BENTHIC FORAMINIFERA COMMUNITIES IN METHANE-RICH ENVIRONMENT SHOWED BY CORE HD319 IN DONGSHA SEA AREA OF THE SOUTH CHINA SEA

Faunal communities of benthic foraminifera in core HD319 in Dongsha area of the South China Sea have been studied in order to investigate the effects of gas methane on benthic foraminiferal populations. Different benthic foraminiferal assemblages were identified between methane-rich environment and non-methane environment. In methane-rich and strongly dysoxic environment,only methane-relative (methane-tolerant) species Uvigerina (U. peregerina,U. hispido-costata, U.rugosa,U. probscidea,spp.),Bulimina (B.aculeata, B.mexicana), Globobulimina glabra,Globocassidulina globosa, Bolivina(B.bradyi, B.quadrilatera),Brizalina superba and Hoglundina elegans were identified; in non-methane and suboxic environment, infaunal species dominated all samples, but epifaunal or trochospire faunal was sporadically recorded.However, in non-methane and oxic environment, epifaunal or trochospire faunal is the dominant species and indicative of influence of intermediate to high seasonal flux of organic matter. The difference in faunal communities of benthic foraminifera between the methane-rich environment and non-methane environment can be explained as the effect of gas methane influence on benthic foraminifera.