Effect of Underwater Acoustics on Whales Essay Example

side of the ocean can hear these calls, facilitating communication between different pods.

Whales travel in pods, which can be likened to schools of fish. Additionally, many other whales utilize infrasound as a means of communication. This includes attracting mates, warning rivals, communicating within their own pods or with individuals from other pods, and locating food (Gerrow, E. 2002). Infrasound is a wave phenomenon that shares the physical properties of sound but operates at frequencies below human hearing range. The marine acoustics impact whales to the extent that their migration patterns are modified.

Marine acoustics involve highly advanced technology. Comparing noise levels in air and underwater is not possible due to the differing standard reference pressures. Measuring underwater sounds in decibels (dB) cannot be used to determine the level of air sounds (Unknown5, 2003). However, there is a noticeable difference in decibel levels when attempting to compare sound in these two environments.

The chart "Chart of Comparable Airborne and Underwater Noise Sources" in the results section highlights the differences. (Horne, J. K. 2000) Substantial levels of noise pollution are present underwater. Sound, especially low frequency wavelengths, has excellent transmission in water and loud noises could severely affect whales. For instance, blue whales employ high-pitched ultrasonic wavelengths for communication, specifically during migration.

(Gerrow E. 2002) Scientific literature consistently states that whales migrate away from sounds at 115-120 dB, according to Richardson, W.J. et al. (1995). Horne's chart also confirms this notion, as it indicates that avoidance behavior is observed in different whale species at levels ranging from 116 to 121 dB.

Controlled experiments have shown that gray whales react with alarm, avoidance, and other changes in behavior when exposed to seismic pulses

at sound levels equivalent to being 2 to 3 miles away from an air gun setup near the coast of California. Field studies also indicate that gray whales may respond to certain low-volume sounds generated by vessels with avoidance and approach behaviors (Unknown1, 2002). Whales are susceptible to noise pollution, such as from navy sonar, which emits significant amounts of infrasound and can lead to beaching incidents (Gerrow E. 2002). Sonar is a term used to describe equipment and accompanying software that receives and potentially transmits sound.

_Generic sonar samples the water by emitting short single or repetitive sound pulses from a specific location, either downwards into the water, upwards from the bottom, or across a body of water (Horne, J.K. 2000)._ One of the most well-known underwater sounds that has a notable impact on whales is Low Frequency Active Sonar (LFAS). LFAS is a military system designed by the U.S. Navy for detecting "quiet" submarines. LFAS functions by emitting an extremely loud low frequency sound into the ocean and subsequently monitoring for the resulting echoes.

This sound is produced at incredibly powerful levels, causing sound waves to travel greater distances in the ocean. The operation of this sonar system is at a level of 230 to 240+ dB (Unknown4, 2001). In 1998, several legal cases were brought to public attention against the use of LFAS. These cases included instances of Humpback whale calves being separated from their mothers and a snorkeler being exposed to LFAS and hospitalized as an acute trauma patient (Unknown 4, 2001). The Navy decided to terminate the LFAS tests and persuaded the judge to dismiss the remaining cases based on the completion

of their research. Furthermore, in 2000, a permit was given to Dr. [Doctor's Name] for[what was given permit for].

Peter Tyack is conducting additional research on Low-Frequency Active Sonar (LFA), which allows him to cause more harm to whales compared to cases from 1998. The Federal Notice for the Tyack permit application sought permission to disturb different cetacean species in the North Atlantic and Mediterranean Sea by exposing them to harmful levels of LFA. Several researchers involved in this new study were also part of the LFAS research. The Tyack Permit enabled Dr. Tyack to conduct research at any frequency he desired.

(Sinkin, 2001)

Methods

The research was primarily conducted at Pennsylvania State University on Abington-Ogontz campus at the Library located in the Woodland Building. Multiple search engines were used to find experiments and researchers in the field of ecology and acoustics. Pro-Quest, one of the search engines, was utilized because it can search all periodicals simultaneously, including magazines, newspapers, and journals. Background information about LFAS and other facts were obtained from the following search engines: Yahoo, Lycos, Go.com, and ask.com. The data was collected, screened, and reviewed to determine its value.

Results: Several studies indicate that gray whales start avoiding sounds at exposure levels of 110 dB, with over 80% of the whales showing avoidance to sounds at 130 dB.

According to a study conducted by Malme C.I. et al in 1989, approximately ninety percent of whales exhibited avoidance behavior when exposed to air gun pulses at 180 dB. This resulted in whales slowing down and changing their direction to move away from the source of sound. In some instances, whales even

moved towards the shallow surf zone as a mechanism to evade the noise. Additionally, the study found that respiration rates increased as a response to the noise, and there were indications that mother-calf pairs were more susceptible to its effects compared to other whales.

In their publication titled "Underwater Noise Pollution and its Significance for Whales and Dolphins," Jonathan Gordon and Anna Moscrop highlight that shock waves generated by intense underwater sound sources can cause direct damage to tissues. They explain that animals possessing air-filled lungs and swim bladders are particularly vulnerable due to the significant impedance disparity between the air present in their lungs and their body tissues or the surrounding seawater.

According to Simmonds, M.P. (1996), animals that were submerged and exposed to explosions at close range displayed lung hemorrhage and ulceration of the gastro-intestinal tract. Alexandros Frantzis associated a stranding event of Cuvier's beaked whales in the Mediterranean with military low frequency active (LFA) sonar trials. Typically, Cuvier's beaked whales do not strand frequently. A Bioacoustics Panel conducted an investigation on this stranding and it is evident that the NATO vessel, which transmitted the LFA sonar, came within 10 km of the beach where the whales were stranded.

The panel found that these whales were exposed to LFA sonar at a sound level of 150-160 dB (Frantzis, A. 1998). Figure1 displays the LFA range with the title "A Schematic of the Propagation of Sound in Convergence Zones" (Unknown6, 2002). The tripartite migration protocols adequately protect animals in unspecified migration corridors and open ocean concentrations (Unknown6, 2002).

Conclusion: Whales are affected by marine acoustics, causing alterations in their migration patterns. There are numerous instances where whales attempt

to avoid loud sounds, become stranded, and are unable to return to the ocean. While most studies have shown behavioral changes with uncertain long-term effects, there are clear indications of altered behavior, including cases where animals have abandoned critical habitats. In a report submitted to the National Marine Fisheries Service in March 1998 regarding the impact of engine noise on Hawaiian humpback whales, researchers at the Ocean Mammal Institute discovered that whales swim 2 to 3 times faster away from engines producing a sound level of 120 dB compared to quieter engines.

Research conducted by the Ocean Mammal Institute reveals that the behavior of humpback whales is significantly altered by the presence of a boat within a distance of up to 1/2 mile. (Unknown3) One of the challenges in studying the impact of sonar on whales involves gathering detailed observations of animals that spend a significant portion of their time submerged and out of sight. Another challenge is the wide range of behaviors exhibited by marine mammals, making it difficult to predict their responses under undisturbed conditions. (Unknown3) While most studies on this subject have been carried out by Navy or other government groups, their findings have not been published in any journals. It is worth noting that whales have existed on Earth for an extensive period.

It is commonly thought that whales should be able to adapt to human-made noise, but in reality, their ears are designed to hear other whales across the extensive ocean. The noise generated by humans is extremely harmful. Unfortunately, both the Navy and the LFAS show a lack of concern for marine animals and are willing to endanger them for the

progress of the Navy. Whales heavily rely on communication, and if they lose this ability, their migration patterns will be disrupted, ultimately leading to their death.