IMIS

Sampling protocol varied slightly beween transects: oblique hauls with a 200 µm mesh-size Bongo (stations off Vigo) or Juday-Bogorov (Coruña) net; vertical hauls with 200 µm mesh-size WP2 net (off Cudillero and Gijón transects, and Santander from 2013 onwards); and oblique hauls with 250 µm mesh-size Juday-Bogorov (Santander until 2013). The nets were towed from 100 m (50 m for the Juday-Bogorov at the Santander transect) or 5 m above the bottom at shallower stations to the surface. In all cases, the samples for abundance were preserved in 4% tetraborate-buffered formaldehyde for subsequent counting and taxonomic identification under a stereoscopic microscope. The biomass samples were filtered and dried at 60 ºC during 48 h before weighing to estimate the dry weight. The samples for biomass collected with the WP2 net (Cudillero, Gijón, and Santander since 2013) were split into three size-fractions: 200-500 µm, 500-1000 µm, and > 1000 µm. "