Our Noisy Oceans

oceans_noise-effect-on-animals.jpg Many underwater realms have become very noisy. An increase in motorboats, primarily commercial shipping traffic, exploration and extraction of oil and other minerals, sonar and even coastal jet ski traffic are contributing to the increased level of underwater noise. "If you could lay down under the shipping lanes at Great South Channel (off Cape Cod) and spend the day there, you would get the impression of being on the tarmac at Logan Airport," said Christopher W.Clark, who runs the Bioacoustics Research Program at Cornell University.

ocean_noise_ambient.png Sound travels four times faster in water (1,230 meters/sec.) than in air (340 meters/sec.) because water molecules are packed tighter together. This results in sound that will also travel farther under water. High intensity sound in the oceans can travel for thousands of miles. In this regard it is important to remember that since water has a much greater density than does air that sound waves travel though water at much higher energy levels and are hence louder.
We know that whales and dolphins use sound to communicate with each other over vast distances. Other marine species use sound to find food and choose mates as well as warn others of potential dangers. Whales communicate at very low frequencies, below 1000 Hertz. This is the same frequency that resonates from many human-caused activities. Man-made sounds are drowning out the calls of mates, calves and other pods that these mammals depend on. High sound levels cause grey whales to deviate from their migration paths, the deviation being greater as sound intensity increases. Full text at: SEE-THE-SEA.org

The three most significant sources of ocean noise pollution are:

1. Ships create noise from their propellers, motors and gears. The amount of noise produced depends on their hull shapes and propulsion systems. ocean_ship_propeller.jpg Most of the noise ships produce is at low frequencies (roughly 20–500 Hz). In the frequency range of roughly 500–100,000 Hz, however, ambient noise is mostly due to breaking waves, rather than shipping. At low frequencies the background sound level in many places in the ocean is dominated by noise from distant ships, even when there is no nearby ship. When a large ship passes close to a receiver, the noise that is generated will temporarily increase the sound levels at that location substantially. Details.....

2. Military strong naval sonar through the deployment of Low Frequency Active Sonar Some systems operate at more than 235 decibels, producing sound waves that can travel across tens or even hundreds of miles of ocean. ocean-sonar_submarine.jpg During testing off the California coast, noise from the Navy's main low-frequency sonar system was detected across the breadth of the northern Pacific Ocean. By the Navy's own estimates, even 300 miles from the source, these sonic waves can retain an intensity of 140 decibels -- a hundred times more intense than the level known to alter the behavior of large whales.

3. And, through oil and gas exploration and associated drilling.
From the extreme noise generated ocean_oil_platform.jpg during exploration for oil or gas to the threat of oil spills, all aspects of oil and gas exploration and production are a potential threat to whales and dolphins and need careful management to avoid excluding whales and dolphins from their homes and causing them harm. High levels of underwater noise is generated during all stages of oil and gas production, though the exploration, installation and decommissioning stages are likely to produce the greatest amounts of noise. Details.....

4. Then there are other types of pollution, i.e. DUMPING - chemicals, illegal radioactive waste, oil spills, plastic ....the list is long. ocean_dump_sealion.png To some, the deep-sea floor may seem safe from the human disturbances that threaten terrestrial and coastal ocean environments. Yet, most natural and artificial wastes -- such as sewage sludge, mining tailings, fly ash from power stations, dredged spoils from harbors and estuaries, dangerous synthetic organic compounds and packaged goods make their way to the sea floor over time. On the left is a picture of a dead seal with a circular plastic around its mouth.... Full text at: oceanexplorer.noaa.gov

Global Shipping Routes

ocean_global_shipping_lanes.jpg In the ocean, sound rules. Unlike on land, where animals (just like us humans!) get a lot of information from light, animals in the ocean have evolved to take advantage of sound, which is much more effective than light under water. Light gets absorbed quickly, but some sounds, like the low-frequency calls of blue whales, can travel hundreds of kilometers under water, under the right conditions. However, when the constant vibrations and propeller noise of commercial shipping block or interfere with their hearing, they are disoriented and cannot always see (HEAR) a massive hulk of a ship heading straight in their paths.

Whale struck and killed by ship in Santa Barbara Channel

ocean_whale_killed.png Collision between vessels and cetaceans (referred to as a 'ship strike') is a problem that is increasing on a global scale. As population sizes of cetaceans increase in some areas and industries such as cruise lines, shipping, oil and gas exploration continue to grow to meet human pressures and the use of pleasure craft continues expand, an increase in cetacean collision events is occurring. Global interest in this issue is growing as there is an increase in the occurrence of ship strikes, and incidents can affect cetacean populations and human life and property.

The overall size of the average ship in the global fleet is increasing,
whether container carrier, bulk carrier or tanker.



Whales Stranded, Kyle of Durness, 22nd July 2011

oceans_long-finned_scotland.png In 2011 and 2012 two large mass strandings of longfinned pilot whales (Globicephala melas) occurred in Scotland. Noise from underwater bombs caused 19 pilot whales to beach and die off the coast of Scotland in 2011, say government scientists Three high order (1000lb) bombs detonated within 24 hours of the stranding. One detonation (250lb) on morning of MSE after long-finned pilot whales sighted in Kyle The magnitude, frequency and proximity of the multiple detonations in the day prior to the stranding, and the single high order detonation shortly after the beginning of the mass standing were plausible sources of significant disturbance to any neighbouring marine mammals. For a list of beahed whales go to:
1. National Library of Australia
2. Whale strandings in New Zealand, 1978–2004


The Silent World ( Le Monde du silence)

1956 French documentary film co-directed by the famed French oceanographer Jacques-Yves Cousteau. 60 years later, 2016 - it is estimated that the ambient ocean noise has increased ten decibels (ten times increase in sound since 1950).

Shipping v/s Whales

ocean_whale_cut_up.png Most reports of collisions between whales and vessels involve large whales, but all species can be affected. Collisions with large vessels often go unnoticed (or unreported if noticed). Animals are injured or killed and vessels can sustain damage. It is thought that the proximity of ships' propellers noise affects whales orientation's ability. Serious and even fatal injuries to passengers have occurred involving hydrofoil ferries, whale watching vessels and recreational craft. Ship strikes are an international problem. Accounting for and reducing the impact of commercial shipping on the oceans' environment, while achieving commercial sustainability, is of increasing importance, especially as it relates to the influence of cumulative noise "footprints" on the great whales.

ocean_whale_collision_marseille.png Above: June 2012, The Mont Ventoux, a cargo ship of the CMA-CGM shipping company, brought back on its bulbous bow a 19-meter fin whale in the Port of Marseille. The necropsy carried out by the members of the National Stranding Network (Réseau National d’Echouage) revealed that the whale was a lactating female; very probably an unweaned calf has almost no chance of surviving in the wild without its mother.

ocean_beached_whales_b.png Above _ Multi-species stranding involved 189 pilot whales and 10 dolphins in Naracoopa, Tasmania. This occurred in 2009 and has been linked to seismic surveying operations occurring in the area.



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