Shoreline foraminiferal thanatacoenoses around five eastern Caribbean islands and their environmental and biogeographic implications

摘要

Foraminiferal thanatacoenoses were examined around five islands in the Caribbean Sea, which forms a single biogeographic province with respect to nearshore (<3. m water depth) foraminifera, which live primarily on marine vegetation. On death, they become incorporated into the sediment. The assemblage at a site reflects the live assemblage and post mortem affects such as dissolution and transport during storms. Reefal species (Amphistegina gibbosa, Asterigerina carinata) are transported towards shore during storms. Foraminiferal thanatacoenoses were examined in 65 nearshore sediment samples from around five eastern Caribbean islands: St. John (US Virgin Islands), St. Kitts, Nevis, Bequia and Tobago. Cluster and principal components analyses distinguished the following environments (indicator species in parentheses):. 1.Sediment associated with mangroves (Ammonia sobrina),2.Bays subject to organic matter enrichment (Quinqueloculina poeyana, Triloculina rotunda, T. trigonula),3.Areas subject to moderate sediment flux during storms (Quinqueloculina auberiana, Nodobaculariella mexicana, Peneroplis proteus, Archaias angulatus),4.Locations subject to high sediment flux during storms (Amphistegina gibbosa),5.Sites little stressed by organic matter enrichment or storms (Discorbis rosea).The majority of samples were from sites in the last category. The data from this study could form the nucleus of a catalogue of Caribbean beaches and their environmental influences.