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This talk presents a noise avoidance model for migrating gray whales. The model assumes each individual animal has a maximum exposure threshold which it will tolerate, which we call its avoidance threshold. The model assumes that as animals approach a consistent noise source, they will adjust their course as little as possible to insure that their individual sound exposure, or received level, will not exceed its avoidance threshold. The model estimates the probability mass function (PMF) of the avoidance threshold for a population by comparing the histograms of the closest point of approach (CPA) to the source between playback and control conditions. Repeating the analysis using bootstrap resampling techniques on the CPA data provides an interval estimate of the avoidance threshold PMF at each received level. The avoidance index PMF was estimated for gray whales from CPA data observed during exposure to a single U.S. Navy SURTASS-LFA source in 1998. The median avoidance threshold for this population was estimated to be 134 /- 3 dB re 1 uPa, with 90% confidence.

[Work supported by US Office of Naval Research]

Speaker Bio:
Dr. John Buck received his Ph.D. from the MIT/WHOI Joint Program in Oceanographic and Electrical Engineering in 1996. He joined the faculty of UMass Dartmouth later that year, and is presently a Professor in the ECE Dept. His honors include the University of Massachusetts Manning Prize for Excellence in Teaching (2016), the IEEE Education Society’s Mac Van Valkenburg Early Career Teaching Award (2005), the UMass Dartmouth Faculty Federation Leo M. Sullivan Teacher of the Year Award (2008), an ONR Young Investigator Award (2000) and an NSF CAREER award (1998). He is a Fellow of the Acoustical Society of America. His research interests include signal processing, underwater acoustics, animal bioacoustics and engineering pedagogy.

In long-lived species, males and females are expected to allocate their time to mating, guarding behavior and self-conditioning behavior during the breeding period. In the chick-rearing period, many species of seabirds display a unique behavioral adaptation for managing their conflicting demands known as dual foraging, in which long trips, largely for self-maintenance, are alternated with short trips, which are primarily for offspring care. In the mating period, seabirds also allocate their time to mate and to forage. However, there is no study how they manage their time during the mating period. In this study, we examined male’s and female’s allocation of their time using geolocators in streaked shearwaters. We found that females took longer trips than males and went to the more distant area of the sea. They did not change their trip length after they stay together with their partner. However, male shearwaters mainly took one-day trips, and they extended their trip length if they met their partner at the nest. This suggests that male shearwaters determine their trip length based on the presence or absence of paired female to control their time between mating and foraging.

Join seminar with CBD, location of the seminar will be in the Dyers Brae Seminar Room.

Within the Southern Ocean, the Northern Scotia Sea contains the largest seasonal uptake of atmospheric carbon dioxide measured yet. In this region, zooplankton can contribute significantly to the deep ocean carbon export and to the food web. However, year-round data for zooplankton abundance in this region are rare, due to the current difficulty of sampling in the austral winter using conventional sampling methods, such as plankton net tows. Moored time-series sediment traps are primarily used to gather information on vertical particle fluxes in the oceans. However, the accidental capture of zooplankton (so called ‘swimmers’) in time-series moored sediment traps deployed year-round provides a unique and much-needed insight into the seasonal variation of zooplankton abundance and diversity in remote areas such as the Southern Ocean. In this study, we show results of pelagic amphipods collected as swimmers from two years (2015-2016) of moored sediment trap deployment at 400m, located in a site in the Northern Scotia Sea close to South Georgia (SCOOBIES mooring platform). Amphipods represent a key link in the food web between meso-zooplankton and higher trophic organisms. Organisms were counted, photographed and measured using Image J software. Dry mass and carbon content were indirectly calculated. In both investigated years, Amphipod numbers reached the seasonal peak in the austral late summer-early autumn, decreasing until the next summer season. A shift in Amphipod assemblage composition was observed in both 2015 and 2016 with Hyperiidea and Gammaridea dominating the total Amphipod assemblage in the austral winter and summer respectively. The data presented, serves as a baseline for future research to explore the opportunity of using sediment traps as tools to monitoring seasonal and inter-annual variability of zooplankton in the Southern Ocean.

Dr Richard Sherley is an ecologist and conservation biologist with the Bristol Zoological Society and the Environment and Sustainability Institute at the University of Exeter.

His research focuses on the population demography, behaviour and conservation of seabirds, particularly how they interact with human impacts in the marine environment.

His work is funded by the Leiden Conservation Foundation and a number of other charitable trusts.