Contribution of the Baikal Amphipod to the Feeding Pattern of Perch in the Littoral Zone of Lake Onega

Abstract. The seasonal feeding pattern of juvenile perch in Petrozavodsk Bay of Lake Onega was studied. It was shown that in the fourth to sixth years of their life, a benthic type of feeding predominates. The fish that inhabit the littoral zone feed actively on the Baikal amphipod, a new food item. During the summer-autumn season, the colonizer accounts for over 50% of the biomass in the stomach of juvenile perch. The invasion of Lake Onega by the Baikal amphipod has thus led to changes in the structure of littoral communities and the availability of a new food item for the fish. Considering the resistance of the Baikal amphipod to unfavorable environmental factors, it is important to study its spatial expansion and the possible penetration of this amphipod via tributaries to other water bodies in the Lake Onega Lake catchment area. Keywords: freshwater ecosystem, perch, trophic interactions, Baikal amphipo

The State of the Lake-river System Affected By Mineral Production

The current state of four water bodies in the upper and middle reaches of the River Kenti system, Western Karelia, affected by long-term industrial potassium-sulphate pollution, is assessed. The upper water body of the system, Lake Kostomukshskoye, is supplied by waste water from an iron mining concentration plant. Lakes Okunevoye, Poppalijärvi and Koivas are located downstream. Analysis of some hydrochemical indices and phyto- and zooplankton communities has shown that as the distance from the pollution source increases, the hydrological regime is stabilized, species diversity increases and the quantitative indices of the biotic constituent of the lake-river system grow. For example, the total mineralization value decreases from 632 дo 45 mg/l, the concentrations of major polluting agents, such as K+ and Na+ ions, decline by an average of two orders of magnitude and the medium reaction passes from alkaline (pН 7.7) to neutral (pН 6.8). The species composition of the phytoplankton varies from 18 to 23 species of six 6 divisions. The number of zooplankton taxa increases from 15 to 24 and average quantitative indices grow from 0.048 g/m3 (1.1 thousand individuals/m3) to 0.368 g/m3 (10.3 thousand individuals/m3), respectively. The data obtained were compared with earlier results

The impact of fish farming on the Tarasmozero Lake ecosystem, Onega Lake basin

The Tarasmozero Lake ecosystem (Onega Lake basin), affected by fish farming was assessed prior to and after the construction of a rainbow trout farm. Lake Tarasmozero receives waste water from the farm. The results of our studies show that when the farm began operating, phosphorus and nitrogen concentrations in the water have increased, affecting aquatic organisms and their environment. It was shown that phytoplankton is now dominated by diatoms, zooplankton species, characteristic of eutrophic water bodies, have appeared, and amphipods now make up the bulk of zoobenthos’ biomass. This evidence indicates that Lake Tarasmozero gradually passes from an oligotrophic type to a mesotrophic type

Morphological and Genetic Variability of the Mass Whitefish Forms in Lake Onega

In Lake Onega, the whitefish Coregonus lavaretus has been shown to occur as a variety of forms. Medium- and sparsely-ranked whitefish are most abundant. Analysis of available data indicates that whitefish populations from Karelia’s large lakes display the maximum values of various genetic variability indices. This fact seems to be due to the history of the colonization of the lake by the discrete evolutionary whitefish lineages from various Late Quaternary habitats followed by their hybridization. A great variety of Onega whitefish haplotypes is probably related to the genetic heterogeneity of the whitefish who until recently had occurred as five ecological forms ranking as subspecies. The median network obtained suggests that many of the populations studied have become less abundant. The well-defined “star-like” network structure is characteristic of populations that passed through a narrow “bottleneck” in the near past and then expanded rapidly, as indicated by the abundance of rare haplotype varieties. It seems that the retreat of the Scandinavian glacier was not a momentary event but took a long time during which the populations formed were subjected to demographic transformations

Developing a Work Personal Development Process and Personal Development Plan Template for an Engineering Design Company

This master's thesis is focused on the creation of a work personal development process and personal development plan template for an engineering design company. Employing the applied action research method, the data was collected through a combination of interviews with employees and management, a review of relevant literature, and a validation workshop. The findings of the current state analysis revealed inconsistencies in the existing development approach of the company, indicating a need for improvements. Based on these findings and best practices collected from literature studies, a comprehensive work personal development process and personal development plan template were designed and presented to management for validation and further implementation within the company. Overall, this thesis provides an efficient framework for integrating a structured employee development process within a geotechnical department of an engineering design company and hands over a tool for the company to actively manage the professional growth of the employees. The designed work personal development process aims to aid the case company in ensuring its market position and achieving its strategic goals

Contribution of the Baikal Amphipod to the Feeding Pattern of Perch in the Littoral Zone of Lake Onega

. The seasonal feeding pattern of juvenile perch in Petrozavodsk Bay of Lake Onega was studied. It was shown that in the fourth to sixth years of their life, a benthic type of feeding predominates. The fish that inhabit the littoral zone feed actively on the Baikal amphipod, a new food item. During the summer-autumn season, the colonizer accounts for over 50% of the biomass in the stomach of juvenile perch. The invasion of Lake Onega by the Baikal amphipod has thus led to changes in the structure of littoral communities and the availability of a new food item for the fish. Considering the resistance of the Baikal amphipod to unfavorable environmental factors, it is important to study its spatial expansion and the possible penetration of this amphipod via tributaries to other water bodies in the Lake Onega Lake catchment area. Keywords: freshwater ecosystem, perch, trophic interactions, Baikal amphipo