Effects of dredging activities on growth of Laminaria saccharina
Lyngby, J.E.; Mortensen, S.M. (1996). Effects of dredging activities on growth of Laminaria saccharina, in: Dworschak, P.C. et al. (1996). Influences of organisms on their Environment, the role of episodic events: Proceedings of the 29th European Marine Biology Symposium Vienna, 29 August-2 September 1994. Marine Ecology (Berlin), 17(1-3): pp. 345-354 In: Dworschak, P.C.; Stachowitsch, M.; Ott, J.A. (Ed.) (1996). Influences of organisms on their environment, the role of episodic events: Proceedings of the 29th European Marine Biology Symposium Vienna, 29 August-2 September 1994. European Marine Biology Symposia, 29. Marine Ecology (Berlin), 17(1-3). 568 pp., more In: European Marine Biology Symposia., more |
| Keywords | Chemical reactions > Photochemical reactions > Photosynthesis
Dredging
Population functions > Growth
Sedimentation
Laminaria saccharina (Linnaeus) J.V.Lamouroux, 1813 [WoRMS]
Marine/Coastal |
| Authors | | Top | - Lyngby, J.E.
- Mortensen, S.M.
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| Abstract | The possible effects of fine-grained deposits on the photosynthesis, growth, and nutrient uptake of Laminaria have been studied in field and laboratory experiments. Some of the plants were treated with fine-grained material for two hours and then transplanted in rows together with untreated plants. At two-week intervals the treatment was repeated and samples collected. The macroalgae were analyzed for growth as well as chlorophyll a, nitrogen, and phosphorus content. In the laboratory experiments, plants of a uniform size were incubated in Plexiglas containers after leaf-marking and treatment in a sediment suspension. At weekly intervals, photosynthesis, growth, chlorophyll a, and nutrients were analyzed.The field study showed that Laminaria growth was significantly affected by the fine-grained material. The growth in the control experiment was 20% higher than in the treated plants. The chlorophyll a concentrations in the treated plants were significantly lower than in the control experiment, and the results indicated a reduced nutrient uptake in the treated plants. In the laboratory experiments the growth of the treated plants was only 30% of the controls, but no differences in photosynthetic capacities were detected. Nitrogen uptake was reduced in the treated plants, but no effects were observed on phosphorus uptake. Thick layers of fine-grained material caused direct harmful effects and rotting. The results are discussed in relation to dredging activities; it is concluded that in heavy sedimentation areas, Laminaria growth may be significantly reduced beyond the indirect effect of shading from suspended material in the water. |
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