Figure 2: Maps of the environmental variables derived for the Hauraki Gulf classification (Depth, SST annual phase, SST semi-annual amplitude, SST monthly standard deviation, Mean orbital velocity, Tidal currents, Freshwater fraction, Slope)

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A map of the EEZ is shown for each variable. The range for each variable is depicted by using colour to express the value. Variables and their data range were as follows: Depth (0.311050 - -180.442001 m), SST Annual Phase (31 - 62.9 days), SST Semi-Annual Amplitude (0.15 - 0.6 °C), SST Within Month Standard Deviation Value (0.4 - 0.9), Orbital Velocity (0 - 32.5 cm/s), Maximum Tidal Current (0.007 - 4.3 m/s), Freshwater Fraction Value (0 - 0.999851) and Slope Value (0 - 4.858312). Generally speaking, water depth decreases as you move into the Firth of Thames. Water temperatures on average become warmer in the Firth of Thames but this is associated with higher temperature variability. Freshwater fractions are concentrated at the bottom of the Firth of Thames and Waitemata Harbour (and generally increase at river mouths). Tidal currents are particularly strong around Cape Colville and within Waitemata Harbour . Changes in orbital velocity and slope are associated with proximity to coastline.