Integration of temporal environmental variation by the marine plankton community

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.

Seasonal temporal dynamics of marine protists communities in tidally mixed coastal waters

“…Microscopic organisms are indeed known to be involved in complex and dynamical networks of interactions (i.e., grazing, parasitism, mutualism, quorum sensing, etc; Kivi et al, 1993;Dakos et al, 2009;Platt et al, 2009;Bjorbaekmo et al, 2020) that are tightly regulating the dynamics of individual species within the whole community structure. Recently, in the WEC at L4 station predator-prey interactions were investigated supporting our hypothesis that they play a role in influencing temporal changes in plankton populations (Barton et al, 2020).…”

“…A seasonal thermocline, occurring from May to October, is only reported in its western entrance, offshore and along the UK coasts (Pingree and Griffiths, 1980). In these seasonally stratified waters sampled regularly by the Plymouth L4 Western Channel Observatory (Pingree and Griffiths, 1978), plankton temporal dynamics has been recently explored (Widdicombe et al, 2010;Edwards et al, 2013, Barton et al, 2020 and both seasonal and inter-annual changes in abundance were observed along with significant long-term changes in community composition and reorganization of plankton food web (Molinero et al, 2013;Reygondeau et al, 2015). The temporal dynamics of planktonic communities in the permanently well-mixed waters that characterize the French coasts of the WEC have been less intensively studied.…”

Intraseasonal predictability of natural phytoplankton population dynamics

“…The larger the amount of noise added, the larger the assemblage size must be to achieve high predictability. Given that there will always be a range of sources of measurement error in phytoplankton time series such as at L4 (see Barton et al, 2020 ), this model result suggests that aggregating across multiple species may be a desirable strategy for making predictions.…”

Marine ecosystem changepoints spread under ocean warming in an Earth System Model

“…using the Bayesian Information Criterion yields the same number of changepoints almost everywhere but different models). The overall incidence of changepoints may be more important than their specific magnitude, as recent work suggests that even small-amplitude ecological and biogeochemical changes can have appreciable consequences (Stock et al, 2014a;Barton et al, 2020).…”

“…Rapid changes in marine plankton populations may occur when changes in environmental conditions generate a sudden forcing on the community (Muller-Karger et al, 2019;Ardyna et al, 2014), or when gradual changes in environmental conditions provoke a nonlinear response (Scheffer et al, 2001;Stock et al, 2014a). With or without environmental forcing, rapid changes can also emerge from the internal dynamics of plankton communities (Di Lorenzo & Ohman, 2013;Barton et al, 2020;Huisman & Weissing, 1999). Because of the challenges of collecting long-term and broad-scale measurements of plankton populations (Benway et al, 2019), much remains unknown about how frequent abrupt changes are in the lower trophic levels of pelagic marine ecosystems, how abrupt changes differ with trophic status or organism size (Barton et al, 2020), how abrupt changes in plankton populations correspond to those in physical or chemical environmental conditions, or how their frequency and distribution will change (or already are changing) with climate change (Beaulieu et al, 2016).…”