Project Manaia

Counting the cost

The real economic harm from canal-borne invasive species remains largely unknown, claim leading academics

Lionfish Pterois Miles (Photo: Oren Klein)

The economic cost of the environmental damage caused by invasive species passing through canals is currently unquantified, according to a recent paper by leading academics, hindering public decision-making and delaying the proactive monitoring of such threats.

Their work: “Knowledge needs in economic costs of invasive species facilitated by canalisation”, published by Queen’s University, Belfast, collected and reviewed all the relevant data and found a “bewildering” gap between the catalogue of invasive species and the costs claimed for the damage they cause.

The research focused on the European inland canals that link the North and Black Seas, plus the Suez and Panama canals, and found that 34 established species had become established in new areas via the European Inland Canals, 411 via the Suez Canal, and 98 via the Panama Canal. The academics then referred to the InvaCost database, where costs from invasive species are logged, and identified all cases that referenced the established invasive populations. 19 such entries were uncovered: 8 for the European Inland Canals and 11 for the Suez Canal, while there were none for the Panama Canal.

$8.6 million in damages was linked to the Suez Canal, due to the economic harm caused by three invasive species: the Silver-cheeked Toadfish Lagocephalus sceleratus, the Lionfish Pterois miles, and the Nomad Jellyfish Rhopilema nomadica.

Nomad Jellyfish Rhopilema nomadica (Photo: Shevy Rothman)

“The most surprising result” according to the paper, “is that costs were recorded for only a few species facilitated by the three canals (9% for European Inland Canals, 0.5% for the Suez Canal, and none for the Panama Canal), and this seems not to depend upon the choice of the countries that could be affected by canal-facilitated invaders, but by the general lack of costs reported for those species.”

Bella Galil, a curator of the Steinhardt Museum of Natural History and Israel National Center for Biodiversity Studies, at Tel Aviv University, was one of the authors, and she says the massive spread of species into the Eastern and Central Mediterranean means that “eradication, or even management and control, of already established marine non-indigenous species is unrealistic – prevention is the only recourse.” Galil attributes the lack of recorded costs of the Suez Canal to the waterway’s economic benefits and the unwillingness of Mediterranean countries and the EU to face the canal’s environmental impacts.

The EU and regional states are parties to The Barcelona Convention, which is the Mediterranean framework for global conservation measures such as the Convention on Biological Diversity which obliges states “to prevent the introduction of, control or eradicate those alien species which threaten ecosystems, habitats or species”. While international measures have been established to prevent invasive species transported by the shipping and mariculture industries, the issue of species introduced through the Suez Canal remains substantially unaddressed.

Galil says: “The Egyptian government is in a position to reduce future introductions. In 2021 Egypt issued tenders for 17 new desalination plants”, that would pump hypersaline brine effluent into the canal, possibly recreating the Bitter Lakes that were credited with preventing the large scale passage of non-indigenous species before their salinity was reduced.

Galil argues for further measures: The “construction of a pair of locks (The Panama Canal famously has triple pairs) would decrease the transit of current-borne biota. The cost of construction should be borne by users (70% of transiting vessels originate from or are destined to Europe or East Asia).”

The Egyptian government and Suez Canal Authority have downplayed the impact of the canal in spreading invasive species, pointing to rising sea temperatures as a principal cause of changing marine populations.

Bulk carrier approaching the Suez Canal Bridge (Photo: Aashay Baindur)

The Barcelona Convention’s Action Plan Concerning Species Introductions and Invasive Species estimated back in 2017 that “the trend of new introductions of alien species in the Mediterranean has been increasing. About 1000 marine alien species have been reported in the Mediterranean Sea up to now, of which more than half are considered established. Many of these species have become invasive with serious negative impacts on biodiversity, human health, and ecosystem services.”

The academics concluded their report by noting “our results underline the paucity of available data. As such, our estimations should be taken with caution, as complex trading relationships and interconnected introduction pathways meant that not all countries invaded as a consequence of canals could be accounted for… More focused research is required to elucidate source-sink dynamics for biological invasions and the large-scale effects of pathways and vectors, as well as to quantify the importance of ‘stepping stones’ for invasion events. In an era of economic uncertainty, severe economic disparities between those benefiting and those negatively affected will have staggering consequences.”

The volume of Red Sea waters and biota increased as the canal was widened and deepened in 2015 to allow the passage of more and larger vessels, while rising seawater temperatures are also easing the establishment of the introduced populations. Although the arrival and spread of venomous and poisonous species such as the Nomad jellyfish and Lionfish (both already recorded in Italy and Tunisia), and Silver-cheeked toadfish (already recorded in Italy, France and Spain) are generating alarm among coastal authorities, a multilateral response to the issue is still not on the horizon.

Written by Robin Llewellyn

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