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Research

A complex crab invasion carries parasites to Argentina

05 May 2021

 

Marine biologists and pathologists at IBIOMAR, (CCT CONICET CENPAT) Argentina, and Teesside University have discovered a new parasite that is infecting crab species off the coast of Argentina and which could have serious consequences for the vital fishing industry in the country.

Research team
Research team

Argentina is a valuable fisheries resource on a global scale with more than 100 different species of fish and crustacean harvested from the region.

The research team received funding from the Global Challenge Research Fund (GCRF) to examine the effects of invasive species that carry disease. Invasive crabs can cause economic and environmental damage, resulting in declines in biodiversity and issues for local fisheries. The invasive population, thought to be Carcinus maenas (the invasive green crab or European shore crab), has been present on the Argentinian shoreline for around 18 years.

The team found that these crabs have carried parasites with them to Argentina and are also immune to native parasites that infect local crab species. Carcinus maenas is a global invader and a top 100 invasive species, reaching large population sizes across America.

Dr Jamie Bojko, a Lecturer in Biology at Teesside University, said: “These crabs have been moving around the world for over 100 years. At this point, they have had a lot of opportunity to develop large populations that can sustain invasive parasites.

“Previous research has found over 10 different parasite groups had made their way to Atlantic Canada in a study conducted between 2015 - 2018. Now that the invasion has made its way to Argentina, it is important to know if the same parasites might invade.”

The researchers were surprised when they found a new parasite infecting one of the crab specimens in Argentina. Antonella Frizzera, a doctoral student who is working on the project, along with her thesis advisors, Dr Florencia Cremonte and Dr Nuria Vázquez, at Parasitology Laboratory of IBIOMAR used histology to look for parasites in crab tissue.

Dr Cremonte contacted Dr Bojko, who is a specialist in parasites of the green crab, and they agreed to carry out genetic analysis. After analysing the data, they confirmed the parasite was a new Microsporidia species, a group of spore-forming fungal-like parasites that can infect a wide range of animal hosts, including humans.

The species does not seem to affect humans, but it could be harmful for fisheries in Argentina.

The research team have been examining whether the invasive crabs might acquire diseases that are native to the Argentinian coastline. Antonella and her colleagues say they exposed trematode (a macroparasite) that infects native crabs, to the invasive crabs and it did not infect them.

“We didn’t find a single trematode in the invasive crabs,” they explained.

“We are wondering whether the crabs might be extra competitive, since the native species are infected by parasites, but the invasive crabs are much healthier.”

Genetic analysis carried out also provides additional details about the crab that hosts the new parasite. The researchers found genetic data that showed greatest similarity to Carcinus aestuarii, a different species from Carcinus maenas. This new species is native to the Mediterranean Sea and has been found in other areas such as Korea.

“Until we saw the genetic data, we had no idea that this species was hiding out in Argentina” said Dr Bojko.

“This species is very difficult to identify and looks the same as the other species, but is genetically different. It might even be possible that the two species can hybridize, so we have a lot of work to do to find some answers.”

The researchers are now planning to add this species, its parasites, and its new location onto invasion databases, which tracks the spread of invasive species across the world. Continued work will aim to name the new parasite and find out whether it might be able to jump into other crabs and marine life in the area.


 
 
 
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