Plankton communities and physical oceanography observed on the Southeast Shoal region, Grand Bank of Newfoundland

• Published in: Journal of Plankton Research
• Main Authors: Anderson, J.T., Gardner, G.A.
• Format: Text
• Language: English
• Published: Oxford University Press 1986
• Subjects: Articles; Newfoundland; Copepods
• Online Access: http://plankt.oxfordjournals.org/cgi/content/short/8/6/1111; https://doi.org/10.1093/plankt/8.6.1111

We report results of a survey carried out in May 1981 over the northern portion of the Southeast Shoal and across the shelfbreak along the axis of Lilly Canyon, Newfoundland Grand Bank. The data indicated a strong thermal gradient at the shelfbreak with an associated change in plankton community composition between shelf and slope waters. Chlorophyll was highest (2–5 μg 1−1) in subsurface waters on the shelf and also overlying a nutricline ∼50 m depth at the shelfbreak and over the slope. Vertical stability, N:P ratios and the physical oceanographic data all indicated enhanced vertical mixing at the shelfbreak. Plankton species distributions indicated invertebrate zooplankton biomass was highest at, and beyond, the shelibreak where calanoid copepods predominated. Over the shelf the ctenophore, Pleurobrachia pileus , was abundant (10–50 animals 10 m−3 Paradoxically, fish eggs and larvae were also most abundant on the shelf, where suitable food appeared sparse and predators more abundant. The distribution of chlorophyll and nutrients in relation to the physical structure emphasized a difference between shelf and slope areas.