Full details of methods and guideline comparisons are accessible in coastal monitoring reports.
Habitat surveys describe and map estuaries according to dominant habitat features combining aerial photography, detailed ground truthing, and Geographic Information System (GIS) data. Changes in the position, size, or type of dominant habitats are monitored over time by repeating the mapping exercise every five years. Once an estuary has been classified according to its main habitats and their condition, representative habitats can be selected and targeted for sediment quality and ecological monitoring.
The environmental characteristics assessed in fine scale surveys include biological attributes (e.g. number of animals) and physical and chemical characteristics (e.g. sediment mud content, metals, nutrients) to assess ecological condition. We also measure the amount of sediment depositing in the harbour using plates buried below the soft sediment in intertidal and subtidal areas to tell us where and how much mud is settling. Results across all years are assessed using estuarine health metrics or condition ratings, which are used to assign one of four ‘health status’ bands (e.g. poor, fair, good, very good) to track changes over time. These data are used to make informed environmental management decisions to protect and improve the resilience of Te Awarua-o-Porirua Harbour.