Impact of grazing and bioturbation of marine benthic deposit feeders on dinoflagellate cysts

The impact of benthic deposit feeders on marine dinoflagellate cysts was studied by adding a concentrated natural Swedish cyst assemblage to sediment with different deposit feeders in replicate 4-l aquaria. The deposit feeders used were the bivalve Abra nitida, the echinoderm Amphiura filiformis, and the polychaetes Melinna cristata and Nereis diversicolor. These species occur naturally near the Swedish west coast and were selected to represent different ways of feeding. The results showed a significant relative decrease of unfossilizable cyst species; whereas, the common fossilizable species Lingulodinium polyedrum significantly increased in the cyst assemblage after grazing. This work suggests that differences in dinoflagellate cyst compositions can in part be caused by different animal grazing behaviors.