Phytoplankton variability on the Faroe Shelf

Characteristics and variability of the inner front of the southeastern Bering Sea

“…In a two-layered stratified water column, tidal energy mixes the lower layer and wind-generated turbulence mixes the upper layer. Tidal fronts have been described in many locations: off the Amazon River (Geyer, 1995), on the Faroe shelf (Gaard et al, 1998), around the British Isles (Simpson and Hunter, 1974;Fearnhead, 1975;Pingree and Griffiths, 1978;Kasai et al, 1999), over Georges Banks (Franks and Chen, 1996;Chen and Beardsley, 1998), in the Yellow Sea (Lie, 1988), in the White Sea (Semenov and Luneva, 1999), and the Bohai Sea (Haung et al, 1999). Because of their impact on the distribution of temperature, salinity and baroclinic currents, tidal fronts influence the distribution of nutrients, phytoplankton, and zooplankton (e.g., Franks and Chen, 1996;Gaard et al, 1998), and hence they influence the character of the ecosystem.…”

Sandeel as a link between primary production and higher trophic levels on the Faroe shelf

“…The average renewal rate of the on-shelf water is estimated to be about 1/75 d −1 (Gaard 2003). The renewal rate is mainly based on the nitrate reduction on-shelf, but is corrected for horizontal nitrate import to the shelf as described by Steingrund & Gaard (2005).…”

“…The shelf water is relatively well separated from the open ocean by a persistent front that surrounds the shelf, usually at a bottom depth of between 100 and 130 m ( Fig. 1) (Gaard et al 1998, Larsen et al 2002, 2009. Tidal rectification and other effects drive a current system that circles the islands in a clockwise direction (Hansen 1992).…”

“…Tidal rectification and other effects drive a current system that circles the islands in a clockwise direction (Hansen 1992). Due to strong tidal currents, the water column in the shallow parts of the shelf is mixed from surface to bottom throughout the year and no summer stratification occurs (Gaard 1996, Gaard et al 1998). The average residence time of the shelf water is estimated to be about 2 to 3 mo, but it is highly variable and the monthly flushing rates may vary by a factor of 6 (Gaard & Hansen 2000, Gaard 2003.…”

“…Due to strong tidal currents, the water column in the shallow parts of the shelf is mixed from surface to bottom throughout the year and no summer stratification occurs (Gaard 1996, Gaard et al 1998). The average residence time of the shelf water is estimated to be about 2 to 3 mo, but it is highly variable and the monthly flushing rates may vary by a factor of 6 (Gaard & Hansen 2000, Gaard 2003. The timing and intensity of the spring bloom on the Faroe shelf can vary considerably from one year to the next (Gaard et al 2002, Debes et al 2008b, and one hypothesis is that these variations are linked to the exchange rate between on-and off-shelf water, where intensive exchange in spring leads to relatively large losses of phytoplankton from the shelf, retarding development of intensive spring blooms .…”