Integration of temporal environmental variation by the marine plankton community

Ad Barton,A Atkinson,Ca Stock,F González Taboada,Ce Widdicombe

doi:10.3354/meps13432

Abstract

Theory and observations suggest that low frequency variation in marine plankton populations, or red noise, may arise through cumulative integration of white noise atmospheric forcing by the ocean and its amplification within food webs. Here, we revisit evidence for the integration of stochastic atmospheric variations by comparing the power spectra of time series of atmospheric and oceanographic conditions to the population dynamics of 150 plankton taxa at Station L4 in the Western English Channel. The power spectra of oceanographic conditions (sea surface temperature, surface nitrate) are redder than those of atmospheric forcing (surface wind stress, net heat fluxes) at Station L4. However, plankton populations have power spectral slopes across trophic levels and body sizes that are redder than atmospheric forcing but whiter than oceanographic conditions. While zooplankton have redder spectral slopes than phytoplankton, there is no significant relationship between power spectral slope and body size or generation length. Using a predator-prey model, we show that the whitening of plankton time series relative to oceanographic conditions arises from noisy plankton bloom dynamics in this strongly seasonal system. The model indicates that, for typical predator-prey interactions, where the predator is on average 10 times longer than the prey, grazing leads to a modest reddening of phytoplankton variability by their larger and longer lived zooplankton consumers. Our findings suggest that, beyond extrinsic forcing by the environment, predator-prey interactions play a role in influencing the power spectra of time series of plankton populations.

Highlights

In the marine environment, plankton populations exhibit considerable variability on a broad range of timescales, from rapid diel changes in cell size (Hunter-Cevera et al 2014) or position in the water column (Lampert 1989) to much longer term and lower frequency interannual- (Behrenfeld et al 2006), Mar Ecol Prog Ser 647: 1–16, 2020 decadal- (Fromentin & Planque 1996, Edwards et al 2013), and centennial-scale fluctuations (Barton et al 2016)
The reddening of SST relative to white noise atmospheric forcing is consistent with the stochastic climate model paradigm (Frankignoul & Hasselmann 1977, Hall & Manabe 1997, Deser et al 2010), where the ocean surface, with its large heat capacity, has a relatively long intrinsic timescale and a
Observations from Station L4 indicate that the physical−chemical environment in the ocean surface (SST, nitrate) has redder power spectral slopes than white noise atmospheric forcing

Summary

Introduction

Plankton populations exhibit considerable variability on a broad range of timescales, from rapid diel changes in cell size (Hunter-Cevera et al 2014) or position in the water column (Lampert 1989) to much longer term and lower frequency interannual- (Behrenfeld et al 2006), Mar Ecol Prog Ser 647: 1–16, 2020 decadal- (Fromentin & Planque 1996, Edwards et al 2013), and centennial-scale fluctuations (Barton et al 2016) These longer term and lower frequency variations in plankton populations present a particular challenge to marine scientists and resource managers. Anthropogenic climate change will continue to alter ocean environments in the coming century (Bopp et al 2013), providing an additional long-term agent of change in marine plankton communities (Edwards & Richardson 2004, Dutkiewicz et al 2015, Barton et al 2016)

Methods

Results

Conclusion