The fate of coccoliths at 48 degree N 21 degree W, Northeastern Atlantic

As part of the Joint Global Ocean Flux Study Program (JGOFS) North Atlantic Bloom Experiment (NABE), coccolithophore fluxes were recorded over one-year period, from April 1989 to April 1990. Three vertically moored sediment traps, synchronized on a 14-day interval, were deployed at 48 degree N 21 degree W at three water depths, at 1, 2 and 3.7 km (sea floor at 4.4 km). We present the results on the vertical variability of coccolith and coccosphere fluxes through the water column. Calcium carbonate was the largest component of the total mass flux, followed by particulate organic matter and opal. Coccolith and coccosphere seasonal fluxes followed the seasonality of the biogeochemical particle fluxes at all three depths, with maxima occurring during the spring particle "bloom". Annual coccosphere and coccolith fluxes were 1.5 x 10 super(8) and 0.9 x 10 super(11) m super(-2) year super(-1) respectively, at 1 km depth (or 3.1 x 10 super(8) and 1.4 x 10 super(11) m super(-2) year super(-1) including the spring 1990 episode). For the 3.7 km trap the corresponding values were 0.5 x 10 super(8) and 1.1 x 10 super(11) (0.6 x 10 super(8) and 1.1 x 10 super(11) including the partially recorded spring 1990 episode). Emiliania huxleyi, Gephyrocapsa muellerae, Calcidiscus leptoporus and Coccolithus pelagicus constitute from 65% (at 1 km depth) to 95% (at 3.7 km depth) of the total coccolith assemblages. The same four coccolith taxa dominate the fossil assemblages in the underlying surface sediments. Selective dissolution continues in the sediments, most notably the abundance of the solution-resistant species C. leptoporus increases from 10 to 15% in the trap samples to 15-40% in the sediments. Annual flux of calcium carbonate in sediment trap samples accounts for about 60% of the total annual mass flux, with the coccolith fraction (