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  • 1
    In: Oceanological and Hydrobiological Studies, Uniwersytet Gdanski, Vol. 46, No. 2 ( 2017-06-27), p. 186-198
    Abstract: The results of the recent (2014-2015) inventory and three historical datasets (1949-1959, 1960-1980 and 1997-2007) were analyzed in order to track the long-term changes of charophytes in the largest estuarine lagoon of the Baltic Sea. The present species composition of charophytes in the estuarine part of the Curonian Lagoon consisted of 7 species, including tolerant to salinity ( Chara aspera , C. contraria , C. globularis and Nitellopsis obtusa ) and typical brackish-water species ( Chara baltica , C. canescens and Tolypella nidifica ). The highest congruence of species was between the 1997-2007 and 2014-2015 datasets, which covered respectively eutrophication and post-eutrophication periods. The 1949-1959 dataset (closest to the reference conditions) differed by the absence of typical brackish-water species. The 1960-1980 dataset (the major period of eutrophication) was relatively poor in study sites and species. During the last 6 decades, only tolerant to salinity freshwater species were constant and abundant; only Nitella mucronata can be considered as extinct. Recently, C. contraria became dominant and widespread. The changes in the charophyte species composition, abundance and distribution can be explained by different intensity of surveys and/or density of study sites, but also by the increased exposure to brackish waters since 1980s and/or recently reduced effect of eutrophication.
    Type of Medium: Online Resource
    ISSN: 1897-3191
    Language: English
    Publisher: Uniwersytet Gdanski
    Publication Date: 2017
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  • 2
    In: Water, MDPI AG, Vol. 12, No. 5 ( 2020-05-14), p. 1392-
    Abstract: Compared to external loads from tributaries and sediment recycling, the role of waterbirds as phosphorus (P) sources in estuaries is overlooked. We performed monthly ship-based surveys of waterbird abundance in the Lithuanian part of the Curonian Lagoon, calculated their potential P excretion, and compared its relevance to the riverine inputs. Phosphorus excretion rates for the censused species were assessed accounting for variations of body weights, daily feces production and their P content, and assigning species to different feeding and nutrient cycling guilds. During the study period (March–November 2018), 32 waterbird species were censused, varying in abundance from ~18,000–32,000 (October–November) to ~30,000–48,000 individuals (June–September). The estimated avian P loads during the whole study period varied between 3.6 and 25 tons, corresponding to an area load between 8.7 and 60.7 mg P m−2. Waterbird release of reactive P to the system represented a variable but not negligible fraction (1%–12%) of total external P loads, peaking in June–September and coinciding with cyanobacterial blooms. This study is the first in the Baltic Sea region suggesting that waterbirds are potentially important P sources to phytoplankton in large estuaries, in particular, during low discharge periods.
    Type of Medium: Online Resource
    ISSN: 2073-4441
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
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  • 3
    In: JOURNAL OF ENVIRONMENTAL ENGINEERING AND LANDSCAPE MANAGEMENT, Vilnius Gediminas Technical University, Vol. 17, No. 4 ( 2009-12-31), p. 236-243
    Abstract: The purpose of this investigation is to assess the corrosive impact of de‐icing salts and product “Safecote” on metals by performing immersion and spraying experiments. Metallic elements such as metallic bridges, road signs, and cars, situated near the road, are exposed to salts used for road maintenance in winter seasons. The salts, used to de‐ice the road surface, can cause metal corrosion. NaCl, CaCl2, also mixture of NaCl and CaCl2are most commonly used salts in Lithuania. Ions of chloride are the main agents which increase corrosion rate and the metal mass loss. This harmful effect could be mitigated by replacing the salts with organic de‐icers, for instance, product “Safecote” based on molasses, which is a by‐product of sugar production. The research of mass loss of metals and metal alloys was carried out with the help of two methods ‐ immersion and spraying. In the first case tested metals were dipped into the solutions of NaCl, CaCl2, NaCl:CaCl2 and NaCl:Safecote, in the other ‐ metals were sprayed with solutions of above mentioned metals. Results of the experimental research showed that CaCl2 has the highest effect on metal corrosion. This solution caused mass loss of galvanized steel 301.71±4.2 mg, and carbon steel ‐ 52.27±1.7mg by immersion method. What is more, aluminium 1.37±0.13 mg, galvanized steel 51.79±0.9mg, stainless steel 2.11±0.2 mg, and carbon steel 266.58±2.5 mg lost their mass by spraying method. The results of the experiment showed that salts, used for road maintenance in winter seasons, should be mixed with “Safecote”, which mitigates corrosion of metals and minimizes their mass loss. Santrauka Tyrimų tikslas – taikant įmerkimo ir purškimo metodus įvertinti kelių priežiūrai žiemą naudojamų druskų ir melasos įtaką metalų korozijai. Metalinius tiltus, kelio ženklus, kitus metalinius kelio elementus bei mašinas žiemą veikia kelio priežiūrai (slydimui sumažinti) naudojamos druskos, vyksta korozija. NaCl, CaCl2 bei NaCl ir CaCl2 mišinys – dažniausiai Lietuvoje naudojamos druskos. Chloridai yra pagrindiniai koroziją sukeliantys ir metalų masę mažinantys jonai. Šis negatyvus chloridų poveikis gali būti sumažintas pakeitus kelių priežiūrai naudojamas druskas organinėmis cheminėmis medžiagomis ledui tirpinti, pvz., „Safecote“. Tai antrinis žemės ūkio produktas, gaunamas iš cukraus pramonės atliekų, dar vadinamas melasa. Metalų ir jų lydinių masės mažėjimo tyrimas buvo atliekamas dviem būdais – įmerkimo ir purškimo. Pirmuoju atveju tiriamieji metalai įmerkiami į NaCl, CaCl2 , NaCl:CaCl2 ir NaCl: „Safecote“ tirpalus, o antruoju atveju – metalai šiais tirpalais purškiami. Pagal eksperimentinių tyrimų rezultatus įrodyta, kad CaCl2 tirpalas sukėlė didžiausią metalų koroziją, t. y. cinkuotoji skarda neteko 301,71±4,2 mg, anglinis plienas – 52,27±1,7 mg masės taikant įmerkimo metodą, o purškimo atveju aliuminis neteko 1,37±0,13 mg, cinkuotoji skarda – 51,79±0,9 mg, nerūdijantis plienas – 2,11±0,2 mg, o anglinis plienas – 266,58±2,5 mg masės. Remiantis atliktų eksperimentinių tyrimų rezultatais siūloma su kelių priežiūrai naudojamomis druskomis naudoti „Safecote“ tirpalą, kuris sumažina metalų koroziją. Pезюме Целью исследования была оценка коррозионного воздействия солей и продукта “Safecote”, применяемых для содержания дорог в зимний период, на металлы. Металлические мосты, дорожные знаки и другие металлические элементы, а также автомобили подвергаются воздействию солей, используемых для уменьшения скользкости дорог в зимний сезон. Чаще всего в Литве используются соли NaCl, CaCl2 , а также смесь NaCl и CaCl2 . Ионы хлорида являются основными агентами, способствующими коррозии металла и потерям их массы. Это вредное воздействие хлоридов может быть уменьшено путем замены солей, используемых для содержания дорог, органическими веществами для удаления льда, например, продуктом “Safecote” на основе мелассы, которая является побочным продуктом производства сахара. Исследование потери массы металлов и их сплавов осуществлялось двумя методами – методом погружения и распыления. В первом случае исследуемые металлы погружались в растворы NaCl, CaCl2 , NaCl: CaCl2 и NaCl:Safecote, а во втором – металлы подвергались распылению этими растворами. Результаты эксперимента показали, что раствор CaCl2 оказывает наибольший эффект на коррозию металлов. В случае применения метода погружения потеря массы из оцинкованной стали составила 301,71±4,2 мг, а массы из углеродистой стали – 52,27±1,7 мг. В случае применения метода распыления металлы также лишились массы: алюминий – 1,37±0,13 мг, оцинкованная сталь – 51,79±0,9 мг, нержавеющая сталь – 2,11±0,2 мг и углеродистая сталь – 266,58±2,5 мг. Результаты эксперимента показали, что соль, используемую для содержания дорог в зимний период, следует смешивать с продуктом “Safecote”, который уменьшает коррозию металлов.
    Type of Medium: Online Resource
    ISSN: 1648-6897 , 1822-4199
    Language: Unknown
    Publisher: Vilnius Gediminas Technical University
    Publication Date: 2009
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  • 4
    In: Biogeochemistry, Springer Science and Business Media LLC, Vol. 154, No. 2 ( 2021-06), p. 385-403
    Abstract: Coastal waters have strong gradients in dissolved organic matter (DOM) quantity and characteristics, originating from terrestrial inputs and autochthonous production. Enclosed seas with high freshwater input therefore experience high DOM concentrations and gradients from freshwater sources to more saline waters. The brackish Baltic Sea experiences such salinity gradients from east to west and from river mouths to the open sea. Furthermore, the catchment areas of the Baltic Sea are very diverse and vary from sparsely populated northern areas to densely populated southern zones. Coastal systems vary from enclosed or open bays, estuaries, fjords, archipelagos and lagoons where the residence time of DOM at these sites varies and may control the extent to which organic matter is biologically, chemically or physically modified or simply diluted with transport off-shore. Data of DOM with simultaneous measurements of dissolved organic (DO) nitrogen (N), carbon (C) and phosphorus (P) across a range of contrasting coastal systems are scarce. Here we present data from the Roskilde Fjord, Vistula and Öre estuaries and Curonian Lagoon; four coastal systems with large differences in salinity, nutrient concentrations, freshwater inflow and catchment characteristics. The C:N:P ratios of DOM of our data, despite high variability, show site specific significant differences resulting largely from differences residence time. Microbial processes seemed to have minor effects, and only in spring did uptake of DON in the Vistula and Öre estuaries take place and not at the other sites or seasons. Resuspension from sediments impacts bottom waters and the entire shallow water column in the Curonian Lagoon. Finally, our data combined with published data show that land use in the catchments seems to impact the DOC:DON and DOC:DOP ratios of the tributaries most.
    Type of Medium: Online Resource
    ISSN: 0168-2563 , 1573-515X
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2021
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  • 5
    In: Freshwater Biology, Wiley, Vol. 63, No. 2 ( 2018-02), p. 187-201
    Abstract: In shallow‐water sediments, the combined action of microphytobenthos and bioturbating fauna may differentially affect benthic nutrient fluxes and exert a bottom‐up control of pelagic primary production. In many cases, the effects of microphytobenthos and macrofauna on nutrient cycling were studied separately, ignoring potential synergistic effects. We measured the combined effects of microphytobenthos and chironomid larvae on sediment–water fluxes of gas (O 2 , TCO 2 and N 2 ) and nutrients (NH 4 + , NO 3 − , NO 2 − , and SiO 2 ) in shallow‐water sediments of a hypertrophic freshwater lagoon. Fluxes were measured in the light and in the dark in reconstructed sediments with low (L = 600 ind/m 2 ), high (H = 1,800 ind/m 2 ) and no (C) addition of chironomid larvae, after 3 weeks of pre‐incubation under light/dark regime to allow for microalgal growth. Besides flux measurements, pore water nutrient (NH 4 + , and SiO 2 ) and dissolved metal concentrations (Fe 2+ and Mn 2+ ) were analysed and diffusive fluxes were calculated. Chironomid larvae increased sediment heterotrophy, by augmenting benthic O 2 demand and TCO 2 and N 2 dark production. However, on a daily basis, treatments C and L were net O 2 producing and N 2 sinks while treatment H was net O 2 consuming and N 2 producing. All treatments were net C sink regardless of chironomid density. Microphytobenthos always affected benthic nutrient exchange, as significantly higher uptake or lower efflux was measured in the light compared with dark incubations. Theoretical inorganic N, P and Si demand by benthic microalgae largely exceeded both dark effluxes of NH 4 + , and SiO 2 and their net uptake in the light, suggesting the relevance of N‐fixation, water column NO 3 − and solid‐phase associated P and Si as nutrient sources to benthic algae. Chironomid larvae had a minor effect on inorganic N and P fluxes while they significantly stimulated inorganic Si regeneration. Their bioturbation activity significantly altered pore water chemistry, with a major reduction in nutrient (highest for NH 4 + and lowest for SiO 2 ) and metal concentration. Underlying mechanisms are combinations of burrow ventilation and bioirrigation with stimulation of element‐specific processes as coupled nitrification–denitrification, co‐precipitation and inhibition of anaerobic paths such as Fe 3+ or Mn 4+ reduction or re‐oxidation of their end products. The combined activity of benthic algae and chironomid larvae may significantly attenuate internal nutrient recycling in shallow eutrophic ecosystems, and contribute to the control of pelagic primary production.
    Type of Medium: Online Resource
    ISSN: 0046-5070 , 1365-2427
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2018
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  • 6
    Online Resource
    Online Resource
    Elsevier BV ; 2017
    In:  Oceanologia Vol. 59, No. 2 ( 2017-04), p. 177-186
    In: Oceanologia, Elsevier BV, Vol. 59, No. 2 ( 2017-04), p. 177-186
    Type of Medium: Online Resource
    ISSN: 0078-3234
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2017
    detail.hit.zdb_id: 120206-6
    detail.hit.zdb_id: 1474539-2
    SSG: 12
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  • 7
    In: Water, MDPI AG, Vol. 11, No. 12 ( 2019-12-05), p. 2567-
    Abstract: Aquatic birds may impact shallow ecosystems via organic and nutrient enrichment with feces. Such input may alleviate nutrient limitation, unbalance their ecological stoichiometry, and stimulate primary production. Herbivorous and piscivorous birds may produce different effects on aquatic ecosystems due to different physiology, diet and feces elemental composition. We analyze the effects of droppings from swans (herbivorous) and cormorants (piscivorous) on phytoplankton growth via a laboratory experiment. These birds are well represented in the Curonian Lagoon, where they form large colonies. As this lagoon displays summer algal hyper-blooms, we hypothesize an active, direct role of birds via defecation on algal growth. Short-term incubations of phytoplankton under low and high feces addition produces different stimulation of algal growth, significantly higher with high inputs of cormorant feces. The latter produces a major effect on reactive phosphorus concentration that augments significantly, as compared to treatments with swan feces, and determines an unbalanced, N-limited stoichiometry along with the duration of the experiment. During the incubation period, the dominant algal groups switch from blue-green to green algae, but such switch is independent of the level of feces input and from their origin. Heterotrophic bacteria also are stimulated by feces addition, but their increase is transient.
    Type of Medium: Online Resource
    ISSN: 2073-4441
    Language: English
    Publisher: MDPI AG
    Publication Date: 2019
    detail.hit.zdb_id: 2521238-2
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  • 8
    In: Journal of Limnology, PAGEPress Publications, Vol. 71, No. 2 ( 2012-07-25)
    Type of Medium: Online Resource
    ISSN: 1723-8633 , 1129-5767
    Language: Unknown
    Publisher: PAGEPress Publications
    Publication Date: 2012
    detail.hit.zdb_id: 2034229-9
    SSG: 12
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  • 9
    In: Freshwater Biology, Wiley, Vol. 64, No. 4 ( 2019-04), p. 619-631
    Abstract: Filter‐feeding mussels couple benthic and pelagic environments and create biogeochemical hot spots. Mussels may exert either top‐down control (via filtration) or bottom‐up stimulation (via biodeposition and excretion) of primary producers. Mussel metabolism may be species‐specific and the disappearance of native species or their replacement by invasive species may affect ecosystem functioning, notably gas exchange, nutrient fluxes, and stoichiometry at the sediment–water interface. In this study, we tested experimentally how native (unionids) and invasive (dreissenids) mussels, singly and in association, affect benthic fluxes of dissolved gas and nutrients in the light and in the dark, and indirectly phytoplankton growth from a freshwater estuary, the Curonian Lagoon, where the two species of mussel coexist. We show that native and invasive mussels stimulated O 2 consumption and the production of total dissolved inorganic carbon and N 2 increasing sediment heterotrophy and nutrient regeneration, with species‐specific effects on nutrient stoichiometry and algal growth. Ammonium and SiO 2 exchanges were similar for both species, while soluble reactive phosphorus fluxes and excretion rates were significantly higher in sediments with dreissenids. Phytoplankton growth was also significantly higher in the presence of dreissenids as compared to unionids. Dreissenid mussels decreased the dissolved inorganic N to P ratio of regenerated nutrients and may favour the growth of cyanobacteria. Hence, the replacement of native with invasive mussels may produce large changes in benthic nutrient cycling and in phytoplankton growth and community composition.
    Type of Medium: Online Resource
    ISSN: 0046-5070 , 1365-2427
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 2020306-8
    detail.hit.zdb_id: 121180-8
    SSG: 12
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  • 10
    In: Freshwater Biology, Wiley, Vol. 66, No. 6 ( 2021-06), p. 1036-1048
    Abstract: Tube‐dwelling chironomid larvae are among the few taxa that can withstand and thrive in the organic‐rich sediments typical of eutrophic freshwater ecosystems. They can have multiple effects on microbial nitrogen (N) cycling in burrow environments, but such effects cease when chironomid larvae undergo metamorphosis into flying adults and leave the sediment. Here we investigated the ecological role of Chironomus plumosus by exploring the effect of its different life stages (as larva and adult midge) on microbial N transformations in a shallow freshwater lagoon by means of combined biogeochemical and molecular approaches. Results suggest that sediment bioturbation by chironomid larvae produce contrasting effects on nitrate ( )‐reduction processes. Denitrification was the dominant pathway of reduction ( 〉 90%), primarily fuelled by from bottom water. In addition to pumping ‐rich bottom water within the burrows, chironomid larvae host microbiota capable of reduction. However, the contribution of larval microbiota is lower than that of microbes inhabiting the burrow walls. Interestingly, dinitrogen fixation co‐occurred with reduction processes, indicating versatility of the larvae's microbial community. Assuming all larvae (averaging 1,800 ind./m 2 ) leave the sediment following metamorphosis into flying adults, we estimated a displacement of 47,787 µmol of organic N/m 2 from the sediment to the atmosphere during adult emergence. This amount of particulate organic N is similar to the entire N removal stimulated by larvae denitrification over a period of 20 days. Finally, the detection of N‐cycling marker genes in flying adults suggests that these insects retain N‐cycling microbes during metamorphosis and migration to the aerial and terrestrial ecosystems. This study provides evidence that chironomids have a multifaceted role in shaping the N cycle of aquatic ecosystems.
    Type of Medium: Online Resource
    ISSN: 0046-5070 , 1365-2427
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2021
    detail.hit.zdb_id: 2020306-8
    detail.hit.zdb_id: 121180-8
    SSG: 12
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