A review of the physical oceanography of the Great Barrier Reef and Western Coral Sea /

Abstract

Pumice is abundant throughout the atolls of the Pacific 23 • 24 , and is continually added through submarine and shoreline eruptions or land-derived pumice carried into the sea by rivers. Immense pumice eruptions have occurred throughout geological time. Several km 3 of drift pumice were produced by the Krakatau eruption 25 of 1883. Pumice-rich pyroclastic rocks are abundant in marine formations throughout the geological record back to the Precambrian 26 , so rafting of organisms on drift pumice has been an important mechanism of long-range dispersal throughout the history of life in the oceans. D MICE carrying mutations at the W (Dominant white spotting) and SI (Steel) loci develop abnormalities in three independent systems: neural crest-derived melanocytes, primordial germ cells and haematopoietic stem cells. Consequently, homozygotes of viable mutant alleles have white coats and are sterile and severely anaemic. Tissue recombination studies predict that the W gene is expressed cell autonomously, whereas the product of the SI locus affects the microenvironment in which the stem cells migrate, proliferate and differentiate 1-6. The W locus encodes the proto-oncogene c-kit, a member of the tyrosine kinase receptor family 7 · 8 •