Abstract

This study presents a first compilation of phytoplankton species composition of a stretch of fresh and brackish water ecosystem in Southern Nigeria. Samples collection spanned a period of sixteen months (January 2003 to April 2004). Phytoplankton samples were collected monthly in the open water using plankton net of 55 &mum mesh size towed horizontally for about five minutes. The net hauls were transferred into 200 mL properly labelled plastic containers and immediately preserved with 4% formation solution. Samples were examined and illustrations made with a Leitz Orthoplan Research Microscope equipped with a tracing and measuring devices at the phycology laboratory in University of Benin, Benin City. A seasonal pattern of phytoplankton variation was observed with a hundred and 154 phytoplankton species recorded. The taxa recorded belong to four divisions namely: Bacillariophyceae (diatoms), Cyanophyceae (blue-green algae), Euglenophyceae (euglenoids) and Chlorophyceae (green algae). The Diatoms were the predominant group and account for 79% of total species composition. Others are Chlorophyceae 19.77%; Cyanophyceae 1% and Euglenophyceae, 0.23%. The brackish water stations recorded relatively higher number of species and number of individuals of each species than the freshwater stations. An array of floristically diverse phytoplankton was observed with notable common and cosmopolitan diatom species like Coscinodiscus and Nitschia spp in abundance.

Keywords:

Brackishwater, freshwater, Nigeria, Osse River, phytoplankton, taxa,

References

Competing interests

The authors have no competing interests.

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The authors have no competing interests.