1 research outputs found
Benthicepelagic coupling and postdepositional processes as revealed by the distribution of opal in sediments: The case of the Rı´a de Vigo (NW Iberian Peninsula)
11 páginas, 5 figuras, 1 tablaOpal concentrations in dry bulk sediment were measured in 43 sampling stations in the RÃa de Vigo at 0e1, 1e2, 4e5, 10e11 and 14e15 cm
sediment depths. The amount of opal was correlated with the biogenic silicon flux to the sediment obtained by means of a box model. The
biosiliceous flux to the sediment (annual mean) is in good agreement with the content of opal found in the uppermost oxic layer, revealing
that pelagic primary production is the main factor controlling the biogenic silica content in surface sediments. This correlation is illustrated
by the equation: Opal (wt.%) ¼ 0.103BSiF þ 0.414 (R2 ¼ 0.95) where BSiF is the biogenic silicon flux to the sediment in g Si m-2 year-1.
In the innermost part of the rÃa, i.e. San Simón Inlet, the content of opal is higher than predicted by the equation, since other biogenic silica
sources to the sediment may be involved, as benthic diatoms proliferation or freshwater diatoms input. Elevated percentages recorded in the
inner rÃa in the subsuperficial sediment respond to the establishment of suboxiceanoxic conditions that enhance the preservation of opal.
The input of faecal pellets to the surface sediment derived from mussel rafts also controls the opal distribution and concentration in the rÃa.This
work was supported by the METRIA REN2003-04106-C03,
REN2003-09394, EVK2-CT-2000-00060, PGIDT04PXIC31
204PN and PGIDT00MAR30103PR projects. P.B. would
like to thank the Xunta de Galicia (Secretarı´a Xeral de Investigación e Desenvolvemento) and Ministerio de Educación,
Cultura y Deporte (SecretarÃa de Estado de Educación y
Universidades) for financial support.Peer reviewe