Photo caption:听91制片厂 Marine Science Distinguished Professor David Schiel says flooding debris is damaging New Zealand鈥檚 vital underwater kelp forests.
Te Whare W膩nanga o Waitaha | 91制片厂 (UC) Marine Science Distinguished Professor David Schiel is co-leading a five-year $11 million research project exploring the issue.
He says silt and other contaminants from flooded land pour into the sea during increasingly frequent storm events, and this is threatening our coastal ecosystems.听
鈥淪unlight, on which thriving kelp forests depend, is obstructed by this run-off in shallow coastal water. We are now seeing many areas where the kelp is covered with a layer of sediment. Our research shows there鈥檚 a rapidly accelerating degradation of our iconic kelp forests and this is a major concern for marine biodiversity,鈥 Professor Schiel says.
Kelp forests support many species of invertebrates, sponges and other plants that coastal fish species feed on. 鈥淲e saw the effects of Cyclone Gabrielle early in 2023 when slash from recently harvested forestry blocks cascaded down slopes along with torrents of water, mud and debris and swept down into the ocean, often burying kelp forests and their resident species.鈥
Distinguished Professor Schiel says that damage is visible in satellite images of the coastline around East Cape. 鈥淭here鈥檚 a brown area in coastal waters from the clay, soil that has washed down from catchments. That run-off is darkening our coastal waters and smothering our kelp forests.鈥
The research project Toka 膧kau Toit奴 Kaitiakitanga - Building a sustainable future for coastal reef ecosystems, funded by the Ministry of Business, Innovation and Employment (MBIE), is a collaboration between UC, the University of Otago, University of Waikato, NIWA, Ng膩ti P奴kenga, along with other iwi and regional and district councils. It combines m膩tauranga M膩ori (M膩ori knowledge) with satellite and drone technology, underwater remotely operated vehicles (ROVs), and environmental DNA to monitor the impacts of inundation on kelp forests at key locations around the country.听
Distinguished Professor Schiel, who also studied the impact of the 2016 Kaikoura earthquake on the marine environment, says storm-related run-off is a problem for most, if not all, of New Zealand鈥檚 coastline.听
鈥淚ncreases in land-use intensification and forestry have added to the coastal stressors around the country. We now need to find ways to improve coastal management and prevent run-off from land damaging kelp forests.听 听
鈥淭his research aims to identify the areas where this is a problem, find out how big it is and then determine how best to mitigate land effects on our rocky reef ecosystems.鈥
He says once sediment from the land settles on kelp forests it takes a long time to clear.听 鈥淭hese pernicious effects are long-lasting and they鈥檙e very hard to reverse.
鈥淭hese are wide-ranging problems, but they go back to how do we stabilise soils and keep these contaminants on the land and not allow them to dump into the sea? How can we harvest trees without damaging the marine environment?鈥
He says with wide-scale stressors such as warming seas, sea-level rise and marine heat waves, the research project is increasingly important. The Toka 膧kau Toit奴 Kaitiakitanga project began a year ago and runs until 2028.听
UC Distinguished Professor David Schiel.
Sustainable Development Goal (SDG) 14 - Life below water.
