The meiobenthos of the North Sea: preliminary results of the North Sea Benthos Survey

During a synoptic survey carried out in April-May 1986, 171 localities were sampled in the North Sea as delimited by the Strait of Dover in the south and approximately by the 100 m isobath in the north.Meiofauna includes Nematoda, Copepoda, Turbellaria, Gastrotricha, Polychaeta, Oligochaeta, Priapulida, Kinorhyncha, Ostracoda, Halacarida, Isopoda, Tanaidacea, Bryozoa, Cnidaria, Sipunculida, Echiurida, Nernertini and Tardigrada.Nematodes are virtually the dominant group in all stations, their densities ranging from 61 to 4167 ind/TOcrn-.Only in the Southern Bight, where nematode numbers are low, harpacticoids sometimes represent the dominant meiofaunal taxon.A total of 278 copepod species belonging to 105 genera and 22 families were identified.Over 40% of the species are new to science; new taxa are particularly found among the interstitial families which are the most important families qualitatively.Five distinct communities could be recognised on the basis of the copepod composition: (1) the Southern Bight assemblage shows high densities of predominantly interstitial species (Cylindropsyllidae, Paramesochridae, Cyclopinidae) and a few characteristic taxa from coarse sediments; (2) the second community is found in the coastal zone of the Netherlands, Germany and Denmark, and in the Dogger Bank, and is dominated by large Ectinosomatidae and Ameiridae and interstitial Leptastacinae; (3) an impoverished community north of the Dogger Bank consists of large pelophilic species of the Diosaccidae, Laophontidae and Ameiridae; (4) between the scottish coast and Norwegian Deeps and in the Silver Pits Zosimidae, Cletodidae and Idyanthidae are the most important families; (5) the Norwegian Deeps, Devil's Hole and Fame Deep show a typical deepwater fauna with Ancorabolidae, Cerviniidae, Stenocopiinae and bathyal c1etodid genera.