Marine tube-dwelling diatoms and their occurrence in the Netherlands

Attached to solid substrate species of the tube-forming diatoms are found th entire Dutch coast. Probably because of the increased eutrophication over the last decades there is an indication that the abundance of certain tube-dwelling species such aParlibellus delognei andParlibellus berkeleya shows also a strong increase. At some favourable sites it is estimated that at there peak of their seasonal development more than 10¹⁰ diatomcells per square metre can be found. The taxonomy of the tube-dwelling species has a long history started in 1803 when the first species were described by the wellknown phycologist Dillwyn. In short this taxonomic history is described. In addition the process of formation and development of the muco-polysaccharide tubes is documented and illustrated. In conclusion the occurance of endo and epitubular symbionts or associates is overviewed. Especially diatoms of the generaNitzschia are found inside the tubes of some species while species from the generaLicmophora, Synedra, Amphora andCocconeis have a preference to become attached to the outer surface of tubes.