Modelling hydrodynamic transport and larval dispersal in North-East Atlantic Shelf seas

• Main Author: Phelps, Jack
• Format: Text
• Language: English
• Subjects: Liverpool Bay; North East Atlantic
• Online Access: http://livrepository.liverpool.ac.uk/2026939/; http://livrepository.liverpool.ac.uk/2026939/1/PhelpsJac_Sep2015_2026939.pdf

This thesis presents a series of numerical modelling studies into hydrodynamic transport and larval dispersal. The initial investigation seeks to evaluate retention timescales in Liverpool Bay. The flushing time and residence time are equal to 136 days and 103 days respectively, however small concentrations of seawater are retained over several years due to vigorous tidal mixing. The age distribution is shown to be highly variable and dependent upon tracer input duration, however salinity can be used to estimate the mean age, which is not directly observable in practice. Chapters 3, 4 and 5 all focus upon the dispersal of meroplanktonic larvae and aim to determine how larval behaviour affects their transport. Vertical migration is a significant influence upon larval dispersal within each case study, although the effect of this behaviour is conditional upon local hydrodynamic conditions. For example diel vertical migration promotes dispersal in the western Irish Sea, however the identical swimming pattern facilitates local retention in the eastern Irish Sea. The ecological implications of these findings are discussed. This thesis concludes with an investigation into the impact of large CO2 leakages on the marine carbonate system at potential carbon sequestration sites in the North Sea. Perturbations to seawater pH are found to vary according to the rate, duration and location of CO2 input. The northern North Sea is particularly vulnerable to large perturbations (> 1 pH units) during the summer months, as the strong seasonal thermocline suppresses CO2 outgasing.