ECOLOGY AND HABITS OF TEMPERATE SALT MARSH FORAMINIFERA AND ASSOCIATED MEIOFAUNA FROM A LABORATORY SALT MARSH SYSTEM

Salt marsh foraminifera attain extremely high abundances in comparison to other flora and fauna in the salt marsh sediments. These foraminifera have been used extensively as paleoenvironmental indicators (i.e. sea- level rise) and current environmental indicators (i.e. oil spills). Despite this, little is known regarding their functional importance in the salt marsh food web, including the biotic and abiotic controls of their distributions and life processes. Although their abundances can exceed 5,000 per 10ml sample, these species have been overlooked in most salt marsh ecological work and are simply lumped with detritus. A salt marsh from Chezzetcook Inlet, Nova Scotia, Canada, was replicated in the Aquatron Facility at Dalhousie University to continuously monitor the salt marsh community from a temperate region in a controlled environment. This mesocosm system is the first to provide high-resolution data on population dynamics and compositions of foraminifera in addition to meiofaunal species coexisting in the sediment with the foraminifera. In addition to this, feeding experiments have been conducted to better understand the roles of foraminifera within the salt marsh community. Transmission electron microscopy has been used to examine the vacuolar components from the common marsh species, Trochammina inflata, from both cultured and in situ samples. As expected, these robust species show a generalist feeding behavior, consuming detrital matter as well as bacteria from the salt marsh sediments. Other feeding experiments have also shown non-specific feeding habits in these foraminifera. At higher trophic levels, it appears that these foraminifera are not targeted food types for meiofauna, but do get consumed as part of the organic matter for many deposit feeders. In addition to other experiments not included here, the goals are to finally understand the specific roles of foraminifera in the salt marsh ecosystem, including interpreting irregularities seen in marsh populations. This is important not only for ecological work and management of existing salt marsh systems, but for better interpretation of fossil foraminifera from salt marsh paleoenvironments.