An extreme marine environment: a 14-month record of temperature in a polar tidepool

Tidepools are not uncommon in Antarctica, but there appear to be no data on the physical environment within polar tidepools and only anecdotal information on their biology. Here we report a high resolution record of temperature in an Antarctic tidepool made over two summers and the intervening winter. During the summer open water season the highest daily mean, and also the maximum temperatures, were recorded during the period of continuous daylight around the summer solstice. This short-term variability of temperature in the tidepool greatly exceeded that in the nearby open ocean, indicating the need for a eurythermal physiology in tidepool biota. In winter the tidepool froze over, the unfrozen water cooled to − 5.5 °C, and freeze concentration increased its salinity to roughly three times normal seawater. A polar tidepool isolated from the sea in winter is probably inimical to many larger marine organisms, which must populate the tidepool afresh each summer.