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  • Model uncertainty and simulated multispecies fisheries management advice in the Baltic Sea.

    Bauer, Barbara; Horbowy, Jan; Rahikainen, Mika; Kulatska, Nataliia; Müller-Karulis, Barbel; Tomczak, Maciej T.; Bartolino, Valerio (2019)
    PLoS ONE
    Different ecosystem models often provide contrasting predictions (model uncertainty), which is perceived to be a major challenge impeding their use to support ecosystem-based fisheries management (EBFM). The focus of this manuscript is to examine the extent of model disagreements which could impact management advice for EBFM in the central Baltic Sea. We compare how much three models (EwE, Gadget and a multispecies stock production model) differ in 1) their estimates of fishing mortality rates (Fs) satisfying alternative hypothetical management scenario objectives and 2) the outcomes of those scenarios in terms of performance indicators (spawning stock biomasses, catches, profits). Uncertainty in future environmental conditions affecting fish was taken into account by considering two seal population growth scenarios and two nutrient load scenarios. Differences in the development of the stocks, yields and profits exist among the models but the general patterns are also sufficiently similar to appear promising in the context of strategic fishery advice. Thus, we suggest that disagreements among the ecosystem models will not impede their use for providing strategic advice on how to reach management objectives that go beyond the traditional maximum yield targets and for informing on the potential consequences of pursuing such objectives. This is especially true for scenarios aiming at exploiting forage fish sprat and herring, for which the agreement was the largest among our models. However, the quantitative response to altering fishing pressure differed among models. This was due to the diverse environmental covariates and the different number of trophic relationships and their functional forms considered in the models. This suggests that ecosystem models can be used to provide quantitative advice only after more targeted research is conducted to gain a deeper understanding into the relationship between trophic links and fish population dynamics in the Baltic Sea.
  • Size assessment in polychaete worms-application of morphometric correlations for common North Atlantic taxa.

    Górska, Barbara; Gromisz, Sławomira; Włodarska-Kowalczuk, Maria (2019)
    Limnology and Oceanography Methods
    Body size is a basic animal feature that defines its functioning in multispecies assemblages. Polychaetes arenumerically dominant components of marine macrobenthos, playing a key role in benthic productivity. Theyare also the most problematic group regarding body-size assessments due to common fragmentation of fragilebodies during sample processing that inhibits direct assessments of their size and biomass. Here, we presentquantified relationships that allow an estimation of the total-body length based on morphometric features(widths of thoracic chaetigers) that remain intact after standard macrobenthic sample treatment. The best-fittedregression equations (p< 0.001,rfrom 0.41 to 0.99) were selected for 28 polychaete families, six orders, twoinfraclasses, and one subclass based on the measurements on 3580 complete individuals collected in the NorthAtlantic (Norwegian and Spitsbergen fjords and continental margin). In Capitellidae, Cirratulidae, Oweniidae,and Trichobranchidae, the shapes of the relationships differed among dominant species/genera, and so, specificformula was proposed. The method has been applied to assess the size spectra of macrozoobenthos based on18 van Veen grab samples collected at six stations in two Spitsbergen fjords. The percentage contribution ofcomplete individuals in polychaete biomass and abundance in size classes varied between 0% and 43%, withthe lowest percentages noted in two dominant families—Cirratulidae and Lumbrineridae. The presentedmethod is likely to be widely applied in studies requiring polychaete individual size assessments (e.g., benthicbiomass size spectra, population dynamics, and secondary production).
  • Polycyclic aromatic hydrocarbon contamination of Polish smoked fish: Assessment of dietary exposure.

    Malesa-Ciećwierz, Małgorzata; Szulecka, Olga; Adamczyk, Maria (2019)
    Journal of Food Processing and Preservation
    The aim of the study was to determine if the smoked fish being produced in Poland complies with the new, stricter limits set for BaP and PAH4. The effect of sample position in the smoking chamber was also studied. The margin of exposure (MoE) approach was used for assessing the risk of dietary exposure to PAHs from smoked fish products. The study material comprised of sprat, herring, mackerel, and salmon from a fish processing plant equipped with smoking chambers with external smoke generators. None of the smoked fish products studied exceeded the new, stricter limits set for BaP and PAH4. The MoE indicators far exceed the limit of 10,000 (values lower than this indicate a potential risk to consumer health). The sensory analysis identified significant differences among the products studied that indicate the high quality of cold‐smoked salmon fillets and the statistically significant lower quality of a smoked salmon abdominal parts.
  • Feeding by two closely related species of Chironomus (Diptera: Chironomidae) in south Baltic lagoons, with implications for competitive interactions and resource partitioning.

    Kornijów, Ryszard; Markiyanova, Marina; Lange, Evgenia (2019)
    Aquatic Ecology
    Four major categories of food items were determined in the gut content of chironomid larvae collected in the Curonian and Vistula Lagoons in the spring–summer period of 2009–2011. These were detritus (range from 88 to 92% of the gut content, by volume), matter of plant (2–7%) and animal origin (0.2–0.5%), and mineral particles (3–7%). Plant matter comprised pine pollen, conidia of fungi, cyanobacteria, green algae and diatoms. Matter of animal origin consisted of remnants of oligochaetes and rotifers. Food content was more diverse in the larvae inhabiting the Curonian Lagoon. The size of mineral particles in gut contents was significantly higher in C. balatonicus, although the distance between the bases of the maxillas, as a predictor of the size of the particles being eaten, was larger in C. plumosus. The gut content analysis suggested lack of clear food selectivity which potentially may lead to interspecific competition for food. However, the strength of interaction can be substantially weakened by several factors: (1) exceptionally favourable food conditions for benthic chironomids in both highly eutrophic lagoons, (2) the ability to occupy areas differing in salinity, (3) different feeding behaviour and (4) the ability to swallow particles of different size spectra.
  • Role of macrophytes in structuring littoral habitats in the Vistula Lagoon (southern Baltic Sea).

    Pawlikowski, Krzysztof; Kornijów, Ryszard (2019)
    Oceanologia
    The objective of the research conducted in the years 2011–2014 in the near-shore zone of the Vistula Lagoon was the verification of the hypothesis that in the coastal lagoon, similarly as in inland waters, habitat conditions can be substantially modified by macrophytic vegetation, depending on the represented life form and its abundance. The research was conducted in the zone of emergent plants (reed rush composed of Phragmites australis) and in the zone of submerged plants occurring as scattered patches of Potamogeton perfoliatus and Stuckenia pectinata. The hypothesis was supported only in the case of the reed rush which substantially modified water insolation, temperature, and oxygenation, as well as the grain size composition of sediments, and concentration of organic matter contained in the sediments. Patches of submerged vegetation had insufficient surface area and were too scarcely overgrown by plants to considerably affect the habitat conditions and weaken the strong mechanical effect of waves and rate of water exchange between the littoral and open water zone.
  • Amphipods in estuarine and marine quality assessment – a review.

    Podlesińska, Weronika; Dąbrowska, Henryka (2019)
    Oceanologia
    Amphipods are a diverse and important group of invertebrates contributing to the functioning of aquatic ecosystems. In spite of their variety, many species of amphipods share important biological and ecological characteristics that make them suitable test organisms for assessment of the ecological quality of estuarine and marine sediments. Their pertinence as test organism includes ecological relevance, close association with sediments, sensitivity to environmental contaminants, and amenability for culture and experimentation. Amphipod bioassays are used to examine the effect of exposure to contaminants, as well as to assess whole sediment quality, improve bioassay methods, develop more sensitive endpoints, and compare sensitivity and utility of species in environmental quality assessment. This work reviews the developments in this area of research over the last decades, focusing on European amphipods. The most often used species, the type of bioassays and endpoints investigated, confounding factors influencing the bioassays outcome, and the main applications of the bioassays have been presented. This review also addresses some aspects of amphipod biology that are relevant for bioassay methods and results analysis.
  • How effective is freezing at killing Anisakis simplex, Pseudoterranova krabbei, and P. decipiens larvae? An experimental evaluation of time-temperature conditions.

    Podolska, Magdalena; Pawlikowski, Bogusław; Nadolna-Ałtyn, Katarzyna; Pawlak, Joanna; Komar-Szymczak, Katarzyna; Szostakowska, Beata (2019)
    Parasitology Research
    The consumption of raw or inadequately cooked marine fish can lead to several disorders caused by the ingestion of viable anisakid nematodes. Although anisakid larvae can be killed by subzero temperatures, making freezing an important control measure for this potential health hazard, these parasites can survive freezing under some conditions. Therefore, the aim of the present study was to experimentally evaluate the time-temperature conditions needed to kill Anisakis simplex and Pseudoterranova spp. The effectiveness of freezing was tested on two species of fish: cod, Gadus morhua from the North Atlantic, and herring, Clupea harengus membras from the southern Baltic Sea. Samples, which comprised skinless fillets of cod (n = 40) with visible parasites and whole herring (n = 240), were separately frozen at − 15, − 18, or − 20 °C for 24 h, or at − 20 °C for 48 h in the single-compressor freezer and at − 20, − 25, or − 35 °C for 24 h in the double-compressor freezer. After thawing, parasites were stained with malachite green and examined under the microscope for viability. All A. simplex and Pseudoterranova spp. larvae in cod fillets died at a temperature of − 15 °C or lower. However, freezing did not kill all the A. simplex larvae in whole herring: spontaneous movement of these parasites was observed in samples stored in the single-compressor freezer at − 15, − 18, and − 20 °C over 24 h. Our results demonstrate that the freezing procedure must consider both the capability of the freezing device and the nature of the fish product to ensure consumer safety.
  • Managing Eutrophication in the Szczecin (Oder) Lagoon-Development, Present State and Future Perspectives.

    Friedland, René; Schernewski, Gerald; Gräwe, Ulf; Greipsland, Inga; Palazzo, Dalila; Pastuszak, Marianna (2019)
    Frontiers in Marine Sciences
    High riverine nutrient loads caused poor water quality, low water transparency and an unsatisfactory ecological status in the Szczecin (Oder) Lagoon, a trans-boundary water at the southern shore of the Baltic Sea. Total annual riverine N (P) loads into the lagoon raised at the 20th century from approximately 14,000 t TN (1,000 t TP) to 115,000 t TN (10,500 t TP) in the 1980ties and declined to about 56,750 t TN (2,800 t TP) after 2010. Nutrient concentrations, water transparency (Secchi depth) and chlorophyll-a showed a positive response to the reduced nutrient loads in the Polish eastern lagoon. This was not the case in the German western lagoon, where summer Secchi depth is 0.6 m and mean chlorophyll-a concentration is four times above the threshold for the Good Ecological Status. Measures to improve the water quality focused until now purely on nutrient load reductions, but the nutrient load targets and Maximal Allowable Inputs are contradicting between EU Water Framework Directive and EU Marine Strategy Framework Directive. According to the HELCOM Baltic Sea Action Plan, the thresholds of the annual riverine nutrient inputs to the lagoon would be about 48,850 t N (1,570 t P). Actions in the river basins that would allow meeting these targets are hardly achievable. Even if the load targets would be fully implemented, they are not sufficient to transfer the lagoon into a non-eutrophic state. The implementation of EU Water Framework Directive is further hampered, as consistent water quality thresholds for the two parts of Szczecin Lagoon are missing. An approach to harmonize them is presented, which incorporates the spatial differences. By implementing consistent water quality targets, Szczecin Lagoon could serve as blueprint for other trans-boundary waters. In the western lagoon, nutrient load reductions in the past decades had no effect on the water quality. High water residence times, frequent sediment resuspension and the missing submerged vegetation inhibit the load reduction effects on the water quality. Internal measures in the western lagoon are necessary, which aim at removing nutrients and increasing water transparency to overcome the hysteresis effect and to initiate a recovery of macrophytes. Cultivation of zebra mussels seems the most promising approach.
  • Organotropism of organic and inorganic mercury in fish from the Vistula Lagoon, Poland.

    Polak-Juszczak, Lucyna; Góra, Agnieszka (2019)
    Journal of Elementology
    Our paper presents the results of a study on the concentrations of total (Hgtotal), organic (CH3Hg+) and inorganic (Hginorg) mercury in freshwater fish from the Vistula Lagoon, coastal waters of the Baltic Sea. Mercury assays were performed on tissues (muscle, skin, gills) and internal organs (heart, spleen, liver, gastrointestinal tract, gonads) of pikeperch, common roach, and common bream. The distributions of Hgtotal, CH3Hg+, and Hginorg depending on fish species, tissue, or organ and bioaccumulation in tissues and biomagnification in the trophic chain were determined. Interspecific and intraspecific differences in mercury concentrations occurred in fish tissues and organs. Muscles of pikeperch, bream and roach accumulated the highest concentration of CH3Hg+, Hginorg dominating in the gastrointestinal tract of bream and roach. The concentration gradations of Hgtotal and CH3Hg+ depending on fish species were as follows: pikeperch > common roach > common bream. For Hginorg, the gradations were as follows: common bream > common roach > pikeperch. The type of food was a determining criterion for the distribution of mercury forms in the tissues and organs of the fish studied, and quantifiable confirmation of this was the different values of the L:M coefficient (Hginorg in the hepatic tissue : CH3Hg+ in muscle). Differences in Hgtotal, CH3Hg+, and Hginorg concentrations in fish tissues and organs were linked with the food the fish consume, their position in the trophic chain and biomagnification in the food chain.
  • High contrast panels and lights do not reduce bird bycatch in Baltic Sea gillnet fisheries.

    Field, Rob; Crawford, Rory; Enever, Robert; Linkowski, Tomasz; Martin, Graham; Morkūnas, Julius; Morkūnė, Rasa; Rouxel, Yann; Oppel, Steffen (2019)
    Global Ecology and Conservation
    Bycatch is a cause of mortality among marine mammals, sea turtles, fish and birds. For some species this mortality may be sufficient to cause population declines. The Baltic Sea is a global ‘hotspot’ for bird bycatch in gillnet fisheries and is globally important for wintering sea ducks, but no technical solution has been found yet to reduce bird bycatch in gillnet fisheries in the Baltic. Here, we report on trials conducted in the Baltic Sea to test whether two different gillnet modifications with visual stimuli can effectively reduce bird bycatch while maintaining volume of fish caught. We conducted paired trials of two types of visual stimuli attached to nets: 1) high contrast monochrome net panels and 2) net lights (constant green and flashing white LED lights). We measured the amount of fish and birds caught in standard nets and those modified with the visual stimuli. Neither of the two most commonly caught species, Long- tailed Ducks (Clangula hyemalis) and Velvet Scoters (Melanitta fusca), were deterred from lethal encounters with nets by either black-and-white panels or by steady green or flashing white net lights. Long-tailed Ducks were caught in larger numbers in nets equipped with flashing white net lights than in unmodified nets at the same location. Catch rates of commercial fish were not affected by net lights or net panels placed within the nets. Hence, while the deterrents that we tested successfully maintained fish catch, they failed to reduce bird bycatch and are therefore ineffective. We discuss likely avenues for future investigation of bycatch mitigation methods for gillnet fisheries, including species and location response to net lights, managed fishery closures, above-water distraction of birds and gear switching.
  • How effective is freezing at killing Anisakis simplex, Pseudoterranova krabbei, and P. decipiens larvae? An experimental evaluation of time-temperature conditions.

    Podolska, Magdalena; Pawlikowski, Bogusław; Nadolna-Ałtyn, Katarzyna; Pawlak, Joanna; Komar-Szymczak, Katarzyna; Szostakowska., Beata (2019)
    Parasitilogy Research
    The consumption of raw or inadequately cooked marine fish can lead to several disorders caused by the ingestion of viable anisakid nematodes. Although anisakid larvae can be killed by subzero temperatures, making freezing an important control measure for this potential health hazard, these parasites can survive freezing under some conditions. Therefore, the aim of the present study was to experimentally evaluate the time-temperature conditions needed to kill Anisakis simplex and Pseudoterranova spp. The effectiveness of freezing was tested on two species of fish: cod, Gadus morhua from the North Atlantic, and herring, Clupea harengus membras from the southern Baltic Sea. Samples, which comprised skinless fillets of cod (n = 40) with visible parasites and whole herring (n = 240), were separately frozen at − 15, − 18, or − 20 °C for 24 h, or at − 20 °C for 48 h in the single-compressor freezer and at − 20, − 25, or − 35 °C for 24 h in the double-compressor freezer. After thawing, parasites were stained with malachite green and examined under the microscope for viability. All A. simplex and Pseudoterranova spp. larvae in cod fillets died at a temperature of − 15 °C or lower. However, freezing did not kill all the A. simplex larvae in whole herring: spontaneous movement of these parasites was observed in samples stored in the single-compressor freezer at − 15, − 18, and − 20 °C over 24 h. Our results demonstrate that the freezing procedure must consider both the capability of the freezing device and the nature of the fish product to ensure consumer safety.
  • The ICES Working Group on Oceanic Hydrography: A Bridge From In-situ Sampling to the Remote Autonomous Observation Era.

    González-Pola, César; Fratantoni, Paula; Larsen, Karin M. H.; Holliday, N. Penny; Dye, Stephen; Kjell, Arne Mork; Beszczynska-Möller, Agnieszka; Valdimarsson, Hedinn; Trofimov, Alexander; Parner, Hjalte; et al. (2019)
    Frontiers in Marine Science
    The ICES (International Council for the Exploration of the Sea)Working Group on Oceanic Hydrography (WGOH) was established in the late 1970’s with the aim of gathering experts in physical oceanography to provide regular science-based assessments of the North Atlantic hydrographical condition (basically termohaline fields). From the beginning, the WGOH has relied on repeated long-term in-situ sampling at key sites around the North Atlantic, the Nordic Seas and adjacent shelf seas. An annual Report on Ocean Climate (IROC), produced by the WGOH since the late 1990’s, summarizes trends in regional hydrography and identifies patterns linking these changes across the North Atlantic. Regional analyses are prepared by local experts who are directly involved in the monitoring programs responsible for collecting data presented in the report. An interactive webpage created in 2013 allows users to browse and download data that inform the IROC. Within the last two decades the physical oceanography community has evolved quickly incorporating technological advances such as autonomous devices into classical in-situ sampling programs. The WGOH has embraced such technological developments without diverting focus from ongoing in-situ long-term monitoring programs. Having longstanding experience synthesizing data and expertise from a large number of operational programs spanning an extensive international footprint, the WGOH has a unique perspective to offer the global ocean observing community. Here we discuss how we might foster connections with ICES to benefit the GOOS (Global Ocean Observing System) community.
  • Two Non-indigenous Dreissenids (Dreissena polymorpha and D. rostriformis bugensis) in a Southern Baltic Coastal Lagoon: Variability in Populations of the “Old” and a “New” Immigrant.

    Wawrzyniak-Wydrowska, Brygida; Radziejewska, Teresa; Skrzypacz, Anna; Woźniczka, Adam (2019)
    Frontiers in Marine Science
    Dreissena polymorpha and D. rostriformis bugensis are freshwater Ponto-Caspian bivalve species, at present widely distributed in Europe and North America. In the Szczecin Lagoon (a southern Baltic coastal lagoon), the quagga was recorded for the first time in 2014 and found to co-occur with the zebra mussel, a long-time resident of the Lagoon. As the two species are suspected of being competitors where they co-occur, their population dynamics was followed at a site the new immigrant was discovered (station ZS6, northern part of the Lagoon) by collecting monthly samples in 2015–2017. The abundance and biomass of the two congeners showed wide fluctuations, significant differences being recorded between months within a year and between years. The abundance and biomass proportions between the two congeners changed from an initial domination of the newcomer quagga until mid-2015 to a persistent domination of the zebra mussel throughout the remainder of the study period. Both the abundance and biomass of the two dreissenids showed a number of significant associations with environmental variables, notably with salinity, chlorophyll a content, and temperature. The co-occurrence of the two dreissenids in the Lagoon is discussed in the context of their invasion stage; it is concluded that while the quagga seems to have achieved the “outbreak” stage, the zebra mussel, an “accommodated” invader present prior to the quagga immigration, reverted to that stage.