This semi-urban walk is a good way to get an introduction to the estuarine ecosystem, which flourishes despite its proximity to the presence of urban demands. The area between Pandora and Embankment Bridge is composed of tidal flats with shallow channels and islands.
The colourful mix of gravels, glasswort and consolidated banks changes with the unceasing ebb and flow of the tides, approximately 500 million litres passing with each influx. This renews the nutrients of the waters twice daily.
The main entrance to the track is from the end of Humber Street, just south of the Westshore Bridge.
The even track surface is a mixture of gravel, boardwalks and tarseal on the Embankment Bridge.
It completes a loop of the estuary with large information panels at each end and smaller interpretation panels dotted along the trackside. The walk is punctuated with benches and marked with orange topped posts.
River water descending to the lagoon carries soil particles and nutrients. On meeting the sea, the higher salinity engenders conflicting currents, which force the river water to deposit its load. This forms sandbars and mudbars. Salt tolerant algae and plants consolidate the sediment and trap more particles, starting a positive feedback process resulting in the formation of tidal salt marshes.
The plant communities consolidating the lagoon edge sediments are dominated by glasswort (Salicornia australis), which forms vast mats. Buck’s horn plantain (Plantago coronopus) and sea rush (Juncus maritimus) also form part of the salt marsh assemblage, before it gives way to grasses higher up.
Up to 60 bird species have been recorded feeding at the fertile waters. These include South Island pied oystercatchers, which feed off marine crustaceans and molluscs. Pied stilts nest in the shallow brackish lagoon and feed on the swarms of insects. Dotterels and white faced herons wait on the banks. In springtime, watch for the Arctic migrants, including bar-tailed godwits, turnstones, golden plovers, whimbrels, sandpipers, sanderlings and knots. These waders feed on marine worms and crabs, taking advantage of the bountiful waters to recondition themselves after their epic flight of over 10,000 km.
The warm water’s high nutrient content, shallow level, slow currents and lack of wave action supports massive numbers of marine organisms. Marine species to look out for include flounder, sole, eels, kahawai, mullets and whitebait in season. Crabs, shrimps, gastropods (snails), and worms submerge in the mud to conceal themselves from their marine predators.
The area is a remnant of the lagoon, which prior to the 1931 earthquake, covered 3840 hectares. To Maori it was known as Te Whanganui-A-Orutu, which was shortened and corrupted to Whanganui o Rutu. In pre-European times there was no outlet. When the water level rose sufficiently, water would spill over the shingle bank and form a temporary opening through a bar.
In the 17th Century, chief Ahuriri was travelling south and at Keteketerau (Bay View) his passage was blocked by the lagoon overspilling into the stormy sea. This story gave rise to William Colenso’s contention that ‘Te Ahuriri’ meant ‘fierce rushing’.
The 1931 Earthquake, which devastated the region measured 7.75 on the Richter scale and lifted the lagoon bed by between 1.5 and 3.4 metres, exposing 1300 previously submerged hectares. Reclamation has since claimed a further 1700 hectares and the margins are demarcated by man made stop banks.
North Island ▷ Hawkes Bay ▷ Napier
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Thanks to all the good people working for the NZ Department of Conservation - for all your hard work - making NZ more beautiful, accessable and healthy! Cheers 😍