Hostname: page-component-7c8c6479df-94d59 Total loading time: 0 Render date: 2024-03-27T12:19:58.479Z Has data issue: false hasContentIssue false

Decadal-scale changes in the climate and biota of the Pacific sector of the Southern Ocean, 1950s to the 1990s

Published online by Cambridge University Press:  06 June 2005

DAVID G. AINLEY
Affiliation:
H.T. Harvey and Associates, 3150 Almaden Expressway, Suite 145, San Jose, CA 95118, USA, dainley@penguinscience.com
ELIZABETH D. CLARKE
Affiliation:
FRS Marine Laboratory, PO Box 101, 375 Victoria Road, Aberdeen AB11 9DB, UK
KEVIN ARRIGO
Affiliation:
Department of Geophysics, Stanford University, Stanford, CA 94305, USA
WILLIAM R. FRASER
Affiliation:
Polar Oceans Research Group, PO Box 368, Sheridan, MT 59749, USA
AKIKO KATO
Affiliation:
National Institute of Polar Research, Itabashi, Tokyo 173-8515, Japan
KERRY J. BARTON
Affiliation:
Landcare Research New Zealand, Private Bag 6, Nelson, New Zealand
PETER R. WILSON
Affiliation:
Landcare Research New Zealand, Private Bag 6, Nelson, New Zealand

Abstract

Simultaneous, but contrary, decadal-scale changes in population trajectories of two penguin species in the western Pacific and Ross Sea sectors of the Southern Ocean, during the early/mid-1970s and again during 1988–89, correspond to changes in weather and sea ice patterns. These in turn are related to shifts in the semi-annual and Antarctic oscillations. Populations of the two ecologically dissimilar penguin species - Adélie Pygoscelis adeliae and emperor Aptenodytes forsteri - have been tallied annually since the 1950s making these the longest biological datasets for the Antarctic. Both species are obligates of sea ice and, therefore, allowing for the demographic lags inherent in the response of long-lived species to habitat or environmental variation, the proximate mechanisms responsible for the shifts involved changes in coastal wind strength and air and sea temperatures, which in turn affected the seasonal formation and decay of sea ice and polynyas. The latter probably affected such rates as the proportion of adults breeding and ultimately the reproductive output of populations in ways consistent with the two species' opposing sea ice needs. Corresponding patterns for the mid-1970s shift were reflected also in ice-obligate Weddell seal Leptonychotes weddelli populations and the structure of shallow-water sponge communities in the Ross Sea. The 1988–89 shift, by which time many more datasets had become available, was reflected among several ice-frequenting vertebrate species from all Southern Ocean sectors. Therefore, the patterns most clearly identified in the Pacific Sector were apparently spread throughout the high latitudes of the Southern Ocean.

Type
Research Article
Copyright
© Antarctic Science Ltd 2005

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)