. At depth, a prominent decrease of most measured parameters was observed, with the exception of particle median diameter that increased substantially in the EMed towards the deep sea, suggesting potentially enhanced aggregation processes. The low particle size distribution slope ξ observed in the EMed, corresponding to larger particle populations, supports the above notion. Basin-wide Rayleigh-type isotopic fractionation in vertical profiles of δ15N-PN across the Mediterranean Sea, underlines the differences in the trophic characters of the two sub-basins and highlights the role of circulation changes on biogeochemical parameters and the redistribution of particulate matter as a source of nutrients in the water column.

RETRACTED ARTICLE: Precipitation anomaly in rainy season based on high resolution SAR and regulation of blood glucose in aerobic exercise for adolescents

This paper contains a large number of radar data information, analyzes the radar scattering characteristics of water masses in different imaging areas, such as quiet open area, wave area, agricultural area, and compares with the application of high-resolution SAR image extraction algorithm. We also use the data analysis of the data center to explore the evolution characteristics of the high-level and low-level atmospheric circulation and water vapor transport field before and after the beginning and end of the rainy season precipitation anomaly in Southwest China. Then, the low-frequency evolution characteristics of the precipitation anomaly series in the rainy season in Southwest China are analyzed, and eight phases are divided according to the 20–60 day intraseasonal oscillation of precipitation, which provides convenience for the transportation of low-frequency water and air. Thirdly, the method is applied to aerobic exercise. However, people with low blood glucose regulation are generally overweight, and drug treatment itself cannot change their health. Exercise has always been the most effective way of muscle strength training. If aerobic exercise and resistance exercise are combined, it can be combined exercise training. If the sequence and duration are long enough, excess sugar in the body can be burned. Training resistance can be used to improve muscle function and maintain strength. Therefore, the process of aerobic exercise is very important for people with poor blood glucose regulation, and it can also provide more meaningful and targeted concept development for the treatment of diabetes. In order to promote the development and application of SAR map, this paper studies the relationship between abnormal precipitation in rainy season and blood glucose regulation of teenagers during aerobic exercise, and applies it to the study of SAR map.

Methodological approaches to phytomediation of productive processes in chalk quarry reservoirs of Belarus

As concerns field work, bathymetric measurements as well as measurements of physical and chemical parameters of water were conducted, and samples were collected for laboratory tests, which included quantitative and qualitative hydrobiological analyses concerning e.g. the abundance, biomass and species composition of phytoplankton, seston and chlorophyll. Six water bodies (situated in flooded chalk pits) with different morphometric parameters (areas ranging from 2.22 to 37.67 ha, depths ranging from 5.1 to 23.0 m and nearshore shallow areas ranging from 0.39 to 2.64 ha) and with different bioproductive characteristics of water mass (eg. transparency – 1.2–6.8 m, phosphates – 0.002–0.110 mg/dm3, nitrates – 0.040–0.600 mg NO-3/dm3, biomass of phytoplankton – 0.075–1.801 mg/dm3, seston – 0.73–5.56 mg/dm3) were selected for the study of the phytomediation mechanism. The specificity of structural and functional relationships between the abiotic and biotic components of productive-macrophyte and productive-phytoplankton reservoirs is determined. It was established that macrophyte water bodies in flooded chalk pits are able to maintain their basic production and trophic characteristics in the long term under anthropogenic influence conditions. An algorithm is proposed for calculating the level (E – 89.58–115.13), productivity index (K – 11.16–54.15) and gradient (E – 2.1–9.8) of eutrophication of chalk (limestone) quarry reservoirs using the morphometric specificity indicator of the trophogenic epilimnial layer (Sτ – 0.05–0.270). The revealed dependence of the productive and functional organization and trophic status of a quarry reservoir on the morphometric features of a technogenic basin is proposed to be used in the design of sustainably functioning macrophyte-type aquatic systems at the stage of mining and engineering reclamation. The possibility of creating ecologically sustainable lake-type aquatic systems on the site of resource depleted chalk quarries in the process of phytomediation of productive processes is substantiated. Research on innovative methods of reclamation of flooded chalk pits is in line with several sustainable development goals.

Winter-Spring Development of the Zooplankton Community Below Sea Ice in the Arctic Ocean

The impact of the rapidly changing Arctic on zooplankton community structure and seasonal behaviour is not yet understood. Here we examine 6 months of under-ice zooplankton observations from the N-ICE2015 expedition (January to June 2015) in the Nansen Basin and on the Yermak Plateau north of Svalbard. Stratified sampling in the water column was done with MultiNet during the entire expedition, and sampling in the upper 5 m below sea ice was performed during April-May by divers using a hand-held net. Hydrographic conditions were dominated by northward-flowing warm and saline Atlantic Water at intermediate depth, and southward-flowing cold Polar Surface Water in the upper 100 m. The mesozooplankton was dominated by copepods. Most numerous were the small ubiquitousOithona similisin the upper 200 m, withMicrocalanusspp. andTriconia borealisfurther down the water column.Calanus finmarchicusdominated among theCalanusspecies whileMetridia longawas also numerous. The most abundant deep-water copepods wereParaeuchaetaspp. andSpinocalanusspp. Arrow worms (Chaetognatha) and comb jellies (Ctenophora) were the most numerous non-copepods. The mesozooplankton community was more dependent on surrounding water mass characteristics, such as salinity and depth, than geographical location. Algal food availability, which was closely linked to seasonality, explained the community changes seen in surface waters in May and June due to seasonal ascent and recruitment. Seasonal changes from winter to spring mostly involved an increase in the herbivorousC. finmarchicusand its nauplii in the upper 200 m of the water column coinciding with the peak of the phytoplankton bloom in late May. The Yermak Plateau and adjacent Nansen Basin were characterised by oceanic North Atlantic and Arctic species, many of which are deep water specialists. Despite the late onset of the spring bloom due to consolidated sea ice, both North Atlantic and Arctic species successfully reproduced in the study area. This explains the species-rich mesozooplankton community in this region as opposed to the less productive central Arctic Ocean. Future prospects of less sea ice and earlier onset of the bloom will likely be positive for the overall secondary production by both Arctic and boreal zooplankton in this region.