Passive acoustic monitoring reveals year-round marine mammal community composition off Tasiilaq, Southeast Greenland

Climate-driven changes are affecting sea ice conditions off Tasiilaq, Southeast Greenland, with implications for marine mammal distributions. Knowledge about marine mammal presence, biodiversity, and community composition is key to effective conservation and management but is lacking, especially during winter months. Seasonal patterns of acoustic marine mammal presence were investigated relative to sea ice concentration at two recording sites between 2014 and 2018, with one (65.6°N, 37.4°W) or three years (65.5°N, 38.0°W) of passive acoustic recordings. Seven marine mammal species were recorded. Bearded seals were acoustically dominant during winter and spring, whereas sperm, humpback, and fin whales dominated during the sea ice-free summer and autumn. Narwhals, bowhead, and killer whales were recorded only rarely. Song-fragments of humpback whales and acoustic presence of fin whales in winter suggest mating-associated behavior taking place in the area. Ambient noise levels in 1/3-octave level bands (20, 63, 125, 500, 1000, and 4000 Hz), ranged between 75.6 to 105 dB re 1 μPa. This study provides multi-year insights into the coastal marine mammal community composition off Southeast Greenland and suggests that the Tasiilaq area provides suitable habitat for various marine mammal species year-round

Preliminary evidence for signature vocalizations among free-ranging narwhals (Monodon monoceros)

Author Posting. © Acoustical Society of America, 2006. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 120 (2006): 1695-1705, doi:10.1121/1.2226586.Animal signature vocalizations that are distinctive at the individual or group level can facilitate recognition between conspecifics and re-establish contact with an animal that has become separated from its associates. In this study, the vocal behavior of two free-ranging adult male narwhals (Monodon monoceros) in Admiralty Inlet, Baffin Island was recorded using digital archival tags. These recording instruments were deployed when the animals were caught and held onshore to attach satellite tags, a protocol that separated them from their groups. The signature content of two vocal categories was considered: (1) combined tonal/pulsed signals, which contained synchronous pulsatile and tonal content; (2) whistles, or frequency modulated tonal signals with harmonic energy. Nonparametric comparisons of the temporal and spectral features of each vocal class revealed significant differences between the two individuals. A separate, cross-correlation measure conducted on the whistles that accounted for overall contour shape and absolute frequency content confirmed greater interindividual compared to intraindividual differences. These data are consistent with the hypothesis that narwhals produce signature vocalizations that may facilitate their reunion with group members once they become separated, but additional data are required to demonstrate this claim more rigorously.I thank the WHOI Academic Programs office, the National Science Foundation Research Fellowship, and the National Defense Science and Engineering Graduate Fellowship for financial support. This field operation was funded by the Greenland Institute of Natural Resources, the National Environmental Research Institute, Department of Fisheries and Oceans, Nunavut Wildlife Management Board and the Danish Cooperation for the Environment in the Arctic (DANCEA). Additional logistical support was provided by the Polar Continental Shelf Project

Which States Matter? An Application of an Intelligent Discretization Method to Solve a Continuous POMDP in Conservation Biology

When managing populations of threatened species, conservation managers seek to make the best conservation decisions to avoid extinction. Making the best decision is difficult because the true population size and the effects of management are uncertain. Managers must allocate limited resources between actively protecting the species and monitoring. Resources spent on monitoring reduce expenditure on management that could be used to directly improve species persistence. However monitoring may prevent sub-optimal management actions being taken as a result of observation error. Partially observable Markov decision processes (POMDPs) can optimize management for populations with partial detectability, but the solution methods can only be applied when there are few discrete states. We use the Continuous U-Tree (CU-Tree) algorithm to discretely represent a continuous state space by using only the states that are necessary to maintain an optimal management policy. We exploit the compact discretization created by CU-Tree to solve a POMDP on the original continuous state space. We apply our method to a population of sea otters and explore the trade-off between allocating resources to management and monitoring. We show that accurately discovering the population size is less important than management for the long term survival of our otter population

Projecting marine mammal distribution in a changing climate

Climate-related shifts in marine mammal range and distribution have been observed in some populations; however, the nature and magnitude of future responses are uncertain in novel environments projected under climate change. This poses a challenge for agencies charged with management and conservation of these species. Specialized diets, restricted ranges, or reliance on specific substrates or sites (e.g., for pupping) make many marine mammal populations particularly vulnerable to climate change. High-latitude, predominantly ice-obligate, species have experienced some of the largest changes in habitat and distribution and these are expected to continue. Efforts to predict and project marine mammal distributions to date have emphasized data-driven statistical habitat models. These have proven successful for short time-scale (e.g., seasonal) management activities, but confidence that such relationships will hold for multi-decade projections and novel environments is limited. Recent advances in mechanistic modeling of marine mammals (i.e., models that rely on robust physiological and ecological principles expected to hold under climate change) may address this limitation. The success of such approaches rests on continued advances in marine mammal ecology, behavior, and physiology together with improved regional climate projections. The broad scope of this challenge suggests initial priorities be placed on vulnerable species or populations (those already experiencing declines or projected to undergo ecological shifts resulting from climate changes that are consistent across climate projections) and species or populations for which ample data already exist (with the hope that these may inform climate change sensitivities in less well observed species or populations elsewhere). The sustained monitoring networks, novel observations, and modeling advances required to more confidently project marine mammal distributions in a changing climate will ultimately benefit management decisions across time-scales, further promoting the resilience of marine mammal populations

The relationship among oceanography, prey fields, and beaked whale foraging habitat in the Tongue of the Ocean

This article is distributed under the terms of the Creative Commons CC0 public domain dedication. The definitive version was published in PLoS One 6 (2011): e19269, doi:10.1371/journal.pone.0019269.Beaked whales, specifically Blainville's (Mesoplodon densirostris) and Cuvier's (Ziphius cavirostris), are known to feed in the Tongue of the Ocean, Bahamas. These whales can be reliably detected and often localized within the Atlantic Undersea Test and Evaluation Center (AUTEC) acoustic sensor system. The AUTEC range is a regularly spaced bottom mounted hydrophone array covering >350 nm2 providing a valuable network to record anthropogenic noise and marine mammal vocalizations. Assessments of the potential risks of noise exposure to beaked whales have historically occurred in the absence of information about the physical and biological environments in which these animals are distributed. In the fall of 2008, we used a downward looking 38 kHz SIMRAD EK60 echosounder to measure prey scattering layers concurrent with fine scale turbulence measurements from an autonomous turbulence profiler. Using an 8 km, 4-leaf clover sampling pattern, we completed a total of 7.5 repeat surveys with concurrently measured physical and biological oceanographic parameters, so as to examine the spatiotemporal scales and relationships among turbulence levels, biological scattering layers, and beaked whale foraging activity. We found a strong correlation among increased prey density and ocean vertical structure relative to increased click densities. Understanding the habitats of these whales and their utilization patterns will improve future models of beaked whale habitat as well as allowing more comprehensive assessments of exposure risk to anthropogenic sound.The data collection and analysis was funded by the Office of Naval Research as N00014-08-1-1162

Gestural communication of the gorilla (Gorilla gorilla): repertoire, intentionality and possible origins

Social groups of gorillas were observed in three captive facilities and one African field site. Cases of potential gesture use, totalling 9,540, were filtered by strict criteria for intentionality, giving a corpus of 5,250 instances of intentional gesture use. This indicated a repertoire of 102 gesture types. Most repertoire differences between individuals and sites were explicable as a consequence of environmental affordances and sampling effects: overall gesture frequency was a good predictor of universality of occurrence. Only one gesture was idiosyncratic to a single individual, and was given only to humans. Indications of cultural learning were few, though not absent. Six gestures appeared to be traditions within single social groups, but overall concordance in repertoires was almost as high between as within social groups. No support was found for the ontogenetic ritualization hypothesis as the chief means of acquisition of gestures. Many gestures whose form ruled out such an origin, i.e. gestures derived from species-typical displays, were used as intentionally and almost as flexibly as gestures whose form was consistent with learning by ritualization. When using both classes of gesture, gorillas paid specific attention to the attentional state of their audience. Thus, it would be unwarranted to divide ape gestural repertoires into ‘innate, species-typical, inflexible reactions’ and ‘individually learned, intentional, flexible communication’. We conclude that gorilla gestural communication is based on a species-typical repertoire, like those of most other mammalian species but very much larger. Gorilla gestures are not, however, inflexible signals but are employed for intentional communication to specific individuals