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| 2. |
- Andersson, Agneta, et al.
(författare)
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Vertical transport of lipid in seawater
- 1993
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Ingår i: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 98:1-2, s. 149-155
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Tidskriftsartikel (refereegranskat)abstract
- Lipids in seawater act as solvents and transporters of lipophilic organic pollutants. To investigate a possible transport route of lipophilic pollutants, the vertical flux of lipid was quantified during an annual cycle in the northern Baltic Sea. The lipid content in both sedimenting material and different size fractions of seawater was analyzed. During the year, 8 g lipid m-2 sedimented out from the photic zone to the benthic system. The sedimentation of lipid accounted for 300 to 400 % of the average standing stock of pelagic lipid and was concentrated in the spring bloom period (April-June) when 70 % of the total lipid sedimentation occurred. About 30 % of the produced pelagic lipid settled out from the system. In seawater the lipid maximum occurred at the end of the spring bloom, shortly after nutrient depletion, indicating a stress response in the algae. Since lipid sedimentation is concentrated in the spring bloom, removal of lipophilic organic pollutants may be important during this period.
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| 3. |
- Andre, C., et al.
(författare)
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Predation on Settling Bivalve Larvae by Benthic Suspension Feeders - the Role of Hydrodynamics and Larval Behavior
- 1993
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Ingår i: Marine Ecology-Progress Series. - 0171-8630. ; 97:2, s. 183-192
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Tidskriftsartikel (refereegranskat)abstract
- Predation by the suspension-feeding infaunal bivalve Cerastoderma edule on settling C. edule larvae was studied in a flume boundary-layer flow. The density of settled larvae was reduced by 33% in an area of 5 cm2 enclosing individual adults. Mean survival time for competent C. edule larvae drifting over sediment populated with feeding adults (380 ind. m-2) was 64 s, and 75% of the observed larvae were inhaled by adults. Observations of the siphonal currents produced by C. edule and the swimming behaviour of larvae were combined in a computer model to assess the importance of adult density and boundary-layer flow on the predation risk experienced by settling larvae. Survival of settling larvae decreased drastically with increasing adult density, whereas increased flow velocity caused only a slightly higher predation risk. Although reduction in larval settlement on the scale of individual adults may be small or moderate, inhalation of settling larvae by populations of resident suspension feeders may cause a significant decrease in settlement on a larger scale (10(1) to 10(3) m).
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| 4. |
- COCHLAN, William P, et al.
(författare)
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SPATIAL-DISTRIBUTION OF VIRUSES, BACTERIA AND CHLOROPHYLL-A IN NERITIC, OCEANIC AND ESTUARINE ENVIRONMENTS
- 1993
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Ingår i: Marine Ecology Progress Series. - Oldendorf : Inter-Research. - 0171-8630 .- 1616-1599. ; 92:1-2, s. 77-87
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Tidskriftsartikel (refereegranskat)abstract
- The spatial distribution of viruses was investigated in the coastal and oceanic waters of the Southern California Bight, USA, and the brackish waters of the Gulf of Bothnia, Sweden, using the direct harvesting technique and transmission electron microscopy. The vertical and horizontal distributions of viruses were examined in relation to bacterial abundance and chlorophyll a. Total virus abundances ranged from 0.3 to 52 X 10(9) l-1; higher concentrations of viruses were found in the upper 50 m of the water column and in coastal environments. Viruses with capsid diameters less than 60 nm dominated the virus community, were morphologically characterized as bacteriophages and were responsible for most of the observed spatial variability. Bacteria abundance alone explained 67 % of the spatial variability in virus numbers, thereby suggesting that bacteria constituted the major host organisms for viruses in these physically diverse habitats.
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| 6. |
- Jonsson, Per R., 1957, et al.
(författare)
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Swimming Behavior of Marine Bivalve Larvae in a Flume Boundary-Layer Flow - Evidence for near-Bottom Confinement
- 1991
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Ingår i: Marine Ecology-Progress Series. - 0171-8630. ; 79:1-2, s. 67-76
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Tidskriftsartikel (refereegranskat)abstract
- The swimming behaviour of settling larvae of the bivalve Cerastoderma edule (L.) was studied in still water and in a flume boundary-layer flow. In still water and slow flow the larvae swam upward in helices with high directionality, which is interpreted as morphological geotaxis. By reducing velar propulsion larvae regularly descended towards the bottom due to gravity. In moderate and fast flow (5 to 10 cm s-1) the larvae became confined to the viscous sublayer, where they slowly drifted in the streamwise direction at 0.45 to 1.6 mm s-1, less than 1 mm above the sediment surface, periodically making contact with the bottom. At flow velocities exceeding 15 cm s-1 the steady near-bottom drift changed to bed-load transport of tumbling larvae with high probability of resuspension. Based on kinematic and force analysis of swimming behaviour we suggest that boundary-shear induced torque restricts the settling larvae to the viscous sublayer. This near-bottom confinment may explain how habitat selection in benthic bivalves is realized under natural flow regimes.
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