A particle separator used to concentrate Dinoflagellate cysts from sediment

Barry C. Smith, Agneta Persson, Gary H. Wikfors

Limnol. Oceanogr. Methods 7:521-526 (2009) | DOI: 10.4319/lom.2009.7.521

ABSTRACT: A device has been developed to separate and collect large numbers of dinoflagellate cysts from sediment samples of several liters volume. The apparatus consists of a 152.5 x 44.5 x 38-cm fiberglass tank with a 20-µm screen inserted diagonally across the long dimension, creating an inclined plane as the bottom of a settling tank. A peristaltic pump delivers resuspended bottom material to the top of the deep end of the tank. The particles settle according to mass and friction as the water moves to a drain near the top center of the shallow end of the screen. The desired particles can be vacuumed from specific areas of the screen and further refined with a final sieving step. More than 16 L marine mud were processed in this apparatus at one time. In a reference sediment sample collected from beneath New Haven Harbor (Connecticut, USA), cyst recovery was 25% for living cysts. The sediment in the uppermost part of the sorter had approximately 376 times more cysts/mL than the sediment originally added. The cyst fraction (particles 20-100 µm) contained ten times more cysts in the uppermost part of the sorter than at the middle or lower ends. Cysts within the cyst-rich zone of the separator settled differently depending upon species, size, and morphology.