Inter-decadal variability of phytoplankton biomass along the coastal West Antarctic Peninsula

Abstract

The West Antarctic Peninsula (WAP) is a climatically sensitive region where periods of strong warming have caused significant changes in the marine ecosystem and food-web processes. Tight coupling between phytoplankton and higher trophic levels implies that the coastal WAP is a bottom-up controlled system, where changes in phytoplankton dynamics may largely impact other food-web components. Here, we analysed the inter-decadal time series of year-round chlorophyll- (Chl) collected from three stations along the coastal WAP: Carlini Station at Potter Cove (PC) on King George Island, Palmer Station on Anvers Island and Rothera Station on Adelaide Island. There were trends towards increased phytoplankton biomass at Carlini Station (PC) and Palmer Station, while phytoplankton biomass declined significantly at Rothera Station over the studied period. The impacts of two relevant climate modes to the WAP, the El Niño-Southern Oscillation and the Southern Annular Mode, on winter and spring phytoplankton biomass appear to be different among the three sampling stations, suggesting an important role of local-scale forcing than large-scale forcing on phytoplankton dynamics at each station. The inter-annual variability of seasonal bloom progression derived from considering all three stations together captured ecologically meaningful, seasonally co-occurring bloom patterns which were primarily constrained by water-column stability strength. Our findings highlight a coupled link between phytoplankton and physical and climate dynamics along the coastal WAP, which may improve our understanding of overall WAP food-web responses to climate change and variability.This article is part of the theme issue 'The marine system of the West Antarctic Peninsula: status and strategy for progress in a region of rapid change'.

Testing the Canyon Hypothesis: Evaluating light and nutrient controls of phytoplankton growth in penguin foraging hotspots along the West Antarctic Peninsula

“…Major penguin breeding colonies around Anvers, Avian, and Charcot Islands are associated with cross‐shelf submarine canyon systems where increased chlorophyll has been recorded throughout the spring/summer season (Prézelin et al ; Ducklow et al ; Oliver et al ; Kavanaugh et al ; Kim et al ). These canyons act as conduits for warm, nutrient‐enriched deep mUCDW to penetrate to the nearshore regions (Prézelin et al ; Martinson et al ).…”

“…These biological hotspots have been identified by the presence of major breeding colonies for the Adélie penguins in the WAP (Schofield et al ). Additionally, increased phytoplankton biomass in these regions was evident from satellite observations of ocean color (Kavanaugh et al ) where phytoplankton biomass increases were found between November and March, with peak biomass found in January (Kavanaugh et al ; Kim et al ). The Northernmost site was located at PD near Anvers Island (64.91°S, 64.58°W); a Mid‐WAP site was located at MT near Avian Island (68.03°S, 69.28°W); and the third site was at the Southernmost accessible point along the ice edge off of Charcot Island (CI) (69.11°S, 76.45°W).…”

“…Sea ice previously lasted for longer periods for most of the Mid‐WAP, where Marguerite Trough (MT) is located, and as the annual days of sea ice have decreased (Stammerjohn et al ) there has been an increase in primary production (Montes‐Hugo et al ; Venables et al ). Positive chlorophyll anomalies have been observed gradually throughout the years starting as early as 2009 in the Northern stations and later on in the most Southern stations evaluated (Kim et al ), and is associated with increased sea ice since 2009/2010 (Schofield et al ). This increase in sea ice has since reversed itself and is consistent with the long‐term declines.…”

Climatic factors and their robust evidences controlling phytoplankton biomass in the Bransfield Strait

“…Interpreting the long-term trends of plankton ecosystems requires an understanding of the link between biological and environmental systems. Because phytoplankton biomass has undergone a significant long-term change since the 1970s (Kim et al 2018), it is necessary to update the previous studies with the recent and longer term environmental and climatic data sets to understand the complexity of phytoplankton biomass variation in the Southern Ocean region.…”

The marine system of the West Antarctic Peninsula: status and strategy for progress

“…Bringing complementary datasets together from different international efforts is especially important if we are to deconvolve regional versus local signals in such a highly heterogeneous environment [22]. Drawing in other disciplines that will mesh with marine science such as glaciology, atmospheric science and palaeoclimate will also be critical, as will engagement with other organizations and with policy, industry, education and with the public via 'citizen science', through dialogues with cruise ship operators, and development of apps and approachable literature.…”