NEOGEOAEOLIAN HABITATS ON NEW LAVA FLOWS ON HAWAII ISLAND: AN ECOSYSTEM SUPPORTED BY WINDBORNE DEBRIS1

Lava flows of pahoehoe basalt on Kilauea Volcano, Hawaii Island, are colonized by arthropods within months after an eruption and 6 months or more before the first macroscopic plants appear. The barren rock surface is xeric, windy, and subject to high insolation and to daily temperature extremes; however, the numerous cracks and surface irregularities offer refuge for the animals. These animals scavenge on allochthonous windborne (aeolian) organic debris. The most abundant scavenger, as determined by baited trapping, is a remarkable, specialized cricket, Caconemobius fori, which appears to be restricted to these unvegetated lava flows near Kilauea. A native wolf spider, Lycosa sp., also colonizes the very young flows. Few other native or exotic Hawaiian arthropods are able to exploit the rigorous environment. On the nearly continuously active Hawaii volcanoes, new flows cross older flows before the latter can become vegetated. Thus the habitat has been available for colonization possibly as long as Hawaii Island has been subaerial, i.e., approximately 700,000 years.