Zooplankton abundance from a right whale habitat study in the Bay of Fundy and SW Scotian Shelf (1999-2001) (OBIS Canada)

Oceanographic surveys were conducted in the lower Bay of Fundy and Roseway Basin during the summers of 1999, 2000 and 2001. Zooplankton sampling was conducted in all years from NOAA Ship ‘Delaware II’ and additional sampling was conducted from NOAA Ship ‘Albatross IV’ in 2001. Zooplankton samples were obtained both in the presence (within a few hundred meters) and absence of right whales.

Depth integrated samples were collected with a 61 cm diameter bongo frame equipped with 333 μm mesh nets and 2 General Oceanics digital flowmeters. A CTD was affixed to the tow wire ~1 m above the bongo to telemeter the depth of the nets to the ship. The bongo was lowered at 0.50ms–1 to within 5–10 m of the bottom and then hauled in at 0.33 m s–1. The ship steamed at 0.8–1.0 m s–1 (1.5–2.0 knots) during tows. A flowmeter was mounted in the centre of each bongo to estimate the volume filtered by the nets.

In the lower Bay of Fundy during 2001, depth-stratified, 1 m2 multiple opening/closing net and environmental sensing system (MOCNESS) tows were conducted during 2001 in lieu of bongo tows. The MOCNESS was equipped with six, 150 μm mesh nets and the first of these remained open during the entire downcast to within 10 m of the bottom. The remaining five nets were towed through contiguous depth strata from the bottom of the downcast to the surface. The MOCNESS was towed at 0.5–1.0 m s–1 (1.0–2.0 knots) and paid out and hauled in at 0.33 m s–1. The volume filtered by the nets was estimated from a flowmeter positioned outside the net mouth.

Zooplankton samples were preserved in a 5% borate-buffered formalin and seawater solution and were subsampled in the laboratory with a Hensen stempel pipette. Subsample volumes were obtained such that 100 or more of the most abundant copepod species were counted. Calanus finmarchicus copepodite stages C3 and higher were counted separately while all other taxa were identified to species or genus level.