Seasonal and inter-annual temperature variability in the bottom waters over the western Black Sea shelf

Long-term changes in the state of the Bottom Shelf Water (BSW) on the Western shelf of the Black Sea are assessed using analysis of intra-seasonal and inter-annual temperature variations. For the purpose of this study the BSW is defined as such shelf water mass between the seabed and the upper mixed layer (bounded by the σθ = 14.2 isopycnal) which has limited ability to mix vertically with oxygen-rich surface waters during the warm season due to formation of a seasonal pycnocline. A long-term time series of temperature anomalies in the BSW is constructed from in-situ observations taken over the 2nd half of the 20th century. The BSW is shown to occupy nearly half of the shelf area during the summer stratification period (May–November).The results reveal a warm phase in the 1960s/70s, followed by a cold phase between 1985 and 1995 and a further warming after 1995. The transition between the warm and cold periods coincides with a regime shift in the Black Sea ecosystem. While it was confirmed that the memory of winter convection is well preserved over the following months in the deep sea, the signal of winter cooling in the BSW significantly reduces during the warm season. The potential of the BSW to ventilate horizontally during the warm season with the deep-sea waters is assessed using isopycnic analysis of temperature variations. It is shown that temperature in the BSW is stronger correlated with the temperature of Cold Intermediate Waters (CIW) in the deep sea than with the severity of the previous winters, thus indicating that the isopycnal exchanges with the deep sea are more important for inter-annual/inter-decadal variability of the BSW on the western Black Sea shelf than effects of winter convection on the shelf itself

Horizontal dispersion in shelf seas: High resolution modelling as an aid to sparse sampling

The ability of a hydrodynamic model to reproduce the results of a dye release experiment conducted in a wide shelf sea environment was investigated with the help of the Massachusetts Institute of Technology general circulation model (MITgcm). In the field experiment a fluorescent tracer, Rhodamine WT, was injected into the seasonal pycnocline, and its evolution was tracked for two days using a towed undulating vehicle equipped with a fluorometer and a CTD. With a 50. m horizontal resolution grid, and with three different forcings initialized in the model (viz: tides, stationary current, and wind stress on the free surface), it was possible to replicate the dye patch evolution quite accurately. The mechanisms responsible for the enhancement of horizontal dispersion were investigated on the basis of the model results. It was found that enhancement of the dye dispersion was controlled by vertically sheared currents that, in combination with vertical diapycnal mixing, led to a substantial increase in the "effective" horizontal mixing. The values of "effective" horizontal mixing found from the model runs were in good agreement with those obtained from in-situ data, and the probable degree to which the observational techniques undersampled the dye patch was revealed

Long term trends in the sea surface temperature of the Black Sea

There is growing understanding that recent deterioration of the Black Sea ecosystem was partly due to changes in the marine physical environment. This study uses high resolution 0.25° climatology to analyze sea surface temperature variability over the 20th century in two contrasting regions of the sea. Results show that the deep Black Sea was cooling during the first three quarters of the century and was warming in the last 15–20 years; on aggregate there was a statistically significant cooling trend. The SST variability over the Western shelf was more volatile and it does not show statistically significant trends. The cooling of the deep Black Sea is at variance with the general trend in the North Atlantic and may be related to the decrease of westerly winds over the Black Sea, and a greater influence of the Siberian anticyclone. The timing of the changeover from cooling to warming coincides with the regime shift in the Black Sea ecosystem

Behavioural responses of a large, benthic elasmobranch to catch-and-release angling

Funding: This work was supported by a PhD Studentship at the University of St Andrews, jointly funded by NatureScot via the Marine Alliance for Science and Technology for Scotland (MASTS), and the Centre for Research into Ecological and Environmental Modelling. Data were collected as part of research funded by NatureScot (project 015960) and Marine Scotland (projects SP004 and SP02B0) via the Movement Ecology of Flapper Skate project. Additional funding was provided from MASTS and Shark Guardian.Catch-and-release angling is widespread, but the impacts of this practice for captured individuals are understudied, especially among elasmobranchs. Studies on sub-lethal behavioural impacts are particularly sparse, despite their importance for the interpretation of biologging data and for assessments of species’ tolerance to capture. In this study, the behavioural responses of flapper skate (Dipturus intermedius) to catch-and-release angling were described for the first time, using archival observations (depth and temperature) for 21 tag deployment/retrieval events and five recreational angling events that occurred during tagged individuals’ time at liberty from charter vessels off the west coast of Scotland in 2016–17. During capture (8–50 minutes), the changes in depth and temperature experienced by individuals typically exceeded natural variability. Post-release, behavioural change was apparent from visual inspection, regression and functional data analysis of the time series. Immediately following release, movements into deeper water and short periods of low vertical activity (usually 1–2 hours in duration) were common. However, overall average vertical activity was typically around 38% higher in the 12 hours following release than in undisturbed activity. A small number of individuals (n = 3, 14%) exhibited irregular post-release behaviour in the form of rapid, transient re-ascents towards the surface following release. Collectively, the evidence for limited, short-term behavioural changes suggests that flapper skate behaviour is relatively resilient to catch-and-release angling from charter vessels, but irregular post-release behaviour in 14% of individuals is sufficiently notable to indicate that further research is required on the impacts of this practice. This study clearly demonstrates the value of biologging data and behavioural analyses for examining the impacts of disturbance and separating ‘disturbed’ and ‘undisturbed’ behaviours in studies of animal movement.Publisher PDFPeer reviewe

Detection of CO\u3csub\u3e2\u3c/sub\u3e leakage from a simulated sub-seabed storage site using three different types of pCO\u3csub\u3e2\u3c/sub\u3e sensors

© 2015 Elsevier Ltd. All rights reserved. This work is focused on results from a recent controlled sub-seabed in situ carbon dioxide (CO2) release experiment carried out during May-October 2012 in Ardmucknish Bay on the Scottish west coast. Three types of pCO2 sensors (fluorescence, NDIR and ISFET-based technologies) were used in combination with multiparameter instruments measuring oxygen, temperature, salinity and currents in the water column at the epicentre of release and further away. It was shown that distribution of seafloor CO2 emissions features high spatial and temporal heterogeneity. The highest pCO2 values (~1250 μatm) were detected at low tide around a bubble stream and within centimetres distance from the seafloor. Further up in the water column, 30-100 cm above the seabed, the gradients decreased, but continued to indicate elevated pCO2 at the epicentre of release throughout the injection campaign with the peak values between 400 and 740 μatm. High-frequency parallel measurements from two instruments placed within 1 m from each other, relocation of one of the instruments at the release site and 2D horizontal mapping of the release and control sites confirmed a localized impact from CO2 emissions. Observed effects on the water column were temporary and post-injection recovery took O2, and when it was influenced by purposefully released CO2. Use of a hydrodynamic circulation model, calibrated with in situ data, was crucial to establishing background conditions in this complex and dynamic shallow water system

Glider observations of enhanced deep water upwelling at a shelf break canyon: a mechanism for cross-slope carbon and nutrient exchange

Using underwater gliders we have identified canyon driven upwelling across the Celtic Sea shelf-break, in the vicinity of Whittard Canyon. The presence of this upwelling appears to be tied to the direction and strength of the local slope current, which is in itself highly variable. During typical summer time equatorward flow, an unbalanced pressure gradient force and the resulting disruption of geostrophic flow can lead to upwelling along the main axis of two small shelf break canyons. As the slope current reverts to poleward flow, the upwelling stops and the remnants of the upwelled features are mixed into the local shelf water or advected away from the region. The upwelled features are identified by the presence of sub-pycnocline high salinity water on the shelf, and are upwelled from a depth of 300 m on the slope, thus providing a mechanism for the transport of nutrients across the shelf break onto the shelf

Оценка in vitro влияния аллогенной костной матрицы на характеристики мезенхимальных стромальных клеток из жировой ткани при создании комбинированных тканеинженерных конструкций

The aim of the study was to evaluate in vitro the effect of native and deproteinized compact and spongy allogenic bone matrices on the characteristics of adipose mesenchymal stromal cells (ASC) in combined tissue engineering.Material and Methods. 24 samples of native and deproteinized compact and spongy bone were examined, which were exposed to mechanical treatment, modeling, followed by sterilization of the samples by ionizing radiation and bacteriological control of sterilization. Some of the samples underwent deproteinization. The characterized cultures of human ASC were used as test cultures to assess the interaction with the bone samples. The Cytation-5 fluorescent imager and Hoechst 3334 fluorochromes (BD Pharmingen™) and calcein (Calcein AM, BD Pharmingen™) were used to characterize the degree of adhesion, migration, and viability of ASC on bone matrix samples. Matrix cytotoxicity was evaluated by MTT assay on days 1 and 7 of extraction.Results. The bone matrix samples are characterized by the absence of cytotoxicity (rank 1). ASC demonstrated good adhesion and migration on any surface of the bone matrix and preservation of cell viability during 7 days of observation. Nuclei sizes of the cells adhered to the deproteinized bone matrix of the spongy structure increased by 25–30% compared to other samples. The cells on deproteinized bone matrix had greater size (the size of the cells from nuclei 8.8 to 11.5 μm, the average size of cells nuclei from an 86.3 μm to 129,0 μm, the average perimeter of the cells nuclei from 30.7 μm to 40.7 μm) than in the native bone matrix samples.Conclusion. The results of the study of various allogeneic bone matrices demonstrate that deep purification of the bone matrix determines the absence of cytotoxicity and the most favorable conditions for the adhesion, migration, proliferation and viability of ASC. Also makes it possible to use tissue engineering based on bone matrices of different structures. Deproteinized spongy bone matrices are best suited for this purpose.Цель исследования — оценка in vitro влияния нативной и депротеинизированной компактной и губчатой аллогенных костных матриц на характеристики мезенхимальных стромальных клеток из жировой ткани (МСК ЖТ) для создания эффективной комбинированной тканеинженерной конструкции.Материал и методы. Исследовали 24 образца нативной и депротеинизированной компактной и губчатой костной ткани, которые подвергали механической обработке, моделированию с последующей стерилизацией образцов ионизирующим излучением и бактериологическим контролем стерилизации. Часть образцов проходила процедуру депротеинизации. В качестве тестовых культур для оценки взаимодействия с исследуемыми образцами костной ткани использовали охарактеризованные культуры МСК ЖТ человека. Для характеристики выраженности адгезии, миграции и жизнеспособности МСК на образцах костного матрикса использовали флуоресцентный имиджер Cytation-5 и флуорохромы Hoechst 3334 (BD Pharmingen™) и кальцеин (Calcein AM, BD Pharmingen™). Цитотоксичность матриц оценивали с помощью МТТ-теста после 1 и 7 сут. экстракции.Результаты. Образцы исследуемых костных матриц характеризуются отсутствием цитотоксичности (ранг 1). Это сопровождается хорошей адгезией и миграцией МСК ЖТ на любой поверхности костного матрикса и сохранением жизнеспособности клеток в течение 7 сут. наблюдения. В большей степени изменения касаются увеличения размеров ядер клеток, адгезированных на депротеинизированной костной матрице губчатой структуры, на 25–30% по сравнению с величиной аналогичного параметра на других образцах. При этом размеры клеток на депротеинизированной костной матрице несколько больше (величина ядер клеток с 8,8 до 11,5 мкм, средняя площадь ядер клеток от 86,3 мкм до 129,0 мкм, средний периметр ядер клеток с 30,7 мкм до 40,7 мкм), чем на образцах нативной костной матрицы.Заключение. Результаты исследования различных аллогенных костных матриц демонстрируют, что глубокая степень очистки костной матрицы определяет отсутствие цитотоксичности и наиболее благоприятные условия для адгезии, миграции, пролиферации и жизнеспособности МСК ЖТ. Это обусловливает возможность создания тканеинженерных конструкций на основе матриц из костной ткани различной структуры. Наилучшим образом для этой цели подходят депротеинизированные губчатые костные матрицы

Implant related complications in patients operated on with expandable pedicle screws and technical solutions for revision surgery

BackgroundIt is reported that expandable pedicle screws are effective and a safer alternative to pedicle screws with cement augmentation application in patients with poor bone quality.AimsTo study implant related complications associated with expandable pedicle screws application and to propose revision options in case of implant failure.Methods A retrospective analysis of a heterogeneous cohort of patients operated on because of traumatic injuries and degenerative diseases of the lumbar spine and thoracolumbar junction was performed. 42 patients with osteopeny or osteoporosis were enrolled, the duration of the follow-up accounted for 18 months. Cases with implant failure (loosening and screw breakage) were registered and revision pedicle screws fixation was performed.Results Out of 42 enrolled patients 3 were presented with implant failure (a screw loosening in one case and a screw rupture and loosening in 2 cases). The attempts to remove retained fractured fragments were unsuccessful, therefore, alternative bypass creation and a direct screw placement into a retained fractured fragment were carried out and suggested as an alternative strategy to osteotomy with a fractured screw fragment removal.ConclusionIn case of rupture, expandable screws have a poor feasibility for a revision pedicle screw fixation because of fractured fragments strong anchorage in bone. The alternative bypass for a revision screw without fractured fragment removal or tapping and direct screw placement into retained expanded fragment of a screw are less invasive alternatives to osteotomy that can help overcome the discussed issue