Marine Environmental Research 12 (1984) 173-189 Organic Pollution of an Inland Marine Cave from Bermuda Thomas M. Iliffe, Timothy D. Jickells Bermuda Biological Station for Research, Ferry Reach 1-15, Bermuda & Martin S. Brewer Bermuda College, Prospect, Devonshire, Bermuda (Received: 23 January, 1984) ABSTRACT Inland marine caves have served as biological refugia and, as such, frequently contain unique assemblages of taxonomically significant relict populations known only from a single cave or cave system. However, the absence of photosynthesis in this totally lightless environment and the presence of a highly stratified water column and long residence times for cave waters, characteristically result in depleted dissolved oxygen levels. Under such circumstances, organic pollution, even at low levels, can produce anoxic conditions and may consequently result in the extinction of entire species of cavernicolous fauna. We here present data on the normal environment of marine caves in Bermuda and cite as an example a cave which has become grossly polluted as a result of indiscriminate dumping. INTRODUCTION Marine caves have recently been recognized as a new type of habitat within the marine environment. On many islands in the Western Atlantic, extensive inland cave systems containing marine or brackish waters have 173 Marine Environ. Res. 0141-1136/84/$03.00 © Elsevier Applied Science Publishers Ltd, England, 1984. Printed in Great Britain