On the size of the Peru upwelling ecosystem

Citation
S. Nixon et A. Thomas, On the size of the Peru upwelling ecosystem, DEEP-SEA I, 48(11), 2001, pp. 2521-2528
Citations number
16
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Aquatic Sciences","Earth Sciences
Journal title
DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS
ISSN journal
0967-0637 → ACNP
Volume
48
Issue
11
Year of publication
2001
Pages
2521 - 2528
Database
ISI
SICI code
0967-0637(200111)48:11<2521:OTSOTP>2.0.ZU;2-S
Abstract
Previously published estimates of the area of the Peru upwelling ecosystem vary by more than an order of magnitude. In an effort to improve this situa tion, we used a 24-month sequence of SeaWiFS satellite images of chlorophyl l in the surface water off Peru from 5 degreesS to 18.5 degreesS during Sep tember 1997-August 1999 to estimate the size of the nutrient enhanced produ ctive habitat associated with the upwelling. The first 12-month period was marked by El Nino conditions, the second by strong upwelling. Using a chlor ophyll threshold of > 1.0 mg m(-3) to define the limit of the productive ha bitat resulted in maximum area estimates of 120 x 10(3) km(2) during Septem ber 1997-August 1998, and 220 x 103 km(2) during September 1998-August 1999 . The latter result is consistent with an area estimate we calculated using total fishery landings and a regression relating fishery yields per unit a rea to annual primary production per unit area. Although year-to-year varia tion in the annual mean size of the upwelling ecosystem must be significant , even discounting El Nino, events, our analysis has shown that at least fi ve of the extreme earlier values are not good estimates of the size of the productive habitat. We may now be close to knowing the average size of the ecosystem to within a factor of about two. (C) 2001 Elsevier Science Ltd. A ll rights reserved.