Climatic Controls on the Spring Phytoplankton Growing Season in a Temperate Shelf Sea

Jardine, JE, Palmer, M, Mahaffey, C, Holt, J, Wakelin, S and Artioli, Y 2022 Climatic Controls on the Spring Phytoplankton Growing Season in a Temperate Shelf Sea. Journal of Geophysical Research: Oceans, 127 (5).

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The Northwest European Shelf is positioned directly beneath the North Atlantic Storm Track, within which the frequency and intensity of transient storms are modulated by large-scale climatic oscillations. In temperate shelf seas, the impact of storms on the physical environment has received considerable attention, but the effect on biogeochemistry is less studied. Here, we use output from a multidecadal (1982–2015) coupled physical-biogeochemical model supported by observations from ocean gliders to investigate phytoplankton growth throughout the winter-spring transition. We define two separate phytoplankton growth events: the spring bloom, defined as the exponential growth following seasonal stratification, and the prebloom, occurring before stratification, and accounting for up to 22% of the total spring growth. Our results support the paradigm that light is a first-order control, with the spring bloom initiating up to 22 days after stratification onset should light levels be too low to trigger the bloom. The prebloom is heavily influenced by the phase of the Atlantic Multidecadal Oscillation (AMO), demonstrated by an acceleration in the rate of increase of total chlorophyll concentrations (±90% confidence limit) from 7.6 ± 2.8 mg m−2 d−1 (during a positive AMO) to 13.1 ± 4.3 mg m−2 d−1 (negative AMO), due to modulation of periods of ephemeral stratification that occur between successive storms. We propose that phytoplankton growth in prebloom events might help buffer the lag between phytoplankton supply and larval recruitment, particularly during years when the spring bloom is delayed.

Item Type: Publication - Article
Divisions: Plymouth Marine Laboratory > National Capability categories > National Capability Modelling
Plymouth Marine Laboratory > Science Areas > Marine System Modelling
Depositing User: S Hawkins
Date made live: 17 Jun 2022 09:22
Last Modified: 17 Jun 2022 09:22

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