How the Subpolar gyre strength influences phytoplankton blooms dynamics in the North Atlantic

• Main Authors: Ferreira, Ana Sofia, Payne, Mark, MacKenzie, Brian, Visser, Andre
• Format: Conference Object
• Language: English
• Published: 2012
• Subjects: Iceland; north atlantic current; North Atlantic
• Online Access: https://orbit.dtu.dk/en/publications/aceb7db0-ceac-4dfc-9b65-d65da0745198; https://backend.orbit.dtu.dk/ws/files/123045050/R0312.pdf; http://ices.dk/products/CMdocs/CM-2012/R/R0312.pdf

Changes in the North Atlantic Subpolar gyre (NASPG) have been linked to the interannual variability of primary production. However, little is known about the mechanisms behind both environmental processes, and how the NASPG strength may extend its potential impacts to higher trophic levels, including early life stages of commercial fish species. We assess NASPG strength effect on North Atlantic phytoplankton bloom dynamics. We analyse time‐series (from 1998 to 2010) of chlorophyll a (Chl a, from the Globcolour project) annual anomaly as a proxy of phytoplankton abundance, and of sea surface height (SSH, from the AVISO project) as a proxy of current strength. Three regions were strategically chosen to characterize positions relative to the NASPG, describing: region 1—the northern part of NASPG, including the Irminger Current (IC); region 2—the North Atlantic Current (NAC), its northwards drift, and the influence of the NASPG strength; and region 3—the within‐NASPG dynamics. It is hypothesized that a strong NASPG index will be associated with a low‐abundance, late phytoplankton bloom, possibly induced by higher heat losses, and thus lower temperatures. A correlation between the annual anomaly in chlorophyll concentrations and the gyre index was found for the southern region (region 3). Indications of a strong influence of NASPG index are related to areas within the gyre, which may have an impact in the ecosystem functioning. The results also suggest that physical forcing other than the strength of the NASPG influence the primary production of the more northerly regions east and west of Iceland