Exciting news! A new paper led by Afonso Ferreira, based on 25 years of satellite Earth Observations (1998-2022), has just been published in Nature Communications. The study explores the impacts of climate change and environmental variability on phytoplankton bloom dynamics in the West Antarctic Peninsula (WAP). Afonso is a promising young researcher at MARE/Ciências-ULisboa and an active collaborator on the CHASE project, whom has done a terrific job combining spatiotemporal data from in-situ and satellite remote sensing to unravel the effects of climate change on marine primary production in this climatically sensitive region of the Southern Ocean. This research forms a key part of his PhD thesis at Ciências-ULisboa.
In this paper, Afonso Ferreira and colleagues implemented the new OC4-SO regional algorithm for Chl-a, specifically calibrated for the Antarctic Peninsula using the largest and highest-quality in-situ regional dataset currently available for this area (Ferreira et al., 2022). This allowed to analyze patterns of phytoplankton biomass and bloom phenology across the Antarctic Peninsula marine ecosystem in relation to regional atmospheric and oceanographic changes driven by ongoing climate change.
Phytoplankton biomass distribution in the Antarctic Peninsula. Key areas within the Antarctic Peninsula region and mean spatial distribution of chlorophyll-a (Chl-a mg m-3) during the full observation period (1998-2022).
The study used a comprehensive dataset of HPLC-derived in-situ surface Chl-a measurements across the WAP (N = 4322), including published data from Valente et al. (2022) and from the Palmer Station Antarctica LTERO (Schofield et al., 2022), as well as unpublished data from the Brazilian High-Latitude Oceanography Group (GOAL-FURG). The GOAL-FURG contributions included 533 in-situ Chl-a measurements collected during 12 austral summer expeditions to the WAP aboard the Brazilian vessels NP Almirante Maximiano and NP Ary Rongel. This also included of course data collected during OPERANTAR 37, when Afonso and Catarina Guerreiro first sailed to the Antarctic Peninsula in January–February 2019, as members of former projects PROPOLAR PHYTONAP and H2020-DUSTCO projects and collaborators of INTERBIOTA. Afonso has since participated in two more OPERANTAR expeditions (2020 and 2022) with the GOAL-FURG team, as member of the projects ECOPELAGOS, PROPOLAR FACT and PROPOLAR PHYTO-UP, of which CHASE members Catarina Guerreiro and Vanda Brotas were also part.
Picture of the Brazilian vessel NP Almirante Maximiano during OPERANTAR 37 in January–February 2019, with the island of King George on the background (photo credits: Catarina V. Guerreiro).
Afonso Ferreira and Catarina V. Guerreiro (on the left) and colleagues from FURG-GOAL Thiago Monteiro and Julia Mansur (on the right) onboard of the Brazilian vessel NP Almirante Maximiano during OPERANTAR 37 in January–February 2019.
A key finding of this study, published in Nature Communications, is the observed increase in phytoplankton biomass and longer bloom durations along the West Antarctic Peninsula (WAP), particularly in early austral autumn. This trend appears to be driven by a long-term decline in sea ice coverage over the past four decades and the recent intensification of the Southern Annular Mode (SAM; 2010-ongoing).
The decline in sea ice along the WAP creates conditions that enhance phytoplankton growth in areas previously covered by ice, offering more space and improved light conditions that support increased productivity and biomass accumulation. Additionally, the positive phase of SAM, which intensifies wind-driven vertical mixing in the upper ocean, may lead to deeper mixed layers along the Antarctic Peninsula. This process likely increases nutrient availability in the photic zone, particularly in offshore waters, further fueling marine phytoplankton growth.
Seasonal cycles of phytoplankton biomass across regions of the Antarctic Peninsula. Location of regions with coherent chlorophyll-a (Chl-a; mg m-3) seasonal cycles stemming from the hierarchical clustering analysis and smoothed mean seasonal cycle during the full observation period (1998–2022; solid lines), 2001–2010 (lines with squares), and 2011–2020 (lines with circles) for each region: DRA, which includes waters in the southern Drake Passage, north of the Southern Antarctic Circumpolar Current Front; BRS, which extends from Elephant Island to the offshore waters south of Anvers Island, including the Bransfield Strait and the South Shetland Islands; WEDN, which is situated between the Bransfield Strait and the outer NW Weddell Sea, off the Northern Antarctic Peninsula; GES, which contains the coastal waters stretching south from the Gerlache Strait; and WEDS, the NW Weddell coastal waters east of the Antarctic Peninsula.
These findings significantly enhance our understanding of the complex interactions between environmental changes and phytoplankton responses in the WAP, a climatically sensitive region of the Southern Ocean. They also raise important questions about the potential global consequences for carbon sequestration and Antarctic food webs in the future.
If you want to know more about this study, click here.