The Tuia Mātauranga GeoTour is about having fun discovering the history of Aotearoa New Zealand by finding sites of significance in local communities from early Pacific voyaging and migration, European settlement to present day. The interaction between people, and people and the land have provided a rich history that the GeoTour invites you to explore.
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Ahuriri Estuary/ Te Whanganui a Orotū The Ahuriri Estuary/ Te Whanganui a Orotū supports 29 species of fish and contains a 160 hectare wildlife sanctuary which provides an important feeding and resting area for over 70 species of water birds, some of which are critically endangered. It is a significant wetland along the east coast of New Zealand and its wildlife and fisheries habitat is recognised as being nationally significant. The estuary’s unique geological history makes it a nationally important example of tectonic processes. Historically, the Tutaekurī and Esk Rivers flowed into Te Whanganui a Orotū which was predominately freshwater and significantly larger at 3,840 hectares in size. In 1931, the Napier earthquake lifted the land by up to two metres and exposed around 1300 hectares of original lagoon. This combined with a significant amount of drainage and reclamation reduced the lagoon to its current size. Much of the estuary’s margin is contained by man-made stop-banks and the Tutaekurī and Esk Rivers were diverted away from the estuary some time ago. The Ahuriri Estuary is a significant recreational resource, providing for a number of recreational activities including swimming, boating and bird watching. A number of cycle pathways surround the estuary. In the past, the estuary has provided significant food gathering opportunities however current information suggests the shellfish is unsafe for human consumption. Te Whanganui a Orotū is situated directly along side the city of Napier. It is located within the Ahuriri catchment which is approximately 13,128 hectares in size. For the Ahuriri Hapū, Te Whanganui-a-Orotū has always held an elevated status, with its own mauri, wairua and spirituality. It is central to their existence and identity. It is named after the ancestor Te Orotu , who was a descendant of the great explorer and ancestor Māhu Tapoanui, who is the very beginning of the Ahuriri people’s history in Aotearoa. Ngāti Pāhauwera regularly travelled between Mohaka and Te Whanganui-a-Orotū, which was a significant mahinga kai for them. A Ngāti Pāhauwera pā and kāinga are located at the northern end of Te Whanganui-a-Orotū and graves of Ngāti Pāhauwera ancestors are located on islands previously in Te Whanganui-a-Orotū. Maungaharuru Tangitū also state an association with Te Whanganui-a-Orotū; the estuary was a vitally important fishing and resource-gathering area for hapū. The area around Te Whanganui-a-Orotū was a very important source of food and was heavily populated. Consequently numerous sites of cultural, historic and archaeological significance are situated around what was its shoreline. From the earliest of times it was highly prized for its enormous food resources and its access to major river systems and forest areas. In the lake were extensive shellfish beds and fishing grounds; in the rivers and streams, eels and freshwater fish. It was known as ‘a place of abundance' for freshwater fish, shellfish, and birds and much prized as a food resource by the people. It was also known as Te Maara a Tawhao (the garden of Tawhao) by Ngāti Kahungunu, Tawhao being the chief who imposed a tapu on it. So greatly was it valued through the generations that songs were sung, poetry composed and dances created in praise of its productiveness. Archaeological evidence confirms that Te Whanganui-a-Orotū was an important place to live. Excavations indicate settlement dates between the late fifteenth and early seventeenth centuries, with very early settlement on Roro o Kuri -somewhere between the twelfth and thirteenth centuries. Surrounding the harbour are 11 recorded pā, some extensive in size. Extensive middens exist in this area. The pā at Te Pakake was a communal gathering place in times of trouble. Ngāti Hinepare, Ngāti Mahu, Ngāti Parau, Ngāti Hawea and Ngāti Kurumokihi are all recorded as having occupied the pā when under threat of invasion. After the Waikato and Hauraki tribes attacked Te Pakake in 1824, the people of Heretaunga went into exile at Mahia peninsula. This invasion caused large scale devastation to the local people. They remained in exile until after the signing of the Treaty of Waitangi in 1840. No pā and kāinga in use prior to the exodus were re-occupied upon their return because they had blood spilt on them and they were now urupā and tapu. Recreation values The Ahuriri Estuary is easily accessible by large numbers of people, making it a highly valued recreational resource in Hawke’s Bay. The lower estuary features broad tidal flats and shallow channels with a partial impoundment area known as Pandora Pond, which is a small sheltered area that has been extensively developed to allow a range of recreational activities to take place. Recreational use of the lower estuary area is quite intensive and includes swimming, boating, fishing, birdwatching, photography and foodgathering. A number of walkways and cycle pathways have been developed around the upper and lower estuary making it popular for walking, running and biking. The middle reaches of the estuary is generally undisturbed by water sports due to the lengthy periods in which tides expose large areas of mudflats. As a result, it attracts shorebirds and is popular for bird-watching. Recreational pursuits on the upper estuary are restricted to bird-watching and duck shooting. In the past, Te Whanganui a Orotū was a rich food source with cockles and flounder commonly gathered from the area. Ecology values The Ahuriri Estuary is the most significant wetland along the coastline of the North Island between East Cape and Wellington. Despite extensive modification, reclamation and discharges, it continues to provide a wide diversity of habitat and an extremely diverse range of ecological communities, all contained within a relatively small area. There are five smaller wetlands, around 175 ha in size which are part of the greater Ahuriri wetland complex. These wetlands are located within reclaimed land near the estuary and are considered to contribute significantly to the overall ecological value of the area. The Ahuriri Estuary has very important wildlife values and is highly rated in the ‘wetlands of ecological and representative importance’, and the ‘sites of special wildlife interest’ databases held by the Department of Conservation. Notably, in 1996 the Ahuriri Estuary was identified as meeting the Ramsar Sites Criteria which is part of an intergovernmental treaty and used to assist countries to identify wetlands of international importance. Fish The Ahuriri Estuary is classified as a nationally significant fisheries habitat. Within Hawke Bay, the Ahuriri Estuary provides a diverse habitat and is the most important estuary in terms of fisheries production. It provides nursery habitat, spawning habitat and feeding areas and is used by species migrating between freshwater and the sea. In the late 1980s it was under consideration for marine reserve status. The estuary makes a significant contribution to Hawke’s Bay marine fisheries, supporting approximately 29 species of fish at some stage during their life cycle. Some species (e.g. short finned eel, kahawai, grey mullet, yellow-bellied flounder, stargazer and parore) use the area for feeding, and around 11 species use the area as a nursery or spawning ground. These include commercially important species such as yellow bellied flounder, grey mullet, sand flounder, common sole, and yellow-eyed mullet. In 1987, the Ahuriri Estuary and Westshore lagoons were identified as a wetland of national importance to fisheries and allocated a Category A (outstanding) rating for fisheries. The wetland met the following five criteria: •A unique or diverse assemblage of fish species •A biologically or scientifically important fishery or fish habitat •A particularly good example of a specific type of fishery or fish habitat •A remnant or regionally representative wetland with significant fisheries values •A nationally important non-salmonid fishery, including commercial and traditional Māori fisheries. In 1996, the Department of Conservation identified the Ahuriri Estuary as meeting the Ramsar Sites Criteria which identifies wetlands of international importance. In respect to native fish the report notes: •The estuary supports 29 species of fish which adds to the estuary’s special value for maintaining the genetic and ecological diversity of the region •The estuary has special value as a breeding ground and nursery for a number of species of fish. Wildlife The Ahuriri Estuary contains a 160 hectare wildlife refuge which protects the areas between the Southern Marsh, Westshore Lagoon and the estuary from the low level bridge to Pandora Pond. The Department of Conservation manages the wildlife sanctuary which is highly ranked as a Site of Special Wildlife Interest (SSWI) in their database. The Ahuriri Estuary is used by over 70 species of waterbirds, 17 of which migrate here every year from the Arctic. Of particular note are the Australasian bittern and the black billed gull which are globally endangered, and the New Zealand Dabchick (Grebe), which is globally near threatened. The estuary regularly supports over 1% of the regional population of Caspian tern. The Wrybill is also present at the Ahuriri Estuary. The Wrybill is special, being endemic to New Zealand and the only species of bird in the world with a beak that is bent sideways one way. Other notable species which use the estuary are the Royal spoonbill, white faced heron, grey teal, New Zealand marsh crake, black fronted dotterel, Pacific reef egret, banded dotterel, far eastern curlew, Asiatic whimbrel, American whimbrel, Siberian tattler, sharp-tailed sandpiper, red-necked stint, Caspian tern and little tern. Flora The Ahuriri Estuary is highly modified and does not support any plant or plant communities of importance or rarity. For these reasons, the area is described as being of ‘moderate botanical interest’. The margins of the estuary support a salt-marsh herbfield of Zostera, glasswort, and shore pimpernel, with Juncus and Leptocarpus rushland on higher ground. The native shore-line communities in the lower estuary are in a healthy state. A small remnant stand of the salt marsh ribbon wood Plagianthus divaricatus survives in the lower estuary, and serves as a reminder of the far more extensive areas present prior to the 1931 earthquake and subsequent reclamation. This is of local importance because of the low occurrence of this species throughout Hawkes Bay. In the upper estuarine section, extending northwards from the Taipo stream confluence, there are substantial remnants of the once extensive wetlands that bordered Ahuriri Lagoon. The native communities in the Westshore Pond, Northern Pond and adjacent areas contain the aquatic plant Ruppia polycarpa and R. megacarpa. These ponds potentially may be one of the best sites for these uncommon plants in the North Island. The saline arm extending west from Westshore Pond, represents a kind of habitat not very common in New Zealand. Its most characteristic plant Puccinellia fasciculateis not a native species. The northern pond extension (up into airport land) contains sea-rush and native herbfield. Invertebrates Thirty-three species of invertebrates have been recorded in the Ahuriri Estuary, including: three species of bivalves, the most abundant being the cockle austrovenus stutchburyi; seven gastropods including whelk Cominella glandiformis and hornshell Zeacumantus lutulentus; six crustaceans, the most common being the tunnelling mud crab Austrohelicecrassa; 14 polychaete worms, the most numerous being Aonides trifidus and Scolecolepides; and one nemertine worm. The aquatic in fauna sampling indicates there is low diversity and abundance of organisms in the upper estuary area. This appears to be because these waters are in an enriched (trophic) state, with a significant amount of sediment and contaminants flowing in through the small streams. There is a plentiful supply of algae and plankton that flourish in the enriched waters of the estuary. The Ahuriri Estuary is located in an urban landscape situated directly alongside the city of Napier, adjacent to a number of industrial and urban areas. There is a network of well-formed tracks around the lower estuary and associated wetland areas. The estuary is a long, narrow estuary with its wide range of fresh to salty, shallow to deep, and sandy to muddy habitats. The estuary is relatively shallow, with about 60% of its bed being exposed at low tide. Geological features In 1931, a magnitude 7.8 earthquake hit Hawke’s Bay instantly lifting the land by 1 -2 metres and exposing about 1300 hectares of the original Ahuriri Lagoon. As a result, the area has been significantly studied and is considered to be a nationally important example of tectonic processes. The Hawke’s Bay Regional Coastal Environment Plan identifies The Ahuriri Estuary as being a nationally important example of tectonic processes, with the former floor of the lagoon, and uplifted channel fossils specifically identified as having Significant Conservation Values (SCA). In 2004, the Ahuriri Estuary was recognised as a Potential Water Body of National Importance for geodiversity features by the Ministry for the Environment. The National Geo-preservation Inventory, which identifies and ranks geological features according to their relative significance, classifies the following features of the Ahuriri Estuary as nationally significant: •Ahuriri Lagoon 1931 uplifted sea floor and islet: Small islet from pre-1931 now sitting in the middle of uplifted farmed grassland which was formerly the intertidal lagoon floor •Ahuriri Lagoon uplifted entrance channel fossils. Best illustration of 2.5 m of uplift during the 1931 Napier Earthquake, in the form of in-situ bivalues (ruditapes) in life position in channel bottom gravelly sand now exposed at high tide level. Naturalness/intactness of water body The Ahuriri Estuary is a remnant of a much larger lagoon. There have been major changes within the Ahuriri Estuary which pre-1931 was predominately freshwater and approximately 3,800 ha hectares size. Historically the Tutaekuri and Esk Rivers previously discharged into the lagoon. In 1931, the Napier earthquake lifted the land by two metres and exposed around 1,300 hectares of original lagoon. This combined with a significant amount of modifications through drainage and reclamation has reduced the lagoon to its current 470 hectare size. Much of the margin of the estuary is contained by man-made stop-banks, and the Tutaekurī and Esk Rivers, which originally flowed into the estuary have been diverted away. The approaches to the Pandora Bridge constrict tidal flow into and out of the estuary, delaying and muting tidal influences. Pandora Pond was artificially created when sediment was excavated in 1977 to provide fill for the cargo handling area in the Port of Napier. In the upper estuarine section there are substantial remnants of the once extensive wetlands that bordered Ahuriri Lagoon.
To be able to complete this Geotour and receive your special geocoin, remember to take a note of the codeword on the log book of the cache. This will need to be recorded in your passport which can be downloaded from here. If the passport is unavailable for any reason just keep a note of the codeword and try again later.