Spatial Variation in Water Column Structure, Nutrients, Chlorophyll and Zooplankton in an Estuarine Transect of Southampton Water

Abstract

Estuary systems are complicated and closely related to humans. The understanding of estuary systems is important to scientific study and human develop. An investigation was conducted on 3rd November 2009 by RV Callista along the Itchen estuary of Southampton Water with the aim of determining spatial variability in physical water column structure, nutrients, chlorophyll and zooplankton of Southampton Water, and recognizing the links between them. The salinity and temperature values are relatively lower at surface upper estuary than that of deep lower estuary. Water stratification is observed around upper and mid estuary. The nutrient Si exhibits conservative behaviour with a linear relationship with salinity gradient, while P shows non-linear with salinity, which may indicate an addition bahaviour. Chlorophyll distributes high concentration at surface upper estuary and relatively uniform and low concentration at downriver area which is mainly due to light and nutrients factors. Water turbidity affects chlorophyll distribution by reducing light availability in the water column, while chlorophyll can in turn influence water turbidity. The abundance dominant species of the estuary are Copepoda and Appendicularia. The mid estuary has the highest zooplankton abundance, while the lower estuary has the most zooplankton groups. Zooplankton distribution is relative to food distribution, temperature, light and salinity profiles.