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How Submarine Cables are Threatening the Fragile Ecosystem of the Mediterranean Seabed

“Mare Nostrum” has been the haven for a wide variety of marine species, the hub for perfect biodiversity conservation. Over the ages, however, it has emerged as one of the major global trading centers in the quickly evolving global economy, a distinct and delicate ecosystem that has been facing several environmental risks brought on by human activity. Among these, submarine cables. 

Though both recyclable and necessary for worldwide energy supply, the installation and operation of these global communication infrastructures has sparked many concerns about the potential environmental impact, the economic issues arising from complex fisheries management, and the need for sustainable policies and regulatory changes to prevent a cyber-war on the seabed.

Cable industry vs. science: game on!

The submarine cables framework appears to be a huge infrastructure that facilitates the flow of data and energy between continents from offshore energy stations to the mainland. In layman's terms, about 67,000 kilometers of new cables were installed worldwide between 2016 and 2020, with a current estimation of 113,000 kilometers to be installed annually by the end of 2023. A huge anthropological ecosystem through which $10 trillion worth of financial transactions are conducted every day on ever-more complicated supply chains, accounting for around 95% of all Internet traffic worldwide. A sizable industry that is projected to increase by 12.9% between 2022 and 2030, reaching a value of $48 billion, according to

The cost of a single cable in the submarine cable sector can reach hundreds of millions of dollars, contingent upon the route's complexity and length. The “private owner” model, wherein a single IT corporation owns and operates the cable for its own purposes, has recently become more prevalent, although the “consortia” one – between telecommunications, large technology businesses, and infrastructure specialized companies – has always been looked upon favorably. Collectively holding more than 66% of the submarine cable network's capacity, submarine cable routes are being redesigned by these companies to connect their data centers in order to scale up digital production and storage, a recent industry report predicts.

High-voltage power cables are bigger and heavier: composed of insulating sheath-encased copper or aluminum conductors, they're usually buried beneath the seafloor for protection as they carry large currents of concentrated electricity. A recent construction concerning the Mediterranean, laid with the new power line built by Italy’s Terna to connect the island of Elba and Piombino city, according to the company’s press release, will “affect on its way out of the Piombino landing a Posidonia oceanic meadow for a stretch of about 3 km in length”. Despite potential biodiversity effects, Terna assures that there is “maximum focus on the environmental impact with the transplantation of Posidonia oceanica from the affected area to a 1,650 m² site in the Gulf of Follonica”. In its official statements, the company speaks of “improvement for the quality of the local infrastructure, bringing significant benefits in terms of security, reliability, and sustainability". Yet it is important to acknowledge that a number of Posidonia, the plant most representative of the Mediterranean infralittoral zone, was removed and replanted during the project, somehow disturbing the marine ecosystem of the area.

“While burying the power cables lessens the intensity of the electromagnetic field at the seabed's surface, it does not completely eliminate it”, says Bastien Taormina, a marine ecology researcher at the Institute Marine Research.

According to one of his papers, their placement can disturb the marine ecosystem by generating electromagnetic fields: “the higher the voltage and current, the stronger the electromagnetic field, the worse the environmental impact”. Taormina believes in the potential of renewable energy, “but its benefits must be weighed against the environmental impact of installing the vulnerable infrastructure to support it”, he says, mainly if it affects the navigation of electrosensitive marine species, such as sharks and even eels, who use their internal magnetic north sense to prey and orientate.

High-voltage cables, also, can be connected to offshore wind farms too that float in the open sea. “If they are also placed on the water surface, the environmental risks will not only affect the benthic environment but also influence the pelagic one”, says Alessandro Cresci, Postdoctoral Research Scientist at the same research institute as Taormina, following the expansion of floating offshore wind farms in the Mediterranean. According to research, the behavior, ecology, and survival of species are among the aspects of life processes that are mostly impacted by EMFs associated with electricity production by offshore wind turbines that have both kinds of wires in marine habitats.

Telecommunication cables, instead, when ashore, end up in a concrete structure embedded in the beach, for later merging with a counterpart that travels to a landing station. Made of optical fiber, they are rather deposited on the seabed's top because the currents they carry are milder, conveying only simple data at low voltage. Much safer then? According to Michael Clare, leader of the Marine Geosystems department at the National Oceanography Centre, they are. To safeguard cables from human activity in shallow waters, burying them may be necessary. In this scenario, "the seabed will be disturbed, but studies have shown that the benthos rapidly recolonizes”, he says.

The greatest differentiation of Clare's vision on the impact of submarine cables on the marine environment from Taormina's lies in their degree of influence on the sea bottom, as well as the potential ecological repercussions: in his recent article, indeed, Clare presents a more “tentative” perspective on the tenuous relationship between environmental influences and marine organism behavior. “Telecommunication cables do have an impact in terms of electromagnetic field disturbance for sea creatures”, he says, “but this is a minimal or even benign footprint on the marine environment”. And this applies to high-voltage power ones too: “Whether they are affected by the EMF intensities generated by power cables”, he says, “remains unclear and the subject of ongoing research".

So Giuseppe Valentino says too. Telecom Italia Sparkle’s Data Product Manager defends his company's strategy in implementing the construction of the BlueMed submarine cable by reiterating one message: “We want to consolidate Sparkle’s leadership in the Mediterranean basin through the extension and enhancement of our regional backbone". With a total system capacity of up to 400 terabits per second and a total length of about 1,000 kilometers, Sparkle's wholly owned BlueMed is an integral part of the Blue & Raman submarine cable system project, together with Google and other operators. This means that the entire project is based on a consortium model in which part of the shares belong to Google and a third partner. In addition, the cable itself shares fiber pairs with Blue.

map with cables underwater
The Blue & Raman submarine cable system from the consortium of Google, Sparkle and other operators, that includes the BlueMed cable owned exclusively by Sparkle (Telecom Italia Group) / Credit: TeleGeography 2023.

According to Valentino, “BlueMed has very little, if any, impact on the environment,” mainly thanks to its mechanical nature: “it is one centimeter wide in diameter and” – despite the very high voltage path that can reach up to 11,000 volts – “the amperage is very low, making it environmentally friendly for both laying and maintenance”. Valentino also highlights that "Sparkle received all authorizations from Italy’s Ministry of the Environment and the Navy to lay on the bottom in Italian seas”. Although the regulations are fairly strict, “there is a great emphasis on maintaining environmental integrity during the cable installation and maintenance process in Europe”, he says.

Cresci, however, speaks of potential effects of underwater communication cables on the ecosystem too: even though EMFs are a poorly understood but potentially important and increasing emission into the marine environment, he says that sensitive species might not receive critical environmental cues due to the electromagnetic fields produced by electric telecommunication cables at high frequencies, which may have negative effects on the local ecology. This is because undersea cables used for power transfer are known sources of EMFs, but telecommunication cables and undersea communication cables also generate alternating current (AC) and direct current (DC) EMFs. Seabed damage, disturbance of organisms, and electromagnetic noise also pertain to this category of impacts. And his thesis is backed up by research: according to it, despite the small physical size of optical cables, which transmit data using pulses of light (it can be considered a form of high-frequency AC), activities such as surveying of cable routes, laying, protecting, and repairing submarine cables may cause pollution or harmful changes to the marine environment.

Fishing…cables? Pulling up…cyber-spies!

The environmental impact found in both high-power and fiber-optic submarine cables, therefore, seems to be common, and characterized by other phenomena such as turbidity, pollution, entanglement, and habitat disturbance. These latter, more specifically, deal with the fishing activity: ICT Solutions and Education reports of around 100 cable breakdowns annually, while European Union Cybersecurity Agency most recent data indicates that human engagement, whether through inadvertent mistakes or deliberate malicious actions, is responsible for 87% of cable incidents. Among these, damages from fishing gear like gillnets and trawls – which can cut them directly by ripping apart or snapping the cable – are very likely since they are usually buried or laid beneath the seabed.

Categorisation of cables faults. | European Union Agency for Cybersecurity (ENISA)
Categorization of cables faults / Credit: European Union Agency for Cybersecurity (ENISA).


“For years there has been no concrete dialogue between the fishing sector and the submarine cable industry,” says Roberto Arciprete, vice-president of the Italian Cooperative Alliance. The middle ground for a greater integration of shared practices “is necessary”, he says, otherwise the “risk of being left out increases, and our demands will never meet a fair industry regulation”. At the European level, it’s Juan Manuel Trujillo Castillo, president of the European Federation of Transport Workers, who raises his voice: “While we are not against these activities", he says, "we call for a balanced approach between the parties."

Trujillo has a strong stance on fisheries: since fishermen contribute to the EU's food supply and food sovereignty, "why are energy and telecommunications more important than healthy and essential food?". According to Marevivo, an NGO that focuses on marine conservation, “no human activities have zero impact”. The NGO states that the EU Marine Strategy Framework Directive's eleven descriptors of good environmental status “serve as a measure of the application of the environmental impacts of submarine cables" and that the Environmental Impact Assessment (EIA) commissions must question the construction of any cables that do not meet these sustainability standards. “If the presence of the cables is an obstacle to legal and sustainable fishing activities, then we think it is fair that those who lay the cables compensate the fishermen for the losses.”

According to Clare, even if fishing activity is nevertheless occasionally conducted near these laying locations, “the volumes of sediment disturbed as a result of cable burial are greater than those disturbed by fishing activity”. According to the 2023 European Commission’s EU Action Plan on sustainability of fish stocks, instead, the impact of fishing on both the seabed and sensitive species is higher and overfishing is projected to have an annual economic effect of over 3 billion dollar per year – significantly above the sustainable level – with an average exploitation rate of 1.4%, says FAO's The State of Mediterranean and Black Sea Fisheries 2022. So, what’s more dangerous for the ecosystem? Cybercrime. Submarine cables are intrinsically geopolitical: they define the physical boundaries of the digital world, manage global power by carrying ever-more-important data and – most importantly – do not wave national flags. Distributed in a system made of jurisdictions, international conventions, and sea laws, they are “invisible” to governments: their “sea blindness” condition – if armed – can increase supply chain risks, technological dependence, and vulnerabilities related to unwelcome foreign interventions.

Mondo Internazionale G.E.O. head researcher Saverio Lesti released a report on the seabed's growing strategic significance, affirming that the primary instruments of the “cyber warfare threat to undersea cables” are sabotage – to inflict financial harm on companies – and cyberattacks – to interfere with vital intelligence networks. “The Mediterranean Sea's undersea cables are a vital target for potential adversaries, as it is a key node in the global communication network”, he says. Therefore, governments must implement “submarine warfare” strategies to “diversify routes to reduce the risk of a single attack, improve security with surveillance systems, and develop international agreements”. 

Simple, right? Not quite, as there are competing interests to consider, including "the lack of political will and legal complexity to regulate the use of the seabed". Same issues encountered by Christian Bueger in his recent paper on the European governance to fight security threats to submarine cables. The professor of ocean governance at the University of Copenhagen argues that “a basic mechanism for information sharing” – initially run by a cross-community working group that includes the cable industry – “needs to be established”. He emphasizes that the European Parliament should push Member States to investigate cables on their own, evaluate any vulnerabilities, identify available reaction mechanisms, and communicate the findings with all EU agencies. 

To do this, the institutions ought to establish a special budget to help with cable maintenance as well as the investigation and creation of new technologies to increase the technologies' durability. “The main obstacles to an EU-wide governance of the cable network are the lack of systemic data on regulatory agencies, current regulatory protection measures, and national surveillance operations”, the professor claims. The necessity of preventing attacks on vital infrastructure is growing as the world observes the conflict between Russia and Ukraine: will Europe act accordingly and fast enough?

Drawing of Russian Seabed Warfare Capabilities
Russian seabed warfare capabilities / Credit: Naval News.

This article was produced with support from Internews' Earth Journalism Network and the Climate Arena Fellowship. It was first published in Wired on 20 November 2023 in Italian VoxEurop on 1 December 2023 in English and has been lightly edited for length and clarity.

Banner image: Underwater reef scene / Credit: NOAA via Unsplash.