Estuary gets clean bill of health

Whangarae Estuary is a great example of a Marlborough river mouth in good health, Council’s Environment and Planning Committee has heard.

Senior Coastal Scientist Katie Littlewood said a report showed the Croiselles Harbour estuary, one of many in the province being observed, benefitted from its remoteness.

“The limited human pressure and lack of development in this catchment make it one of the most natural estuaries in Marlborough,” she said. “Being a regenerating native catchment means there are not a lot of land use effects compared to many of our other estuaries.”

The Marlborough coastal marine environment includes more than 60 estuaries and intertidal areas which are biodiversity hotspots providing habitat and nursery grounds for many species, with numerous ecosystem functions.

The 125-hectare estuary was dominated by regenerating native forest, had well flushed tidal flats with prolific shellfish beds and seagrass.

“Estuaries are an important biogenic habitat providing a nursery ground for juvenile fish species,” Katie said. “Monitoring is critical as they are an interface between the land and sea and are strongly impacted by land use practices.”

Whangarae Estuary was an important reference to compare with other estuaries that were impacted by human activities.

“Estuary and intertidal monitoring includes broad and fine scale mapping and seagrass and sediment monitoring which gives Council robust information about the changing state of each estuary,” she said. “This report shows everything here is tracking quite beautifully.”

Native bush surrounding Whangarae Estuary helps keep it natural and in good health. Photo credit: Salt Ecology