For two hours on Wednesday, the long-running dispute between the Navy and NRDC over mid-frequency active sonar had its day in the Supreme Court, and while the Justices did broach some questions about the relative likelihood of harm to cetaceans or Navy training, the legal case itself rests on more procedural grounds having to do with the powers of Federal Judges to invoke new environmental standards, and of the Executive Branch to set aside judicial rulings in the name of national security. Court watchers suggested that the Justices seemed to split in a traditional left-right formation, based on comments made during the hearing. A ruling is not expected until spring. Read the rest of this entry »
AEI laymans summary of the following paper:
Hester, Peltzer, Kirkwood, Brewer. Unanticipated consequences of ocean acidification: A noisier ocean at lower pH. Geophysical Research Letters, Vol. 35, L19601.
This is a theoretical, rather than field research, study that calculates the likely current and future decreases in sound absorption caused by increasing ocean acidity (lower pH). The bottom line result is sobering for anyone who is already concerned about the rising tide of ambient noise in the world’s oceans. Increasing shipping noise, in particular, is reducing the effective communication ranges of great whales and creating an urbanized environment in many coastal areas. This research suggests that the well-documented increases in ocean acidification are already helping sound to travel further, with dramatic increases likely in coming decades.
The paper considers four causes of increasing ocean acidity, including deposition of CO2, Nitrogen, and Sulphur, and some chemical effects of warming (which itself contributes in a much smaller way to decreased sound absorption). The net result is that it appears likely that low- and mid-frequency sound absorption has already decreased by 10-15% as ocean pH has gone down by .12; Read the rest of this entry »
Miller, Solangi, Kuczaj II. Immediate reponse of Atlantic bottlenose dolphins to high-speed personal watercraft in the Mississippi Sound. Journal of the Marine Biological Association of the United Kingdom (2008), 88:1139-1143 [ABSTRACT, CONTACT AUTHOR]
This study, using opportunistic observations in the Mississippi Sound (a 90-mile intercoastal waterway, between the coast and a series of barrier islands; depths up to 20 feet), evaluated the responses of bottlenose dolphins to the appearance of personal watercraft (jetskis). In just under half the incidents, a dolphin group’s behaviour changing within one minute of the presence of a high-speed personal watercraft. The most notable changes were that groups that were feeding shifted dramatically to “traveling”mode. Interestingly, groups of dolphins that were already in “traveling” mode often paused and began “milling.” In addition, mean dive duration increased dramatically, from 12-16 seconds to 42-82 seconds. Researchers note that “The results demonstrated an immediate, short-term change in dolphin behaviour, suggesting that an increase in the frequency of high-speed personal watercraft in this area could produce long-term detrimental effects.” The authors suggest more research into the differences in reactions to high-speed and lower-speed jetskis and the effects of increasing distance of jetski approach; in addition, they note that long term studies of growth and reproduction in places with different densities of personal watercraft would help clarify any population-level impacts that may accumulate over time.
An interesting sidelight to this research highlights the difficulty inherent in almost all field research of cetaceans: the study took place over two years, four days per month, and resulted in 329 encounters with dolphin groups, among which there 137 instances in which a watercraft passed by. However, only 17 of these 137 were suitable for the study purposes (ie, they were high speed personal watercraft, and 10 minutes of video of the dolphins was captured before the watercraft passed). Two years of diligent study resulted in just 17 useable encounters! And, truthfully, n=17 is pretty impressive compared to most cetacean field studes….
The BBC has run a three-story series that reflects on the stranding deaths of six beaked whales during NATO sonar training exercises in late September 2002. Coming two years after a similar incident in the Bahamas during a US Navy sonar training exercise, the Canaries stranding cemented a growing concern about the potential for injury in the deep-diving beaked whale family. Studies that took place in nearby Las Palmas revealed the first clear evidence of tissue damage in the injured whales, and while scientists still are not certain of what sort of disruptions in the dive patterns may cause the injuries, this set of tissue lesions has become a “smoking gun” for sonar-induced injury. Read the rest of this entry »
Oral arguments on the California sonar case will take place before the Supreme Court on Wednesday, October 8, in the culmination of perhaps the most convoluted sonar challenge to date. The case began as a simple NEPA challenge to routine Naval sonar training off the Southern California coast in early 2007, and has turned into a test of the powers of both the executive and judicial branches to set environmental standards. Read the rest of this entry »