Do all studies include open ocean sampling?
ASK {
  {
    SELECT (COUNT(?ocean_sampling) AS ?counter)
    WHERE {
      orkgr:R155561 orkgp:compareContribution ?contrib.
      ?contrib orkgp:P41379 ?ocean_sampling.
      FILTER(?ocean_sampling = "F"^^xsd:string)
    }
  }
  FILTER(?counter = 0)
}