Protecting estuaries

By Christine Rose

Estuaries are beautiful. Estuaries are where rivers widen and meet the sea, and because they are ‘ecotones’, where several ecosystems meet, they are naturally rich in biodiversity. But they have other significant values too. They are some of the last places of peace and quiet, where nature remains relatively undisturbed and undeveloped. They are the last refuges for endangered and shy birds. They are an important intermediate zone acting as a buffer and mitigating the effects of land-based activities on the sea. Some animals spend their entire lives in these rich estuarine environments, but many others rely on these places for key parts of the tide or life cycles.

Rodney’s estuaries are home to the region’s largest and healthiest cockle beds. Estuaries are also breeding areas and nurseries for fish that go on to spread and populate wider areas. And some of the region’s rarest birds such as banded rail live in our local estuaries. At least 22 birds species are found in the Sandspit estuary for example – and most of them are either rare or endangered, and rely on this area not just for their own feeding and breeding but often also for the health of the species as a whole. The role of local estuaries in international ecology is important too. Our estuaries are vital flocking sites for the congregation of migratory birds as they rest and feed on their way to or from Asia and Alaska, in some of the longest migrations on the planet. So retaining estuarine habitats has implications far beyond just local concerns.

Estuaries also have sublime visual beauty. These landscapes are ever changing as the sea comes in and out, exposing or submerging sand and shell banks. Reflections of bushy escarpments, the effect of light and wind on water, the swooping and calls of birds, plopping of fish are all things to sooth the soul. Saltmarshes, sea grasses and glassworts all add colour and texture, as well as filtering nutrients from the land and providing habitat and food for the creatures who call these places home. Estuaries are important for human activity as well – fishing, coastal access, recreation, respite, are all more prosaic roles; Orewa estuary adds huge value to the town’s location, character and recreational needs.

But both incremental damage such as from sedimentation and significant singular threats such as marina
developments put our estuaries at risk. How to balance human use with intrinsic and habitat value is a major challenge as pressure comes on for more access, more development, and as estuaries and other last nature refuges are the spaces of least defence. There’s a clash of values fought out in nature, between those who value these places for their own sake, versus those who seek to modify, use or destroy for some ‘higher value’ economic purpose called development. Estuaries are finite, and for local and global reasons they need better protection.

Published 1 February 2012