Natalia Sidorovskaia –nas@louisiana.edu
Dept. of Phys.
Univ. of Louisiana at Lafayette
Lafayette, LA 70504-4210
Azmy S. Ackleh
Baoling Ma
Nabendu Pal - ackleh@louisiana.edu
Dept of Mathematics
Univ. of Louisiana
Lafayette, LA 70504
Christopher Tiemann - tiemann@arlut.utexas.edu
Applied Research laboratories
Univ. of Texas at Austin
Austin, TX 78713
George E. Ioup
Juliette w. Ioup – geioup@uno.edu
Department of Physics
Univ. of New Orleans
New Orleans, LA 70148
Popular version of paper 4aAB6
Presented Thursday morning, November 3, 2011
162nd ASA Meeting, San Diego, Calif.
Scientists from the Littoral Acoustic Demonstration Center (LADC), a consortium of scientists from four Gulf State Universities (UNO, UL Lafayette, UT Austin, USM), use sounds made by marine mammals to understand the impact of the recent oil spill in the Gulf of Mexico on the resident populations of these animals, particularly endangered sperm whales and beaked whales. Despite the fact that immediate effects may be difficult to assess, the long term impact can be significant and reflect environmental stresses on the whole deepwater ecosystem since whales are at the top of the ocean food chain.
Acoustical signals are the main source of information about the ocean for deep diving marine mammals, and by recording and analyzing sounds animals produce while diving, scientists can learn a lot about the animals themselves: population dynamics, stock composition, food availability, migration patterns etc. LADC has a 10-year history of studying marine mammals in the Gulf of Mexico by using passive acoustic systems, and this put LADC in the unique position of possessing multi-year pre-spill acoustic data in the vicinity of the Deep Water Horizon incident site.
Supported by the NSF RAPID program, in September 2010 LADC scientists returned to their previous experimental sites aboard the Greenpeace ship Arctic Sunrise and redeployed their acoustic recording systems. Acoustic activity of sperm and beaked whales before and after the spill at different distances from the incident site were compared revealing that average daily acoustic activity of sperm whales at the nearest site 9 miles from the spill decreased by a factor of 2 while it slightly increased at a site 25 miles away. On the other hand, this trend was not observed for beaked whales. A change in acoustic activity may be an indication that the short term responses of different animals to the oil spill may vary depending on habitat utilization and prey distribution.
A variety of information still needs to be extracted from the collected acoustic data to understand the short-term impact of the spill on marine mammals and to plan future experiments for studying long-term trends that can manifest themselves over many years. LADC is planning to conduct additional studies of information present in acoustic data (anthropogenic noise, presence of prey catching signals etc.) to gain more insight into observed trends. The use of passive acoustics in abundance estimates is still a novel approach with potential for advancing population studies which are currently based on visual observations. Long-term monitoring of species abundance from acoustic recordings has not yet been pursued, so LADC proposes a first attempt to do so with its multi-year acoustic data to study the impact of the 2010 Gulf of Mexico oil spill on the population of marine mammals. We are currently seeking funding to continue the multi-year data collection critical for understanding any long-term impact.