Benthic macrofauna of the mangrove swamp treated with municipal wastewater

Abstract

Benthic macrofauna and possible effects on community structureofdischarging municipal wastewater to Futian National MangroveReserve, the People‘s Republic of China, were investigated.Eighty-four species of ground-dwelling fauna belonging to 7Phyla,9 Classes, 46 Families and 65 Genera were identified. Abundantfamilies were Assimineidae, Melanidae, Potamididae,Ocypodidae,Grapsidae and Periophthalmidae. Between April 1991 to January1993,no obvious seasonal fluctuation in species compositionoccurred.Total biomass also remained unchanged. However, total densityshowed peaks in January and July (both in section A and B),probably due to the molluscs.A selected site of the mangroves was treated with municipalwastewater (60 m3 per week for 16 consecutive months). Incomparison to a control site, the effect of wastewaterdischarge ontotal mean biomass and density (particularly of molluscs andcrustaceans) appeared non-significant P?0.05). Thecommunity structure remained unchanged although some saprobicspecies emerged and total biomass in the area close to thewastewater front increased slightly. Multivariate analysisindicated that there probably was an initial inhibition periodanda subsequent recovery period for benthic fauna in response tothedischarged wastewater in the mangrove swamp.The study confirms that the benthic macrofauna withinmangroves islow in species diversity and high in population counts incomparison with a frontal mudflat. Longitudinal zonation ofthefauna from landward to seaward will also bediscussed.