CIRCADE RHYTHMS OF PINCHUK'S GOBY PONTICOLA CEPHALARGOIDES (PINCHUK, 1976) IN LABORATORY CONDITIONS

Introduction. Circadian rhythms help the body to anticipate changes in environmental conditions and adapt to the daily fluctuations of external factors. The presence of such mechanisms, which provide early preparation of the organism, gives an advantage in the struggle for survival. The dynamics of light is one of the main factors, which determines the level of growth, development, nutrition, metabolism, affects hormonal activity. Aim. The aim of the study was to study the circadian rhythms of motor activity of Pinchuk's goby Ponticola cephalargoides (Pinchuk, 1976) in the laboratory. Methods. To study the activity of the fish individuals of the Pinchuk's goby caught in the Gulf of Odesa on a fishing rod were selected. The experiments were performed in an aquarium with two lighting options – under natural light and in the complete round-the-clock absence of lighting. Measurements of the fish activity were recorded at 1 hour intervals for 5 days. Results. The study revealed that the activity in constant darkness is generally lower than in the natural light. In both cases, the maximum value of the motor activity occurs in the first half of the day. Under the natural light, the activity of the Pinchuk's goby reaches the maximum value from 06:00 to 07:00, in constant darkness the activity reaches the maximum from 07:00 to 08:00. The difference in the activity of the fish between the two lighting modes is most noticeable from 16:00 to 22:00. Conclusion. It is established that the activity of Pinchuk's goby is cyclical both under the natural light conditions and in the absence of light. From 00:00 to 16:00 Pinchuk's goby has an endogenous circadian rhythm, from 16:00 to 22:30 the rhythm is exogenous.

Adult zebrafish anaesthesia: a study of efficacy and behavioural recovery of different anaesthetics

The use of proper anaesthesia in zebrafish research is essential to ensure fish welfare and data reliability. However, anaesthesia long-term side effects remain poorly understood. The purpose of this study was to assess anaesthesia quality and recovery in adult zebrafish using different anaesthetic protocols and to determine possible long-term effects on the fish activity and anxiety-like behaviours after anaesthesia.Mixed sex adult AB zebrafish were randomly assigned to 5 different groups (control, 175mg/L MS222, 45 mg/L clove oil, 2 mg/L etomidate and 5mg/L propofol combined with 150mg/L lidocaine) and placed in the respective anaesthetic bath. Time to lose the equilibrium, response to touch and to tail pinch stimuli, and recovery after anaesthesia administration were evaluated. In addition, after stopping anaesthesia, respiratory rate, activity and anxiety-like behaviours in the novel tank test were studied.Overall, all protocols proved to be adequate for zebrafish anaesthesia research as they showed full recovery at 1h, and only etomidate had minor effects on fish behaviour in the novel tank, a validated test for anxiety.

Land Suitability for Sustainable Aquaculture of Rainbow Trout (Oncorhynchus mykiss) in Molinopampa (Peru) Based on RS, GIS, and AHP

Peruvian aquaculture, specifically trout production, has had significant growth over the past ten years. However, the establishment and expansion of small-scale aquaculture have been carried out without considering the suitability of the land. In Peru, such land suitability studies have yet to be reported. Therefore, a methodological framework is presented for inland aquaculture, which may be replicated, with the necessary complements, for the entire Fisheries and Aquaculture sector in Peru. This work modeled the suitability of land for sustainable rainbow trout aquaculture in the Molinopampa district (Peru). Fifteen key criteria (socioeconomic, environmental and physicochemical) were identified for the proper development of fish activity. These were mapped using Remote Sensing (RS) and Geographic Information Systems (GIS). The Analytical Hierarchy Process (AHP) was applied to build peer-to-peer comparison matrices and weight the importance of the criteria. The weighted overlay of maps (criteria) made it possible to determine that 4.26%, 23.03% and 69.73% of the territory is “very suitable”, “moderately suitable” and “marginally suitable”, respectively, for the development of aquaculture. The implementation of this methodology will contribute to more effective investment planning and efforts, both by the government and by private initiative.

The influence of discharge, current speed, and development on the downstream dispersal of larval nase (Chondrostoma nasus) in the River Danube

We investigated the mode (active versus passive) of larval downstream dispersal and its influencing factors in the nase carp (Chondrostoma nasus). Marked larvae (early and later stages), together with equivalent numbers of passive particles, were released in the main channel of the River Danube (Austria) at different flow (low, high) and current (over-critical, under-critical) conditions. Larvae and particles were recaptured with stationary nets at varying distances from release. We assumed that differences in the spatial dispersal patterns between larvae and particles were due to fish activity. We hypothesized that river discharge, developmental stage, current speed, and distance from release would influence these differences. We found that activity was independent of developmental stage or current speed at release, although activity was higher during low flow conditions. It may be that larvae deliberately enter the current during low flow, because the hydraulic conditions facilitate active dispersal. Furthermore, activity was greatest near the release site. This might be due to an intrinsically greater activity when fish are placed into novel surroundings or a result of rheoreaction. The discharge-dependent dispersal patterns observed represent an important ecological link between flow and recruitment and demonstrate the importance of inshore conditions for the early life stages of fish in large rivers, especially with regard to river modification and restoration schemes.