Changes in phytoplankton bloom phenology over the North Water (NOW) polynya: a response to changing environmental conditions

• Published in: Polar biology 2017-09, Vol.40 (9), p.1721-1737
• Main Authors: Marchese, Christian, Albouy, Camille, Tremblay, Jean-Éric, Dumont, Dany, D’Ortenzio, Fabrizio, Vissault, Steve, Bélanger, Simon
• Format: Article
• Language: English
• Subjects: Amplitude; Amplitudes; Analysis; Annual variations; Biogeochemistry; Biomedical and Life Sciences; Blooms; Chlorophyll; Chlorophyll a; Climate change; Correlation analysis; Duration; Ecological monitoring; Ecology; Ecosystems; Empirical analysis; Environmental changes; Environmental conditions; Environmental factors; Environmental quality; Global temperature changes; Ice cover; Indicators (Biology); Interactions; Life Sciences; Marine ecology; Marine ecosystems; Mathematical models; Microbiology; Oases; Ocean, Atmosphere; Oceanography; Orthogonal functions; Phenology; Phytoplankton; Plankton; Plant Sciences; Polynyas; Predators; Satellite imagery; Satellites; Sciences of the Universe; Sea ice; Sea surface; Sea surface temperature; Stress concentration; Surface temperature; Trophic relationships; Variability; Wind stress; Zoology; Zooplankton
• ISSN: 0722-4060; 1432-2056
• DOI: 10.1007/s00300-017-2095-2

Marine ecological indicators can be used to assess the condition of the pelagic ecosystems. The bloom onset provides a warning bell for possible changes in trophic interactions and biogeochemical processes. However, depicting the phenology of phytoplankton blooms at high latitudes, where long-term observations are sparse or unavailable, is not a straightforward task. A data-interpolating empirical orthogonal function algorithm was applied to daily satellite-retrieved chlorophyll- a images to produce a long-term (1998–2014) and cloud-free data set over the North Water (NOW) polynya. The seasonal bloom was modeled using a multi-Gaussian approach from which a baseline of phenological characteristics was extracted. The correlation analysis highlights the influence of environmental factors, such as sea surface temperature, cloud fraction, wind stress, and sea-ice concentration, in modulating the bloom start date, its duration, and amplitude. The year-to-year variability in bloom onset appears to be controlled by a delicate balance between oceanographic and meteorological conditions. Blooms last longer during years characterized by a longer open-water period and are shorter during those characterized by greater sea-ice coverage. Noteworthy is the decrease in phytoplankton bloom amplitude over the 17 years examined. Collectively, these outcomes depict the NOW as a climate-sensitive region in which the pelagic marine ecosystem seems to be going toward a decline in chlorophyll- a concentrations. Satellite time series are still too short to differentiate between inter-annual variability, inter-decadal variability, and climate change signal. Should these changes persist; however, the NOW may no longer act as a productive regional oasis supporting thriving populations of zooplankton and top predators.