Field survey on juvenile bivalve densities October 2007Measurements made of density of chlorophyll, the velocity of the current and temperature.vessel: RV POSEIDON (IFM Geomar, Germany)sampling stations: 20 stations in OWEZ and 10 stations in each of the 5 reference areas R2, R3, R4, R5, RL (for geographic positions of stations see worksheet geographical positions stations)sampling design: 1 boxcore per stationsampling gear: NIOZ boxcorer, sampling depth 20 cm, sampling diameter 30 cmsample surface juvenile bivalves: 0.024 m2 (i.e. 3 sub-cores each with diameter 10 cm2 per boxcore)sample depth juvenile bivalves: 5 cmsorting procedure lab: stacked sieves 1.0, 0.5 and 0.2 mmfollowing worksheets describe: *number of identified juvenile bivalve species (> 0.5 mm) found per boxcore (0.024m2) and per m2Station,Date time,species,n bivalves > 0.5 mm per 0.024m2,n bivalves > 0.5 mm per m2

Observation of species living on the bottem of the North Sea.Field survey on macrobenthos communities February 2011vessel: RV PELAGIA (NIOZ, TEXEL)sampling stations: 16 stations in OWEZ and 8 stations in each of the 6 reference areas R1, R2, R3, R4, R5, R6sampling design: 1 boxcore per stationsampling gear: NIOZ boxcorer, sampling depth 20 cm, sampling diameter 30 cmsorting procedure lab:nested sieves 11.2 mm, 6.7 mm, 2 mm, and 1 mm; identification species:macrofauna identified to species level under a stereomicroscope;polychaetes, crustaceans, molluscs and echinoderms identified to species level;juveniles and damaged animals, if unidentifiable, identified at higher taxonomic level (usually the genus); anthozoans, phoronids, oligocheates, nemerteans and turbellaria identified on their taxon level;further procedures:all individuals counted; Individual lengths (mm) of molluscs and echinoids measured;blotted wet weights of polychaetes, larger crustaceans, and ophiuroids measured to the nearest mg; remaining taxa determined per species/group. Small crustaceans (amphipods and cumaceans) only counted.