Coupling between the thermohaline, chemical and biological fields during summer 2006 in the northeast continental shelf of the Gulf of Cádiz (SW Iberian Peninsula)

• Main Authors: Eleonora Anfuso, Rocio Ponce, Carmen Gonzalez Castro, Jesús M. Forja
• Format: Article
• Language: English
• Published: Consejo Superior de Investigaciones Científicas 2010-12-01
• Series: Scientia Marina
• Subjects: nutrients; chlorophyll a; nitracline; river guadalquivir; gulf of cádiz
• Online Access: http://scientiamarina.revistas.csic.es/index.php/scientiamarina/article/view/1217

The coupling between the thermohaline, chemical and biological variables on the northeast continental shelf of the Gulf of Cádiz was determined during the Emigas I survey in summer 2006. Samples were collected to chemically characterize the different water types and to analyze the chlorophyll a distribution. Four different water masses were identified: North Atlantic Central Water (NACW), Surface Atlantic Water (SAW), considered a modification of NACW, and South and North Surface Waters. The highest nutrient levels were found in subsurface NACW, while surface waters were almost nutrient-depleted except in the Guadalquivir region. The isopycnal level of 26.3 kg m-3 marked the limit between nutrient-rich NACW and nutrient-poor surface waters. At the offshore stations, the subsurface cholorophyll a maximum was located at the depth of nitracline and associated with the 26.3 kg m-3 isopycnal level rather than with the pycnocline depth. At the inshore stations, chlorophyll a maxima were observed at the bottom, except for the surface maximum in the River Guadalquivir region.