OSPAR request to investigate spatial representation of existing CEMP sediment monitoring stations

ICES advises that there is nosingle method that can be recommended to determine the geographic representativeness of existing  sediment  monitoring  stationsthat  would  meet  all  monitoring  purposes. Four  different  methods  might  be considered,depending on the monitoring purpose:

i) Sediment transport models are not yet sufficiently developed to be able to describe (with sufficient detail on a region scale) where sampling stations should be located;

ii) Existing monitoring stations that are in areas of fine sediment can be used for regional-scale assessment of status  in  relation  to GES  for MSFD Descriptor  8,based  on  whole  sediment  concentrations  (i.e.  not normalized or sieved). Monitoring of temporal change should,however,use data from sieved samples.If only  sieved  samples  are  available,  then  whole  sediment  concentrations  can  be  back-calculated  from concentrations in the sieved fraction.

iii) There is no strong relationship between variability of concentrations and size of a geographic area/strata.

iv) Visual   representations   of   existing   data   can   provide   information   on   the   geographic   pattern   of concentrations of sediment contamination.

It is apparent from several lines of enquiry that the degree of variability will differ for different substances and between geographic areas.