Blue crab and IAS (invasive alien species)

The issues hidden behind the blue crab uproar

An underestimated threat

According to the Intergovernmental Platform on Biodiversity and Ecosystems Services (IPBES), invasive alien species are not only a global threat, but also an issue that is often underestimated and unrecognized (1). Indeed, a report published on September 4, 2023 by the intergovernmental platform indicates that 3,500 of the 37,000 alien species – both plant and animal – introduced into the ecosystems by human activities are invasive and harmful. Moreover, the damages affect several different spheres: first and foremost, they upset the balance of biodiversity, but they also jeopardize the economic human activities exploiting natural resources.

Invasive alien species (IAS) are animal and plant species introduced, deliberately or otherwise, into a natural environment where they have not traditionally been present. Their spread has serious negative consequences: IAS are a major threat to native plants and animals and one of the top five causes of biodiversity loss (2). In addition, the problem is exacerbated by the fact that, as mentioned earlier, the risk is only rarely identified in time to implement appropriate damage prevention, causing the spread of the species to be very wide.

The blue crab issue

During the summer months of 2023 problems linked to the blue crab in the Mediterranean Sea have gained great visibility in Italy. The crab – or Callinectes sapidus – is a crustacean considered a native species of the American continent that is normally found from the coasts of Nova Scotia to those of Uruguay. Even though the topic has become a focus for the media only in the past few years, it is actually speculated that the first sightings of the blue crab in the Mediterranean date back as far as 1935 (3).

Clearly, the number of individuals of this species has grown exponentially in Italy only recently, partly due to the rise in water temperatures caused by climate change. Furthermore, since the blue crab needs the supply of fresh water, it is hypothesized that, for example, the floods that occurred in Emilia-Romagna in May 2023 contributed to a favorable environment for the proliferation of the species in areas such as the Po Delta (4).

The recent alarmism of the media would, therefore, stem from an economic issue rather than an environmental one: even though the public has been informed about the importance of biodiversity, what really attracted attention was the invasion and devastation of the clam and mussel farms, especially in the areas of the Goro lagoon and the Po Delta (5), which have caused considerable economic damage to local business.

The solutions

The apprehension of the commercial activities of fishermen in the areas exposed to the phenomenon was immediately followed by one of the possible and more intuitive solutions: including the blue crab as a product in the food trade. This is, in fact, the area in which the benefit company Mariscadoras operates: five women entrepreneurs from Rimini have, indeed, carried out the Blueat project, which aims to shift consumer attention to invasive alien species, as opposed to traditional and overexploited ones. In addition, this start-up has shipped the first 16 tons of produce to the United States, where this species is normally consumed.

A different hypothesis concerning the use of the blue crab, specifically its calcium- and magnesium-rich carapace, considers it as a dietary supplement within aquaculture. Aquaculture is the process of cultivating aquatic organisms, primarily for human consumption, but the possible environmental benefits of this activity have recently been highlighted.

Among them we find species recovery, habitat restoration and protection, and climate change mitigation (6). Alessio Bonaldo’s research is focused on this possibility. Bonaldo is a professor at the Department of Veterinary Medical Sciences and, with the University of Bologna, has developed the NewTechAqua project, whose main goal is to expand and diversify European aquaculture of fish, mollusks and microalgae by developing advanced, resilient and sustainable technologies and applications – including, possibly, the use of allochthonous species in the feed used within aquaculture. Moreover, the project won the Best Project Award 2023 from the WestMed initiative, which promotes blue economy related efforts in Europe.

An issue with public perception

In reality, however, these solutions are not enough to solve an issue that has been neglected for years. This may be a good opportunity to address a problem that is often underestimated such as invasive alien species, both animal and plant.

Despite the existence of awareness-raising campaigns such as Life Asap – a project co-funded by the European Union that aims not only to reduce the rate of IAS introduction on Italian territory, but also to increase public awareness on the problem and to promote a proper management of these species by public agencies – public opinion still seems to be poorly informed on this topic, if we exclude cases such as the one discussed here or others such as the pond slider (Trachemys scripta), which since the 1980s, following its release into the wild by individuals, has caused extensive damage to ecosystems and native species in Italy (7).

Invasive allochthonous species have always been present within ecosystems: another example is Carpobrotus acinaciformis, a plant native to South Africa and widespread almost all around the world. It should therefore be questioned why certain issues take on a certain prominence within the sphere of media and public perception: very often, unfortunately, the answer is that the discussion acquires visibility only when it goes to undermine our economic activities.

In reality, however, globalization and human migration have been and still are responsible for transporting invasive species that have damaged ecosystems immensely, although without affecting economic activities. This highlights the importance of increasing public awareness on this topic, also in order to prevent both environmental and economic risks.

Irene Zombolo

Graduated in Journalism, Editorial Culture and Multimedia Communication, she loves travelling and learning about cultures and languages. She is interested in social and environmental justice to raise awareness.