Population Dynamics of Diatoms in a Spring-Neap Tidal Cycle in an Estuarine Creek of the Bonny River System

Abstract

The present study focused on the aspects of diatom population changes through the spring-neap-spring tidal phases along the Elechi creek - an estuary of the Bonny River. Water samples at high and low tide were collected during a cycle of spring-neap-spring cycle between September and November 2015. Diatoms were counted at different magnifications of x250 and x400. Counting was in 100 fields of view along several transects. Total diatoms were calculated as a relationship between the area of grid (mm2), number of grids counted and area of counting chamber (1000 mm2). Diatoms density ranged from 1678 cells L-1 (high tide) to 3731 cells L-1 (low tide) with a mean value of 8.87 ± 6.64 cells L-1. During the lunar phases diatoms abundance ranged from 431 ± 0.2 cells L-1 (last quarter) to 396 ± 0.2 cells L-1 (new moon), to 430 ± 0.3 cells L-1 (full moon), to 421 ± 0.2 cells L-1 (first quarter). The result revealed evidence of changes in diatom abundance and variability. At low tide, the abundance and variability of diatom was higher than the observation at high tide. There was also a significant difference between mean counts of the diatoms during various moon phases; but there was no significant difference in the abundance between spring and neap tide. These findings are crucial for ecological inference during environmental assessment surveys. A consideration of these factors is suggested as necessary to avoid poor estimates that can drastically alter impact assessment conclusions.