Temperature change and chlorophyll readings at paired Antarctic coastal stations

Authors: names of authors including presenter Jacqueline Joosten, Carolina Duarte and Caio Cesar Ribeiro

Affiliations: for each author ECHO - Ecotoxicology and Chemical Oceanography Group, Centre of Marine Sciences (CCMAR), University of Algarve, Faro, Portugal.

Abstract: At 19 paired stations near King George Island, we tested whether temperature change between 26 January and 5 February 2026 was associated with chlorophyll change. Mean temperature rose from 2.20 to 2.61 °C, while mean chlorophyll readings fell from 1.31 to 0.45 relative units. Chlorophyll declined at 18 stations; station-level changes were negatively associated (Spearman ρ = −0.69, p = 0.001, n = 19), and the association persisted after excluding the station with the largest temperature increase (ρ = −0.63, p = 0.005, n = 18). Stations with greater temperature increases therefore tended to show larger chlorophyll declines during this interval. Antarctic phytoplankton responses to climate change are context dependent: warming and sea-ice changes alter light, stratification and nutrient supply, while glacial meltwater can deliver iron and support phytoplankton biomass (Deppeler & Davidson, 2017; Pan et al., 2025). Under global warming, local chlorophyll could rise or fall depending on which processes dominate. Our two-date result identifies a short-term temperature–chlorophyll association; it cannot establish causation or a long-term climate trend. Longer time series with measurements of nutrients, light, stratification and meltwater are needed to determine the mechanisms and likely trajectory.

Keywords: Antarctic coastal waters, temperature, chlorophyll, phytoplankton, climate change