DISTRIBUTION OF BENTHIC FORAMINIFERA IN SURFACE SEDIMENTS OF THE LAIZHOU BAY,BOHAI SEA AND ITS ENVIRONMENTAL SIGNIFICANCE

A total of 240 samples from surface sediments of the Laizhou Bay,Bohai Sea were quantitatively analyzed for benthic foraminifera. There are 42 common benthic foraminifera species found in these samples. The benthic foraminiferal fauna is dominated by hyaline group with an average abundance of 70.9%. The porcellaneous group is the second and arenaceous group is the least. Both abundance and diversity of benthic foraminifera show an increasing trend from the Yellow River mouth to the open sea. Water salinity and sediment type are found to be the major factors controlling the distribution of benthic foraminifera. According to the distribution of dominant benthic foraminifera,two assemblages have been recognized:the Ammonia beccarii -Quinqueloculina spp. assemblage is distributed in the coastal transitional area with lower salinity,and the Cribrononion subincertum-Protelphidium tuberculatum assemblage is located in the offshore shallow sea with higher salinity.