MACROPHYTE COMMUNITY DEVELOPMENT AND ITS IMPLICATION FOR FISHERIE&IN MAIGANA FISH FARM, KADUNA STATE, NIGERIA

摘要

Maigana fish farm (located approximately between latitude 11 7 N and longitude 7 46'E) along Jos Road from Zaria was established in 1970 by the Kaduna State Government for production of fish and fingerlings of Clarias gariepinus, Cyprinus carpio and Oreochromis niloticus. Agricultural activities, and poor management practices over the years have led to high siltation rates and consequent extensive growth of emergent aquatic macrophytes such as Typha australis, Nymphaea lotus, Echinochloa pyramidalisand Leersia hexandra, as well as marginal plants such as Mimosa pigra and Sesbania bispinosa. These plants have been established to varying extents and at least five serai stages of aquatic succession were seen in the production ponds. These serai stagesin the pattern of macrophyte community development were seen to be approximately annual. Ponds that had stayed up to one year without clearance were typified by presence of species such as Nymphaea lotus, which gradually accommodated others such as Ludwigia erecta in the second year. Later serai stages were characterized by occurrence of species such as Polygonum lanigerum, Typha australis, Echinochloa pyramidalis etc. Ponds that are not cleared become completely taken over by terrestrial plants withina period of less than five years. In the reservoir area, population of marginal plants such as Neptunia prostrata, Sesbania bispinosa and Mimosa pigra were rapidly expanding towards the open water. Urgent management and control measures are needed.