Mesozooplankton abundances at time series station Helgoland Roads since 1974

Zooplankton was sampled with an oblique haul using a 150µm hand net at the "Kabeltonne" site (54°11.3′N, 7°54.0′E). Live samples were counted with a stereomicroscope until 1981, since then samples are preserved in 4% formaldehyde (buffered with Borax) to allow for storage and later examination.

Samples are counted depending on the density either as whole or subsamples. However, at least 60 individuals of each key species are counted per subsample to ensure counting of a representative part of the sample. This data collection includes mesozooplankton abundances since 1974 until present.