Seasonality, phytoplankton succession and the biogeochemical impacts of an autumn storm in the northeast Atlantic Ocean

Painter, Stuart C.; Finlay, Madelaine; Hemsley, Victoria S.; Martin, Adrian ORCID: https://orcid.org/0000-0002-1202-8612. 2016 Seasonality, phytoplankton succession and the biogeochemical impacts of an autumn storm in the northeast Atlantic Ocean. Progress in Oceanography, 142. 72-104. 10.1016/j.pocean.2016.02.001

Before downloading, please read NORA policies.

Preview	Text (Open Access paper) 1-s2.0-S0079661116000173-main.pdf - Published Version Available under License Creative Commons Attribution 4.0. Download (3MB) | Preview
	Text pickup_jgr_rev.pdf - Submitted Version Restricted to NORA staff only Download (351kB) | Request a copy

Abstract/Summary

Phytoplankton chemotaxonomic distributions are examined in conjunction with taxon specific particulate biomass concentrations and phytoplankton abundances to investigate the biogeochemical consequences of the passage of an autumn storm in the northeast Atlantic Ocean. Chemotaxonomy indicated that the phytoplankton community was dominated by nanoplankton (2-20 μ), which on average represented 75±8% of the community. Microplankton (20-200 μ) and picoplankton (<2 μ) represented 21±7% and 4±3% respectively with the microplankton group composed of almost equal proportions of diatoms (53±17%) and dinoflagellates (47±17%). Total chlorophyll-a (TCHLa = CHLa + Divinyl CHLa) concentrations ranged from 22 to 677 ng L-1, with DvCHLa making minor contributions of between <1% and 13% to TCHLa. Higher DvCHLa contributions were seen during the storm, which deepened the surface mixed layer, increased mixed layer nutrient concentrations and vertically mixed the phytoplankton community leading to a post-storm increase in surface chlorophyll concentrations. Picoplankton were rapid initial respondents to the changing conditions with pigment markers showing an abrupt 4-fold increase in proportion but this increase was not sustained post-storm. 19’-HEX, a chemotaxonomic marker for prymnesiophytes, was the dominant accessory pigment pre- and post-storm with concentrations of 48-435 ng L-1, and represented 44% of total carotenoid concentrations. Accompanying scanning electron microscopy results support the pigment-based analysis but also provide detailed insight into the nano- and microplankton communities, which proved to be highly variable between pre-storm and post-storm sampling periods. Nanoplankton remained the dominant size class pre- and post-storm but the microplankton proportion peaked during the period of maximum nutrient and chlorophyll concentrations. Classic descriptions of autumn blooms resulting from storm driven eutrophication events promoting phytoplankton growth in surface waters should be tempered with greater understanding of the role of storm driven vertical reorganization of the water column and of resident phytoplankton communities. Crucially, in this case we observed no change in integrated chlorophyll, particulate organic carbon or biogenic silica concentrations despite also observing a ∼50% increase in surface chlorophyll concentrations which indicated that the surface enhancement in chlorophyll concentrations was most likely fed from below rather than resulting from in situ growth. Though not measured directly there was no evidence of enhanced export fluxes associated with this storm. These observations have implications for the growing practice of using chlorophyll fluorescence from remote platforms to determine ocean productivity late in the annual productivity period and in response to storm mixing.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1016/j.pocean.2016.02.001
ISSN:	0079-6611
Additional Keywords:	autumn bloom; northeast Atlantic; chemotaxonomy; storm-impacts; biogeochemistry; succession
NORA Subject Terms:	Marine Sciences
Date made live:	22 Feb 2016 13:56 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/512110

Actions (login required)

View Item

Document Downloads

More statistics for this item...