BENTHIC MACROFAUNA OF THE MANGROVE SWAMP TREATED WITH MUNICIPAL WASTE-WATER

Benthic macrofauna and possible effects on community structure of disc harging municipal wastewater to Futian National Mangrove Reserve, the People's Republic of China, were investigated. Eighty-four species of ground-dwelling fauna belonging to 7 Phyla, 9 Classes, 46 Families and 65 Genera were identified. Abundant families were Assimineidae, Melan idae, Potamididae, Ocypodidae, Grapsidae and Periophthalmidae. Between April 1991 to January 1993, no obvious seasonal fluctuation in specie s composition occurred. Total biomass also remained unchanged. However , total density showed peaks in January and July (both in section A an d B), probably due to the molluscs. A selected site of the mangroves w as treated with municipal wastewater (60 m(3) per week for 16 consecut ive months). In comparison to a control site, the effect of wastewater discharge on total mean biomass and density (particularly of molluscs and crustaceans) appeared non-significant (P>0.05). The community str ucture remained unchanged although some saprobic species emerged and t otal biomass in the area close to the wastewater front increased sligh tly. Multivariate analysis indicated that there probably was an initia l inhibition period and a subsequent recovery period for benthic fauna in response to the discharged wastewater in the mangrove swamp. The s tudy confirms that the benthic macrofauna within mangroves is low in s pecies diversity and high in population counts in comparison with a fr ontal mudflat. Longitudinal zonation of the fauna from landward to sea ward will also be discussed.