Soundscape Ecology of Hawaiian Spinner Dolphin Resting Bays

Sound is a key sensory modality for Hawaiian spinner dolphins. Like many other marine animals, these dolphins rely on sound and their acoustic environment for many aspects of their daily lives, making it is essential to understand soundscape in areas that are critical to their survival. Hawaiian spinner dolphins rest during the day in shallow coastal areas and forage offshore at night. In my dissertation I focus on the soundscape of the bays where Hawaiian spinner dolphins rest taking a soundscape ecology approach. I primarily relied on passive acoustic monitoring using four DSG-Ocean acoustic loggers in four Hawaiian spinner dolphin resting bays on the Kona Coast of Hawai‛i Island. 30-second recordings were made every four minutes in each of the bays for 20 to 27 months between January 8, 2011 and March 30, 2013. I also utilized concomitant vessel-based visual surveys in the four bays to provide context for these recordings. In my first chapter I used the contributions of the dolphins to the soundscape to monitor presence in the bays and found the degree of presence varied greatly from less than 40% to nearly 90% of days monitored with dolphins present. Having established these bays as important to the animals, in my second chapter I explored the many components of their resting bay soundscape and evaluated the influence of natural and human events on the soundscape. I characterized the overall soundscape in each of the four bays, used the tsunami event of March 2011 to approximate a natural soundscape and identified all loud daytime outliers. Overall, sound levels were consistently louder at night and quieter during the daytime due to the sounds from snapping shrimp. In fact, peak Hawaiian spinner dolphin resting time co-occurs with the quietest part of the day. However, I also found that humans drastically alter this daytime soundscape with sound from offshore aquaculture, vessel sound and military mid-frequency active sonar. During one recorded mid-frequency active sonar event in August 2011, sound pressure levels in the 3.15 kHz 1/3rd-octave band were as high as 45.8 dB above median ambient noise levels. Human activity both inside (vessels) and outside (sonar and aquaculture) the bays significantly altered the resting bay soundscape. Inside the bays there are high levels of human activity including vessel-based tourism directly targeting the dolphins. The interactions between humans and dolphins in their resting bays are of concern; therefore, my third chapter aimed to assess the acoustic response of the dolphins to human activity. Using days where acoustic recordings overlapped with visual surveys I found the greatest response in a bay with dolphin-centric activities, not in the bay with the most vessel activity, indicating that it is not the magnitude that elicits a response but the focus of the activity. In my fourth chapter I summarize the key results from my first three chapters to illustrate the power of multiple site design to prioritize action to protect Hawaiian spinner dolphins in their resting bays, a chapter I hope will be useful for managers should they take further action to protect the dolphins.

Passive Acoustics: A Multifaceted Tool for Marine Mammal Conservation

Marine mammals exploit the efficiency of sound propagation in the marine environment for essential activities like communication and navigation. For this reason, passive acoustics has particularly high potential for marine mammal studies, especially those aimed at population management and conservation. Despite the rapid realization of this potential through a growing number of studies, much crucial information remains unknown or poorly understood. This research attempts to address two key knowledge gaps, using the well-studied bottlenose dolphin (Tursiops truncatus) as a model species, and underwater acoustic recordings collected on four fixed autonomous sensors deployed at multiple locations in Sarasota Bay, Florida, between September 2012 and August 2013. Underwater noise can hinder dolphin communication. The ability of these animals to overcome this obstacle was examined using recorded noise and dolphin whistles. I found that bottlenose dolphins are able to compensate for increased noise in their environment using a wide range of strategies employed in a singular fashion or in various combinations, depending on the frequency content of the noise, noise source, and time of day. These strategies include modifying whistle frequency characteristics, increasing whistle duration, and increasing whistle redundancy. Recordings were also used to evaluate the performance of six recently developed passive acoustic abundance estimation methods, by comparing their results to the true abundance of animals, obtained via a census conducted within the same area and time period. The methods employed were broadly divided into two categories – those involving direct counts of animals, and those involving counts of cues (signature whistles). The animal-based methods were traditional capture-recapture, spatially explicit capture-recapture (SECR), and an approach that blends the “snapshot” method and mark-recapture distance sampling, referred to here as (SMRDS). The cue-based methods were conventional distance sampling (CDS), an acoustic modeling approach involving the use of the passive sonar equation, and SECR. In the latter approach, detection probability was modelled as a function of sound transmission loss, rather than the Euclidean distance typically used. Of these methods, while SMRDS produced the most accurate estimate, SECR demonstrated the greatest potential for broad applicability to other species and locations, with minimal to no auxiliary data, such as distance from sound source to detector(s), which is often difficult to obtain. This was especially true when this method was compared to traditional capture-recapture results, which greatly underestimated abundance, despite attempts to account for major unmodelled heterogeneity. Furthermore, the incorporation of non-Euclidean distance significantly improved model accuracy. The acoustic modelling approach performed similarly to CDS, but both methods also strongly underestimated abundance. In particular, CDS proved to be inefficient. This approach requires at least 3 sensors for localization at a single point. It was also difficult to obtain accurate distances, and the sample size was greatly reduced by the failure to detect some whistles on all three recorders. As a result, this approach is not recommended for marine mammal abundance estimation when few recorders are available, or in high sound attenuation environments with relatively low sample sizes. It is hoped that these results lead to more informed management decisions, and therefore, more effective species conservation.

Analyse des variables statiques et dynamiques associées à la prédiction de la récidive sexuelle chez trois catégories d'agresseurs sexuels

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

(Table 1) Radiocarbon ages of core AB01/94 obtained in the Tromper Wiek, western Baltic Sea

In the Tromper Wiek northeast of Rügen, acoustical investigations using Air Gun, Boomer, Chirp Sonar and Sediment-Echosounder were carried out. Together with sediment core information, it allowed the identification of five seismostratigraphic units (E1 to E5). Conventional and AMS-14C-datings supported their chronostratigraphical classification. The uppermost till (E1) was incised by late glacial channels filled with glaciolacustrine sediments (E2) of the early Baltic Ice Lake stages. These were regionally overlain with a sharp unconformity by a thick (locally >20 m) sedimentary complex (E3) of acoustically laminated silts of freshwater origin. This lower part of the E3-complex (E3a) is overlain by fluvial to coastal silty fine sands (E3b) deeper towards the Arkona Basin. Fine plant debris in the uppermost part of sub-unit E3a yielded ages of 10,100 and 10,500 14C-years B.P., representing the final phase of the Baltic Ice Lake. The fine sands of sub-unit E3b were deposited after the final drainage of the Baltic Ice Lake. In the shallower central part of the bay, the silts of sub-unit E3a were covered by a younger unit (E4) of fine sand with plant debris. A sedge peat occurring at the basis of unit E4 yielded an age of 9,590 14C-years B.P. The fine sands overlying the unit E3 in the central part of Tromper Wiek were deposited in the Ancylus Lake. Their position at about 20 m below present sea level (b.s.l.) reflects the maximum highstand in this area. The character and distribution of the Early Holocene deposits at greater depth suggest a lake water level at about 30 m b.s.l. after this highstand. Below 25 m b.s.l. muddy Littorina Sea sediments are observed. The thickness of these muds and sandy muds increases gradually towards the Arkona Basin. Locally, they are found in a channel-like structure immediately north of Jasmund.

Monthly air temperatures, snow density and snow and ice thickness at Malcolm Ramsay Lake, North America

In northern regions where observational data is sparse, lake ice models are ideal tools as they can provide valuable information on ice cover regimes. The Canadian Lake Ice Model was used to simulate ice cover for a lake near Churchill, Manitoba, Canada throughout the 2008/2009 and 2009/2010 ice covered seasons. To validate and improve the model results, in situ measurements of the ice cover through both seasons were obtained using an upward-looking sonar device Shallow Water Ice Profiler (SWIP) installed on the bottom of the lake. The SWIP identified the ice-on/off dates as well as collected ice thickness measurements. In addition, a digital camera was installed on shore to capture images of the ice cover through the seasons and field measurements were obtained of snow depth on the ice, and both the thickness of snow ice (if present) and total ice cover. Altering the amounts of snow cover on the ice surface to represent potential snow redistribution affected simulated freeze-up dates by a maximum of 22 days and break-up dates by a maximum of 12 days, highlighting the importance of accurately representing the snowpack for lake ice modelling. The late season ice thickness tended to be under estimated by the simulations with break-up occurring too early, however, the evolution of the ice cover was simulated to fall between the range of the full snow and no snow scenario, with the thickness being dependant on the amount of snow cover on the ice surface.

Late-Holocene Mass Movements in High Arctic East Lake, Melville Island (Western Canadian Arctic Archipelago)

East Lake, located at Cape Bounty (Melville Island, Canadian High Arctic), was mapped using a high-resolution swath bathymetric sonar and a 12 kHz sub-bottom profiler, allowing for the first time the imaging of widespread occurrence of mass movement deposits (MMDs) in a Canadian High Arctic Lake. Mass movements occurred mostly on steep slopes located away from deltaic sedimentation. The marine to lacustrine transition in the sediment favours the generation of mass movements where the underlying massive mud appears to act as a gliding surface for the overlying varved deposits. Based on acoustic stratigraphy, we have identified at least two distinct events that triggered failures in the lake during the last 2000 years. The synchronicity of multiple failures and their widespread distribution suggest a seismic origin that could be related to the nearby Gustaf-Lougheed Arch seismic zone. Further sedimentological investigations on the MMDs are however required to confirm their age and origin.

Representation of odometry errors on occupancy grids

SOUZA, Anderson A. S. ; SANTANA, André M. ; BRITTO, Ricardo S. ; GONÇALVES, Luiz Marcos G. ; MEDEIROS, Adelardo A. D. Representation of Odometry Errors on Occupancy Grids. In: INTERNATIONAL CONFERENCE ON INFORMATICS IN CONTROL, AUTOMATION AND ROBOTICS, 5., 2008, Funchal, Portugal. Proceedings... Funchal, Portugal: ICINCO, 2008.

Algorítmo de mapeamento usando modelagem probabilística

SOUZA, Anderson A.S. ; MEDEIROS, Adelardo A. D. ; GONÇALVES, Luiz Marcos G. . Algorítmo de mapeamento usando modelagem probabilística. In: SIMPOSIO BRASILEIRO DE AUTOMAÇÃO INTELIGENTE, 2007, Natal. Anais... Natal, 2007.

Caracterização geológica e geofísica da área do porto da Figueira da Foz

No âmbito de um projeto realizado para a Administração Portuária do Porto da Figueira da Foz, foram recolhidos dados geofísicos no offshore da costa da Figueira da Foz, utilizando um sistema combinado de sonar de varrimento lateral e de sísmica de alta resolução com o objetivo de compreender a distribuição de sedimentos ao longo do fundo marinho e assim entender melhor a sua origem. Os dados de varrimento lateral foram processados, analisados e representados em mosaicos recorrendo ao software integrado TRINTON Prespective. Foram colhidas 10 amostras de sedimentos de fundo que foram analisadas do ponto de vista granulométrico e que foram usadas para a calibração dos mosaicos do sonar de varrimento lateral de modo a produzir um mapa semi-quantitativo de classificação dos sedimentos de fundo. Os dados de reflexão sísmica foram processados e analisados através dos softwares SPW e RadExPro. Os mapas de sonar de varrimento lateral produzidos (mosaicos) mostram uma relação entre o tamanho de grão e composição dos depósitos de plataforma interna e os processos geológicos que ocorrem na zona costeira adjacente. Também se verifica uma relação entre a orientação da costa e a sua consequente exposição às ondas incidentes, e como isso afeta e altera a distribuição do tamanho grão. Neste contexto, a interpretação combinada dos mosaicos do sonar de varrimento lateral com os dados de granulometria e a batimetria dos sedimentos permitiram uma cartografia interpretativa detalhada da morfologia do mar, uma melhor compreensão do controlo da linha costeira na propagação das ondas e correntes e, por conseguinte, na transferência de sedimento no litoral. Os dados de sísmica permitem ainda verificar a espessura das várias camadas geológicas em profundidade.

Swath bathymetry using phase difference: Theoretical analysis of acoustical measurement precision

The phase difference principle is widely applied nowadays to sonar systems used for sea floor bathymetry, The apparent angle of a target point is obtained from the phase difference measured between two close receiving arrays. Here we study the influence of the phase difference estimation errors caused by the physical structure of the backscattered signals. It is shown that, under certain current conditions, beyond the commonly considered effects of additive external noise and baseline decorrelation, the processing may be affected by the shifting footprint effect: this is due to the fact that the two interferometer receivers get simultaneous echo contributions coming from slightly shifted seabed parts, which results in a degradation of the signal coherence and, hence, of the phase difference measurement. This geometrical effect is described analytically and checked with numerical simulations, both for square- and sine-shaped signal envelopes. Its relative influence depends on the geometrical configuration and receiver spacing; it may be prevalent in practical cases associated with bathymetric sonars. The cases of square and smooth signal envelopes are both considered. The measurements close to nadir, which are known to be especially difficult with interferometry systems, are addressed in particular.

Monumento al Salvador del Mundo

13 p.

Representation of odometry errors on occupancy grids

SOUZA, Anderson A. S. ; SANTANA, André M. ; BRITTO, Ricardo S. ; GONÇALVES, Luiz Marcos G. ; MEDEIROS, Adelardo A. D. Representation of Odometry Errors on Occupancy Grids. In: INTERNATIONAL CONFERENCE ON INFORMATICS IN CONTROL, AUTOMATION AND ROBOTICS, 5., 2008, Funchal, Portugal. Proceedings... Funchal, Portugal: ICINCO, 2008.

Algorítmo de mapeamento usando modelagem probabilística

SOUZA, Anderson A.S. ; MEDEIROS, Adelardo A. D. ; GONÇALVES, Luiz Marcos G. . Algorítmo de mapeamento usando modelagem probabilística. In: SIMPOSIO BRASILEIRO DE AUTOMAÇÃO INTELIGENTE, 2007, Natal. Anais... Natal, 2007.

Geological Evolution of Coastal and Marine Environments off the Campania Continental Shelf Through Marine Geological Mapping - The Example of the Cilento Promontory

The geological evolution of coastal and marine environments offshore the Cilento Promontory through marine geological mapping is discussed here. The marine geological map n. 502 “Agropoli,” located offshore the Cilento Promontory (southern Italy), is described and put in regional geologic setting. The study area covers water depths ranging between 30 and 200 m isobaths. The geologic map has been constructed in the frame of a research program financed by the National Geological Survey of Italy (CARG Project), finalized to the construction of an up-to-date cartography of the Campania region. Geological and geophysical data on the continental shelf and slope offshore the southern Campania region have been acquired in an area bounded northward by the Gulf of Salerno and southward by the Gulf of Policastro. A high-resolution multibeam bathymetry has permitted the construction of a digital elevation model (DEM). Sidescan sonar profiles have also been collected and interpreted, and their merging with bathymetric data has allowed for the realization of the base for the marine geologic cartography. The calibration of geophysical data has been attempted through sea-bottom samples. The morpho-structures and the seismic sequences overlying the outcrops of acoustic basement reported in the cartographic representation have been studied in detail using single-channel seismics. The interpretation of seismic profiles has been a support for the reconstruction of the stratigraphic and structural setting of the Quaternary continental shelf successions and the outcrops of rocky acoustic basement in correspondence to the Licosa Cape morphostructural high. These areas result from the seaward prolongation of the stratigraphic and structural units, widely cropping out in the surrounding emerged sector of the Cilento Promontory. The cartographic approach is based on the recognition of laterally coeval depositional systems, interpreted in the frame of system tracts of the Late Quaternary depositional sequence.

Seamount abundances and abyssal hill morphology on the eastern flank of the East Pacific Rise at 14 degrees S

Bathymetric data from a Hydrosweep multibeam sonar survey of a 720 km long tectonic corridor on the east flank of the southern EPR at 14 degrees 14'S covered about 25,000 km(2) of zero-age to 8.5 m.y. old crust (magnetic anomaly 4A). In this corridor we document a strong correlation of robust along flowline changes in abyssal hill morphology and seamount size distribution with spreading rate changes deduced from our magnetic data. Indeed, we find that both rms height of abyssal hills and abundance and height of seamounts increase significantly as spreading rate changes from similar to 75 mm/yr to over 85 mm/yr (half rate). Moreover, we identified 46 seamounts taller than 100 m. Previous studies on the southern EPR reported a larger density of seamounts, organized primarily in chains. Our investigation, however, revealed seamounts not associated with major chains, leading us to the conclusion that different forms of off-axis volcanism occur along the spreading center.