Cyclonic eddies reveal Oegopsida squid egg balloon masses in the Agulhas Current, South Africa

  • MJ Roberts
  • T Zemlak
  • A Connell

Abstract

In 2005, 2006, 2007 and 2011, distinct Oegopsida squid egg masses were observed by scuba divers on the narrow southern KwaZulu-Natal (KZN) shelf in depths of 35–50 m off the coastal resorts of Park Rynie, Pumula and Port Edward, South Africa. In 2006, larvae in the egg balloons were sampled. DNA barcoding (i.e. cytochrome c oxidase subunit 1 sequencing) linked the larvae to the genus Lycoteuthis, a group commonly found on the continental slope of the Agulhas Bank and the west coast of South Africa. In all cases, the sightings were concomitant with low water temperatures of 14–18 °C, indicative of shelf edge upwelling. Historical ship-collected CTD data show these cooler waters to originate from a depth of 100–180 m on the KZN continental slope. Complementary satellite imagery revealed the cooler water and discoveries of the egg balloons to be coincident  with cold core cyclonic eddies embedded in the shoreward boundary of the Agulhas  Current. The temperature data suggest that these egg balloons, in the absence of  cyclonic eddy activity, would normally be found in the current on a density surface at a depth of ~130 m where velocities are typically around 100 cm s–1.

Keywords: DNA barcoding, egg masses, in situ observations, larvae, Lycoteuthidae, spawning, upwelling

African Journal of Marine Science 2011, 33(2): 239–246

Author Biographies

MJ Roberts
Oceans and Coasts, Department of Environmental Affairs, Private Bag X2, Rogge Bay 8012, South Africa;  Bayworld Centre for Research and Education, PO Box 7296, Rogge Bay 8012, South Africa
T Zemlak
Department of Integrative Biology, University of Guelph, Ontario, N1G 2W1, Canada
A Connell
South African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown 6140, South Africa
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Articles

Journal Identifiers


eISSN: 1814-2338
print ISSN: 1814-232X