Benthic Genera Presence and Absence in the North Sea from 1990 to 2011

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The OBIS and Cefas-collected benthic data was subject to an initial clean-up process in which duplicated entries were eliminated and OBIS data on pelagic larvae of benthic species (obtained from pelagic sampling) was discarded. In order to limit this study to open waters, records at less than 2 nautical miles from the shoreline were discarded. Taxonomic information for all data was checked on the World Register of Marine Species (WoRMS, 2018) and updated when necessary. Benthic genera with less than 100 presence records were discarded, in order to limit the number of hard-to-detect taxa in the study for which absences may be due to lack of suitability of the sampling method (rather than being true absences). The study region was partitioned into a 0.25° x 0.25° regular grid with all presence records aggregated into “samples” by their grid cell and the year they were recorded. Only samples comprising at least 20 different genera were included, in order to exclude data from surveys targeting specific taxa and from surveys where insufficient or untargeted sampling effort resulted in an incomplete inventory of genera. It was considered an infauna sample when at least 33% of all its genera were infaunal, and similarly for epifauna. A sample could be both infaunal and epifaunal if it contained enough genera of both groups. Infauna (epifauna) genus absences were assumed where an infauna (epifauna) sample did not include that genus. The data is provided as two separate files with information for infauna and epifauna genera respectively. For each sample, the year is provided together with the longitude and latitude of the centre of the grid cell, followed by the complete list of presences (1) and absences (0) of infauna (or epifauna) genera. For full details of the procedure and the analysis carried out with this dataset, see E. Couce, G.H. Engelhard and M. Schratzberger, “Capturing threshold responses of marine benthos along gradients of natural and anthropogenic change”, Journal of Applied Ecology, 2020 ( `https://doi.org/10.1111/1365-2664.13604`_). .. _`https://doi.org/10.1111/1365-2664.13604`: https://doi.org/10.1111/1365-2664.13604