A particle separator used to concentrate Dinoflagellate cysts from sediment

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 × 44.5 × 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.