With an average of one sighting recorded every four days, the Spot the Alien campaign has undoubtedly been successful in raising awareness and collecting data on alien species. Even now, after ten years, ‘it is very important that we keep monitoring the aliens,’ says Prof. Alan Deidun. The campaign, which started in 2015, relies on observations from citizen scientists to look out for alien fish and other alien marine species. (If you were hoping to read about extra-terrestrial aliens, sorry, wrong article.)
Monitoring for aliens
Thanks in no small part to the Oceanography Malta Research Group’s campaigns, the public is generally well aware that, in recent years, several marine species that are not native to our waters – alien species – have been sighted, filmed, captured, and seem to be making themselves at home. The first sighting of an alien species is very important because it indicates a range expansion of the species. However, continued records of the presence of a species are equally, if not more, important for monitoring purposes. This is why, after ten years, everyone and anyone is still encouraged to inform the Spot the Alien campaign whenever they spot an alien species.
The more observers scientists have, the more information they can glean. From the information scientists get from alien reports, they can learn about the species’ seasonal trends and how established they are in the new habitat, leading to some educated assumptions on how they were introduced to Maltese waters. They can also use the data for innovative research, such as training computer vision algorithms to identify species from photos.
If you are not sure if you spotted an alien species or not, you can find information online, on social media, through educational videos, and on beach signs, with the sister Spot the Jellyfish campaign including beach signs with alien jellyfish species. You will also get a response for every observation you submit to the campaign.
Alien invaders
By definition, alien species are species that have been introduced to a new habitat through human intervention. Some people buy tropical fish and algae for their aquariums and then, accidentally or on purpose, release those species into the wild. This is likely how the Australian algae Caulerpa racemosaand Caulerpa taxifolia were introduced to the Maltese coastal habitat years ago. The aquarium trade is also likely to blame for how the tropical lionfish[1] , native to the Indo-Pacific, has spread from the Caribbean to the northwestern Atlantic and recently into the Mediterranean too. The highly invasive and destructive lionfish has been spotted in Sicily and in Tunisia, so it will likely be spotted in Malta very soon – Spot the Alien Fish is implementing an early warning system in this case by giving away a brand-new Go-Pro 12 model to the first person to report it.
Empirically, about 90% of alien species are not invasive. However, the 10% that are invasive can drastically change the ecosystem to the point that, globally, alien species are considered a top threat to the conservation of marine ecosystems. Usually, invasive species are not fussy eaters, have high fecundity, and have few natural predators. These adaptations allow them to thrive in various habitats and quickly increase in numbers, outcompeting native species. In the process, the newly introduced species can change how the ecosystem functions, disrupt nutrient and carbon cycles, and in a worst-case scenario, lead to ecosystem breakdown. These ecosystem disruptions impact economic activity and human health by disrupting fisheries and decreasing water quality, for example.
In Malta, impacts on human health have been direct, as some alien species, like silver-cheeked toadfish (Lagocephalus sceleratus[2] ), are highly toxic. Incidentally, five of this type of pufferfish were caught in Marsamxett harbour in January of this year. The presence of five individuals caught in one place shows that the species is reproducing and increasing in abundance, demonstrating the importance of continuing to report records of alien species. Fishers are familiar with pufferfish and know that it should not be consumed. However, in 2019, two patients were admitted to Mater Dei suffering from neurotoxicity after eating octopus. Almost no octopi have the neurotoxin tetrodotoxin, but it is hypothesised that the octopus had eaten a pufferfish, thus poisoning its own consumers via secondary intoxication.
Solutions
Alien species have been with us for so long that five have even been christened with Maltese names: Qawsalla, Trumbettier, Ħmar tal-Lvant, Gurbell tal-Port, and Xkall tal-Lvant. According to Prof. Deidun, we can prepare to name many more because ‘we can expect a quantum increase in the amount of alien species in our waters.’
Controlling the spread of alien species is a difficult and sometimes impossible task. The Environment and Resources Authority has a national strategy for preventing and mitigating the impact of alien species, but efforts so far have been primarily focused on non-marine species. That said, good efforts have been made to remove invasive crayfish from freshwater habitats such as Chadwick Lakes, and invasive plants from Comino despite a late start.
As usual with big structural problems, an individual is limited in what they can do to help. However, knowing the extent of the problem helps, and any citizen can lend a hand, so keep an eye out for the aliens!
This abridged article by Sarah Schembri featured in Issue 46: Species of THINK Magazine, the official research magazine of the University of Malta. For the full article or to read the edition, pick up a copy on Campus or read here. (Republished courtesy of THINK).