The Influence of High-Tides on the Physiochemical Properties of Tidal Creeks of the Wouri Estuary

The Wouri estuary is surrounded by numerous tidal creeks transecting a wide range of communities and geology. Diverse ecosystems, varied human activities, and diurnal tidal changes are expected to significantly influence the chemical properties of these tidal creeks. We evaluated two selected tidal creeks to understand physiochemical changes resulting from rising tides. For this study, we conducted spatial measurements of water samples from the Dr. Creek to the East and the Mowasse Creek to the West of the Wouri Estuary in Cameroon. To capture the physiochemical variations, a multi parameter probe was used to measure pH, salinity, dissolved oxygen, temperature, total dissolved solutes. Alkalinity in mg/L of CaCO3 of the samples were also measured using a portable digital titrator. We sampled 13 locations at an interval of 1km along the Dr. Creek and 8 locations at 2km interval along the Mowasse Creek during high tide. Results showed that the measured properties were relatively uniform from the estuary to 7 km and 11 km into the Dr. Creek and the Mowasse Creek, respectively. Beyond these distances from the estuary, the measured properties showed non uniform behaviors. We interpret the distances to be the limits of significant tidal effect on water properties. These distances as observed in the field are suggested to also represents locations where anthropogenic effects on water properties predominates. The greater tidal effect distance on the Mowasse creek in comparison to the Dr. Creek is interpreted to be due to wider opening into the estuary ensuring larger surface for interaction with the estuary. We also note that unlike Mowasse creek, the Dr. creek is strewn with dwellings and therefore subject to significant anthropogenic activity which is able to explain the greater variability in measured properties beyond 7 km from the estuary. Our results show that, depending on the chemistry of the environment, each creek responds in a particular way to tidal inputs and also that anthropogenic activity disrupts the behavior of the waters and therefore the behavior of nearby ecosystems.