Coastal scientist Sam Thomas said the council’s monitoring results for the health of eight estuaries along the region’s coast, recently published on the Land, Air, Water Aotearoa (Lawa) website, show Otago’s estuaries exhibited a range of health indicators.
Tautuku Estuary in the Catlins was in good condition.
On the other hand, Tokomairaro near Milton and Kaikorai in Dunedin were showing signs of modification and degradation, Dr Thomas said.
"The state of an estuary is a reflection of land-use practices throughout the river catchment from both current and historic land use.
"Estuarine health can be impacted by land use such as forestry, intensive agricultural practices, urbanisation and water discharge practices.
"The monitoring results help the council understand trends in estuarine health to inform catchment management, but equally the results also determine whether land-use activities impacting on estuaries are being managed effectively," he said.
Tautuku Estuary represented a high bar against which long-term changes in other estuaries along the Otago coast could be compared.
It had excellent freshwater health indicators and 97.9% of its indigenous vegetation remained in the catchment.
Papanui Inlet and Blueskin Bay were examples of estuaries in good health, despite being in catchments which were more developed.
They had extensive seagrass and cockle beds that were important for ecosystem health, he said.
Lawa’s new estuary health information was a "fantastic free science resource", he said.
The Lawa data covered 81 estuaries nationally from 389 monitoring sites, including 19 sites in the eight Otago estuaries.
Estuaries provided a transition from the river environments to the sea, and were dynamic, tidal environments that provided important ecosystem functions and habitats for plants and animals.
Three indicators of estuary health measured nationally by councils were mud content, contaminants and estuary macrofauna, he said.
