Fine-scale planktonic habitat partitioning at a shelf-slope front revealed by a high-resolution imaging system

Adam T. Greer, Robert K. Cowen, Cedric M. Guigand, Jonathan A. Hare

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

Ocean fronts represent productive regions of the ocean, but predator-prey interactions within these features are poorly understood partially due to the coarse-scale and biases of net-based sampling methods. We used the In Situ Ichthyoplankton Imaging System (ISIIS) to sample across a front near the Georges Bank shelf edge on two separate sampling days in August 2010. Salinity characterized the transition from shelf to slope water, with isopycnals sloping vertically, seaward, and shoaling at the thermocline. A frontal feature defined by the convergence of isopycnals and a surface temperature gradient was sampled inshore of the shallowest zone of the shelf-slope front. Zooplankton and larval fishes were abundant on the shelf side of the front and displayed taxon-dependent depth distributions but were rare in the slope waters. Supervised automated particle counting showed small particles with high solidity, verified to be zooplankton (copepods and appendicularians), aggregating near surface above the front. Salps were most abundant in zones of intermediate chlorophyll- a fluorescence, distinctly separate from high abundances of other grazers and found almost exclusively in colonial form (97.5%). Distributions of gelatinous zooplankton differed among taxa but tended to follow isopycnals. Fine-scale sampling revealed distinct habitat partitioning of various planktonic taxa, resulting from a balance of physical and biological drivers in relation to the front.

Original languageEnglish (US)
Pages (from-to)111-125
Number of pages15
JournalJournal of Marine Systems
Volume142
DOIs
StatePublished - Feb 1 2015

Keywords

  • Diatom aggregates
  • Fronts
  • Gelatinous
  • Georges bank
  • Larval fishes
  • Predator-prey
  • Salps
  • Shelf edge
  • Zooplankton

ASJC Scopus subject areas

  • Aquatic Science
  • Oceanography
  • Ecology, Evolution, Behavior and Systematics

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