Preparing for a Northwest Passage: A Workshop on the Role of New England in Navigating the New Arctic

Preparing for a Northwest Passage: A Workshop on the Role of New England in Navigating the New Arctic (March 25 - 27, 2018 -- The University of New Hampshire) paired two of NSF\u27s 10 Big Ideas: Navigating the New Arctic and Growing Convergence Research at NSF. During this event, participants assessed economic, environmental, and social impacts of Arctic change on New England and established convergence research initiatives to prepare for, adapt to, and respond to these effects. Shipping routes through an ice-free Northwest Passage in combination with modifications to ocean circulation and regional climate patterns linked to Arctic ice melt will affect trade, fisheries, tourism, coastal ecology, air and water quality, animal migration, and demographics not only in the Arctic but also in lower latitude coastal regions such as New England. With profound changes on the horizon, this is a critical opportunity for New England to prepare for uncertain yet inevitable economic and environmental impacts of Arctic change

Ambient acoustic environments and cetacean signals: Baseline studies from humpback whale and gray whale breeding grounds

The past two centuries have seen an increased exploitation of marine habitats by humans, so a growing appreciation of the role ambient noise plays in cetacean studies has resulted. To achieve a broad acoustical view of understudied areas (namely Mexican waters), this dissertation tackles three overarching principles: (1) parameterizing current baseline ambient acoustic environments for subsequent comparisons, (2) determining whether the sounds that animals introduce into their environments can provide employable information for population estimation purposes, and (3) cataloguing and characterizing the sounds whales use to communicate so they can later be compared across time, geography, and ambient xxi noise levels. Only when we have a handle on the relative contributions of anthropogenic, physical / geological, and biological sounds in a whales habitat can we begin to understand how each source may elicit and / or change their calling behaviors. Chapter 2 uses an 8-year acoustic dataset from Laguna San Ignacio (LSI), M´exico, to investigate a complex acoustic environment, and to quantify the extent that human-generated noise contributes to this environment relative to natural sound sources. This lagoon has been deemed to be a critical habitat for breeding whales and calving mothers, so vessel traffic is minimized and regulated. I found that humans contribute some noise to the lagoon, but crepuscular snapping shrimp and dusk-centric croaker fish are more intense and pervasive. Therefore, my research validates current management policies for the lagoon and provides a baseline account of a stable acoustic environment that can be compared to future years, should tourist traffic increase. Chapter 3 develops a model to estimate humpback whale density using ambient noise arising from the songs of many individual animals. What initially began as an analytical model for wind-generated ambient noise, using a collection of randomly distributed sources near the surface, was adapted for randomly-distributed calling whales. The model was tested using data collected in the Los Cabos region of M´exico, which is a breeding ground and part of the migration route for the North Pacific substock. A Generalized Linear Model was used to link humpback-generated ambient noise intensity to concurrent visual surveys. I found that the analytical model provided good predictions of how the intensity of humpbackgenerated noise varies as a function of acoustic frequency, singer population size, and singer spatial density. In particular, the ambient noise model accurately predicted that singing humpback whales maintain the same separation distance from each other, regardless of singer population size. Chapter 4 assembles a catalogue of social calls used by humpback whales in the same Los Cabos region and compares them to known social calls from Alaska, Hawaii, xxii and Australia. By using acoustic tags to collect twenty-one samples from three different social group types over two years, I was able to determine the geographical uniqueness, call rate, repertoire diversity, and repertoire entropy of the whales in that breeding ground. I then determined the variability of these behaviors between differently composed social groups. This work provides a starting point for subsequent studies of social calling behavior of Mexican whales, such as temporal changes in social call repertoire, behavioral context of calls between different social groups, and geographical comparisons between the acoustic composition of other humpback whale habitats. By tackling all three of these acoustic principles, this dissertation aims to set the stage for understanding ambient noise as part of cetacean habitats by laying out how to measure it, how to use it to our advantage, and how to characterize and compare calls within it. With the new novel tools to quantify sound sources in ambient acoustic environments and to monitor population levels that this dissertation provides, my future research can delve into exploring any geographic and temporal commonalities and disparities

The ambient acoustic environment in Laguna San Ignacio, Baja California Sur, Mexico

Each winter gray whales (Eschrichtius robustus) breed and calve in Laguna San Ignacio, Mexico, where a robust, yet regulated, whale-watching industry exists. Baseline acoustic environments in LSI’s three zones were monitored between 2008 and 2013, in anticipation of a new road being paved that will potentially increase tourist activity to this relatively isolated location. These zones differ in levels of both gray whale usage and tourist activity. Ambient sound level distributions were computed in terms of percentiles of power spectral densities. While these distributions are consistent across years within each zone, inter-zone differences are substantial. The acoustic environment in the upper zone is dominated by snapping shrimp that display a crepuscular cycle. Snapping shrimp also affect the middle zone, but tourist boat transits contribute to noise distributions during daylight hours. The lower zone has three source contributors to its acoustic environment: snapping shrimp, boats, and croaker fish. As suggested from earlier studies, a 300 Hz noise minimum exists in both the middle and lower zones of the lagoon, but not in the upper zone