TU Delft researchers visit Great Barrier Reef to rehabilitate coral

This week a team of researchers from TU Delft, Van Oord and Australia’s national science agency CSIRO are travelling to the Great Barrier Reef off the coast of Australia to test a new method for the large-scale rehabilitation of coral. In this rehabilitation method, coral eggs are collected from healthy parts of the reef and the resulting larvae returned to the location on the reef where they need to grow. Working with coral larvae has been tried and tested on a small scale and in special tanks. The researchers will now be investigating on location whether this process can be upscaled by collecting coral eggs on a much larger scale than hitherto, using adapted pumping installations that can be used on dredgers for example.

Full moon

At some time during the five days following the full moon in November there is a single moment that all the coral on the Great Barrier Reef releases eggs en masse into the ocean, the coral spawning. Shortly after spawning, the eggs float to the water surface where they accumulate depending on the current. The researchers locate these floating clouds of eggs from the air using a small aircraft. "It's an exciting process," says Professor Mark van Koningsveld from TU Delft, "because we then have to get to the eggs really quickly with the boat containing our pumping and research equipment so we can do our tests; the next opportunity to test this process in the wild isn't for another 12 months, when the coral spawns again."

Fragile eggs

It is important that the fragile eggs are still alive when they reach the storage tank. To make their journey as smooth and safe as possible, TU Delft’s and Van Oord’s researchers have spent the past few months optimizing the pumping systems. For example, the pump needs to cause no eddies during suction and has to stay floating on the surface of the water. Also, the type of pump turned out to play an important part in the design. Over the coming weeks, testing on location will show how the pumping systems really perform in currents and waves. The researchers will be testing two types of pumps and two types of storage tanks in Australia. During the Dutch lab tests, alternatives were used to mimic the structure of coral eggs as closely as possible, such as fish spawn, peas, blueberries and little balls of gel.

Coral rehabilitation

If the pumps and tanks prove to be an effective way of collecting coral eggs on a large scale so they can later be released to settle on the reef, this will be an important step towards the rehabilitation of coral reefs. "With a single ship, we could collect and transport some two billion eggs. That sounds like a lot, but on healthy parts of the Great Barrier Reef, that is only a negligible amount of the available total. However, if we can get them to develop into larvae and subsequently release them in spots where the reef is damaged, that would solve one of the main bottlenecks for the rehabilitation of such reefs”, Van Koningsveld explains. “Sufficient scale is essential to maximise the positive effect, besides other management and protective measures that remain necessary to create the best possible conditions for reef rehabilitation.”

More information and contact

This project is subsidised by the Australian and Queensland Governments and is part of the Advance Queensland SBIR initiative.Follow the researchers on TU Delft Instagram from 26 Nov to 2 Dec.

Carola Poleij, science information officer at TU Delft, C.Poleij@tudelft.nl, +31 (0)15 27 87538, +31 (0)6 41611510