‘Double trouble’, the expansion of the Suez Canal and marine bioinvasions in the Mediterranean Sea by Galil et alii

Most of the NIS introduced via the Suez Canal have established thriving populations along the Levant, from Libya to Greece, and several spread in the Western Mediterranean. The individual and cumulative impacts of these NIS adversely affect the conservation status of particular species and critical habitats, as well as the structure and function of ecosystems and the availability of natural resources.

Fistularia commersonii a lepssian migrant from wikipedia

Some species are noxious, poisonous, or venomous and pose clear threats to human health. Significant and often sudden decline of native species, including local population extirpations, have occurred and are occurring concurrent with proliferation of Canal-introduced NIS. Among many examples, the introduced goldband goatfish, Upeneus moluccensis has replaced the native red mullet, Mullus barbatus, in the Levantine fisheries; introduced prawns, though considered a boon by local fishers, have displaced the native prawn, Melicertus kerathurus, which supported a commercial fishery throughout the 1950s and the introduced Spiny oyster, Spondylus spinosus, has completely outcompeted the native congener S. gaederopus off the Israeli coast within a decade of its first record (Galil 2007). Local population losses and niche contraction of native species may not induce immediate extirpation, but they augur reduction of genetic diversity, loss of functions, processes, and habitat structure, increase the risk of decline and extinction, and lead to increased biotic homogenization.

Rhopilema nomadica

From an unfortunately long list of examples of NIS that have led to profound environmental, economic, and human-health issues, we cite a few. A scyphozoan jellyfish, Rhopilema nomadica, has since the early 1980s formed huge swarms each summer along the Levantine coast, which adversely affect tourism, fisheries and coastal installations. The annual swarming stops coastal trawling and purse-seine fish catch due to net clogging and inability to sort yield. Jellyfish-blocked water intake pipes interfere with the operation of desalination plants and power plants (www.​bbc.​co.​uk/​news/​world-middle-east-14038729). Based on evidence elsewhere, the impacts of a 180 km long swarm of large planktivores on the local food web must be considerable (Boero 2013). Last, Rhopilema’s stings result in envenomation effects that may last weeks and even months (Benmeir et al. 1990). Its swarms have been recorded as far away as Tunisia (Daly Yahia et al.2013).

The recent spread of a pufferfish, Lagocephalus sceleratus, throughout the Levant and westwards to Italy and Tunisia, poses severe health hazards: its internal organs contain tetrodotoxin, a strong paralytic neurotoxin, inducing symptoms ranging from vomiting to respiratory arrest, seizures, coma and death. Between 2005 and 2008, 13 persons were treated for poisoning in Israel alone (Bentur et al. 2008). Two herbivorous rabbit fish, Siganus luridus and S. rivulatus, are responsible for an extraordinary shift in the Levantine rocky infralittoral from well-developed native algal assemblages to ‘barrens’ with a dramatic decline in biogenic habitat complexity, biodiversity and biomass (Sala et al. 2011).

Although effects of many NIS have not been evaluated to date, some significant ecological and social consequences are known and the potential reach and magnitude of the cumulative impacts are enormous. The effects of past invasions are continuing to increase, as the ranges of NIS continue to expand through the Mediterranean basin and beyond, since impact is partly a function of occupied area (Parker et al. 1999). The United Nations Division for Ocean Affairs and the Law of the Sea (DOALOS) calls for ” … the management of human activities, based on the best understanding of the ecological interactions and processes, so as to ensure that ecosystems’ structures and functions are sustained for the benefit of present and future generations.” (http://​www.​un.​org/​Depts/​los/​ecosystemapproac​hes/​ecosystem_​approaches.​htm).

Signatories to the Convention on Biological Diversity (CBD) are required to “ … prevent the introduction of, control or eradicate those alien species which threaten ecosystems, habitats or species” (Article 8 h) and “In the case of imminent or grave danger or damage, originating under its jurisdiction or control, to biological diversity within the area under jurisdiction of other States or in areas beyond the limits of national jurisdiction, notify immediately the potentially affected States of such danger or damage, as well as initiate action to prevent or minimize such danger or damage; (Article 14d) (www.​cbd.​int/​convention, viewed August 13, 2014). 

Moreover, the 18th Ordinary Meeting of the Contracting Parties to the Convention for the Protection of the Marine Environment and the Coastal Region of the Mediterranean and its Protocols, United Nations Environment Programme (i.e. the ‘Barcelona Convention’), aimed “… to preserve a healthy Mediterranean that was productive and biologically diverse” and to that effect discussed definitions of ‘Good Environmental Status’ (GES) and targets, including ‘Invasive non-indigenous species introductions are minimized’ and ‘Introduction and spread of NIS linked to human activities are minimized, in particular for potential IAS’ (UNEP(DEPI)/MED IG.21/9, Annex 1, operational objective 2.1, 16 December 2013). Yet, despite these well-meaning international conventions, and a century worth of scientific publications documenting the spread and impact of NIS introduced through the Suez Canal to the Mediterranean Sea—not to mention a vast literature that speaks to the staggering economic, cultural, and environmental impacts of marine NIS around the world—we are faced with a seeming fait accompli.

While global trade and shipping are vital to society, the existing international agreements also recognize the urgent need for sustainable practices that minimize unwanted impacts and long term consequences. It is not too late for the signatories to the ‘Barcelona Convention’ and the CBD to honor their obligations and urge a regionally-supervised, far-reaching ‘environmental impact assessment’ (including innovative risk management options) that would curtail, if not prevent, an entirely new twenty first century wave of invasions through a next-generation Suez Canal.