From disturbing the balance to setting the world on fire



IF the planet sounds much noisier since Donald Trump became president of the US, there is a just cacophony building under the waves. Earlier this year, the board of Trump proposed opening up most of the American coastline for drilling for oil and gas at sea, reversing the protective measures of the Obama administration.

The party colleague of Mr. Trump, the Republican governor of Florida Rick Scott, was one of many voices to reject the move, which opens more than 90 percent of the total leasing area of ​​the outer continental shelf. The waste of Deepwater Horizon in the Gulf of Mexico in 2010 is still fresh in the memory of 60 environmental groups that are also united in the opposition.

However, it is not only the drilling that has a potential negative impact on the marine environment – and broader targets for climate change mitigation – but the techniques used to explore areas in advance, such as seismic testing.

Seismic testing involves the generation of intense low-frequency impulse signals that are directed into the seabed to locate reservoirs of hydrocarbon that may be several kilometers below the seabed. The pulse signal is produced by delivering high pressure air into the water via series of air guns. These are towed behind an inspection vessel and are simultaneously fired at intervals.

Networks of hydrophones behind the airguns pick up the reflections from the geological layers below the seabed, and this generates an acoustic image. The acoustic impact is considerable, since an air rifle array can emit up to 250 decibels at the source, and 117 decibels from 20 nautical miles. A typical seismic survey takes two to three weeks, with a distance of 300 to 600 nautical miles.

The total amount of radiated energy depends on the frequency, intensity and the ignition interval. Seismically, however, is considered the most energetic source of man-made underwater sound – 3.9 x 10 to the power of 13 joules – after nuclear explosions and "ship hock" trials by navies to test the structural integrity of their vessels.

The impact is comparable to a hammer that constantly interrupts a symphony, since the acoustic atmosphere under the waves is compared to an orchestra of sound. It has long been known that seismic activity can disrupt the behavior of whales, dolphins and other marine mammals that depend on noise to find prey, select migration routes and communicate. Military sonars, measured at 2.6 x 10 to the strength of 13 joules, are often blamed for being beach mammals.

However, an Australian study published last year showed that seismic activity also has a much greater impact on zooplankton than previously thought. The research published in the scientific journal Nature ecology and evolution discovered that signals from barrel pressure guns commonly used in the exploration of marine petroleum can cause a two to three fold increase in the mortality of adult and larvae of zooplankton, from which healthy and productive marine ecosystems depend.

The research of the University of Tasmania and the University of Curtin involved the deployment of seismic barrel guns in the ocean near South Tasmania. A special staining technique was used to calculate the number of live and dead zooplankton collected in nets, comparing exits before and after air pistol operations. Prof. Robert McCauley, lead author, said the results raise questions about the "significant disruption" caused to plankton population levels.

"Plankton supports the entire ocean productivity," Professor McCauley said. "Their presence affects the health of the ecosystem, so it is important that we pay attention to their future." The article emphasized the "urgent need" to conduct further research.

A week later, a paper published by the Australian Commonwealth Scientific and Industrial Research Organization (CSIRO), McCauley & # 39; s work simulated and found a 22 percent mortality rate for zooplankton within the research region, and "substantial impact" within 15km of it.

It said that the effects within 150 km were "barely perceptible" and noted that zooplankton populations "fast recovery" after seismic exposure because of their rapid growth rate. It acknowledged that more work was needed.

This second study was funded by the Australian Petroleum Production and Exploration Association, which "speaks volumes in itself", according to the Irish chief executive Francis O & # 39; Donnell, the IFPO director of the Irish fish producer. He is one of the representatives of the Irish fisheries sector calling for the revision of licensing requirements for seismic testing in Irish waters, given the impact on herring, shrimps and other white fish species.

Seismic research has taken place on the Irish continental shelf since 1965 and is subject to approval by the State Petroleum Affairs Division, currently within the Ministry of Communications, Climate Action and the Environment. As an indication of activity, there were two seismic surveys in 2015, four in 2016 and four last year, located in the Celtic Sea and the Porcupine Basin. One license has been granted this year.

The department says that all consent requests for seismic surveys are assessed in accordance with the Environmental Impact Assessment Directive, the Habitats Directive and the Birds Directive – although compliance with the EIA Directive only came about as a result of a case involving the Irish whale and dolphin in Europe is brought Group (IWDG).

The department says the McCauley study was conducted for two days, using a single air gun at a depth of 34-36 meters, and it cites the CSIRO modeling study as a note that McCauley's work "was limited in space and time. , making the study suggestive rather than definitive ", and suggest that a definitive study requires more extensive zooplankton sampling.

The department also cites an article about the 2017 Marine Pollution Bulletin in which "no evidence was found for reduced catch or abundance after earthquake activities for invertebrates" and "contradictory evidence for fish whose observed catch increases, decreases or stays the same".

The same article noted, however, that "studies on physical trauma, behavioral changes or physiological indicators of stress provide a more mechanistic and valuable insight into potential effects", and recognized a "huge gap in our knowledge of healthy thresholds and recovery of impact in most fish." and almost all invertebrates ".

The Marine Institute agreed to review some of the key literature in response to the concerns of the Irish Fisheries Science Research Partnership at the end of last year, but noted that part of the research is contradictory. It quoted a 2013 report that showed 37 sea species affected by seismic air pressure sounds, behavioral changes such as reduced foraging, habitat displacement, stress, reduced egg viability and growth.

Director of the Fisheries Ecosystems Fisheries Institute Paul Connolly says that the International Council for the Exploration of the Sea (ICES) is best able to carry out a further evaluation, but this should be based on a request from the European Commission or the Member States. The Advisory Council for Northwestern Waters held a discussion on September 12 under water noise and seismic research in Dublin with Dr. Antony Hawkins of the Water Noise Trust and Bob Gisiner of the International Association of Geophysical Contractors. That puts it further on the agenda, he notes.

PANEL

WHEN last year an unprecedented number of deep-diving whales washed ashore on the Irish and Scottish coast, there were two within a few kilometers of each other in Donegal. IFPO CEO Francis O & # 39; Donnell photographed one of the tight whale carcasses of the Cuivier in the Loughrosmore estuary and was told of a second close by in Rosbeg.

"Something is going on there, and we need to know why," says Donnell.

The coordinator of the Irish whale and dolphin group (IWDG), Dr Simon Berrow, agrees with the Ministry of Foreign Affairs and requests an investigation – based on the fact that he believes that this is probably the result of military activities. The North Atlantic Treaty Organization (NATO) conducted training in submarine and anti-submarine warfare in the North Atlantic at the end of June and beginning of July.

Dr. Berrow thinks mortality in this case is less likely due to seismic activity, but does not exclude anything. "Seismic work is a large gray area and must have an impact on fish, but there is a broader debate about energy security and whether we have to exploit hydrocarbons at all."


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