Spatial and temporal variability in interstitial water quality of soft-bottom flats at Bodo Creek, Eastern Lower Niger Delta, Nigeria

Abstract

Spatio-temporal dynamics of interstitial water physical and chemical characteristics were investigated on 5 intertidal platforms at Bodo Creek for
2 years (May 2006 – April 2008). Temperature and Hydrogen ion concentration (pH) varied, 25^oC - 34^oC and 6.64 - 8.10 respectively. Salinity fluctuated between 5 psu (mesohaline) and 28 psu (polyhaline). Dissolved Oxygen content (DO) and Biological Oxygen Demand (BOD) values were 0-7.60 mg/L and 0.64-38.40 mg/L respectively. Alkalinity ranges from 2.8–64.0 mg/L, while conductivity fluctuated between 1400and 53850 μS/Cm. Inter-site variations (P<0.05) occurred in temperature, Dissolved Oxygen, pH, conductivity and alkalinity, while salinity and Biological oxygen demand (BOD) did not vary (P>0.05). Temporally, all the physico-chemical parameters varied monthly (P<0.05). Seasonal differences (P<0.05) were also recorded in all the parameters, except for DO and BOD. Inter-annual comparison revealed salinity (Anova = 0.06< P (22.11)_0.05), BOD (Anova = 1.48 < P (2.11)_0.05) and DO (Anova = 0.30 < P (2.11)_0.05) were temporally stable. Fluctuation in the water quality is discussed in relation to tidal fluxes, local weather conditions, mangrove services, leaf litter decomposition, allocthonous inputs, and intrinsic activities of zoobenthos.

Key words: spatial, temporal variation, interstitial, water quality, soft-bottom flats