ASSESSMENT OF PHYSICO-CHEMICAL CHARACTERISTICS IN RELATION TO ZOOPLANKTON COMMUNITIES IN PONDS IN OGHARA, DELTA STATE.

ABSTRACT

Zooplankton constitute a diverse assemblage in most freshwater habitats. A study on the assessment of physico-chemical Characteristics in relation to zooplankton communities in fresh water habitats in Oghara, Delta State was conducted from January – March 2021. Water and Zooplankton samples were collected at monthly and fortnightly respectively at three different sampling stations. Physicochemical parameter were determined using standard methods while Zooplankton Samples were preserved with 4% formaldehyde solution. Mean temperature ranged from (26.00 ±0.577 - 28.83 ± 1.589). Mean Value of Ph was slightly acidic to neutral, ranging from (6.76 – 6.05). Dissolved Oxygen was quite low typical of most eutrophic water bodies. BOD mean value was relatively high (5.80 – 8.40) owing to increased organic decomposition by organisms during the study period. Nitrate ranged from (0.57 to 5.27) during the study period. The result of zooplankton composition indicated the presence of 33 species of Zooplanktons belonging to three major classes; Cladocera 1108 individual taxa (93.5%), Rotifera 5 individual taxa (0.43%) and Copepoda 72 individual taxa (6.07%). Cladocera were more diverse with 21 representative species, followed by Copepods and Rotifers with 9 and 3 species respectively. Indices of general diversity (H) and evenness (E) were in the following order station 3 > station 2 > station 1 respectively. Margalef’s index for richness shown that station 2 had the highest species richness and indicated the following trend station 2 > station 3 > station 1. Families Daphnidae, Macrothricidae and Sididae dominated the Cladoceran group while copepods was singly represented by family Cyclopidae. Rotifers were represented by families, Lecanidae, Asplanchidae and Proalidae. Zooplankton taxa generally showed negative correlation with nutrients and positive correlation with dissolved oxygen. Presence of tolerant and dominance groups such as Cladocera, Copepods and Rotifers that survive under higher organic conditions indicate the eutrophic status of the ponds.