Phenological shuffling of major marine phytoplankton groups over the last six decades

Abstract

Aim: Phytoplankton form the basis of the marine food web and are responsible for approximately 50% of the world's photosynthesis. Changes to their ecology are, therefore, important: here, we examined seasonal patterns in ocean phytoplankton abundance for 45 taxa over 59 years collected from circa 410,000 km of line-transect sampling at temperate latitudes. Location: The North Sea. Methods: For our analysis we used plankton abundance data from the Continuous Plankton Recorder (CPR) survey, sea surface temperature measurements from the Hadley Centre, UK Meteorological Office and wind speed data from the International Comprehensive Ocean-Atmosphere Data Set, NOAA. Results:We found large differences in changes in the timing of peak abundance between the major phytoplankton groups. Late-summer blooming dinoflagellates (n = 10 taxa) tended to show a large seasonal advancement, the timing of peak abundance for dinoflagellates as group advancing 39 days over these six decades. By contrast diatoms (n = 35) did not show any change as a group in their timing of peak abundance over the time series. Granger causality testing suggested a major driver of these phenological changes has been ocean warming in general but more specifically the rate of spring temperature rise as the most important factor. We also found differences in the timing of peak abundance of harmful algal bloom taxa, with some showing peak abundance earlier while others have moved later. Main conclusions:There has been a fundamental transformation of the classic seasonal progression from blooms of diatoms to dinoflagellates, which lies at the heart of temperate marine food chains, as the classic bimodal diatom and dinoflagellate seasonal peaks are eroded to a more continuous, single, longer-lasting phytoplankton peak. This phenological shuffling within and between major taxonomic groups is likely to have profound implications for the transfer of energy to higher trophic levels. K E Y W O R D S climate change, marine plankton, phytoplankton abundance, phytoplankton phenology, sea surface temperature, spring temperature rise | 537 CHIVERS Et al. B I OS K E TCH E S William Chivers is a quantitative ecologist researching the effects of climate change on ecological communities. Martin Edwards is a marine ecologist looking at environmental change impacts on marine ecosystems including biodiversity, biogeographical and phenological changes. Graeme Hays is a marine ecologist looking at patterns of animal movement and abundance and their responses to climate change. Additional supporting information may be found online in the Supporting Information section. How to cite this article: Chivers WJ, Edwards M, Hays GC. Phenological shuffling of major marine phytoplankton groups over the last six decades. Divers Distrib. 2020;26:536-548.

Putting the Pacific marine heatwave into perspective: The response of larval fish off southern California to unprecedented warming in 2014–2016 relative to the previous 65 years

“…Altered productivity (Asch, 2015;Cushing, 1975). Subsequent to Asch (2015), incidents of altered phenology have been documented in phytoplankton (Chivers et al, 2020;Salgado-Hernanz et al, 2019), crustaceans (Emond et al, 2020), and fish (Lombardo et al, 2020) in various locations around the world. Within the CCE, anchovy was very abundant during the winter off Oregon even though it had never been observed to spawn in this season, and sardine and hake were much more copious than normal in winter of the MHW (Auth et al, 2018).…”

No evidence for fitness signatures consistent with increasing trophic mismatch over 30 years in a population of European shag Phalacrocorax aristotelis

“…158 marine taxa vs. 2,918 terrestrial taxa analysed). In the marine environment, rising sea surface temperatures (SSTs) have been correlated with advances in the timing of plankton blooms (Chivers et al, 2020) and fish spawning events (Asch, 2015), and there is increasing evidence to support the MMH (Burthe et al, 2012;.…”

“…158 marine taxa vs. 2,918 terrestrial taxa analysed). In the marine environment, rising sea surface temperatures (SSTs) have been correlated with advances in the timing of plankton blooms (Chivers et al., 2020) and fish spawning events (Asch, 2015), and there is increasing evidence to support the MMH (Burthe et al., 2012; Régnier, Gibb, & Wright, 2017, 2019). On average, the phenology of higher trophic‐level marine groups such as seabirds has not changed over time or in response to rising SST (Keogan et al., 2018; Poloczanska et al., 2013, but see Descamps et al., 2019 for details of regional exceptions).…”

Interannual variability of the initiation of the phytoplankton growing period in two French coastal ecosystems

“…While this study shows comparable IPGP dynamics when based on 1DV model simulations or in situ observations, we will next investigate the effect on phytoplankton dynamics of a fully realistic hydrodynamics (including horizontal and vertical advections; mixing processes; remote sources of nutrients from rivers) 3D model. We will focus on exploring the variability of phytoplankton communities during the IPGP to assess whether community change is occurring, as observed in other studies and for other ecosystems (Ianson et al, 2001;Edwards and Richardson, 2004;Chivers et al, 2020). When interannual evolutions in the phytoplankton growth are explored, the detection and the understanding of harmful algal bloom dynamics can also be addressed based on similar approaches.…”

“…Depending on the morphology and hydrodynamics of coastal zones (estuaries, bays, lagoons), the importance of controlling factors can be variable (Cloern, 1996). Temporal variation in the IPGP is of great importance in coastal ecosystems because it impacts not only phytoplankton by changing species composition or the succession of species (Ianson et al, 2001;Edwards and Richardson, 2004;Chivers et al, 2020) but also several other biological compartments, such as zooplankton and fish, by species replacements (Sommer et al, 2012).…”