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Shane Gero

Individuals which live in complex social environments must not only deal with the challenges of the physical environment but must also solve problems related to their social interactions. Therefore, communication is vital to animal survival, yet the functions of most animal communication signals are still speculative; particularly for large whales in the ocean, where identifying the signaller and receiver or the behavioural context of the interaction is challenging. My current research will be the first synthesis between a long-term behavioural study of individual cetaceans and the comprehensive fine-scale data collection of acoustic accelerometer tags. This combined approach will entail the simultaneous placement of Dtags on several strategic members of well-known social units of sperm whales. The resulting mobile acoustic array would effectively record all codas produced by all unit members, as well as their individual orientations in the water column and positions with respect to one another. Combined with the background knowledge of the animals from the last 10 years of my research through The Dominica Sperm Whale Project, I will be able to identify the caller (e.g., Female #5560) for each call type (e.g. Type '5R') as well as their genetic (e.g. aunt) and social (e.g. babysitter) relationship to the respondent (e.g. calf #6068). This study would provide both the social and behavioural context in which vocal exchanges are made between individual whales and allow for the first time for functional interpretation of their vocal signals. In effect, this would be the first study to accurately answer the Who, What, Where, and When questions about vocal exchanges between sperm whales and thereby allowing us to begin to ask Why. A study of acoustic communication at this detailed a level has never been attempted in any species of marine mammal and would stand as a pivotal step forward in our understanding. Insights into the contextual use and syntax of social calls will uncover how large, free-ranging animals coordinate as a group, identify conspecifics, and transfer information. More broadly, this study contributes to our understanding of the coevolution of functionally diverse communication systems and complex societies.

The overarching objective of this research is to study how a marine apex predator coordinates group behaviour and transfers information through its complex communication system. In order to do so, the study will focus on 5 specific objectives: 1) to determine usage patterns of different call types across behavioural contexts (separations during deep foraging dives, reunions after dives, and socializing with unit members), such that I can investigate functional and contextual usage of particular calls; 2) to examine ordering and syntax of codas during conversational exchanges between individuals, in order to assess the communication capacity of this species’ system of vocal signals; 3) to test for vocal asymmetries based on initiation of vocal exchanges across repeated interactions with the same individuals, in order to ascertain the potential for group leadership; 4) to quantify echolocation rates of synchronously diving individuals, in order to assess group coordination and information sharing during foraging and the potential for cooperative feeding; and 5) this study will have the unique opportunity to test if social role, gregariousness, or social and genetic relationships affect any of the previous objectives’ analyses through the pre-existing social and genetic knowledge of the individuals under study.

Acoustic communication in common bottlenose dolphins (Tursiops truncatus) in an urbanized coastal environment

Ida Marie Kragh

Bottlenose dolphins develop individually distinctive signature whistles that they use to facilitate group cohesion and for individual recognition of familiar conspecifics. These animals often live in urbanized coastal environments where ambient noise from abundant watercraft traffic may have deleterious impacts on the acoustic behaviour of bottlenose dolphins, e.g. by preventing detection of whistles from conspecifics. In my master thesis, I will use data from acoustic and movement logging DTAGs deployed on common bottlenose dolphins (Tursiops truncatus) in 2014-2017 in Sarasota Bay (Florida, USA) to investigate how these animals modulate their acoustic output and thus communication range in the field. I will test three hypotheses: (1) Are signature whistles emitted at consistently higher output level compared to non-signature whistles? (2) Do allied males emit signature whistles at higher rates and output level compared to mother-calf pairs? (3) Do bottlenose dolphins modify the output level of signature and non-signature whistles to compensate for increasing ambient noise? Answers to these questions will help us understand the scope that animals have for adapting to increasing underwater noise.

Cognitive Modulation of the Diving Response in Harbor Seals

Jeppe Kaczmarek

There is evidence that harbour seals to some extent have the ability to modulate their heart rate cognitively. I wish to investigate this further by measuring heart rate on trained harbour seals during different settings on land. The experiments are conducted at the Fjord & Bælt center, where we can maintain somewhat constant settings and thereby work with the cognitive aspect of their heart rate.

Acoustic communication in southern right whales

Mia Lybkær Kronborg Nielsen

Southern right whales (Eubalaena australis) migrate from their feeding grounds in the Antarctic Ocean to lower latitude coastal waters to breed and nurse their calves. While at the nursing grounds the mother and calf pairs generally remain very close to the coast, presumably to avoid predation and attention from males. For the mothers there is a large energetic investment associated with reproduction and raising a calf. While she is at the breeding ground the mother does not feed, and she and her calf both live off of her energy stores. It is therefore extremely important that the mother and calf are able to keep contact in order to assure survival and a healthy development of the calf. But little is known of how the mother and calf communicate and how the suckling is mediated, as well as what might have a negative effect on this communication.

My master´s project will be focusing on the acoustic communication between mother and calf in relation to nursing behavior and suckling, and whether the communication related to suckling is vocal or tactile. This will be investigated from data collected with DTAGs that were deployed on southern right whale mothers at their nursing ground in Flinders Bay, Western Australia during July-August 2016. The tags provide acoustic information as well as information of the movements of the mother, which will enable me to investigate how the mother and calf communicate acoustically, as well as provide insight into suckling rates and whether acoustic or mechanical cues are used to mediate suckling, and finally, how nursing behavior could potentially be affected by an increase in human activities in the environment.

Acoustic behavior in a bat studied with a tag

Laura Stidsholt

Bats echolocate to navigate and to find, discriminate, pursue and catch a prey. In a few milliseconds, the bat has to extract the desired auditory information from the complex scene, and react with a new set of calls and motor responses. Research in the last 50 years has revealed how bats change their biosonar emissions when approaching a target. However, little is known about how bats perceptually organize the very complex barrage of echoes returning to its auditory system when echolocating for prey in the wild. This lack of ecological validity stems from methodological constraints on what can be measured from free flying bats in a complex environment over longer time periods. With this PhD project I will change that by using a newly developed acoustic tag - weighing 2.6 grams - which can be attached on the back of echolocating bats and record the emitted calls and the echoes returning from the environment, concomitant with the movements of the bat. This will allow me to tap into the sensory stream that guide changes on behaviour and vocal-motor patterns of free flying bats echolocating for prey under controlled laboratory settings and in the wild.

Gitte McDonald

Cetaceans are among the largest animals ever to evolve, and as apex predators in marine ecosystems, they have a significant top-down effect on prey targeted during long, deep breath-hold dives. It is therefore essential to understand the energetic requirements and oxygen management of cetaceans if we are to interpret and understand their role in the trophic energy cascades, their foraging ecology, limits of dive performance and ability to adapt to environmental change and disturbance. However, very little is known about the field physiology of cetaceans due their size and hostile habitats. At the Fjord and Bælt center a unique opportunity exists to measure metabolic rate, heart rate, and activity in captive porpoises that live in a large net pen experiencing similar conditions to wild porpoises. By having access to this one of a kind facility, we will be able to compare these data on captive porpoises to heart rate and activity data of wild porpoises in the same Danish waters. This provides a unique opportunity to examine the field energetics and diving physiology of a wild cetacean. The harbor porpoise is particularly interesting because it is the world’s smallest cetacean that lives in cold water at high latitudes. It is therefore hypothesized that is has very high heat loss and hence a very high metabolic rate that leads to very short dive times in the wild.

With this project we propose to study the energetic requirements and oxygen management strategy during diving in the harbor porpoise. The four main objectives are: 1) Determine the field metabolic rate of harbor porpoises using a combination of field and laboratory studies. 2) Measure heart rate in freely diving harbor porpoises, which will for the first time document the level of bradycardia in a naturally diving cetacean. 3) Determine muscle workload/activity during dives. The relationship between heart rate and activity will be used to assess the potential level of muscle perfusion during dives with different activity levels. And 4) develop a self-contained biologger to measure blood flow and heart rate that can be used to measure cardiac output in freely diving marine mammals.

Acoustic and nursing behavior in humpback whale calves

Simone Videsen

The humpback whale, Megaptera novaeangliae, has a cosmopolitan distribution and migrates seasonally from higher latitudes to their wintering grounds in lower latitudes. They fast during these migrations and while on their wintering grounds. These grounds serve as both breeding and calving areas for the humpback whales. The gestation is presumed to last 11-12 months and the calves are weaned, when they are approximately 6 months old. In this study we are focusing on the population migrating along the western coast of Australia.

The acoustic behavior of singing male humpback whales in mating aggregations has been intensely studied for many years, but it is increasingly clear that humpback whales also use vocalizations for a range of other functions. Recent studies have focused on how both females and males use social sounds e.g. percussive sounds and vocalizations as a means of communication. They are presumed to communicate both during migration and while on their wintering grounds; perhaps including that of contact calls between mother and calf. It is well known how toothed whales use social sounds as a means of communication, recognition and locating conspecifics, however, our knowledge on how baleen whales use these sounds and in what context is still lacking. Further more it is questionable, whether humpback whales would have specific calls functioning as individual recognition as other well-studied toothed whales have e.g. pulsed calls in killer whales and signature whistles in dolphins. Humpback whales tend to form small unstable groups and the group compositions are greatly influenced by their mating behavior on the wintering grounds. Mother-calf pairs can either form their own groups or one or multiple male escorts can accompany them. Humpback whale calves have been reported to vocalize on their wintering grounds, but these vocalizations may come at the cost of increased predation risk from killer whales. It may therefore be hypothesized that humpback whale calves only use low-level vocalizations in very specific contexts to reduce this risk.

In my master’s project I will test that hypothesis, by deploying Dtags on humpback whale calves on their breeding grounds in Exmouth Gulf, WA, to investigate their nursing behavior and the vocalizations associated with these nursing events. Furthermore, how these behaviors are potentially affected by the presence of male escorts.

Diving response of the Harbour porpoise

Siri Elmegaard

All tetrapods share an immediate response to apnoea and submergence in water to conserve blood oxygen for the brain and heart. This response is know as the dive reflex, which is constituted by bradycardia and peripheral vasoconstriction. Marine mammals spend substantial parts of their lives submerged, and thus benefit from modulating this dive reflex to manage oxygen levels optimally according to e.g. the length and activity level of their dives.

In my masters project I investigate the ability of Harbour Porpoises (Phocoena phocoena) to cognitively modulate their dive response to differential dive demands, i.e. obtain an optimal heart rate according to the length of the dive. Since it is a fine line between conserving oxygen longest possible and risking hypoxic harmful conditions in sensitive tissues, an extreme bradycardia would lengthen the time limit of a dive, yet be redundant and even overly risky for a short dive. To measure these heart rate dynamics, and reveal implications of cognitive control, trained harbour porpoises in Kerteminde Fjord & Bælt Center are tagged with electrode-equipped Dtags measuring heart rate during different accustomed dive types.

Acoustic communication in porpoises

Pernille Meyer Sørensen

Calls of porpoises classified as communication ...

'Head mounted fast recording tri-axial accelerometers to measure behavior of large terrestrial herbivores, in this case the red deer Cervus elaphus

Mette Vesterhaab

Measuring continuous animal behavior on free ranging individuals can cause an amount of difficulties. The most commonly known method is to visually observe the animals, however not all animals are easy to follow and the observer may cause the animal to behave differently. Using fast recording tri-axial accelerometers to measure the orientation and the specific acceleration will give a high resolution account of what that tag has experienced. The attachment area on the animal will therefor have a big impact on what the accelerometer will 'see'.

So far there has been some work done on measuring behavior with accelerometers on large terestrial herbivores. However, most if not all of these studies have been dual-axis activity sensors attached to a collar. Collars can slide and give secondhand accelerations from the collar and not actually measuring the movements of the animal.Here we attach the accelerometer directly to the forehead of the animal, getting primary accelerations and maybe better, more accurate data will emerge which can unravel discrete acceleration signals such as chewing and swallowing. .

Echolocation in sperm whales

Pernille Tønnesen

Sperm whales (Physeter macrocephalus) use echolocation in order to find food, primarily squids, in the darkness at 500 to 1000 meters depth. The sperm whale is a cosmopolitan species, and therefore encounters a wide range of habitats and different prey types. Hence, groups of sperm whales in different geographical regions might use different foraging strategies in order to adapt to their specific habitat.

The aim of my Master’s thesis is to study whether female sperm whales from the Eastern Caribbean show similar foraging behavior as female sperm whales studied in other areas, i.e. the Gulf of Mexico, the Sargasso Sea, the Mediterranean Sea and the Azores. Using DTAG data from The Dominican Sperm Whale Project season 2014, 2015 and 2016 I am able to study the dive behavior and acoustic activity of sperm whales during foraging. This allows me to determine detailed aspects of the foraging behavior such as the amount of time spend searching for food, the number of prey catch attempts during a dive and the foraging efficiency. It is my hope that this study will aid determining whether foraging strategy of sperm whales is driven by habitat specialization or other factors such as physical limitation and optimizing of the long-range echolocation.

Echolocation in sperm whales

Anne Bøttcher

Sperm whales (Physeter macrocephalus) live in a multileveled society where individuals are a part of a stable long-term structure called a ‘social unit’. Members of units travel together for life over large distances. Two or more units sometimes socialize for short periods in groups and, at the highest level, dozens of units are members of the same vocal clan. In a vocal clan, all units by definition share a common vocal repertoire of codas that are the primary communication call between sperm whales. Codas are Morse code like stereotyped patterns of clicks. However, it is not understood how individuals use codas to maintain contact and exchange information. Some codas appear to be used in social recognition of individuals, units or clans. Therefore, it is expected that some calls are exchanged over short distances and others over long. The range over which a signal can be detected is called the active space and depends on different parameters, including the source level of the emitted sound, the transmission loss between the signaler and receiver, as well as the detection threshold of the receiver.

During my master’s thesis, I intend to define the acoustic active space over which sperm whales communicate. I will use data from synchronous Dtag deployments on the sperm whales around Dominica in 2014-2016 which grant me with both the source and received levels of codas as they are produced and heard at sea. This will help us to understand how communication mediates group living in the wild as well as expanding our knowledge about sperm whales and hence how to act in their habitat.

Michael Ladegaard

Most toothed whales rely heavily upon echolocation in their search for prey items. The majority of the toothed whales are marine species, but a handful of species have adapted to a life in freshwater river systems. Most models for echolocation in water assume free field conditions in open water with few reflections. River dolphins are examples of species living in habitats where these assumptions are far from being met. Nonetheless do river dolphins, that are often found in murky waters, likely rely more on echolocation than most marine toothed whales where vision is also used for hunting. It therefore seems ironic that toothed whales species for which echolocation is most needed also seem to face the biggest challenges in terms of operating their sonars. Shallow waters present a habitat different from perfect acoustic free field conditions, because reflections from the surface, bottom and vegetation will generate echoes (so-called clutter) that interfere with the weak echoes from prey items.

This poses a problem to a biosonar system that is not easily overcome according to the way we currently understand echolocation in toothed whales. The delay between the outgoing click and returning echo provides the echolocating animal with range information, and the level and spectral composition of the returning echo yields information about the size and the properties of the ensonified target. All of these information carrying aspects of toothed whale sonar require that the returning echo can unambiguously be attributed to an emitted click and that the echo is not overlapping in time with echoes from other echoic objects. Marine toothed whales normally operate their sonars at high source levels and low click rates to acoustically probe many tens of meters ahead of them, but the shallow waters of river dolphins would render such a strategy futile. I therefore hypothesize that river dolphins click at lower source levels and at higher clicks rates to provide a short range sonar system with high update rates. If that is true, it also means that the sensory volume or the acoustic field or view is much reduced compared to marine toothed whales. This may in part be compensated for by an extremely flexible neck that will allow the river dolphins to sweep its sound beam and hence increase sampled volumes of water.

In this study I propose to address these questions by investigating the echolocation behaviour and sonar performance of wild river dolphins (Inia geoffrensis) in the Amazon, trained porpoises and a river dolphin in captivity. This combination will generate a synergistic effect between controlled lab conditions where specific mechanisms can be explored experimentally and measurements in the wild under circumstances for which these biosonars evolved.

Line Hermannsen

Noise has recently been acknowledged as an important source of pollution in EU’s Marine Strategy Directive. Danish waters are heavily ship-trafficked, and shipping noise may affect marine mammals negatively by impeding their use of sounds for echolocation and communication. The scale of impact of anthropogenic ocean noise is difficult to quantify and still largely unknown.

In my biological project I recorded broad-band noise (25Hz-160kHz) in Aarhus Bay to investigate the effect of shipping noise on ambient noise levels. Recordings were correlated with an audiogram for harbor porpoises (phocoena phocoena) to assess the potential impact on the high-frequency species, which have their most sensitive hearing range at 100-140kHz, and produce echolocation clicks at 120-150kHz.

I found that shipping noise significantly increased oceanic noise levels across all frequencies, reaching noise levels up to 180dB re μPa (at 1kHz), and that both conventional and fast-ferries emit significant levels of high-frequency noise in the range of harbor porpoise hearing and echolocation (100-150kHz). Contrary to common beliefs the slower conventional ferry emitted the highest levels of high-frequency noise, potentially causing acoustic masking for porpoises more than 1000m away, compared to a masking zone of 500m for the fast-ferry.

In my master thesis I am recording ship noise levels more thoroughly by recording different types of vessels such as ferries, cargo ships and motorboats. I will record the vessels at varying distances to be able to approximate the attenuation of noise, and with longer timeframes to better assess the impacts of shipping noise on harbor porpoises. Approaching the scale of impact of anthropogenic noise is necessary to optimize the demands EU is sets for vessels in the Marine Strategy Directive, and highly relevant for the ongoing planning of an improved future for the Baltic Sea.

Danuta Maria Wisniewska

Up until recently most underwater biosonar research has focused on how a stationed dolphin can detect stationary objects. These experiments have shown that toothed whales can detect objects at long ranges and discriminate between targets differing not only in shape and size, but also their internal structure and composition. These studies however provide little information on the performance of biosonar systems of animals operating in their natural environments, under different noise and clutter conditions. Furthermore, as shown, inter alia, for humans and bats, auditory perception goes beyond the detection, discrimination and localization of sound stimuli. It requires organization of the extracted acoustic information to allow the listener to identify and track sound sources in the environment, through processes of both auditory scene analysis and auditory selective attention. Finally, biosonar is an active system, where the animal analyses an actively generated auditory scene using echoes of its own signals and has therefore the capability to react to the received information by adjusting both its locomotive and acoustic behaviour.

Recently a non-invasive, acoustic archival tag, the Dtag, has been developed to record the 3D movements of free ranging animals along with sounds emitted and received during echolocation, including, for the first time, echoes from prey. That has allowed researchers to tap directly into the streaming of information back to the auditory system of the tagged whale, and monitor in high resolution how the locomotor and acoustic behavior of the animal adapt to that information flow. Recent size reductions applied to the original Dtag have widened the applications of the device to smaller toothed whale species, making them available in research conducted on captive animals.

In my project, I plan to use such archival tags on captive, trained animals under controlled conditions as well as free-ranging toothed whales in a synergistic approach to address the governing principles of biosonar-based navigation, auditory scene analysis, prey detection and discrimination.

Neural and Muscle function in diabetic rodents

Jeppe Seamus Bayley

A study on diabetically induced neuropathy and myopathy in rodents. The study investigates a number of aspects of neuromuscular function in the diabetic animal including excitability of the muscle and motor neuron, force production, force-frequency relation, speed of contraction/relaxation and more.

Andrea Fais

The sperm whale (Physeter macrocephalus) hypertrophied nasal sound production apparatus can generate source levels in excess of 230 dB re 1μPa (pp). This makes their echolocation clicks suitable for long-range echolocation. Sperm whale echolocation has been studied for some time, however there is still much to learn about how the whales adapt the way they use their biosonar to exploit different habitats and prey types.

In my project, I am using onboard multisensor digital tags (Dtags) on free-ranging sperm whales to address the question how the whales use their long-range sonar capabilities to resolve complex auditory scenes in the wild and catch small and apparently agile prey items.