Contribution
Settling seston in a hypertrophic lake
Alvarez Cobelas, M.; Velasco Díaz, J. L.; Rubio Olmo, A.
Archiv für Hydrobiologie Volume 127 Number 3 (1993), p. 327 - 343
48 références bibliographiques
publié: Jun 9, 1993
DOI: 10.1127/archiv-hydrobiol/127/1993/327
ArtNo. ESP141012703005, Prix: 29.00 €
Abstract
Settling seston rates have been measured with sediment traps in a 6 m deep central station of a hypertrophic, gravel-pit lake close to Madrid (Spain). On the average, sedimentation rate amounted to 61 ± 37 g m-2d-1, with maximal values during the mixing and early stratification. Settling organic matter peaked at the end of mixing. However, resuspension was shown to occur very often and could be attributed to random resuspension and sliding on slopes. Since organic allochthonous matter inputs were negligible, settling organic seston mainly resulted from phytoplankton primary production and ranged from 5 to 49 % out of the latter. Time courses of settling C, N and P were uncoupled with increasing P deposition being an effect of calcite co-precipitation. Sedimentary losses accounted for ca. 25 % of total phytoplankton losses in the water column, with primary production and losses balancing each other. Finally, a positive dependence of organic settling matter on lake trophic degree is suggested but allochthonous inputs and resuspension should be also taken into account for explaining the variance involved.
Mots-clefs
resuspension • gravel-pit • allochthonous • seston rates