Salp blooms are common around New Zealand in summer, but Northland’s warm currents and nutrient-rich waters make it a hotspot.
Reports of salps at several beaches, including around the Poor Knights Islands, Ocean Beach at Whangārei Heads, Sandy’s Bay, Woolleys Bay near Matapōuri, and Whale Bay, suggest a widespread regional bloom rather than isolated patches.
Marine scientists expect salps to linger for several weeks, depending on ocean conditions.
According to National Institute of Water and Atmospheric Research (Niwa) scientists, salps are barrel-shaped, gelatinous animals belonging to the Tunicata group – making them more closely related to humans than jellyfish.
They move by pumping water through their bodies, filtering out microscopic phytoplankton as food – a feeding method that has earned them the nickname “vacuum cleaners of the sea”.
When conditions are right, salps reproduce rapidly by cloning themselves, forming long chains that can look like strings of glass beads drifting through the water. These blooms can cover vast areas and persist for weeks, depending on currents and food supply.
Salp chains washed ashore. Photo / Earth Sciences NZ
Although they may feel strange to swim among, Niwa research shows salps are ecological powerhouses. By consuming phytoplankton and producing dense waste pellets that sink quickly, they help transfer carbon from the ocean surface to the deep sea. Scientists estimate salps and other gelatinous organisms lock away billions of tonnes of carbon globally each year – a process that helps curb climate change.
Swimmers need to know:
Salps are harmless. They don’t sting, bite or pose any danger to humans.They’re mostly water – about 97% – so accidental contact or even swallowing one is unlikely to cause harm.Washed-up salps quickly lose their transparency and turn opaque, making them look more like jelly lumps on the sand. They’re fragile and disintegrate easily.
Although they can clog fishing nets when present in large numbers, NRC says salps are more of a nuisance than a threat. Overseas, massive blooms have occasionally disrupted industrial water intakes, but that’s not an issue here.
Sarah Curtis is a news reporter for the Northern Advocate focusing on a wide range of issues. She has nearly 20 years’ experience in journalism, most of which she spent court reporting in Gisborne and on the East Coast.