Chlorophyll a Concentrations in the North Pacific: Does a Latitudinal Gradient Exist?

• Published in: Limnology and oceanography Vol. 38; no. 8; pp. 1813 - 1818
• Main Authors: Dickson, Mary-Lynn, Wheeler, Patricia A.
• Format: Journal Article
• Language: English
• Published: Waco, TX American Society of Limnology and Oceanography 01-12-1993
• Subjects: Biomass production; Chlorophylls; Cruises; Earth, ocean, space; Exact sciences and technology; External geophysics; Marine; Mars; Oceans; Physical and chemical properties of sea water; Physics of the oceans; Phytoplankton; Plankton; Primary productivity; Sea water; Vacuum; Pacific Ocean; North Pacific; IN, North Pacific; Gradient; Spatial distribution; Latitudinal distribution; Vertical profile; Phytoplankton; Concentration; Chlorophyll a
• ISSN: 0024-3590; 1939-5590
• DOI: 10.4319/lo.1993.38.8.1813

Chlorophyll a concentrations were measured as a function of depth from 28 to $48\circ N$ along $152\circ W$ in March 1991 with Whatman GF/F and $0.2-\mum$ Nuclepore filters. Surface Chl a concentrations measure with $0.2-\mum$ Nuclepore filters were up to fourfold higher than those measured with Whatman GF/F filters. The largest difference between the two filter types was found in subtropical waters, where picoplankton were major constituent of the phytoplankton assemblage. Chl a concentrations integrated from 0 to 175 m showed a threefold increase $(9-26 mg Chl a m^-2)$ between 28 and $48\circ N$ when Whatman GF/F filters were used. However, integrated Chl a concentrations based on measurements with $0.2-\mum$ Nuclepore filters were nearly constant $(25-31 mg Chl a m^-2)$ over the transect. These results lead us to question the existence of previously reported latitudinal gradients in integrated Chl a concentrations in the North Pacific Ocean.