C.G. Oronsaye

Two aquarium tanks labelled A and B were each half filled with water. They were kept open outside the laboratory for seven days so that mosquito larvae will develop in them. Then plankton samples were collected from Ikpoba dam with two plankton nets of 55µm and 100µm mesh sizes. Copepod species were sorted out from the plankton samples and poured into tank A, while tank B was left alone as control. The two tanks were examined after five days. Results showed that the copepod species have eaten up all the mosquito larvae in tank A while in tank B, mosquito larvae were seen in abundance.

Two aquarium tanks labelled A and B were each half filled with water. They were kept open outside the laboratory for seven days so that mosquito larvae will develop in them. Then plankton samples were collected from Ikpoba dam with two plankton nets of 55µm and 100µm mesh sizes. Copepod species were sorted out from the plankton samples and poured into tank A, while tank B was left alone as control. The two tanks were examined after five days. Results showed that the copepod species have eaten up all the mosquito larvae in tank A while in tank B, mosquito larvae were seen in abundance.

The ecology and growth of the shellfish, Tympanotonus fuscatus was studied in a mangrove swamp of the Warri River, Abiotic and Biotic factors such as temperature, salinity, hydrogen ion concentration, nature of substrate, associated fauna and flora, micro – habitat were investigated. Weight/Length relationship of the shellfish was measured to determine the growth rate. Results showed a low range (27.5°C – 31.0°C) in temperature variation and high range (0.3% - 7.1%) in salinity variation, while pH values were between 6.5 – 7.8.

Investigations into the seasonality of cyclopoid (crustacean: copepoda) with regards to rainfall variations were carried out in Forcados river. Samples were collected by towing two plankton nets of 55µm and 100µm mush sizes at 5knots for 5 minutes behind an engine boat. Meterological station in Warri gave the rainfall data. Centigrade thermometer was used for measuring the surface water temperature. Results showed low temperature range (27.5ºC – 31.5ºC), while that of rainfall was high (25.8-602.6mm).

Plankton sampling and investigation of the Lagos harbour, some adjourning creeks and rivers was carried out using plankton, nets of 55µm and 100µm mesh sizes. Yewa river which is located between Lat. 6°25’ – 6°30’N and Long. 2°50’ – 2°55’E was one of the sampling, stations with salinity values ranging from 0.17 – 0.43% for the 8 months of sampling period, indicating a constant freshwater condition. In the course of analysis and identification of the copepoda, Salmincola species which is an ectoparasite of fish was found, and this is its first record from Nigeria water body

Studies on the occurrence and seasonality of some harpacticoid copepods (crustacean) from a West African coastal river were carried out. An all year round sampling was made to cover the twelve months of the year, using plankton nets of 55µm and 100µm mesh sizes. Three species of harpacticoid copepods were identified, namely: Nannopus palustris, Diarthrodes cf major and Bryocampus minutes. While Nannopus palustris showed peaks in the dry season months of January and February, Diarthrodes cf major and Bryocamptus minutes showed peaks in the rainy season months of July and August.