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Abstract In the North Atlantic, euphausiids (krill) form a major link between primary production and predators including commercially exploited fish. This basin is warming very rapidly, with species expected to shift northwards following their thermal tolerances. Here we show, however, that there has been a 50% decline in surface krill abundance over the last 60 years that occurred in situ, with no associated range shift. While we relate these changes to the warming climate, our study is the first to document an in situ squeeze on living space within this system. The warmer isotherms are shifting measurably northwards but cooler isotherms have remained relatively static, stalled by the subpolar fronts in the NW Atlantic. Consequently the two temperatures defining the core of krill distribution (7–13 °C) were 8° of latitude apart 60 years ago but are presently only 4° apart. Over the 60 year period the core latitudinal distribution of euphausiids has remained relatively stable so a ‘habitat squeeze’, with loss of 4° of latitude in living space, could explain the decline in krill. This highlights that, as the temperature warms, not all species can track isotherms and shift northward at the same rate with both losers and winners emerging under the ‘Atlantification’ of the sub-Arctic. 

Abstract Annual plankton succession has been investigated for many decades with hypotheses ranging from abiotic to biotic mechanisms being proposed to explain these recurrent patterns. Here, using data collected by the Continuous Plankton Recorder (CPR) survey and models originating from the MacroEcological Theory on the Arrangement of Life, we investigate Annual Phytoplankton Succession (APS) in the North Sea at a species level. Our results show that this phenomenon can be predicted well by models combining photosynthetically active radiation, temperature and macro-nutrients. Our findings suggest that APS originates from the interaction between species’ ecological niches and the annual environmental fluctuations at a community level. We discuss our results in the context of traditional hypotheses formulated to explain this recurrent pattern in the marine field. 

Abstract. Plankton form the base of the marine food web and are sensitive indicatorsof environmental change. Plankton time series are therefore an essentialpart of monitoring progress towards global biodiversity goals, such as theConvention on Biological Diversity Aichi Targets, and for informingecosystem-based policy, such as the EU Marine Strategy Framework Directive.Multiple plankton monitoring programmes exist in Europe, but differences insampling and analysis methods prevent the integration of their data,constraining their utility over large spatio-temporal scales. The PlanktonLifeform Extraction Tool brings together disparate European planktondatasets into a central database from which it extracts abundancetime series of plankton functional groups, called “lifeforms”, according toshared biological traits. This tool has been designed to make complexplankton datasets accessible and meaningful for policy, public interest, andscientific discovery. It allows examination of large-scale shifts inlifeform abundance or distribution (for example, holoplankton beingpartially replaced by meroplankton), providing clues to how the marineenvironment is changing. The lifeform method enables datasets with differentplankton sampling and taxonomic analysis methodologies to be used togetherto provide insights into the response to multiple stressors and robustpolicy evidence for decision making. Lifeform time series generated with thePlankton Lifeform Extraction Tool currently inform plankton and food webindicators for the UK's Marine Strategy, the EU's Marine Strategy FrameworkDirective, and for the Convention for the Protection of the MarineEnvironment of the North-East Atlantic (OSPAR) biodiversity assessments.The Plankton Lifeform Extraction Tool currently integrates 155 000 samples,containing over 44 million plankton records, from nine different planktondatasets within UK and European seas, collected between 1924 and 2017.Additional datasets can be added, and time series can be updated. The PlanktonLifeform Extraction Tool is hosted by The Archive for Marine Species andHabitats Data (DASSH) at https://www.dassh.ac.uk/lifeforms/ (last access: 22 November 2021, Ostle et al., 2021). The lifeform outputs are linked to specific, DOI-ed, versions of thePlankton Lifeform Traits Master List and each underlying dataset.