Abstract

The Western Antarctic Peninsula (WAP) has undergone significant changes in air and seawater temperatures during the last 50 years. Although highly stenotherm Antarctic organisms are expected to be severely affected by the increase of seawater temperature, high-resolution datasets of seawater temperature within coastal areas of the WAP (where diverse marine communities have been reported) are not commonly available. Here we report on within-year (2016–2017) variation in seawater temperature at three sites on Doumer Island, Palmer Archipelago, WAP. Within a year, Antarctic organisms in South Bay were exposed to water temperatures in excess of 2 °C for more than 25 days and 2.5 °C for more than 10 days. We recorded a temperature range between −1.7° to 3.0 °C. Warming of seawater temperature was 3.75 times faster after October 2016 than it was before October. Results from this study indicate that organisms at South Bay are already exposed to temperatures that are being used in experimental studies to evaluate physiological responses to thermal stress in WAP organisms. Continuous measurements of short to long-term variability in seawater temperature provides important information for parametrizing meaningful experimental treatments that aim to assess the local effects of environmental variation on Antarctic organisms under future climate scenarios.

Highlights

  • There is an absence of continent-scale warming over Antarctica over the last 100 years (Stenni et al, 2017), during the last 50 years the Western Antarctic Peninsula (WAP) has undergone significant warming in air and seawater temperatures, with the later increasing by ∼2 ◦C (Cook et al, 2016; Meredith & King, 2005; Stenni et al, 2017)

  • The use of continuous measurements of environmental data, such as seawater temperature, can provide key information to identify current patterns of long- and short-term variability in Antarctic coastal waters. Such information is important in informing realistic scenarios for experimental work assessing the local effect of environmental variation on Antarctic organisms

  • Our results show that benthic organisms at South Bay were exposed to high local variability in seawater temperature, rates of warming (0.04 to 0.15 ◦C day−1), and duration of elevated temperatures

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Summary

Introduction

There is an absence of continent-scale warming over Antarctica over the last 100 years (Stenni et al, 2017), during the last 50 years the Western Antarctic Peninsula (WAP) has undergone significant warming in air and seawater temperatures, with the later increasing by ∼2 ◦C (Cook et al, 2016; Meredith & King, 2005; Stenni et al, 2017). These changes highlight the complexity of environmental change occurring at the WAP and the need for high-resolution information on regionalto local-scale patterns of climate change, to address its implications for marine polar ecosystems (e.g., Clarke et al, 2007; Meredith, Stefels & Van Leeuwe, 2017). Some Antarctic species are sensitive to even small changes in temperature (2–3 ◦C above the annual average), losing the ability to perform essential functions (Ingels et al, 2012; Peck, Morley & Clark, 2010; Peck, Webb & Bailey, 2004; Peck, 2005; Pörtner, Peck & Somero, 2007). To inform the design of studies that are relevant to future climate scenarios high-resolution records of local to regional patterns of water temperature are required

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