Phytoplankton response to climate change in the North Atlantic and Southern Ocean

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Phytoplankton response to climate change in the Antarctic Peninsula

Publication . Ferreira, Afonso Miguel Barros Barreto; Gonçalves, Vanda Costa Brotas; Brito, Ana Cristina Florindo de; Mendes, Carlos Rafael Borges

The Western Antarctic Peninsula (WAP) is one the fastest-warming regions on Earth, with temperatures rising significantly since the 1950s. This rapid warming has profoundly impacted its marine ecosystems, including phytoplankton, the foundation of the food web. However, the regional effects of climate change are highly complex, making it challenging to fully understand the extent of impacts on phytoplankton and their broader ecological implications. This thesis aims to enhance the current understanding of phytoplankton response to climate change in the WAP by integrating in-situ observations, satellite data, and laboratory experiments. Five key objectives guided this work: i) review and synthesize current knowledge on observed phytoplankton changes; ii) identify knowledge gaps and propose future research directions; iii) evaluate and validate ocean colour remote sensing products for assessing phytoplankton biomass; iv) assess trends in biomass and bloom phenology; and v) compare the responses of key phytoplankton taxa to specific environmental changes associated with climate change. Results show multiple recent changes in phytoplankton, including shifts in biomass, bloom timing, community composition, and size structure. A new regional satellite algorithm (OC4-SO) was developed to more accurately estimate phytoplankton biomass in the WAP, which allowed to conclude that climate change has been associated with higher biomass and longer bloom periods since 1998. Community-wise, cryptophytes were seen to be potentially more efficient in handling periods of excessive light than diatoms, helping explain why cryptophytes are increasingly outcompeting diatoms in meltwater-influenced coastal areas during the summer, where phytoplankton can become entrapped in a well-lit, shallow mixed layer. Future research must focus on better understanding the seasonal and spatial dynamics of phytoplankton. Given the logistical and financial difficulties of conducting research in Antarctica, acquiring the long-term data necessary for fully comprehending climate change impacts on the WAP ecosystem will require a sustained collaborative effort among multiple Antarctic observation programs.

2024-11-12Tese de doutoramento

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Fundação para a Ciência e a Tecnologia

Número da atribuição

SFRH/BD/144586/2019