A huge biocatalytic filter in the centre of Barents Sea shelf?

A primary production model for the Barents Sea shows a hot spot of organic carbon settlement to the sea bed over 100 km long, a shallow pile of highly permeable sediments (mainly large Balanus, Mya and Pecten shell fragments over 1 cm in size) of glacial origin. Hydrodynamic flow models suggest an intensive, deep flow of near-bottom waters into the sediment. Depending on wave height, water in shallow (30 m depth) places may percolate more than 5 m into the sediment. During 10 days of stormy weather as much as 4 to 8 kg wet weight pelagic biomass can be processed per square metre through this extremely permeable sediment. Analogous processes known in coastal waters lead to intense biocatalytic phenomena and metabolism of organic carbon within the seabed, estimated here as more intense than surface consumption. Spitsbergenbanken may be acting as a huge sink for organic carbon and an important source of nutrients in one of the most productive areas of the North Atlantic

Acute aquatic toxicity of arsenic-based chemical warfare agents to Daphnia magna

Sea dumping of chemical warfare (CW) took place worldwide during the 20th century. Submerged CW included metal bombs and casings that have been exposed for 50-100 years of corrosion and are now known to be leaking. Therefore, the arsenic-based chemical warfare agents (CWAs), pose a potential threat to the marine ecosystems. The aim of this research was to support a need for real-data measurements for accurate risk assessments and categorization of threats originating from submerged CWAs. This has been achieved by providing a broad insight into arsenic-based CWAs acute toxicity in aquatic ecosystems. Standard tests were performed to provide a solid foundation for acute aquatic toxicity threshold estimations of CWA: Lewisite, Adamsite, Clark I, phenyldichloroarsine (PDCA), CWA-related compounds: TPA, arsenic trichloride and four arsenic-based CWA degradation products. Despite their low solubility, during the 48 h exposure, all CWA caused highly negative effects on Daphnia magna. PDCA was very toxic with 48 h D. magna LC50 at 0.36 mu g x L-1- and Lewisite with EC50 at 3.2 mu g x L-1 . Concentrations at which no immobilization effects were observed were slightly above the analytical Limits of Detection (LOD) and Quantification (LOQ). More water-soluble CWA degradation products showed no effects at concentrations up to 100 mg x L-1.Peer reviewe

Baltic Sea Gastrotricha—one new species and one new record of Chaetonotida from Poland

Kolicka, Małgorzata, Jankowska, Emilia, Kotwicki, Lech (2015): Baltic Sea Gastrotricha—one new species and one new record of Chaetonotida from Poland. Zootaxa 4027 (4): 487-508, DOI: 10.11646/zootaxa.4027.4.

Sandy coasts

1. Sandy coasts, including the epilittoral part of sandy beaches and the shallow sandy sublittoral, are particularly extensive in the southern and southeastern part of the Baltic Sea. 2. In the Baltic Sea ecosystem, sandy coasts function as biocatalytic filters by decomposing organic matter (including detritus) most of which originates directly or indirectly (e.g. via waterbirds) from the sea. 3. Sandy coasts are unstable, erodable environments which change in time and space due to e.g. erosion in winter and deposition of sand on the beaches in summer, and to the constant shifting of the substrate by winds and currents. 4. The sandy epilittoral and shallow sublittoral habitats support a variety of life forms, from microbes to birds, and are the space in which diverse processes involved in energy flow and matter cycling operate at different temporal and spatial scales. 5. The sandy coast food webs are partly based on the direct input of solar energy and nutrients used by primary producers (phytoplankton, microphytobenthos, macrophytes) whose production is subsequently utilised by invertebrates (meiobenthos, macrozoobenthos), fish and birds. 6. Another part of the sandy coast food webs is based on the input of organic material in the form of detritus, a source of energy for microbial communities consisting of bacteria, fungi, yeasts and actinomycetes as well as of heterotrophic protists living attached to sand grains and in the interstices. 7. Birds collect invertebrate prey from the sand on the beach or from the shallow sublittoral and contribute to the organic matter pool of the sandy habitat. 8. The sandy coasts of the Baltic Sea experience heavy anthropogenic pressure which primarily involves tourism and recreation, but also effects of eutrophication, establishment of non-indigenous species, sand extraction and dredging, fishing, infrastructure and shore defence constructions

Evidence of season-dependency in vegetation effects on macrofauna in temperate seagrass meadows (Baltic Sea).

Seagrasses and associated macrophytes are important components of coastal systems as ecosystem engineers, habitat formers, and providers of food and shelter for other organisms. The positive impacts of seagrass vegetation on zoobenthic abundance and diversity (as compared to bare sands) are well documented, but only in surveys performed in summer, which is the season of maximum canopy development. Here we present the results of the first study of the relationship between the seasonal variability of seagrass vegetation and persistence and magnitude of contrasts in faunal communities between vegetated and bare sediments. The composition, abundance, biomass, and diversity of macrozoobenthos in both habitats were compared five times throughout the year in temperate eelgrass meadows in the southern Baltic Sea. Significant positive effects of macrophyte cover on invertebrate density and biomass were recorded only in June, July, and October when the seagrass canopy was relatively well developed. The effects of vegetation cover on faunal species richness, diversity, and composition persisted throughout the year, but the magnitude of these effects varied seasonally and followed changes in macrophyte biomass. The strongest effects were observed in July and coincided with maximums in seagrass biomass and the diversity and biomass of other macrophytes. These observations indicate that in temperate, clearly seasonal systems the assessment of macrophyte impact cannot be based solely on observations performed in just one season, especially when that season is the one in which macrophyte growth is at its maximum. The widely held belief that macrophyte cover strongly influences benthic fauna in marine coastal habitats, which is based on summer surveys, should be revisited and complemented with information obtained in other seasons

Total benthic oxygen uptake in two Arctic fjords (Spitsbergen) with different hydrological regimes

Summary: Benthic total oxygen uptake (TOU) was measured in two Arctic fjords (NW Spitsbergen shelf) with different hydrological regimes: Hornsund with “cold” coastal Arctic waters and Kongsfjorden with “warm” Atlantic shelf waters. TOU rates in Kongsfjorden were more than 50% higher than in Hornsund. This is presumably related to the relatively higher biomass of bacterial and faunal (meiobenthos and macrofauna) communities in Kongsfjorden as compared to Hornsund caused by the source of organic matter: Kongsfjorden is dominated by marine, Hornsund by terrigenous organic matter. We conclude that the quality of organic matter supplied to marine sediments influences the biomass of benthic organisms and the rate of oxygen consumption. Therefore the Kongsfjorden sea bed has much higher oxygen uptake and hence a greater carbon demand than Hornsund. Keywords: Sediment oxygen uptake, Respiration partitioning, Carbon demand, Svalbard fjord, Arcti