Wetlands
DOI 10.1007/s13157-012-0312-x
Intra-Annual Variation of Modern ForaminiferalAssemblage in a Tropical Mangrove Ecosystem in IndiaDOI 10.1007/s13157-012-0312-x
Mitali Dey & Dipnarayan Ganguly &Chumki Chowdhury & Natasha Majumder & Tapan Kumar Jana
Abstract This study relates the abundance of foraminifera with the fluctuations in hydrobiological characteristics gener- ated by the monsoonal cycle in a tropical mangrove ecosys-tem. Monthly variation of physicochemical properties of water and sediment, phytoplankton production, foraminifera assemblages were measured in the littoral zone of the Sundar- bans mangrove forest. Intra-annual variation of foraminifera exhibited a maximum abundance during the post-monsoon period and out of the 25 genera, numbers of calcareous and agglutinated forms were 16 and 9, respectively. Live benthic foraminifera were found to inhabit a wide range of sedimen depths and inhabiting a high energy environment their abun- dance was not restricted to the uppermost centimeter. Owing to mechanical damage (due to high energy system), chemical dissolution and intense bioturbation, the taphonomic process- es in this mangrove swamp could result in the destruction of the small size fraction of foraminifera, including agglutinatedtests. The low numbers of agglutinated foram could be due to silty clay substrate. Abundance of more calcareous dead specimens over live ones could be attributed to predation and transportation of dead marine species.Most of the marine species could not survive in this freshwater dominated system.Anthropogenic nutrient input and diatombloomin association with enhanced food to benthos are important controlling fac- tors on foraminiferal abundance and composition.
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