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  • 1
    Online Resource
    Online Resource
    Uniwersytet Gdanski ; 2011
    In:  Oceanological and Hydrobiological Studies Vol. 40, No. 1 ( 2011-03-01), p. 46-56
    In: Oceanological and Hydrobiological Studies, Uniwersytet Gdanski, Vol. 40, No. 1 ( 2011-03-01), p. 46-56
    Abstract: To date, no characterization of spawning habitats on scientific basis was made for the eastern Baltic salmonid populations. The aim of the present study was to characterize spawning habitat preferences and redd gravel structure of sea trout in lowland streams of western Lithuania. The redd position at the habitat-unit scale, microhabitat hydrological characteristics and the redd gravel structure have been analyzed. The spawning site selection by sea trout was related to the in-stream characteristics, but not to the riparian features. Redds were positioned mainly in the transitional pool-riffle zones, associated with close proximity to potential cover for spawners. At the microhabitat scale, sites with relatively consistent hydrological parameters (mode of water depth 0.25–0.40 m, flow velocity 0.4–0.7 m s−1 and Froude number 0.2–0.4) were selected from a wide range of available sites. Egg incubation conditions, in terms of the redd gravel structure in the spring, were of intermediate quality, while varied widely within particular reaches. According to the results of the present study, it is apparent that sea trout have particular preferences for spawning sites, which should be considered in emerging river-restoration projects.
    Type of Medium: Online Resource
    ISSN: 1897-3191
    Language: English
    Publisher: Uniwersytet Gdanski
    Publication Date: 2011
    detail.hit.zdb_id: 2128611-5
    detail.hit.zdb_id: 2241495-2
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  • 2
    In: Frontiers in Marine Science, Frontiers Media SA, Vol. 9 ( 2022-6-13)
    Abstract: Submerged macrophytes are essential elements of sublittoral ecosystems to maintain a diverse fish fauna. The aim of this study was to assess juvenile fish associated with macrophyte habitats in the Curonian Lagoon by means of modified pop net method. We focused on two dominant littoral habitats with different structure (pondweed and charophyte stands). The pop nets sampling was carried out on two study sites located in the freshwater and oligohaline part of the lagoon in July and September 2019-2020. Our upgraded pop nets reduced the risk of under sampling and are recommended for monitoring fishes since this method has relatively low disturbance on fish behavior and on the habitat itself. The most efficient time of sampling with pop nets in shallow macrophyte habitats is at night, where at least 4 samples collected are sufficient to represent the biggest part ( & gt; 70%) of the fish assemblage, but the sampling covering different times of day is recommended. In total, 14 juvenile species were recorded, where perch and European roach dominated (respectively 48% and 24%). Half of the species (8) were associated with macrophyte stands, although water salinity and temperature were the most important factors explaining the variance of fish abundance followed by the sampling time and the biomass of macrophytes. Based on the abundance and the duration of species within these habitats, European roach, nine-spined and three-spined stickleback were mainly associated with the pondweed biomass and stands, while spined loach, round goby, perch, ruffe and gudgeon were mainly associated with the charophyte biomass and stands. The increase of charophyte stands since 2005 affected the fish assemblage where it should have enhanced the abundance of perch, ruffe, spined loach and partly round goby.
    Type of Medium: Online Resource
    ISSN: 2296-7745
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
    detail.hit.zdb_id: 2757748-X
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  • 3
    Online Resource
    Online Resource
    Walter de Gruyter GmbH ; 2012
    In:  Archives of Polish Fisheries Vol. 20, No. 4 ( 2012-01-1)
    In: Archives of Polish Fisheries, Walter de Gruyter GmbH, Vol. 20, No. 4 ( 2012-01-1)
    Type of Medium: Online Resource
    ISSN: 2083-6139 , 1230-6428
    Language: Unknown
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2012
    detail.hit.zdb_id: 2977801-3
    detail.hit.zdb_id: 2407822-0
    SSG: 21,3
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  • 4
    In: Water, MDPI AG, Vol. 15, No. 3 ( 2023-01-23), p. 452-
    Abstract: Multiple stressors, such as overfishing, pollution, climate change, biological invasions etc., are affecting fish communities, and thus can have versatile effects on marine ecosystems and socio-economic activities as well. Understanding the changes in the fish community structure is ecologically and economically important, yet a very complex issue, requiring comprehensive analysis of multiple factors. The role of regional oceanographic variability, namely, coastal upwelling, is often neglected when it comes to the analysis of fish assemblages. In this perspective, we were aiming, for the first time in the Baltic Sea, to assess the upwelling influence on fish communities and fish community-based ecological indices used under Marine Strategy Framework Directive. The study covered a long-term period (2000–2019) for upwelling identified by satellite data analysis and fish gillnet surveys, performed in three distinct locations in the coastal waters of the SE Baltic Sea. Overall, our study revealed that temporal dynamics of fish abundance and community composition were associated with the presence of coastal upwelling. The study outcomes suggest that the fish community was more diverse and a higher number of some fish species was observed before upwelling. During upwelling, there was more evident dominance of 1–2 main marine fish species. Through the changes in fish abundance and species composition upwelling was also responsible for the changes in fish community structure-based indices for marine environment status, i.e., in the majority of the cases a decrease in Trophic, Piscivorous Fish, and Diversity indices were observed. Our study demonstrates that upwelling can affect both, the quantitative and qualitative characteristics of coastal fish communities, therefore, it is important to consider this when predicting shifts in the distribution of fish stocks or assessing environmental status indicators, especially under changing climate. We believe that our approach adds novel information to the study of coastal ecosystems of the Baltic Sea and is important for better management of socio-economic activities in the coastal zone.
    Type of Medium: Online Resource
    ISSN: 2073-4441
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2521238-2
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  • 5
    In: Water, MDPI AG, Vol. 13, No. 7 ( 2021-04-06), p. 1002-
    Abstract: Lampreys spend their larval stage within fine sand fluvial sediments, where they burrow and act as filter feeders. Lamprey larvae (ammocoetes) can significantly affect benthic-pelagic coupling and nutrient cycling in rivers, due to high densities. However, their bioturbation, feeding and excretion activities are still poorly explored. These aspects were investigated by means of laboratory incubations of intact sediments added with ammocoetes and of animals alone. Oxygen respiration, nutrient fluxes and excretion rates were determined. Individual ammocoete incubations suggested that biomass-specific oxygen consumption and ammonium, reactive phosphorus and silica excretion were size-dependent, and greater in small compared to large individuals. The comparison of ammocoetes metabolic rates with rates measured in intact sediments revealed that ammocoetes activity decreases significantly when they are burrowed in sediments. Furthermore, results suggest that a major fraction of ammonium excreted by ammocoetes was assimilated by benthic microbes or microalgae to overcome in situ N-limitation. Alternatively, part of the excreted ammonium was oxidized and denitrified within sediments, as nitrate uptake rather increased along with ammocoetes density. Ammocoetes excreted reactive phosphorus and silica but such production was not apparent in bioturbated sediments, likely due to microbial or microalgal uptake or to immobilization in sediments.
    Type of Medium: Online Resource
    ISSN: 2073-4441
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2521238-2
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