Methane emissions from three sea animal colonies in the maritime Antarctic

Methane (CH4) emissions from domestic animals and their excreta have been extensively studied. However, little investigation has been carried out for CH4 emissions from wild animal colonies. On a global scale, the most sea animal colonies are distributed in the maritime Antarctic. To evaluate temporal and spatial variations of CH4 fluxes from sea animal colonies in the maritime Antarctic, net CH4 fluxes were measured from the penguin, skua and seal colonies during the summertime of 2005/2006, using a static chamber technique. It was found that the CH4 emission rates from these colonies were considerably high. The mean fluxes from the wet sites of penguin, skua and seal colonies were 230.7, 142.5 and 94.1 μg m−2 h−1, respectively; the fluxes from the mesic sites were 123.8, 19.8 and 23.9 μg m−2 h−1, respectively. The CH4 fluxes were significantly affected by the deposition of the organic matter and nutrients from sea animal excreta, and soil water conditions. The single environmental factors cannot explain the seasonal variations of CH4 fluxes from the colonies. The fluxes from the skua colony showed a daily variation with a maximum at noon or midnight and a minimum at 20:00 h. These sea animal colonies are the “hotspots” of CH4 emissions in the maritime Antarctic, and their fluxes could constitute an important part of the annual CH4 budget for Antarctic tundra ecosystems.