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- Sundbäck, Kristina, 1949, et al.
(författare)
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Importance of benthic nutrient regeneration during initiation of macroalgal blooms in shallow bays
- 2003
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Ingår i: Marine Ecology-Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 246, s. 115-126
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Tidskriftsartikel (refereegranskat)abstract
- Fast growing ephemeral algae are increasingly observed in shallow coastal waters worldwide. This is generally considered a symptom of coastal eutrophication. It has been suggested that the reoccurrence of macroalgal mats, despite ongoing efforts to decrease nutrient loadings, may be explained by the fact that sheltered bays function as self-regenerating systems through benthic regeneration of nutrients. The importance of benthic nutrient regeneration during the initiation of the growth of filamentous green algal mats was investigated in 2 shallow-water bays on the west coast of Sweden. Nutrient regeneration was assessed in situ and in the laboratory, using sediment-water light/dark incubations and pore water distribution patterns. Benthic efflux of inorganic nutrients could supply up to 55 to 100% of the estimated nitrogen demand and 30 to 70% of the phosphorus requirements for the initial macroalgal growth from May to June. However, the availability of the pore water nutrient pool was influenced by the amount and functional type of infauna, and by competition from microphytobenthos. Because of the internal nutrient source of the embayments, it is suggested that there may be a significant time lag between a decreased nutrient supply to coastal waters and improved conditions of shallow water embayments.
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| 2. |
- Caradec, S., et al.
(författare)
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Macrofaunal reworking activities and hydrocarbon redistribution in an experimental sediment system
- 2004
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Ingår i: Journal of Sea Research. - : Elsevier BV. - 1385-1101. ; 52:3, s. 199-210
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Tidskriftsartikel (refereegranskat)abstract
- The influence of macrofaunal reworking activities on the redistribution of particle associated hydrocarbon compounds (HC) was experimentally investigated. Two distinct hydrocarbon mixtures adsorbed on montmorillonite particles (< 4 gm diameter) were added to the surface and deeper (2.5 cm) sediment layers. For comparison, luminophores (100-160 mum diameter) were added in the two deposit layers. At the start of the experiment, four macrobenthic species (the bivalve Abra nitida, the polychaete Scalibregma inflatum, and the echmoderms Amphiura filiformis and Echinocardium cordatum) were added to the sediment surface. The macrofauna added rapidly transferred HC from the surface sediment down to similar to5 cm depth by both continuous (biodiffusion) and non-continuous (biotransport) transport. Hydrocarbon compounds initially added to the deeper sediment layer were only subject to biodiffusion-like transport. Apparent biodiffusion coefficients (Db) quantified by using a 1-D model were between 0.5 and 8.4 x 10(-3) cm(2) d(-1), and biotransport coefficients (r) ranged from 2.0 to 27.6 X 10(-3) d(-1). Thus, the four species studied did not have the same effect on particle redistribution and, consequently, on HC repartition in the sediments. E. cordatum was the most efficient reworker. The present study demonstrated the importance of particle size selectivity by benthic fauna, and verified that macrofaunal reworking activities may redeposit sediment from deeper sediment layers on the sediment surface. Both processes have obvious implications for rates and pathways during organic matter mineralisation in marine sediments. (C) 2004 Elsevier B.V. All rights reserved.
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| 5. |
- Gilbert, F., et al.
(författare)
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2-D optical quantification of particle reworking activities in marine surface sediments
- 2003
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Ingår i: JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY. - 0022-0981. ; 285, s. 251-263
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Tidskriftsartikel (refereegranskat)abstract
- Particle and solute transport by faunal activities may significantly influence rates and pathways of organic matter mineralization during early diagenesis in surface sediments. One of the most frequently utilized techniques to quantify benthic biological reworking activities involves the calculation of a biodiffusion coefficient (D-b) estimated from model predictions of 1-D tracer distribution patterns. This technique is labor-intensive and time-demanding. Furthermore, it is normally used for measurements over several days and averages overall transport mechanisms from 3-D to 1-D on a cm scale. In the frame of this work, we developed a new technique based on the nondestructive screening of fluorescent particles (luminophores) using optical discrimination and CCD camera detection of fluorescence (2-D). At a site characterized by a dense population of the brittle star Amphiura filiformis and a high biodiffusion coefficient (obtained from 1-D distributions; D-b = 3 5.5 +/- 3.7 cm(-2) year(-1); n = 3), the optical reworking coefficient (ORC), estimated from the 2-D luminophore distribution patterns, was calculated (ORC = 27.4 +/- 9.1 DeltaQ cm(-2) h(-1); n=24). A nondestructive 2-D approach to quantify particle reworking may provide a powerful and complementary tool to further understand particle transport by the benthic fauna in surface sediments. The optical technique for 2-D detection of luminophores is relatively fast and easy to perform, with the ability to detect small scale (mm) particle movements on a time resolution of minutes or less. (C) 2002 Elsevier Science B.V. All rights reserved.
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