Te Whakaorangatanga o Te Wai
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Toitū te Waitematā
The urbanization of Tāmaki has come with an environmental cost. This is especially so for water, which generally been neglected, and often seen as a convenient means of waste disposal. Large parts of the City still have combined wastewater and stormwater networks, with deliberately engineered overflow points which discharge paru to our waterways, and ultimately the moana. For Ngāti Whātua Ōrākei this process reached its nadir in 1914 when the main sewer discharge line for Auckland was laid across the Ōkahu Bay foreshore – discharging directly onto our traditional kai harvesting areas.
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Te Mana o Te Wai
We are working with Council and other agencies to address these legacy issues and retore the health of our waters. Recently we have worked with Watercare and the Council Healthy Waters team to achieve separation of the waste and storm water networks in Ōrākei. We are also working with Revive Our Gulf on a project to re-establish mussel beds in Ōkahu Bay.
In the longer term we have plans to “daylight” waterways which have been lost in pipes and culverts. Ultimately we aim to restore our ability to gather kai and swim safely as we did freely in the past. This work is guided by the Ōkahu Bay Environmental Restoration Plan.
This year we will also start work on a policy statement for Te Mana o te Wai.
1 Year Update - Ōkahu Bay Restoration
Here are the highlights on how the reefs are doing.
After one year on the seafloor, the density of the mussel reefs was substantially lower than when they initially went in. This initial change is to be expected and was observed in the one-month survey and could be for a range of reasons including the mussels spreading out. However, there was little to no change in mussel densities from the previous (seven-month) surveys suggesting densities, and possibly mussel losses, have leveled out and are remaining consistent. Most mussels were generally oriented upright – in a vertical position.
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The mussel size (growth) changed very little over the first year on the seafloor. Our team suggests that in general mussels have slower growth rates when they’re already adult in size, and also the environmental conditions at Ōkahu Bay are sub-optimal for mussel growth so we do not expect to see fast growth rates in the short-term.
Similar to the 7-month survey, we observed epibiota in the mussel reefs. Epibiota are organisms that live on other organisms – so in this case, we’re talking about the organisms that attach to mussels. The team observed small amounts of kelp, several sea stars, sponges, and encrusting ascidians (more commonly known as sea squirts) during their survey.
Two unwanted organisms, the Mediterranean fanworm, and the clubbed tunicate were observed in the reefs, but do not appear to be spreading extensively and are found elsewhere in the area off the mussel reefs as well.
For those following this project closely, you’ll know that half of the mussels were placed on a shell base, and the other half were placed directly onto the seafloor (mud). At this early stage, there’s little discernible difference in the results between the two sites.
Although this research is still in its infancy, these reefs provide a valuable test case for learning and knowledge building. We’ll collectively hold our breath over the summer with the forecast warm water temperatures and look forward to sharing further updates with you throughout 2023.
