The at-home pregnancy testing kit has been repurposed to detect the presence of the destructive crown-of-thorns starfish species in coral reef ecosystems. Using a dipstick-like testing strip, researchers can quickly carry out necessary measures to protect valuable corals like those in our beloved Great Barrier Reef.
The New Kit On the Block
A pretty well-known, tried, and tested method has been reinvigorated for use in protecting our marine habitats. The classic pregnancy testing kit that can be purchased from a wide variety of stores has been used as a guiding reference for determining the presence of certain harmful species beneath the ocean surface. A specially-designed “dipstick” has been garnering attention in its ability to pick up microscopic amounts of DNA from a particularly destructive starfish species by just dipping it into the water. This species, the crown-of-thorns starfish, is infamous for its ability to cause mass killings of corals when they migrate to new regions. In particular, the species has a bad reputation for adding insult to injury in the Great Barrier Reef where corals are already exposed to a plethora of harmful events—not the least warming waters, increasing microplastics, acidification, and widespread bleaching. For over half a decade, the species has actively played a role in wiping out entire coral habitats along the Great Barrier Reef.
The Crowned Star
Contrary to what its name suggests, the crown-of-thorns starfish (Acanthaster planci) is not king of the stars and fishes. It is a sea star named for the spines that riddle its entire body as well as its multitude of arms. Typically, starfish tend to have five arms, presenting to us as the classic star shape. But these crowns like to do things a little more effortlessly, with up to 21 arms totally covered in poisonous spines to do their bidding. The spines are flexible in their function, being used for movement in addition to the more obvious and necessary means of defense. They can grow up to 35 cm in diameter and are the second-largest sea star found in the world’s water today.
As touched on above, the species is a fierce and well-known predator of corals and has consequently been dubbed “coralivore”. Outbreaks of this enormous starfish along reef ecosystems have been documented wreaking havoc and inflicting long-term damage on corals. They are capable of eating an amount of coral equivalent to their own body weight every single day; experiencing frequent population booms and dominating habitats in their wake. They are also nocturnal hunters so tracking them is pretty difficult; even though their diet is almost exclusively dedicated to corals—which would seem to make them easily trackable because their movements are likely to be angled towards reef locations.
They are ferocious in their hunt, gliding over corals and slowly devouring thin layers of soft tissue before sucking all off the valuable nutrients from within. In order to feed, these coralivores—like all other starfish species—completely invert their stomachs through their mouths. They then cover the digestible parts of the coral—i.e., the soft tissue—with their stomach lining to feed. Essentially enveloping a section of the organism and just degrading it slowly.
Crown-of-thorns sea stars reproduce through broadcast spawning behavior, where both males and females take part in simultaneous release of their sperms and eggs into the water column. This near-explosion of spawning means they have a higher chance of fertilizing, significantly contributing to their boosts in population numbers.
Conservation Importance of the Test
Historically, it has been challenging to pin down exactly where outbreaks of crown-of-thorns starfish will occur. They migrate and adapt so quickly that researchers and scientists have been scrambling to mitigate the damage they inflict after passing through a reef. It is for this reason that the conservation and citizen science community is so excited about this seemingly simple pregnancy-style testing kit. Being able to track the sea stars in an easy and extremely quick way means it will be cost-effective in the long run and can hopefully involve people all over the world.
The Great Barrier Reef is most commonly the victim of the crown-of-thorns starfish slaughter sprees. Since 1962, numerous outbreaks have been documented with mostly muddy views on the reasoning behind the population spikes. Even though the underlying cause of these outbreaks is still relatively unknown, all conservation and research efforts have now been directed at how to remove them entirely as a threat from the ecosystem.
A multitude of methods have been tried to remove them from coral reefs, such as physical removal by divers, introducing new predators, poisoning them, and physically cutting each individual starfish through the middle. All of these methods are not ideal in an already sensitive environment. Cutting them up has even resulted in them regenerating up to half of their bodies, inadvertently doubling their population. At the end of the day, these methods do not work, not only because they are not that ideal, but mostly because these invertebrates are inherently difficult to track. Their juveniles are often less than a centimeter in size and the adults, being nocturnal hunters, harbor beneath reefs during the day, hiding pretty much in plain sight.
The Kit: What and How
All of these reasons and presumably more have contributed to this new rapid testing kit. Developed by researchers at the Australia Institute of Marine Science, the kit has the potential to shift panic to focus. The dipstick, which is more technically known as the lateral flow assay, enables quick and accurate identification of the infamous species by just dipping a stick into the surface of the water. Much like an at-home pregnancy testing kit, the stick has identification material within it that shows as a visible strip based on if it detected certain DNA present in the water or not. Tiny particles of genetic material released by the crown-of-thorns starfish are detectable even in trace amounts. This ability hints at being able to inform of not only immediate starfish presence below the surface, but also that of nearby habitats.
Aside from potentially being able to drastically contribute to protection and preservation of ecologically-significant coral reefs, this kit is awesome because it is so easy. It really is just a small kids’ play briefcase-sized box with a small sensor, a pipe, and a stick for dipping. At the risk of being overdramatic, innovations such as this testing kit are the ones that will revolutionize the conservation game going forward. Particularly when facing climate change and all of its ugly heads. Re-purposing technology that already exists and packaging it in an application that regular citizens can take part in is how active change can take place.
This simple and easy-to-use technology could be mass-produced and given to a multitude of people that live and work in marine environments and along coastlines. Fisherfolk, tourism operators, divers, lovers of the sea: all could take part in collecting these tracking trends. Meaning that data can be quickly uploaded and responded to, inevitably saving valuable corals from devastation. Specifically, for the Great Barrier Reef, this technology could remove one major environmental stressor, allowing for some space so that it might attempt to recover from the multitude of other stresses it is currently under.