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  • 1. Allan, Ian J.
    et al.
    Nilsson, Hans C.
    Tjensvoll, Ingrid
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Bradshaw, Clare
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Naes, Kristoffer
    Mobile passive samplers: Concept for a novel mode of exposure2011In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 159, no 10, p. 2393-2397Article in journal (Refereed)
    Abstract [en]

    Integrative passive sampling with devices such as semipermeable membrane devices generally relies on rigs for month-long static exposures in water. We evaluate here whether mobile exposures of passive samplers can provide reliable estimates of dissolved contaminant concentrations. Mobile exposures were obtained by towing samplers fastened to the end of a benthic trawl net. Significant and reproducible absorption of polycyclic aromatic hydrocarbons during 5 h-long deployments was made possible by high sampling rates resulting from high water turbulences during towing at 1.2-1.5 knots. Sampling rates (72-215 L d(-1)) estimated from the dissipation of performance reference compounds were supported by in situ calibration with samplers exposed for a 30 days in the vicinity of the test site. Higher fluoranthene and pyrene absorption in samplers exposed to the trawling-induced sediment plume could be attributed to desorption from re-suspended sediments. This mode of exposure has the potential to be used in monitoring programmes.

  • 2. Allan, Ian J.
    et al.
    Nilsson, Hans C.
    Tjensvoll, Ingrid
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Bradshaw, Clare
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Naes, Kristoffer
    PCDD/F release during benthic trawler-induced sediment resuspension2012In: Environmental Toxicology and Chemistry, ISSN 0730-7268, E-ISSN 1552-8618, Vol. 31, no 12, p. 2780-2787Article in journal (Refereed)
    Abstract [en]

    Benthic trawling can cause the resuspension of large amounts of sediments. Such regular practice in the Grenland fjord system in the south of Norway has the potential to affect the fate, movement, and bioavailability of sediment-associated polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). A novel mode of exposing passive sampling devices consisting of towing semipermeable membrane devices attached to the trawl net was used to gauge in situ changes in the freely dissolved concentration of PCDD/Fs on benthic trawlerinduced sediment resuspension. Significant accumulation of a number of PCDD/F congeners was observed despite the short (5?h) sampler exposure times. On average, a one order of magnitude increase in freely dissolved PCCD/F concentrations was seen within minutes of the sediment being resuspended. This observation was supported by similar changes in filtered PCDD/F concentrations measured by high-volume sampling prior to resuspension and in the sediment plume. Environ. Toxicol. Chem. 2012; 31: 27802787.

  • 3.
    Bradshaw, Clare
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Tjensvoll, Ingrid
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Sköld, M.
    Allan, I. J.
    Molvaer, J.
    Magnusson, J.
    Naes, K.
    Nilsson, H. C.
    Bottom trawling resuspends sediment and releases bioavailable contaminants in a polluted fjord2012In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 170, p. 232-241Article in journal (Refereed)
    Abstract [en]

    Sediments are sinks for contaminants in the world's oceans. At the same time, commercial bottom trawling is estimated to affect around 15 million km(2) of the world's seafloor every year. However, few studies have investigated whether this disturbance remobilises sediment-associated contaminants and, if so, whether these are bioavailable to aquatic organisms. This field study in a trawled contaminated Norwegian fjord showed that a single 1.8 km long trawl pass created a 3-5 million m(3) sediment plume containing around 9 t contaminated sediment; ie. 200 g dw m(-2) trawled, equivalent to c. 10% of the annual gross sedimentation rate. Substantial amounts of PCDD/Fs and non-ortho PCBs were released from the sediments, likely causing a semi-permanent contaminated sediment suspension in the bottom waters. PCDD/Fs from the sediments were also taken up by mussels which, during one month, accumulated them to levels above the EU maximum advised concentration for human consumption.

  • 4. Kutti, Tina
    et al.
    Bannister, Raymond J.
    Fossa, Jan Helge
    Krogness, Cathinka M.
    Tjensvoll, Ingrid
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Sövik, Guldborg
    Metabolic responses of the deep-water sponge Geodia barretti to suspended bottom sediment, simulated mine tailings and drill cuttings2015In: Journal of Experimental Marine Biology and Ecology, ISSN 0022-0981, E-ISSN 1879-1697, Vol. 473, p. 64-72Article in journal (Refereed)
    Abstract [en]

    Northeast Atlantic sponge beds are recognized as local hotspots for biodiversity and nutrient cycling. Despite their important functional role little is known about their sensitivity to effluents from the expanding hydrocarbon-, mining- and bottom trawling industry. Here, data on physiological and biological responses of the common demosponge Geodia barretti to short (4 h) and long-term (50 day) cyclic exposure of suspended particles are presented. The laboratory study showed that 4 hour pulse exposures with crushed rock particles at 500 mg l(-1) caused a 50% drop in oxygen consumption but with a quick recovery to pre-exposure oxygen consumption once suspended sediment loads returned to background levels. Long-term cyclic exposure (12 h each 24 h) for 29 days caused a permanent drop in oxygen consumption with 60% in sponges exposed to 50 mg l(-1) of crushed rock but with no apparent effect on the energy content of the sponge. Oxygen consumption and energy content of sponges exposed to natural bottom sediments at the same concentration remained unchanged. In conclusion, G. barretti appears to have well developed mechanisms to resist sediment stress, however, the study demonstrated that operations releasing large amounts of suspended crushed rock such as exploration drilling and submarine tailings disposal near sponge beds should be carefully planned to avoid long-term losses of benthic ecosystem functions, such as organic matter re-mineralization.

  • 5.
    Tjensvoll, Ingrid
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Sediment resuspension: Impacts and extent of human disturbances2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Resuspension of sediment by anthropogenic disturbances is a concern due to the impacts it has on organisms and ecosystems. Bottom trawling is one major cause of sediment resuspension. A field study showed that a small trawl created a sediment plume 120 - 150 m wide and 15-18 m high (Paper 1). The sediment in the same study was highly contaminated. Blue mussels exposed to the sediment plume showed an increased uptake of contaminants and after 1 month reached levels toxic for human health (Paper 1). In the Baltic Proper, bottom trawling is the main cause of sediment suspension in waters >73 m, where resuspension by wind induced waves is minimal. Compared with dredging, bottom trawling annually resuspends 23-88 times more sediment in this area (Paper 4).

    Bottom trawling is expanding to deeper waters where sediment resuspension is expected to have larger impacts on organisms compared with shallow water. Deep water sponges create important habitats that are attractive fishing grounds. A laboratory experiment (Paper 3) showed that deep water sponges had a rapid respiratory response to short exposure of elevated turbidity.

    Boat activities in harbours are another major cause of sediment and contaminant remobilisation to the water column. A laboratory experiment showed that suspension of sediment with high TBT concentrations induced higher mortality in blue mussels, Mytilus edulis, and faster growth inhibition of the alga Ceramium tenuicorne than unsuspended sediment (Paper 2).

    This thesis clearly shows that resuspension due to human activities, in particular bottom trawling, is widespread and can have impacts on a range of organisms. However, there are large differences in management of these activities as they are covered by different legislative frameworks. When managing dredging, it is the most cited concern, whereas it is not considered in the management of bottom trawling.

  • 6.
    Tjensvoll, Ingrid
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Eklund, Britta
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Johansson, Lisen
    Bradshaw, Clare
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Suspension of TBT-contaminated sediment causes physiologicalstress in macroalgae and blue musselsManuscript (preprint) (Other academic)
    Abstract [en]

    Tributyltin is a toxic compound that has been used in antifouling paint for boats andships. Due to the immediate toxic effects at very low concentrations it was banned in many countries in 1986. Due to its slow degradation it is expected to be stored in the sediment for many decades. This experiment simulated a small boat harbour with frequent resuspension events of TBT-contaminated sediment to measure the impacts onthe release, bioavailability and effects of tributyltin. Physiological stress responses were measured in two coastal species, the blue mussel, Mytilus edulis, and the red algaCeramium tenuicorne. Response variables measured were respiration, ammonia excretion, clearance rate and survival rate (for mussels) and growth inhibition (for thealga). Resuspension released both dissolved and particle-bound TBT to the surrounding water and made it bioavailable for both organisms. There was a clear toxic effect of the highest concentrations and it was evident that both mussels and algae showed a fasterand more negative response when the sediment was suspended. Repeated or continuous exposure to suspended TBT-contaminated sediment can exert a risk to the organisms living in environments such as harbours.

  • 7.
    Tjensvoll, Ingrid
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Kutti, T.
    Fossa, J. H.
    Bannister, R. J.
    Rapid respiratory responses of the deep-water sponge Geodia barretti exposed to suspended sediments2013In: Aquatic Biology, ISSN 1864-7782, E-ISSN 1864-7790, Vol. 19, no 1, p. 65-73Article in journal (Refereed)
    Abstract [en]

    Sponges often dominate deep-water benthic faunal communities and can comprise up to 90% of the benthic biomass. Due to the large amount of water that they filter daily, sponges are an important link between benthic and pelagic ecosystems. Across the Tromso-flaket, Barents Sea, Norway, there are high biomasses of deep-water sponges. This area is also an important fishing ground, with fishing activity in some areas >27000 trawl hours yr(-1). Bottom trawling suspends large quantities of sediment into the water column, with measured concentrations up to 500 mg l(-1). This is the first study on the effects of suspended sediment exposure on deep-water sponges. In a laboratory experiment, Geodia barretti (Bowerbank 1858) (Class: Demospongiae) was exposed to 5 different sediment concentrations (0, 10, 50, 100 and 500 mg l(-1)). Respiration rates were measured before, during and after the exposure period. The results demonstrate that G. barretti physiologically shuts down when exposed to concentrations of 100 mg l(-1) (86% reduction in respiration), with thresholds of responses occurring between 10 to 50 mg l(-1). However, rapid recovery to initial respiration levels directly after the exposure indicates that G. barretti can cope with a single short exposure to elevated sediment concentrations. Given the high bottom-trawling frequency in Tromso-flaket, sponges may be frequently exposed to suspended sediments. Therefore, it is important that further investigations on the effects of suspended sediments on filter feeding organisms focus on the effects of repeated and long-term suspended sediment exposures to evaluate the overall ecological impacts.

  • 8.
    Tjensvoll, Ingrid
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Sköld, Mattias
    Swedish University of Agricultural Sciences (SLU), Department of Aquatic Resources, Institute of Marine Research.
    Jönsson, Anette
    Bradshaw, Clare
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    The extent of sediment resuspension caused by bottom trawling, storms, and dredging in the Baltic ProperManuscript (preprint) (Other (popular science, discussion, etc.))
    Abstract [en]

    This study compares the extent and frequency of seafloor disturbances due to anthropogenic processes (bottom trawling and dredging) with those due to wind-driven waves in the Baltic Proper. There is little overlap between areas affected by bottom trawlers and naturally from waves, and bottom trawling is the main cause of sediment resuspension at greater (>73m) depths. Swedish bottom trawlers annually suspend between 3.8 and 13.6 M tonnes in this area, while from the reported dredging projects (reported between 2007 and 2009) the estimated maximum annual spillage was 0.14 M tonnes. The dominance of bottom trawling as a factor suspending sediment is clear, but management approaches for bottom trawling and dredging are different, despite similar expected effects on organisms and the environment. 

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