Seagrass critical to estuary health
Healthy seagrass beds in Bottle Bay in the Marlborough Sounds
Seagrass is a positive indicator of a healthy estuary and the Marlborough Sounds has many productive intertidal areas, where seagrass beds of varying health and extent can be found.
Council’s Environment and Planning Committee heard recently that seagrass beds carry a number of important ecosystem functions including providing habitat for juvenile fish, shellfish and other species.
Coastal Marine Scientist Jorgia McMillan outlined the importance of seagrass beds as an “incredibly effective” carbon sink, able to capture carbon at a rate 35 times faster than tropical rainforest, providing a powerful nature-based solution to tackle climate change impacts on marine life.
“The Marlborough coastal marine area includes more than 65 estuaries across Te Hoiere/Pelorus and Tōtaranui/Queen Charlotte Sound, where our Coastal Science team monitors seagrass abundance and health” she said.
As well as providing a nursery habitat, seagrass helps to stablise the benthic substrate and acts as a buffer between land activities and intertidal areas.
In the Marlborough Sounds many seagrass beds are found in sheltered areas with low currents where sedimentation run-off and warming ocean temperatures can severely impact them.
“Although providing multiple ecosystem benefits, seagrass itself is very vulnerable to changes in its environment and human-caused stressors,” Jorgia said. “Trampling, anchoring and dredging can cause degradation to mass die-offs.”
Council’s ongoing estuary monitoring programme showed healthy and productive seagrass beds in areas including Umungata Bay, Fence Bay and Mistletoe Bay while there are some areas with lower seagrass extent including Kaiumu Bay, Mahakipawa Arm and Ohinetaha.
The Coastal Science team plans to provide more education to landowners and community groups and create more awareness around estuary and inter-tidal health as a whole, Jorgia said.
“It’s important to better understand how we can start using nature-based solutions such as seagrass to help protect our marine areas from climate change impacts.”
