Preliminary study of aquatic fungi biodiversity of Rooro and Orisa rivers in Nigeria

Abstract

The biodiversity of aquatic fungi were investigated in two rivers; Rooro and Orisa located at Omu- Aran and Olla in Kwara State, Nigeria. Water samples and decayed debris were collected at the mid and lower courses of the two rivers and analysed for fungi and physicochemical parameters. Identification was by microscopic examination and fungal identification monographs. A total of 22 fungal taxa belonging to the class Hyphomycetes, Oomycetes and Zygomycetes, and distributed into 14 genera were identified. The representative genera are Alternaria, Anguillospora, Aspergillus, Corollospora, Cylindrocladium, Fusarium, Penicillium, Trichoderma, Achyla, Dictyuchus, Phytophthora, Saprolegnia, Rhizopus and Mucor. River Rooro accounted for 16 species while 15 fungal taxa was recorded for river Olla. Mucor sp. occurred in all sites while Anguillospora longissima, A. crassa and Saprolegnia sp. were limited in distribution and prevalence. Simpson’s index (D) showed fungal diversity indices (D) values of 0.02849 and 0.021645 for rivers Rooro and Orisa respectively. This is a direct reflection of their physico-chemical characteristics and reduced environmental variations. There is high prevalence of conidial Hyphomycetes and Deuteromycetes, and reduce presence of filamentous Zygomycetes in the rivers. This underscores the significance of the knowledge of aquatic fungi in fish hatchery and other aspects of aquaculture production.

Key Words: Simpson’s diversity index, aquatic fungi, fungal diversity, physico-chemical
parameters