Eric Delory

Instrument interface standards for interoperable ocean sensor networks

The utility and cost-effectiveness of instrument networks are enhanced by instrument interoperability. Todays oceanographic instruments are characterized by very diverse non-standard software protocols and data formats. This diversity of protocols poses serious challenges to integration of large-scale sensor networks. Standard instrument protocols are now being developed to address these challenges. Some of these standards apply at the IP-network level and enable integration of existing “lower level” proprietary instrument protocols and software components. Other approaches are intended to be implemented by the instrument device itself. These native instrument protocol standards offer the possibility of more uniform and simpler system architectures. We compare these various approaches, describe how they can be combined with one another, and describe some prototypes that implement them.

A comparison of model and non-model based time-frequency transforms for sperm whale click classification

We tried to find discriminating features for sperm whale clicks in order to distinguish between clicks from different whales, or to enable unique identification. We examined two different methods to obtain suitable characteristics. First, a model based on the Gabor function was used to describe the dominant frequencies in a click, and then the model parameters were used as classification features. The Gabor function model was selected because it has been used to model dolphin sonar pulses with great precision. Additionally, it has the interesting property that it has an optimal time-frequency resolution. As such, it can indicate optimal usage of the sonar by sperm whales. Second, the clicks were expressed in a wavelet packet table, from which subsequently a local discriminant basis was created. A wavelet packet basis has the advantage that it offers a highly redundant number of coefficients, which allow signals to be represented in many different ways. From the redundant signal description a representation can be selected that emphasizes the differences between classes. This local discriminant basis is more flexible than the Gabor function, which can make it more suitable for classification, but it is also more complex. Class vectors were created with both models and classification was based on the distance of a click to these vectors. We show that the Gabor function could not model the sperm whale clicks very well, due to the variability of the changing click characteristics. Best performance was reached when three subsequent clicks were averaged to smoothen the variability. Around 70% of the clicks classified correctly in both the training and validation sets. The wavelet packet table adapted better to the changing characteristics, and gave better classification. Here, also using a 3-click moving average, around 95% of the training sets classified correctly and 78% of the validation sets. These numbers lowered by only a few per cent when single clicks, instead of a moving average, were classified. This indicates that, while the features may show too much variability to enable unique identification of individual whales on a click by click basis, the wavelet approach may be capable of distinguishing between a small group of whales.

Requirements and approaches for a more cost-efficient assessment of ocean waters and ecosystems, and fisheries management

Development of a new generation of multifunctional sensor systems is underway to address ocean monitoring challenges. These range from more precise monitoring of the marine environment to an improved management of fisheries and, among other things, address improved life cycle cost-efficiency. These advances will be achieved through innovations such as multiplatform integration, greater reliability through better antifouling management and greater sensor and data interoperability. Requirements for the sensors have been refined through surveys and discussions with science and industry users. This paper will describe these developments in the NeXOS project.

Identifying Cetacean Hearing Impairment at Stranding Sites

While noise is now considered a marine hazard that can directly affect cetaceans and induce a stranding, no clinical approach has yet introduced the detection of a possible hearing loss at a stranding site as a necessary practice. This can be explained by the lack of time when facing vital decisions for the animal’s welfare as well as the unavailability of reliable, lightweight, autonomous, and portable audiometry equipment. Herein, we correlate measured electrophysiological evidence of a permanent threshold shift (PTS) in a rehabilitated striped dolphin (Stenella coeruleoalba) that prevented its release, with the postmortem analysis of an abnormal dilatation of the central nervous system ventricles that prevented the correct acoustic reception of the animal. We further propose to follow a five-minute auditory evoked potential (AEP) standard protocol of hearing measurements in-air on cetaceans at a stranding site that includes the stimulation of auditory brainstem responses (ABRs) with a single 4-μs broadband (> 150 kHz) pulse at three decreasing levels (129, 117, and 105 dBpp re 1 μPa at 15 cm), which covers most of the cetaceans’ known maximum acoustic sensitivity and allows the immediate sensing of an individual’s hearing capability before any final clinical decision is taken.

Cetacean biosonar and noise pollution

Noise pollution in the marine environment is an emerging but serious concern. Its implications are less well understood than other global threats and largely undetectable to everyone but the specialist. In addition, the assessment of the acoustic impact of artificial sounds in the sea is not a trivial task, certainly because there is a lack of information on how the marine organisms process and analyze sounds and how relevant these sounds are for the balance and development of the populations. Further, this possible acoustic impact not only concerns the hearing systems but may also affect other sensory or systemic levels and result equally lethal for the animal concerned. If we add that the negative consequences of a short or long term exposure to artificial sounds may not be immediately observed one can understood how challenging it is to obtain objective data allowing an efficient control of the introduction of anthropogenic sound in the sea. To answer some of these questions, the choice to investigate cetaceans and their adaptation to an aquatic environment is not fortuitous. Cetaceans, because of their optimum use of sound as an ad-hoc source of energy and their almost exclusive dependence on acoustic information, represent not only the best bio-indicator of the effects of noise pollution in the marine environment, but also a source of data to improve and develop human underwater acoustic technology. Here, we present how the characteristics and performance of the sperm whale mid-range biosonar can be used to develop a mitigation solution based on passive acoustics and ambient noise imaging to prevent negative interactions with human activities by monitoring cetacean movements in areas of interest.

From ESONET multidisciplinary scientific community to EMSO novel European research infrastructure for ocean observation

Environmental and climate changes are crucial challenges for sustainable living because of their significant impact on the Earth system and the important consequences for natural resources. Oceans have a primary role in these changes as they regulate heat flux, greenhouse gases and climate whilst harboring many different life forms and resources. Understanding processes in the marine environment is of paramount importance for any prediction of short-, intermediate- and long-term global change.

Environmental aspects of designing multi-purpose offshore platforms in the scope of the FP7 TROPOS Project

The objective of the FP7 funded TROPOS project is to design a modular multi-use platform for use in deep waters, with a focus on the Mediterranean, tropical and sub-tropical regions. In this paper, the related environmental aspects are considered, where both legal and technical issues are addressed. The multiple purpose platforms can enlarge the benefit from different functions, and reduce the environmental impacts through synergies among single impact as well. This proposed study demonstrates the impact assessment through multiple, integrated technologies.

Objectives of the NeXOS project in developing next generation ocean sensor systems for a more cost-efficient assessment of ocean waters and ecosystems, and fisheries management

The NeXOS project aims to develop new multifunctional sensor systems supporting a number of scientific, technical and societal objectives, ranging from more precise monitoring and modelling of the marine environment to an improved management of fisheries. Several sensors will be developed, based on optical and passive acoustics technologies, addressing key environmental descriptors identified by the European Marine Strategy Framework Directive (MSFD) for Good Environmental Status (GES). Two of the new sensors will also contribute to the European Union Common Fisheries Policy (CFP), with a focus on variables of interest to an Ecosystem Approach to Fisheries (EAF). An objective is the improved cost-efficiency, from procurement to operations, via the implementation of several innovations, such as multiplatform integration, greater reliability through better antifouling management, greater sensor and data interoperability and the creation of market opportunities for European enterprises. Requirements will be further analysed for each new sensor system during the first phase of the project. Those will then be translated into engineering specifications, leading to the development phase. Sensors will then be tested, calibrated, integrated on several platform types, scientifically validated and demonstrated in the field. Translation to production and broad adoption are facilitated by participating industry. Overall, the paper presents an overview of the project objectives and plans for the next four years.

A compact real-time acoustic bandwidth compression system for real-time monitoring of ultrasound

Many animals and systems radiate ultrasound that contains valuable information, from bats to high-voltage power lines. We set out to develop a real-time bandwidth compressor that can convey the prominent features of ultrasound in the human hearing band of 50 Hz to 16 kHz that requires no assumption of where in the ultrasonic frequency band of interest or when in the time domain the information is encoded. A primary application is in dolphin communication, which is believed to be both sophisticated and ultrasonic. Real-time studies of their acoustic communication patterns together with their behavior with the added capability to be able to react and respond in a timely manner to interact with them could rapidly generate important findings, greatly improving the efficiency of dolphin-human interactions. This is not possible without a real-time interface between ultrasound and human hearing. As is well known, there is no pictorial representation that readily conveys the richness of a sound. We are therefore driven to find an efficient acoustic interface, translating ultrasound into audible sounds. This is easy to do in post-processing (simply play back at reduced speed), but continuous streaming real-time processing presents a challenge. The total information-carrying capacity of a signal can be represented by the time-bandwidth product. If the time is constrained to be the same and the bandwidth must be reduced, some information must be discarded. Choosing how and where to do this is the key to a successful algorithm. In this paper we present an algorithm that compresses ultrasound signals into the audio band of human hearing while maintaining the overall signatures and structures of the signal, regardless of the signal type. This algorithm can be demonstrated to be optimal under the applied constraints. This is followed by the design of a prototype system that provides realtime bandwidth compression and a preliminary test result of the system capability. The algorithm has a time-domain implementation that makes it possible to downshift signals sampled at up to 1 MSa/s to audio range using a DSP. The system is autonomous and compact so that it can be carried by operators, including divers, allowing them to swim among dolphins while listening to their communications. The system is demonstrated using high frequency acoustic signals from a bottlenose dolphin

Classification of Sperm Whale Clicks (Physeter Macrocephalus) with Gaussian- Kernel-Based Networks

Abstract: With the aim of classifying sperm whales, this report compares two methods thatcan use Gaussian functions, a radial basis function network, and support vector machineswhich were trained with two different approaches known as C -SVM and ” -SVM. The meth-ods were tested on data recordings from seven different male sperm whales, six containingsingle click trains and the seventh containing a complete dive. Both types of classifiers coulddistinguish between the clicks of the seven different whales, but the SVM seemed to havebetter generalisation towards unknown data, at the cost of needing more information andslower performance.Keywords: classification; sperm whale; radial basis function; support vector machine1. IntroductionSperm whales (Physeter macrocephalus) , when living in a social community, often forage in smallgroups. During their feeding dive, which may be to depths up to 2 kilometres [1], they start producingsonar signals fairly soon after the start of a dive and generally continue until the ascent back to thesurface. Usually one click per second is produced on average, but at times this frequency is increased(presumably when they have found prey) and up to fifty signals per second may be produced [2]. This