Rueda, M.J., M.G. Villagarcía, J. Godoy, J. Pérez, A. Cianca, L. Maroto, L. Cardona, C. Barrera and O. Llinás

Instituto Canario de Ciencias Marinas (ICCM), Apdo. 56, Taliarte, 35200 Las Palmas de Gran Canaria, Spain, Tel: +34-928-132900, Fax: +34-928-132908, E-mail: mjrueda@iccm.rcanaria.es

Chlorophyll "a" and gelbstoff fluorescence for oceanic waters in the eastern Central Atlantic

Since observations at station ESTOC (European Station for Time Series in the Ocean Canary Islands) were initiated, chlorophyll "a" determination has been made as part of the basic protocol of monthly sampling. This continuous sampling has produced up to now a 9-year data set which has enabled both the establishment of the main characteristics of its annual cycle and the study of the interannual variability for the same time period. As a mean value along the year, the vertical chlorophyll distribution shows a deep chlorophyll maximum (DCM) located at a depth of around 90m; however, in winter the vertical mixing gives a very homogeneous vertical profile. At the same time, in 1997 was started the gelbstoff fluorescence estimation at the same levels than the chlorophyll "a", having completed a 5-year series. Gelbstoff fluorescence values increase with depth, showing a stronger gradient from the inflection point of the density curve. The surface values where the gradient starts are greater during the winter period as compared to the rest of the annual cycle. The basically linear correlation found between both parameters from the surface layer to the depth of the deep chlorophyll maximum, enables the classification of the ESTOC station location as case I waters from an optical point of view. It also allows the calculation of primary production with a better approximation for the area.