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q-bio.PE · Populations and Evolutionphysics.ao-ph · Atmospheric and Oceanic Physics

North Atlantic CPR plankton temperature indices followed year-to-year SST in 1958–2019, but three copepod taxa caused all of the long-term copepod change

Question: when the North Atlantic is warmer, do plankton communities contain more warm-water taxa, by how much relative to the spatial temperature gradient, and did a 1958–1989 relation predict 1990–2019? Data: all public Continuous Plankton Recorder Survey v1.3 records (OBIS, 234,397 samples in 606 2-degree cells, 30–72 N, 1958–2019) matched to ERSSTv5 monthly SST; 37 copepod and 47 diatom and dinoflagellate species recorded in at least 80% of years. Method: species temperature index (STI) from occupancy-weighted cell SST; community temperature index (CTI) = mean STI of present taxa; cell-month anomalies; spatial versus year-to-year slopes; year-block and cell bootstraps; 999 shuffles of STI among taxa; fit on 1958–1989 and test on 1990–2019; eight variants. Results: for copepods the spatial slope was 0.50 C per C and the year-to-year slope was 0.33 (cell-years) to 0.42 (basin years), 67–84% of the spatial slope; the CTI trend was 96% (25–159%) of the trend that the spatial slope predicts, and the 1958–1989 fit predicted +0.23 C for 1990–2019 (observed +0.28 C). But Calanus finmarchicus, Centropages typicus and Calanus helgolandicus gave 68% of the response, shuffled STI values gave slopes this large often (p = 0.20–0.24), and STI did not predict taxon responses (rho = 0.13). Without these three taxa, the CTI of the other 34 taxa followed year-to-year SST (slope 0.27–0.30, 53–59% of the spatial slope, shuffle p = 0.006–0.058) but had no 1958–2019 trend (-0.000 C per decade; predicted +0.26 C for 1990–2019, observed +0.05 C); rare warm taxa decreased and Arctic Calanus increased. The copepod CTI rose much more than predicted in the North Sea (+0.77 against +0.17 C) and as predicted in the subpolar gyre. For diatoms and dinoflagellates the year-to-year slope (0.15–0.17) was larger than the small spatial slope (0.11), STI predicted taxon responses (rho = 0.51, p <= 0.0001), and the CTI rose 2.9 (1.9–5.4) times faster than SST predicts. Results were stable across abundance weights, STI definitions, split-sample STI, genera, stricter sampling and day/night strata. Limitations: STI and benchmark come from the same data; 2-degree surface SST; possible changes in taxonomic practice over 62 years cannot be tested; causes of the phytoplankton excess are not identified.

Continuous Plankton Recorder · community temperature index · copepods · phytoplankton · climate tracking · North Atlantic · sea surface temperature · space-for-time · out-of-sample test · Calanus finmarchicus · Calanus helgolandicus · thermal niche

Admitted 4 citing publications

References

14
  1. usesdoi:10.17031/1629

    All CPR Survey v1.3 records (CC BY 4.0), downloaded from OBIS, are the plankton data of this study.

  2. usesdoi:10.1175/JCLI-D-16-0836.1

    ERSSTv5 monthly SST gives the temperature of each sample cell and month.

  3. usesCalCOFI larval fish community temperature index changed 0.20 °C per °C of year-to-year 10 m temperature in 1951–2021, 59–117% of the spatial relation; a 1951–2013 fit predicted the 2014–2016 heatwave sci:sha256:16e7fa6aa99994401effde45c652662aa580554e63da0947c4b7aae50a0c6c26

    We use its design (spatial versus year-to-year CTI slopes, shuffled STI null, out-of-sample period) on a different data set, and compare its larval fish ratio with ours.

  4. Reef fish temperature index followed sea temperature across 2,781 Australian reef sites, but changed only 0.15 °C per °C year to year at 333 sites in 1992–2025, with lags and persistence sci:sha256:295af9c08fb0e6173cd08bd3baa36d912ea20c7702201ebd8c91fc3c8f367520

    Reef fish CTI comparison (0.15 C per C year to year).

  5. North American breeding-bird community temperature index fell in 1970–1996 and rose in 1997–2024 in all 30 tested BBS regions, at 25% of full tracking, but not more where June warming was larger sci:sha256:6a8e1da8f1a7e0d437f757e71aecaed395480e2280f2c33adc493e307ad75a1c

    Bird CTI comparison (25% of full tracking).

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    UK bird CTI comparison.

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    UK butterflies followed year-to-year temperature but not long-term warming, as our less common copepods did.

  8. Year-to-year biomass responses of demersal fish to bottom temperature were about 3% of their spatial temperature slopes in 13 trawl survey units (1963–2023) sci:sha256:73ec8e55114714e88c3a1d65b19dc7fbadba02fb93318f40a435610325a52c6a

    Trawl fish year-to-year responses were about 3% of spatial slopes.

  9. doi:10.1126/science.1071329

    Reported the northward shift of warm-water copepod assemblages in CPR data.

  10. doi:10.1038/ncomms14434

    Reported mismatch between CPR plankton range movements and climate velocity.

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    CPR taxa temperature index for krill.

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    CTI trends of plankton and other groups in European seas.

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    Community temperature index method and lag behind warming.

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    Origin of the community temperature index.

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