Professor Marcelo Soares from the Federal University of Ceará in Brazil is an Alexander von Humboldt fellow in the Reef Systems group at ZMT. For his publication on the invasion of lionfish (Pterois spp.) in the South Atlantic he worked together with 21 scientists from 14 institutions from Germany, Brazil and the US. The team of researchers collected data on lionfish by conducting field surveys, diving activities, and by interviewing local fishers and recreational divers. The scientists also used social media for their work, which allowed them to detect the presence of lionfish in remote locations that were difficult to access. The study has also sparked a citizen science project. The researchers have just launched a mobile application in Brazil. Anyone who sees a lionfish in local waters can let Soares and his team know via the app and the researchers can then check out the sightings.
What prompted your study?
Invasive marine species are a major problem around the world and one of the main drivers of species extinction. They can lead to multiple socio-economic and environmental impacts. The invasion of the lionfish Pterois spp. is potentially harmful and can become the most damaging marine fish invasion globally to date. The lionfish invasion of the Caribbean Sea and, more recently, of the Mediterranean has raised widespread concerns due to the impacts on marine biodiversity hotspots and negative effects on economic sectors such as fisheries. Now we have a new and vast region that is undergoing a new invasion process: the South Atlantic Ocean.
What makes the lionfish so problematic?
The lionfish is a voracious predator feeding on the native fish. The species also has high reproduction rates and grows quickly. The lack of natural predators in invade areas combined with the species’ low parasite load, its defensive venomous spines and its high competitive ability severely impact the native species and also change the habitat.
What was the situation like in the South Atlantic before your study?
In the South Atlantic Ocean, only two lionfish individuals were recorded on the Rio de Janeiro coast – one in 2014 and another one in 2016. Since then, no other individuals had been documented in the region. The species had not formed an established population in the area. As these particular records were far away – approximately 5,500 km – from the Caribbean Sea and too isolated an incident, the recorded individuals were most likely not dispersed from the Caribbean but released from an aquarium in Brazil. However, in 2020 things changed and three new individual lionfish were detected on tropical reefs in a depth of 30 to 100 metres. They were found on the offshore coast of the Amazon and in the Fernando de Noronha Archipelago situated 370 km from the Brazilian coast. Our paper describes a new phenomenon because until then there had been no multiple records of lionfish in shallow waters in the tropical South Atlantic.
What are your new findings?
When we investigated the Brazilian semiarid coast between March and May of 2022 we discovered 72 lionfish individuals. This might not sound that many, but they were the first multiple records of Pterois spp. off the Brazilian coast that had been found in shallow-water estuaries, seagrass beds, and artificial and natural reefs. It is the first detection of the species in these environments as well as the largest simultaneous record of lionfish on these tropical shallow habitats. These individuals included mature males, and some of the females had already ovulated, which suggests an already established population in the South Atlantic.
What else does your data show?
We consider these findings an important track of the invasion of lionfish down to the South Atlantic. For the first time we also found lionfish individuals in breakwaters, fishing weirs, and so-called marambaias, artificial reefs used as fishing grounds off the Brazilian coast. Our records also show that these man-made structures are suitable living environments and stepping-stone habitats for this species. Since more than half of the 72 lionfish individuals were detected in artificial reefs and fishing weirs it raises concerns as to what impact their presence will have on fisheries – especially in a region with high social inequality and risks to food security. We conducted our study back in the spring and the numbers have been increasing since. Now more than 200 animals have been found. In other words, it is a growing threat and it is underestimated.
What conclusions do you draw from your findings?
The multiple records in estuaries, seagrass beds, natural reefs, and artificial habitats show the fast invasion and pervasive presence of lionfish in shallow waters in the South Atlantic and also suggest that the invasion progress is more rapid than expected. However, the effects of this process on coastal biodiversity, human safety, and artisanal fisheries need to be studied further. Moreover, we detected lionfish individuals in reefs and estuaries characterised by moderately turbid water and high sedimentation rates. This particular finding not only highlights the adaptability of this invasive species but also means that detecting and managing the lionfish by using spear guns – as done for example in Caribbean clear-water coral reefs – is going to be much more difficult in the regions we studied.
How exactly did the lionfish get to the tropical South Atlantic?
Contrary to what happened eight years ago when lionfish individuals were thought to have been released from an aquarium in Rio de Janeiro state, we think that this time the invasion must have spread out from the Caribbean. After reaching Venezuela in 2010, it took ten years for the lionfish to move from there to Brazil passing through French Guiana on the way. This was because of the Amazon River – it took time for the fish to overcome the Amazon-Orinoco barrier between the Great Caribbean and the Brazilian Province. The barrier consists of an enormous freshwater and sediment discharge and influences an area of 2,300 km along the northern platform of South America. The North Brazil Current flows towards the Caribbean, but the lionfish adults managed to successfully swim against it. The current slowed down the invasion and prevented the flow of larvae and eggs but the adults were still able to reach an inviting new habitat with no predators and plenty of food.
What can be the effects of a lionfish invasion?
Now that the species has arrived in shallow waters on the coast and with no more natural barriers to hold it back, the currents will help it to move further along south. In the five months since March it already managed to cover a distance of 700 km and we expect the species to rapidly invade the remaining 6,000 km of the coast along the South Atlantic in the coming months. So something needs to be done because the cost of inaction would multiply quickly, not only for Brazilian coastal communities, but also for marine life in one of the world’s biodiversity hotspots. The small-scale artisanal fisheries may be highly impacted, with possible harm to human safety resulting from physical contact with venomous lionfish in fishing weirs and artificial reefs. The sting of a lionfish causes excruciating pain and marked inflammation, with localised redness and edema.
How can fisheries and food security be impacted?
The coastal region of Northeast Brazil has considerable artisanal fishing activity, which is vital for food security in an area with substantial social inequality. Models also suggest a high probability of considerable impacts from lionfish on native reef fish, including some of socioeconomic importance, such as snappers and groupers. Reduce fishery or aquaculture can lead to job losses and also have consequences for international trade or tariffs. It has recently been estimated by that the expansion of the lionfish into non-native ecosystems provokes losses in the order of US$ 24 million per year. A delayed response to an invasive species, meanwhile, may incur seven times greater costs than the rapid implementation of preventive measures. Therefore, impacts on marine biodiversity, public health, and artisanal fisheries in this newly invaded region must be urgently prevented and mitigated.
How can this latest invasion of lionfish be dealt with?
There are different measures that we would suggest from a scientific point of view. We need further solution-based ecological research, real-time online inventories, and an update of environmental and fishery legislation. Participatory monitoring supported by citizen science is also something we propose and have already started. But we also need a national and unified plan to try to combat the lionfish invasion by removing them. An early detection and control of populations by divers and fishers alike is necessary. In the Caribbean and in Florida there are professional tournaments to collect and remove lionfish from their invaded habitats. Such events also serve to inform and educate the public about the problems this invasive species causes. In some parts of the Caribbean, populations have been controlled at low levels and in others they have not. Catching 100% of lionfish is impossible, but keeping lionfish populations small and with reduced environmental impact is possible.
Publication:
Soares M.O., Feitosa C.V., Garcia T.M., Cottens K.F., Vinicius B., Paiva S.V., Duarte O.d.S., Gurjão L.M., Silva G.D.V., Maia R.C., Previatto D.M., Carneiro P.B.M, Cunha E., Amâncio AC, Sampaio CLS, Ferreira CEL, Pereira PHC, Rocha LA, Tavares TCL and Giarrizzo T. (2022) Lionfish on the loose: Pterois invade shallow habitats in the tropical southwestern Atlantic. Frontiers in Marine Science, 9:956848. DOI: 10.3389/fmars.2022.956848
Link: https://www.frontiersin.org/articles/10.3389/fmars.2022.956848/full
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