Impact of Nypa Palm (Nypa fruticans) and Mangroves Forests on Plankton Community along Andoni River, Nigeria

Abstract

The invasion of mangroves forest by nypa palm is said to affect the ability of the mangroves to act as a spawning ground for fishes. It is thus hypothesized that nypa palm presence in mangrove forest will impact their fish spawning ability due to the reduction in plankton population. A total of four stations were chosen: station 1 (open water), Station 2 (nypa palm dominant), station 3 (Rhizophora and Avicennia dominant), Station 4 (Mixed forest). Results of water quality parameters include; pH (6.99 ± 0.16), temperature (28.20°C ± 0.05°C), DO (4.71 ± 0.18 mg/L), conductivity (19.52 ± 0.20 µm/s), salinity (10.76 ± 0.07 ppt) and TDS (13.45 ± 0.27 ppt). Mean values of the physico-chemical parameters were not significantly different from each other (P > 0.05). In all 737 zooplankton in eleven genera were collected. Copepoda dominated with 75.1%. Similarly, 4774 phytoplankton in six taxa were collected. Bacilliarophyceae dominated with 87.45%. Shannon Weiner index across the stations was highest in station 4 (0.36) and lowest in station 1 (0.33). Margalef’s index was highest in stations 2, 3, and 4 (3.48) and lowest in station 1 (2.67). Pielou’s index of evenness was highest in station 4 (0.099) and lowest in station 1 (0.089). The composition and abundance of plankton showed no significant difference across the four stations (P > 0.05). This implies that the presence of  Nypa fruticans  (Wurmb) did not have negative impact on the abundance and diversity of plankton.