Murray River flood sent 200,000 tonnes of organic carbon to the ocean boosting marine life

A massive flood on the Murray River in 2022-23 carried over 200,000 tonnes of organic carbon into the Southern Indian Ocean, according to new CSIRO research. The flood, the largest in 66 years, flushed millions of invasive carp into saltwater where they died and became food for crabs and fish. Scientists tracked the nutrient pulse using chemical fingerprints in animal tissues. Researchers found that 35% of the tissue of scavengers like crabs and yellow-eye mullet came from flood-borne organic matter. Predators like Australasian snapper also benefited indirectly. The study highlights how floods restore connections between river and ocean ecosystems that have been weakened by dams and irrigation. The article also notes a possible link between the flood's nutrient pulse and a harmful algal bloom off South Australia in 2025, though this connection remains unconfirmed due to data gaps.