Spatial and temporal variations in the community structure of meiobenthos in the mangrove area near the Karachi coast, Pakistan

Spatial and temporal variations in relation to environmental and biological parameters were carried out from three stations in Sands pit backwater along the coast of Karachi, Pakistan from January 1999 to December 1999. Various meiofauna taxa were identified from the sample procured during low tide. The total mean densities of meiofaunal were (30.42 ±6.81) and (3628 ± 5958) individuals per10 cm2 in 500 μm and 63 μm size fractions respectively. Total densities were lowest during post monsoon (5890 ± 6145) and southwest monsoon periods (4844 ± 8399) and highest during (21247 ±16660) northeast monsoon period in 63 μm fraction. In 500 μm size fraction lowest densities were observed during post monsoon (7.96 ± 5.67) and highest during southwest monsoon periods (8.73 ±7510), there were significant differences between stations (F 2, 35 = 8.45, P<0.05) and seasons (F 3, 35 = 6.84, P<0.05) for meiofauna collected in 63 μm fraction. Nematodes contributed up to 88% of the total biomass followed by harpacticoid copepods, polychaetes, ostracods, turbellarians, and other meiofaunal taxa. The result of Bray-Curtis similarity measures, examining total meiofauna, and all ancillary environmental parameters (a biotic, biotic) and sediment properties were shown in four major clusters includes mollusks density, salinity water and pore, pH water and pore. A second cluster composed of root density, Eh water and pore, 500 μm fraction, percent moisture content, Porosity, standard deviation phi and kurtosis.