Global warming impacts phytoplankton at a long-term Pacific Ocean coastal station

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Ajani, Penelope; Davies, Claire ORCID ID icon; Eriksen, Ruth ORCID ID icon; Richardson, Anthony


Journal Article

Frontiers in Marine Science - Marine Ecosystem Ecology



Understanding impacts of global warming on phytoplankton – the foundation of marine ecosystems – 14 is critical to predicting changes in future biodiversity, ocean productivity, and ultimately fisheries 15 production. Using phytoplankton community abundance and environmental data that span ~90 years 16 (1931-2020) from a long-term Pacific Ocean coastal station off Sydney, Australia, we examined the 17 response of the phytoplankton community to long-term ocean warming using the Community 18 Temperature Index, an index of the preferred temperature of a community. With warming of ~1.8 C 19 at the site since 1931, we found a significant increase in the community temperature index from 20 1931-1932 to 2009-2020, suggesting that the relative proportion of warm-water to cold-water species 21 has increased. Providing greater confidence that the long-term change in the Community 22 Temperature Index was real, was its clear seasonal cycle, with highest values at the end of austral 23 summer (Feb/Mar), and lowest at the end of winter (Aug/Sept), a pattern well supported by other 24 studies at this location. The shift in CTI was a consequence of the decline in the relative abundance 25 of the cool-affinity (optimal temperature = 18.69C), chain-forming diatom Asterionellopsis glacialis 26 (40% in 1931-1932 to 143% in 2009 onwards), and a substantial increase in the warm-affinity 27 (21.53℃), also chain-forming diatom Leptocylindrus danicus (20% in 1931-1932 to 57% in 2009 28 onwards). L. danicus reproduces rapidly, forms resting cysts under nutrient depletion, and displays 29 extremely high morphological and physiological strain variability. Species such as L. danicus may 30 provide a glimpse of the functional traits and phenotypic/genetic variation necessary to be a ‘winner’ 31 under climate change.


climate change, community temperature index, time-series, diatom

Ecological Impacts of Climate Change

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Journal article - Refereed


Ajani, Penelope; Davies, Claire; Eriksen, Ruth; Richardson, Anthony. Global warming impacts phytoplankton at a long-term Pacific Ocean coastal station. Frontiers in Marine Science - Marine Ecosystem Ecology. 2020; 7:1.

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