Whale bones: a key and endangered substrate for cryptogams in Antarctica

摘要

Whale bones are very abundant at coastal sites across the Admiralty Bay, King George Island, Antarctica, since whale hunting was common in the beginning of the XX century. Since then, these bones became suitable substrate and true oasis for many mosses and lichenized fungi, but their number is dramatically changing in the coastal zones, due to the sea erosion, degradation, and anthropization. In this work, whale bones found in Keller Peninsula were mapped with drone images coupled with field work, and the covering and diversity of moss and lichen species was registered for 37 vertebrae using the square method of Braun-Blanquet. Comparing the number of whale bones remaining at Keller Peninsula during a 21 years period revealed a dramatic reduction, with skull bones 55.8% lower than previous records. In addition, vertebrae and ribs are reduced in size, and so mobile and disrupted that no longer represent stable substrates for a normal plant succession (average covering of 31.6%). We detected 4 moss species and 19 lichens associated with whale bones. Muscicolous lichens occurred on 35.1% of the bones, and 5.4% showed more than 50% cover by mosses, whereas the rest are at the earliest stage of colonization due to constant displacement. Measures are suggested to preserve the bones still remaining to ensure the protection of vegetation in this part of Antarctica. The vegetation oasis found on Antarctic bone ecosystems are highly prone to anthropic and climatic disturbances and represent key sites of plant succession.