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Southern Bay of Biscay Associated Investigators: Related Web Sites: Related Time Series: The Santander transect is part of the time-series program RADIALES (Instituto Español de Oceanografiía). Station 4 of the Santander transect, used for this site summary, is located off the North Iberian coast (43 34.4'N, 3 47.0' W). Zooplankton samples were collected from 50 m to surface (oblique hauls) on a monthly basis with a Juday-Bogorov net (50 cm diameter) fitted with a 250 µm mesh. Samples were preserved in 4% formalin in sodium borate-buffered seawater and then examined in the laboratory for identification and counting of mesozooplankton by rarefaction method (Omori and Ikeda, 1984). Biomass was calculated as dry weight (Lovegrove 1962) in the laboratory after 2 months of preservation. The seasonal cycle of zooplankton abundance and biomass is characterized by a unimodal pattern with sustained high densities from March to September. It is the interannual variability during these months that mainly drives the year to year differences in average biomass and abundance (Figure W2). Higher biomass and abundance were observed at the beginning and end of the time series suggesting that there is a low frequency cycle. Nevertheless a slightly decreasing trend in zooplankton biomass is observed even though the last two years have been higher than average. Both in situ temperature and Reynolds SST show an increasing trend, over the length of the time series and since 1900, with the last five years being at or above the highest temperatures seen in the last 100 years (Figure W3). CPR copepod abundance anomalies for the standard area adjacent to Santander (Figure W3) also show a clear decreasing trend in total copepod abundance. This decrease is in opposition to the upward trend shown by the water column stratification index (Valdes et al, 2007) and SST temperature. This relationship between zooplankton and environmental conditions highlights the importance that the longer duration of water column stratification could have in limiting the interchange of nutrients from deeper to surface waters and consequently limiting the growth of phytoplankton and zooplankton (Valdes and Moral, 1998). REFERENCES: Valdes L, Lopez-Urrutia A., Cabal J., Alvarez-Ossorio M., Bode A , Miranda A, Cabanas M , Huskin I, Anadon R, Alvarez-Marques F , Llope M, Rodriguez N . 2007. A decade of sampling in the Bay of Biscay: What are the zooplankton time series telling us?. Progress in Oceanography, 74 (2-3): 98-114 Lovegrove, T. 1962. The effect of various factor son dry weight values. Rapp. P-V reun. Cons. Perm. Int. Explor. Mer 1953:86-91. Omori M. and T. Ikeda 1984. Methods in Marine Zooplankton Ecology. John Wiley & Sons, Inc., Toronto, 332 pp. |