Cyanobacteria of a Man-Made lake in Southern Nigeria

Abstract

A study of the Ikpoba dam was undertaken to explore the taxonomic  composition of blue-green algae. Twenty-six taxa of blue-green  algae  comprising three Orders, five Families and 16 genera were identified.  The bulk of the taxa (12) belong to the Oscillatoriales and  Family  Oscillatoriaceae. Others were Chroococcales, Chroococcaceae (6) and  Nostocales (8). These span through a variety of  morphological types of  unicellular forms (Chroococcus), colonial forms (Microcystis,  Merismopedia Calothrix and Gloeotrichia,  Gomphosphaeria and  Snowella) to filamentous forms (Oscillatoria, Nostoc, Achroonema,  Scytonema, Spirulina, Phormidium, Moorea (Lyngbya),   Dolichospermum and Anabaena). Of the collection, the heterocystous  and nitrogen fixing forms were Anabaena, Nostoc and   Oscillatoria species. Global distribution of the identified cyanobacteria in the Ikpoba  Reservoir shows the species with the highest global  distribution is Calothrix parietina, and the one with the least global distribution is  Phormidium cincinnatum. The toxin-producing genera  include  Anabaena, Lyngbya, Microcystis, Nostoc and Oscillatoria. Bloom formation of such taxa presents implication for human and animal  health, coupled with increased water treatment costs for the reservoir as  a source of water supply