The “MetaCopepod” project: Designing an integrated DNA metabarcoding and image analysis approach to study and monitor the diversity of zooplanktonic copepods and cladocerans in the Mediterranean Sea

The timely and accurate analysis of marine zooplankton diversity is a challenge in ecological and monitoring studies. Morphology-based identification of taxa, which requires taxonomy experts, is time consuming and cannot provide accurate resolution at species level in several cases (e.g. immature stages, cryptic species, broken specimens). The “MetaCopepod” project is aimed at overcoming these limitations by developing a high-throughput and cost effective methodology that integrates DNA metabarcoding and image analysis. Utilizing the accuracy of DNA metabarcoding in species recognition and the quantitative results of image analysis, zooplankton diversity (mainly of copepods and cladocerans) is assessed both qualitatively (species' composition) and quantitatively (abundance, biomass and size-distribution). To achieve this goal, bulk zooplankton samples are first scanned and analyzed with ZooImage and then massively sequenced for a selected fragment of the mitochondrial 16S rRNA gene. Through a bioinformatic pipeline, sequences are compared to a reference genetic database, constructed within the project, and identified at species- level. The methodology was calibrated by using both mock and taxonomically identified samples and demonstrated on samples collected monthly from monitoring stations across the Mediterranean Sea. It is currently optimized for higher integration and accuracy and is expected to become a powerful tool for monitoring zooplankton in the long term and for early warning of bioinvasions and other ecosystem change

Investigation of stationary trajectories with associated milling by spur gears

When milling in a steady state, unlike, for example, turning, there are periodic elastic deformation displacements of the tool relative to the workpiece along the machining path. Instead of an equilibrium point, we consider a certain closed trajectory of elastic deformations. This is the trajectory to which all the trajectories approach asymptotically, while forces and deformations that mutually affect each other through the mechanism of changing the area of the cut-off layer are redistributed. The article proposes a mathematical apparatus and algorithms for calculating the trajectory of establishing a stationary state. The case of milling with spur mills is considered. A mathematical description of the “basic” dynamic model of the associated milling by the side teeth of the end mills for the complete non-stationary nonlinear connection formed by the milling process is presented. It differs from known models by considering spatial oscillations, taking into account the dependence of forces on the cutting speeds, taking into account the rates of elastic deformation displacements, taking into account the retardation of forces with respect to deformation displacements, and also by nonlinear damping caused by forces acting on the trailing edge of the tool. In addition, periodic changes in the parameters and the formation of the surface at the previous contact of the tooth are taken into account

Abundance of mesozooplankton during the long-tern mesozooplankton analysis in Sevastopol Bay from 1976 to 2003

The present dataset includes results of analysis of 227 zooplankton samples taken in and off the Sevastopol Bay in the Black Sea in 1976, 1979-1980, 1989-1990, 1995-1996 and 2002-2003. Exact coordinates for stations 1, 4, 5 and 6 are unknown and were calculated using Google-earth program. Data on Ctenophora Mnemiopsis leidyi and Beroe ovata are not included. Juday net: Vertical tows of a Juday net, with mouth area 0.1 m**2, mesh size 150µm. Tows were performed at layers. Towing speed: about 0.5 m/s. Samples were preserved by a 4% formaldehyde sea water buffered solution. Sampling volume was estimated by multiplying the mouth area with the wire length. The collected material was analysed using the method of portions (Yashnov, 1939). Samples were brought to volume of 50 - 100 ml depending upon zooplankton density and mixed intensively until all organisms were distributed randomly in the sample volume. After that 1 ml of sample was taken by calibrated Stempel-pipette. This operation was produced twice. If divergence between two examined subsamples was more than 30% one more subsample was examined. Large (> 1 mm body length) and not abundant species were calculated in 1/2, 1/4, 1/8, 1/16 or 1/32 part of sample. Counting and measuring of organisms were made in the Bogorov chamber under the stereomicroscope to the lowest taxon possible. Number of organisms per sample was calculated as simple average of two subsamples meanings multiplied on subsample volume. Total abundance of mesozooplankton was calculated as sum of taxon-specific abundances and total abundance of Copepods was calculated as sum of copepods taxon-specific abundances

Mesozooplankton composition and distribution in Izmir Bay, Aegean Sea: With special emphasis on copepods

Mesozooplankton are a diverse group of heterotrophic organisms and an important component of the food web in transferring energy to higher trophic levels. Studies on mesozooplankton composition and distribution in Izmir Bay, Aegean Sea, are scarce and they included mostly the data from early 2000s. The present study provides updated information on the status of this important component of the bay. Mesozooplankton composition and distribution were studied in June and November 2017, February and April 2018 from eight stations situated along a transit from inner to the outer region in Izmir Bay, Aegean Sea. Samples were collected vertically by using WP2 net with 200 mu m mesh size. The total mesozooplankton abundance varied from 708 ind. m(-3) in June to 42045 ind. m(-3) in April. The high abundance of polychaeta larvae, cirriped nauplii, copepods and appendicularians were observed in the inner region, while the abundance of echinoderm larvae, chaetognaths, siphonophores and pteropods were high in the central and outer regions. The contribution of copepod to the total mesozooplankton abundance was the highest (>= 56 %) in February in all regions. The lowest contributions were in November (32 %) in the inner region and in June in the central (27 %) and the outer (29 %) regions. A total of 38 copepod species were identified during the study period. Acartia clausi successively dominated the copepod community in February and April. Oithona nana was the most abundant oithonid in February and April, while O. davisae in November. O. similis, Paracalanus parvus, Oncaea media group, Temora stylifera and Centropages typicus were abundant in the central and outer regions of the bay. Four new species, Parvocalanus crassirostris, Pseudodiaptomus marinus, Centropages ponticus and Oithona tenuis were detected for the first time in the bay. The reported abundance of C. ponticus, P. crassirostris and P. marinus, together with their spatial and temporal occurrence in the present study, indicate that these species have already settled in Izmir Bay. Results indicate that the mesozooplankton distribution and composition were associated mostly with salinity and depth rather than temperature in group and species level. Substantial changes in the copepod species composition have been observed over decades in Izmir Bay. The number and abundance of smaller and egg-sac carrying non-indigenous species appear to be increasing over time in the bay. (C) 2022 Elsevier B.V. All rights reserved

State and Trends of Zooplankton Community in the Coastal Black Sea Ecosystems of Varna and Sevastopol Bays

The paper focuses on the comparison of the zooplankton quality and quantity parameters in two vulnerable coastal areas Sevastopol Bay (Northern Black Sea) and system Varna Bay-Varna Lake- Beloslav Lake (Western Black Sea). The objectives are: 1) to reveal the structure of zooplankton communities in both areas; and 2) to compare the temporal variability of plankton fauna structure in the coastal ecosystems of Northern and Western Black Sea. The numerical abundance of zooplankton of Varna and Beloslav Lakes showed high density during the whole period compared with Varna and Sevastopol Bays. Zooplankton structure demonstrated a similarity in the investigated regions, evident in: the dominance of N. scintillans at the end of the 1980s-early 1990s; increased percentage share of Meroplankton after 1990s till nowadays; similar changes in species diversity (mostly in Copepoda and Cladocera groups). Diversity and evenness indices in average for a year were rather similar for the three regions and varied from 1.99 (in the lakes 1990-1991) to 3.30 (in Varna Bay, 1997). Fairly better was the ecological state of the zooplankton community in Varna and Sevastopol Bays compared to the Lakes. Cluster analysis differentiated between two main groups (Varna Bay and Sevastopol Bay) with 50 % similarity of Bray-Curtis. More faunal similarities appear between coastal areas of the Black Sea compared to the more polluted lakes watersJRC.H.3-Global environement monitorin

Temporal Fluctuations of Zooplankton Communities in Varna Bay (Western Black Sea) and Sevastopol Bay (Northern Black Sea): A Comparative Study

Human activities are mainly concentrated in the coastal regions which appeared less capable to assimilate the adverse effects of those threats. The consequences of foremost pressures to European coastal areas, respectively to the Black Sea such as water pollution, eutrophication, loss of biological diversity, introduction of non-indigenous species, over fishing, land use and landscape deterioration, and coastal erosion have been already well documented (Moncheva et al., 2001, Prodanov et al., 2001, Gubanova et al., 2002, Kamburska, 2004, Kideys et al., 2005, Oguz, 2005, Kamburska et al., 2006). Insufficiency of comparable time series data across the coastal areas of the Black Sea is still a key problem for a comprehensive assessment of the marine environment. The present study is focused on the comparison of the zooplankton quality and quantity parameters in two vulnerable coastal areas Sevastopol Bay (Northern Black Sea) and Varna Bay (Western Black Sea). It aims to assess the current state and long-term trends of zooplankton communities of the two regions of the Black Sea and the response to anthropogenic and environmental shifts. The objectives are: 1) to reveal the structure of zooplankton community in both areas; 2) to contrast temporal variability of the plankton fauna structure in the coastal ecosystems of Northern and Western Black Sea. Observations are based on the long-term data for mesozooplankton abundance, key species and taxonomic groups, temperature and salinity collected at monitoring stations in Varna and Sevastopol Bays during the period 1967 - 2005 (Varna Bay) and 1976-2005 (Sevastopol Bay). The results of inter-annual dynamics of mesozooplankton quantity revealed similarities in the timing of maximum abundance during the 1980s in both areas. The structure of the community significantly shifted over the decades and the reorganization was mainly with respect to dominant groups and species. Thus Oithona nana maintained high density in the period 1976-1980, while Acartia clausi (dominant over the year) and Pleopis polyphemoides were constant components of the plankton fauna with similar dynamics mode in the study regions. In spite of the observed similarities, zooplankton communities in Varna and Sevastopol Bays manifested peculiar features. The total abundance in Varna Bay ranged from 1083 ind.m-3 to 52 978 ind.m-3, while in Sevastopol Bay it varied from only 276 ind.m-3 to 14501 ind.m-3. During the period 1976-1980, the zooplankton amount in Sevastopol Bay was from 2 to 12 fold higher than in Varna Bay. Since the 1980 the total mesozooplankton abundance increased in Varna Bay in contrast to Sevastopol Bay. Noctiluca scintillans was regularly presented in Sevastopol Bay, but with lower numerical abundance compared to Varna Bay where it often reached ¿blooming¿ concentrations. The alterations in zooplankton assemblages could be further attributed to the impacts of climate and anthropogenic activities in both regions.JRC.DDG.H.3-Global environement monitorin

Bifurcations of stationary manifolds formed in the neighborhood of equilibrium in the dynamic cutting system

The work objective is to study the formation of orbitally asymptotically stable limit cycles and two-dimensional invariant tori including bifurcations near the attracting sets. The investigators use primarily methods based on the mathematic simulation of the dynamic systems. Some problems of the nonlinear dynamics of the material cutting are considered. A mathematical model of the dynamic system considering the dynamic link formed by the cutting process is offered. Here, the following key features of the dynamic coupling are taken into account: dependence of the cutting forces on the area of a cut-off layer, delay of forces towards the elastic deformation shifts of the tool in relation to the workpiece, restrictions imposed on the tool movements when the back of the instrument is approaching the treated part of the workpiece, forces - cutting velocity relation. The dynamic subsystem of the tool is presented by a linear dynamic system in the plane orthogonal to a cutting surface. Following the research, some guidelines for designing systems with the required stationary manifold in the state space are provided. Importantly, in the neighborhood of equilibrium, various criteria of set causing regular or irregular features of the formed in-cut surface can develop depending on the models interacting under processing

DETERMINATION OF OPTIMAL TRAJECTORIES UNDER TREATMENT WITH ACCOUNT FOR CUTTING PROCESS DEVELOPMENT

The task of selecting optimal coordinates of the switching cycles at which the controlled process performance attains a maximum is formulated. This is some refinement of the optimal control problem applied to the machining processes for the case when the treatment mode control providing stabilization of various cutting conditions occurs. A typical example of such a problem necessitating the treatment mode switching for deephole machining with twistdrills is given. The necessary optimum condition to which minimum velocity values equal among themselves correspond is proved. On this basis, a velocity calculation technique providing the time minimum is proposed. A concrete example for the case of deep pinhole machining (diameter — 2.15 mm, hole depth — 140 mm) is given. The obtained results are generalized in the case when problems on any evolutionary system control machining are solved