Abbott Kathleen

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Last Name
Abbott
First Name
Kathleen
ORCID
0000-0002-5504-6730

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  • Article
    A single Prochlorococcus ecotype dominates the tropical Bay of Bengal with ultradian growth
    (Wiley, 2024-03-22) Grone, Jonathan ; Poirier, Camille ; Abbott, Kathleen ; Wittmers, Fabian ; Spiro Jaeger, Gualtiero ; Mahadevan, Amala ; Worden, Alexandra Z.
    The Bay of Bengal (BoB) spans >2.2 million km2 in the northeastern Indian Ocean and is bordered by dense populations that depend upon its resources. Over recent decades, a shift from larger phytoplankton to picoplankton has been reported, yet the abundance, activity, and composition of primary producer communities are not well-characterized. We analysed the BoB regions during the summer monsoon. Prochlorococcus ranged up to 3.14 × 105 cells mL−1 in the surface mixed layer, averaging 1.74 ± 0.46 × 105 in the upper 10 m and consistently higher than Synechococcus and eukaryotic phytoplankton. V1-V2 rRNA gene amplicon analyses showed the High Light II (HLII) ecotype formed 98 ± 1% of Prochlorococcus amplicons in surface waters, comprising six oligotypes, with the dominant oligotype accounting for 65 ± 4% of HLII. Diel sampling of a coherent water mass demonstrated evening onset of cell division and rapid Prochlorococcus growth between 1.5 and 3.1 div day−1, based on cell cycle analysis, as confirmed by abundance-based estimates of 2.1 div day−1. Accumulation of Prochlorococcus produced by ultradian growth was restricted by high loss rates. Alongside prior Arabian Sea and tropical Atlantic rates, our results indicate Prochlorococcus growth rates should be reevaluated with greater attention to latitudinal zones and influences on contributions to global primary production.
  • Technical Report
    Data Report: Observations from the CALYPSO 2022 Field Campaign
    (Woods Hole Oceanographic Institution, 2025-06) Middleton, Leo ; Abbott, Kathleen ; Berta, Maristella ; Mahadevan, Amala
    This report describes the data set from the CALYPSO 2022 campaign and the processing and quality-control steps that were taken to produce the data set. The CALYPSO Campaign was conducted from the R/V Pourquoi Pas? (February 17 – March 12, 2022) and the R/V Pelagia (February 20 – March 16, 2022).
  • Technical Report
    Biogeochemical Data Report CALYPSO 2022
    (Woods Hole Oceanographic Institution, 2025-06) Abbott,, Kathleen ; Middleton, Leo ; Wittmers, Fabian ; Grone, Jonathan ; Matantseva, Olga ; Carlson, Craig A. ; Halewood, Elisa ; Achterberg, Eric P. ; Riebesell, Ulf ; Mahadevan, Amala
    This report describes the biogeochemical data set from the CALYPSO 2022 Campaign and the processing and calibration steps taken to quality control the data.
  • Article
    Why is the monsoon coastal upwelling signal subdued in the Bay of Bengal?
    (American Geophysical Union, 2024-12-10) Abbott, Kathleen ; Mahadevan, Amala
    The Indian summer monsoon, which brings heavy precipitation to the densely populated Indian subcontinent, plays an important role in the development of a coastal upwelling circulation that brings colder, nutrient-rich water to the surface. Although the western shores of the Arabian Sea (AS) and Bay of Bengal (BoB) both experience upwelling-favorable winds during June-August, only the AS coastline exhibits significant surface cooling. In contrast, the BoB remains warm and its upwelling is characterized by a transient, weak sea surface temperature (SST) response confined to the east coast of India. A weaker mean alongshore wind stress and coastal circulation do not sufficiently explain the lack of SST response in the BoB. Here, we examine other reasons for the differing behavior of these two coastal margins. Firstly, we show that while winds are persistently upwelling-favorable in the western AS, intraseasonal wind variability in the BoB induces intermittent upwelling. Secondly, the vertical density stratification is controlled by salinity in the BoB, and upwelled waters are saltier, but only marginally cooler than surface waters. By contrast, the density in the AS is temperature-controlled, and upwelled waters are substantially colder than the surface. Additionally, satellite-based SST in the BoB does not adequately resolve the upwelling signal. Using a numerical model, we find that salinity stratification has a greater influence on the mean SST, while wind frequency alters near-shore SST and its temporal variability. This work has implications for the sensitivity of upwelling regions and their response to wind stress and stratification in a warming climate.