The pollution load in Australia’s Great Barrier Reef has increased following the impacts of land-based activities and climate change, a scientific study involving over 200 experts found on Thursday.

The Scientific Consensus Statement assessed evidence from 4,000 publications over decades, led by consultancy C2O and funded by the Australian government.

The study on the impact of land-based activity on the reef found that “historical and continuing land management … impair water quality through extensive vegetation degradation, changed hydrology, increased erosion, and expansion of fertilised land uses, urban centres, and coastal developments”.

It also found that pollutant loads from the catchment area to the reef have increased over pre-development loads by 1.4-5 times for fine sediments, and 1.5-3 times for dissolved inorganic nitrogen.

Poor water quality, especially higher levels of fine sediments, nutrients, and pesticides, continues to impact the reef, with the “greatest impacts on freshwater, estuarine, coastal, and inshore marine ecosystems”.

Climate change is the primary threat to the reef, but lower water quality makes recovery from issues like mass bleaching more difficult.

“Meeting water quality improvement targets within the next 10 years is imperative,” the statement said.

Cost-effective land management practices to improve water quality must be ramped up, the report said.

There needs to be a greater focus on “locally effective” management solutions that drive faster adoption. These can be improved via collaboration between landholders, Indigenous communities, the broader community, policy makers, and scientists.

Existing monitoring, modelling, and reporting programmes could be further improved by expanding their coverage to capture local and regional differences, balancing land use and ecosystems, and reducing uncertainties, it said.

“Managing water quality, along with carbon emissions reductions, and research to improve the recovery and resilience of corals, will help the Great Barrier Reef survive climate change,” said Katharina Fabricius, senior principal research scientist and lead author.

In June, the Australian federal Labor government announced an allocation of A$28.5 million ($18.9 mln) to support the coastal habitats around the reef.

The government selected 18 projects and awarded grants of up to A$2 mln for rehabilitating blue carbon ecosystems such as seagrasses, mangroves, salt marshes, and wetlands.

By Helen Clark – helen@carbon-pulse.com

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