By Giuseppe Mazza and Elena Tricarico, Università degli Studi di Firenze, Italy
Invasive species are becoming a popular topic in newspapers: when articles appear, they mainly report the damages invasive species can cause to our ecosystems (e.g. reduction or disappearance of native species as well as habitat modification) or to our economic activities: fishing or boating can be halted by mats of the South American water hyacinth, several insects can affect our agricultural production or new diseases can be transmitted to reared species. However, these species can also heavily affect human health and wellbeing.
While dealing with this aspect, we often think about mosquitoes transmitting severe diseases such as Dengue, chikungunya or Zika virus, or of plants that can be toxic or strongly allergenic, such as the common ragweed or the giant hogweed. But other notable invasive species can affect our health in various ways and ignoring this issue is probably the most fundamental harm we can do to ourselves.
An interesting example is the case of the silverstripe blaasop, Lagocephalus sceleratus: this pufferfish is native to the Indian Ocean and Red Sea. One specimen was recorded for the first time in 2003 in the Mediterranean Sea, probably introduced through the Suez Canal (Akyol et al. 2005). After this first record, its number increased in the Levantine Sea. The species has a strong neurotoxin, the tetradotoxin, which causes several severe symptoms to people consuming the fish, such as nausea and vomiting, dizziness, headaches, abdominal pain and progressive muscular paralysis, eventually causing death due to respiratory paralysis. However, when the species arrived in the Mediterranean Sea, locals were unaware of the risks and couldn’t identify the species – fishermen caught and sold it for human consumption, and incidents of poisoning occurred in Egypt, Israel and Lebanon. The species started spreading and is now common and abundant in the Mediterranean Sea, particularly in the Eastern area.
Studies have been carried out proving the toxicity of the silverstripe blaasop, leading to official bans of its fishery. Despite this, a survey conducted in Turkey in 2012 on species awareness showed that fishermen, though understanding that the fish is poisonous, admitted selling it to local markets and hotels, providing themselves with good income (Beköz et al. 2013). Restaurant managers and fish mongers denied selling the pufferfish, though specimens were in fact displayed for sale. Most customers had not heard of the pufferfish, and were not aware of its lethality, and admitted to relying on the sellers’ advice. The majority of physicians surveyed (76%) were not aware that pufferfish are poisonous, whilst 98% were unfamiliar with the symptoms of pufferfish poisoning and believed an antidote to tetradotoxin exists.
Invasive species can also affect the goods and services provided by the ecosystems, decreasing availability of both drinking water and products from fisheries, agriculture and forestry, altering pollination, and impoverishing culture and recreation. Unfortunately, most consequences of global change, biological invasions included, affect the weakest sectors of the society, i.e. developing countries, and children. A better understanding of management options as well as joint efforts in educating public and decision-makers is crucial to prevent serious problems to human health and wellbeing.
Giuseppe Mazza and Elena Tricarico are editors of Invasive Species and Human Health, recently published by CABI.
Akyol, O., Unal, V., Ceyhan, T. and Bilecenoglu, M. (2005) First confirmed record of Lagocephalus sceleratus (Gmelin, 1789) in the Mediterranean. Journal of Fish Biology 66, 1183–1186
Beköz, A.B., Beköz, S., Yilmaz, E., Tüzün, S. and Beköz, Ü. (2013) Consequences of the increasing prevalence of the poisonous Lagocephalus sceleratus in southern Turkey. Emergency Medicine Journal 30, 954–955