Abundance and Distribution of meiofauna at Mangawhai Harbour Estuary, New Zealand

Abstract

Meiofaunal assemblages in Mangawhai harbour estuary were sampled for community analysis in summer (March 2013) and winter (October 2013). The main objective of this study was to provide a baseline survey of meiofaunal assemblages and to understand how environmental characteristics affect abundance and diversity of meiofauna. In the estuary nine sampling sites were chosen containing mangroves, pneumatophore zones, sandflats and/or mudflats, and saltmarshes. Besides meiofauna also sediment grain size, organic content, and primary benthic productivity (chlorophyll α) were measured. Twelve major taxa were identified within the study site. Densities of meiofauna ranged between 269 to 8090 ind.10 cm-2. Out of the twelve identifiable taxa, five dominant taxa which were present in all sites and habitats contributed to about 90% of the total observed abundance, with nematodes being the most abundant taxon (accounting for 55 - 70% of the total individuals observed). On average, meiofaunal abundances were higher in fine grained organically rich sediments compared to coarse grained sediments. Variations in overall species abundance appeared to be related to changes in species assemblages, which were strongly marked within habitat boundaries, such as between mangroves and sandflats. These results also suggest that meiofaunal abundance and taxa distribution is highly sensitive to local conditions and meiofaunal taxa can be greatly affected by physical and biological parameters. The abundances observed were similar to those observed within tropical estuaries.