Biogeochemical cycles of carbon transformation throughout the euphotic zone of the sea are controlled by physical processes, e.g., daily thermocline, variation in solar irradiance, thermohaline convection, and intermittent mixing. These processes should be regularly observed with sufficient time resolution at fixed geographical locations. This study provides a brief overview of the carbon observational site in the Northeastern Black Sea. The focus is on the design of a new tethered profiler Winchi for the inner continental shelf part of the site. The profiler hull and two outriggers comprise an open trimaran platform that is positively buoyant and tends to maintain a horizontal position in the water. The lower end of the winch wire is secured to the bottom anchor. By unwinding/winding the wire, the profiler ascends/descends while measuring the depth profiles of marine environment parameters ranging from the seafloor to air–sea interface. After surfacing, the profiler determines its location using the Global Positioning System (GPS) and transmits data to (and from) a server on land through the Global System for Mobile Communications (GSM). Initial field tests with the Winchi profiler at the Northeastern Black Sea shelf exhibited promising results. We report these early tests to demonstrate the use of Winchi.

Equipment and methods of simultaneous continuous long-term recording of electric activity of clariid catfish (Clariidae) is elaborated. All electric organ discharges (EOD) in any position and orientation of free swimming fish are fixed by simultaneous recording of electric voltage with two mutually perpendicular pairs of electrodes. Light-emitting diodes controlled by a microprocessor allow for the possibility to observe the moments of discharge emission both in real time and during scanning of videorecords. According to its parameters, the created equipment corresponds to characteristics of EOD of clariid catfish, performs primary treatment of signals, and stores in its inner flash memory all discharges recorded in a prolonged experiment (duration up to several days, number of EOD up to several tens of thousands). Various examples of EOD are presented recorded by means of the elaborated methods in clariid catfish (C. macrocephalus, C. batrachus, C. fuscus, and hybrids C. gariepinus × C. macrocephalus) when they manifested aggressive-defensive and spawning behavior. The procedure of treatment of EOD is suggested, including that of special bursts of EODs generated by females in pairing.

The use of different nanoparticles (NPs) is growing every year since discoveries of their unique properties. The wide use of nanomaterials has raised concerns about their safety and possible accumulation in the aquatic environment. Mussels are being considered as one of the most suitable organisms for bioaccumulation monitoring. Within our study, we focused on developing the method that can be applied in field studies of ecotoxicity and can be nondestructive and informative at early times of exposure, while at the same time being based on changes of physiological parameters of fresh water mussels. The changes in the cardiovascular and neural systems of mollusks (Anodonta anatina and Unio tumidus) were measured as biomarkers of toxic effects. Different monometallic and bimetallic NPs, silicon NPs with various ligands were applied as test substances. Changes in cardiovascular and neural functions were in good correlation with accumulation tests for all tested NPs.

The underwater electric field signal can be excited by underwater vehicles, such as the shaft-rate electric field and the corrosion electric field. The electric field signature of each vehicle exhibits significant differences in time and frequency domain, which can be exploited to determine target positions. In this paper, a novel passive localization method for underwater targets is presented, leveraging a uniform linear electrode array (ULEA). The ULEA manifold along the axial direction is derived from the electric field propagation in an infinite lossy medium, which provides the nonlinear mapping relationship between the target position and the voltage data acquired by the ULEA. In order to locate the targets, the multiple signal classification (MUSIC) algorithm is applied. Then, capitalizing on the rotational invariance of matrix operations and exploiting the symmetry inherent in the ULEA, we streamline the six-dimensional spatial spectral scanning onto a two-dimensional plane, providing azimuth and distance information for the targets. This method significantly reduces computational overhead. To validate the efficacy of our proposed method, we devise a localization system and conduct a simulation environment to estimate targets. Results show that our method achieves satisfactory direction and reliable distance estimations, even in scenarios with low signal-to-noise ratios.

Laboratory experiments were performed to compare the electrical activity and behavior in Clarias fuscus during spawning. Each of the multiple matings of the male and female was preceded by an amplexus – a mutual pose in which the male tightly covers the female’s head and remains in close contact with it until the end of mating. The spawning behavior of C. fuscus was accompanied by monopolar electrical pulses (MP) of two types: single MPs, similar to those observed in other behavioral situations (aggression, hunting) and specific MPs, observed only during spawning bursts of serial MPs (burst MPs), at intervals which are comparable with their duration. Each recorded burst MPs (71) corresponded to one mating, and each recorded single MP (63) corresponded to an attack of one fish on another. In different behavioral situations (matings and attacks), MPs differ significantly in amplitude and duration; and for MPs in bursts, in their degree of asymmetry. It can be assumed that the involvement of MPs in the spawning behavior of C. fuscus is similar to that studied earlier in Clarias macrocephalus, and is a common feature for Clariidae.