Biology

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https://hdl.handle.net/1912/5

WHOI biological oceanographers study the biology of individual marine organisms, their spatial and temporal distributions, and how they interact both with their surrounding environment and with each other.

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  • Article
    A 1000-yr-old tsunami in the Indian Ocean points to greater risk for East Africa
    (Geological Society of America, 2020-05-12) Maselli, Vittorio ; Oppo, Davide ; Moore, Andrew L. ; Gusman, Aditya Riadi ; Mtelela, Cassy ; Iacopini, David ; Taviani, Marco ; Mjema, Elinaza ; Mulaya, Ernest ; Che, Melody ; Tomioka, Ai Lena ; Mshiu, Elisante ; Ortiz, Joseph D.
    The December 2004 Sumatra-Andaman tsunami prompted an unprecedented research effort to find ancient precursors and quantify the recurrence time of such a deadly natural disaster. This effort, however, has focused primarily along the northern and eastern Indian Ocean coastlines, in proximal areas hardest hit by the tsunami. No studies have been made to quantify the recurrence of tsunamis along the coastlines of the western Indian Ocean, leading to an underestimation of the tsunami risk in East Africa. Here, we document a 1000-yr-old sand layer hosting archaeological remains of an ancient coastal Swahili settlement in Tanzania. The sedimentary facies, grain-size distribution, and faunal assemblages indicate a tsunami wave as the most likely cause for the deposition of this sand layer. The tsunami in Tanzania is coeval with analogous deposits discovered at eastern Indian Ocean coastal sites. Numerical simulations of tsunami wave propagation indicate a megathrust earthquake generated by a large rupture of the Sumatra-Andaman subduction zone as the likely tsunami source. Our findings provide evidence that teletsunamis represent a serious threat to coastal societies along the western Indian Ocean, with implications for future tsunami hazard and risk assessments in East Africa.
  • Article
    A 1000-yr-old tsunami in the Indian Ocean points to greater risk for East Africa: reply
    (Geological Society of America, 2020-12-22) Maselli, Vittorio ; Oppo, Davide ; Moore, Andrew L. ; Gusman, Aditya Riadi ; Mtelela, Cassy ; Iacopini, David ; Taviani, Marco ; Mjema, Elinaza ; Mulaya, Ernest ; Che, Melody ; Tomioka, Ai Lena ; Mshiu, Elisante ; Ortiz, Joseph D.
    We appreciate Somerville’s (2020) interest in our work, and the opportunity to further expand the discussion about the occurrence of a trans-oceanic tsunami in the Indian Ocean generated by a megathrust earthquake ~1000 years ago. Somerville suggests a connection between the inferred tsunami deposit presented by us (Maselli et al., 2020) and a tsunami event reported to have occurred in Nagapattinam (India) in the year 900 CE and described in Kalaki Krishnamurty’s book (Rastogi and Jaiswal, 2006).
  • Preprint
    17β-Hydroxysteroid dehydrogenase (17β-HSD) in scleractinian corals and zooxanthellae
    ( 2005-12-18) Blomquist, Charles H. ; Lima, P. H. ; Tarrant, Ann M. ; Atkinson, M. J. ; Atkinson, S.
    Steroid metabolism studies have yielded evidence of 17β-hydroxysteroid dehydrogenase (17β-HSD) activity in corals. This project was undertaken to clarify whether there are multiple isoforms of 17β-HSD, whether activity levels vary seasonally, and if zooxanthellae contribute to activity. 17β-HSD activity was characterized in zooxanthellate and azooxanthellate coral fragments collected in summer and winter and in zooxanthellae cultured from M. capitata. More specifically, 17β-HSD activity was characterized with regard to steroid substrate and inhibitor specificity, coenzyme specificity, and Michaelis constants for estradiol (E2) and NADP+. Six samples each of M. capitata and T. coccinea (three summer, three winter) were assayed with E2 and NADP+. Specific activity levels (pmol/mg protein) varied 10-fold among M. capitata samples and 6-fold among T. coccinea samples. There was overlap of activity levels between summer and winter samples. NADP+/NAD+ activity ratios varied from 1.6 to 22.2 for M. capatita, 2.3 to 3.8 for T. coccinea and 0.7 to 1.1 for zooxanthellae. Coumestrol was the most inhibitory of the steroids and phytoestrogens tested. Our data confirm that corals and zooxanthellae contain 17β-HSD and are consistent with the presence of more than one isoform of the enzyme.
  • Preprint
    A 3D stereo camera system for precisely positioning animals in space and time
    ( 2015-02) Macfarlane, Nicholas B. W. ; Howland, Jonathan C. ; Jensen, Frants H. ; Tyack, Peter L.
    Here we describe a portable stereo camera system that integrates a GPS receiver, an attitude sensor, and 3D stereo photogrammetry to rapidly estimate the position of multiple animals in space and time. We demonstrate the performance of the system during a field test by simultaneously tracking the individual positions of 6 long-­‐ finned pilot whales, Globicephala melas. In shore-­‐based accuracy trials, a system with a 50 cm stereo baseline had an average range estimation error of 0.09 m at a 5 m distance increasing up to 3.2 m at 50 m. The system is especially useful in field situations where it is necessary to follow groups of animals traveling over relatively long distances and time periods while obtaining individual positions with high spatial and temporal resolution (up to 8Hz). These positions provide quantitative estimates of a variety of key parameters and indicators for behavioural studies such as inter-­‐animal distances, group dispersion, speed and heading. This system can additionally be integrated with other techniques such as archival tags, photo-­‐ identification methods or acoustic playback experiments to facilitate fieldwork investigating topics ranging from natural social behaviour to how animals respond to anthropogenic disturbance. By grounding observations in quantitative metrics the system can characterize fine-­‐scale behaviour or detect changes as a result of disturbance that might otherwise be difficult to observe.
  • Article
    A compilation of global bio-optical in situ data for ocean colour satellite applications – version three
    (Copernicus Publications, 2023-12-23) Valente, André ; Sathyendranath, Shubha ; Brotas, Vanda ; Groom, Steve ; Grant, Michael ; Jackson, Thomas ; Chuprin, Andrei ; Taberner, Malcolm ; Airs, Ruth ; Antoine, David ; Arnone, Robert ; Balch, William M ; Barker, Kathryn ; Barlow, Ray ; Bélanger, Simon ; Berthon, Jean-François ; BeÅiktepe, Åükrü ; Borsheim, Yngve ; Bracher, Astrid ; Brando, Vittorio ; Brewin, Robert J. W ; Canuti, Elisabetta ; Chavez, Francisco P ; Cianca, Andrés ; Claustre, Hervé ; Clementson, Lesley ; Crout, Richard ; Ferreira, Afonso ; Freeman, Scott ; Frouin, Robert ; García-Soto, Carlos ; Gibb, Stuart W ; Goericke, Ralf ; Gould, Richard ; Guillocheau, Nathalie ; Hooker, Stanford B ; Hu, Chuamin ; Kahru, Mati ; Kampel, Milton ; Klein, Holger ; Kratzer, Susanne ; Kudela, Raphael ; Ledesma, Jesus ; Lohrenz, Steven ; Loisel, Hubert ; Mannino, Antonio ; Martinez-Vicente, Victor ; Matrai, Patricia ; McKee, David ; Mitchell, Brian G ; Moisan, Tiffany ; Montes, Enrique ; Muller-Karger, Frank ; Neeley, Aimee ; Novak, Michael ; O'Dowd, Leonie ; Ondrusek, Michael ; Platt, Trevor ; Poulton, Alex J ; Repecaud, Michel ; Röttgers, Rüdiger ; Schroeder, Thomas ; Smyth, Timothy ; Smythe-Wright, Denise ; Sosik, Heidi M ; Thomas, Crystal ; Thomas, Rob ; Tilstone, Gavin ; Tracana, Andreia ; Twardowski, Michael ; Vellucci, Vincenzo ; Voss, Kenneth ; Werdell, Jeremy ; Wernand, Marcel ; Wojtasiewicz, Bozena ; Wright, Simon ; Zibordi, Giuseppe
    A global in situ data set for validation of ocean colour products from the ESA Ocean Colour Climate Change Initiative (OC-CCI) is presented. This version of the compilation, starting in 1997, now extends to 2021, which is important for the validation of the most recent satellite optical sensors such as Sentinel 3B OLCI and NOAA-20 VIIRS. The data set comprises in situ observations of the following variables: spectral remote-sensing reflectance, concentration of chlorophyll-a, spectral inherent optical properties, spectral diffuse attenuation coefficient, and total suspended matter. Data were obtained from multi-project archives acquired via open internet services or from individual projects acquired directly from data providers. Methodologies were implemented for homogenization, quality control, and merging of all data. Minimal changes were made on the original data, other than conversion to a standard format, elimination of some points, after quality control and averaging of observations that were close in time and space. The result is a merged table available in text format. Overall, the size of the data set grew with 148 432 rows, with each row representing a unique station in space and time (cf. 136 250 rows in previous version; Valente et al., 2019). Observations of remote-sensing reflectance increased to 68 641 (cf. 59 781 in previous version; Valente et al., 2019). There was also a near tenfold increase in chlorophyll data since 2016. Metadata of each in situ measurement (original source, cruise or experiment, principal investigator) are included in the final table. By making the metadata available, provenance is better documented and it is also possible to analyse each set of data separately. The compiled data are available at https://doi.org/10.1594/PANGAEA.941318 (Valente et al., 2022).
  • Article
    A note on the friction of different ropes in right whale (Eubalaena glacialis) baleen: an entanglement model
    (International Whaling Commission, 2023-03-15) Cavatorta, Derek ; Starczak, Victoria ; Prada, Kenneth ; Moore, Michael
    Entanglement in fishing gear, particularly fixed trap, constitutes a significant source of North Atlantic right whale (Eubalaena glacialis) mortality. Entanglements may initiate with rope fouling baleen plates before snagging other appendages. Low friction between rope and baleen may minimise the risk of a sustained, progressive entanglement. The friction of eight different rope types against right whale baleen was examined by measuring the tension as each rope was pulled through two baleen plates held underwater. Polypropylene rope generated less friction with the baleen than all other fibres tested, including nylon, polyester, and commercial sinking line (a polypropylene/polyester blend). Thus, new commercial floating line (3-strand polypropylene) generates less friction than new commercial sinking line, both of which are commonly used in the fixed gear industry. Therefore, minimising rope friction should be one of the design parameters for whale-safe fixed fishing gear. Further study is required on the impact of rope aging, mouth closing and operator safety before recommendations can be made to industry.
  • Article
    A survey of Dinophysis spp. and their potential to cause diarrhetic shellfish poisoning in coastal waters of the United States
    (Wiley, 2023-03) Ayache, Nour ; Bill, Brian D. ; Brosnahan, Michael L. ; Campbell, Lisa ; Deeds, Jonathan R. ; Fiorendino, James M. ; Gobler, Christopher J. ; Handy, Sara M. ; Harrington, Neil ; Kulis, David M. ; McCarron, Pearse ; Miles, Christopher O. ; Moore, Stephanie K. ; Nagai, Satoshi ; Trainer, Vera L. ; Wolny, Jennifer L. ; Young, Craig S. ; Smith, Juliette L.
    Multiple species of the genus Dinophysis produce diarrhetic shellfish toxins (okadaic acid and Dinophysis toxins, OA/DTXs analogs) and/or pectenotoxins (PTXs). Only since 2008 have DSP events (illnesses and/or shellfish harvesting closures) become recognized as a threat to human health in the United States. This study characterized 20 strains representing five species of Dinophysis spp. isolated from three US coastal regions that have experienced DSP events: the Northeast/Mid‐Atlantic, the Gulf of Mexico, and the Pacific Northwest. Using a combination of morphometric and DNA‐based evidence, seven Northeast/Mid‐Atlantic isolates and four Pacific Northwest isolates were classified as D. acuminata, a total of four isolates from two coasts were classified as D. norvegica, two isolates from the Pacific Northwest coast were identified as D. fortii, and three isolates from the Gulf of Mexico were identified as D. ovum and D. caudata. Toxin profiles of D. acuminata and D. norvegica varied by their geographical origin within the United States. Cross‐regional comparison of toxin profiles was not possible with the other three species; however, within each region, distinct species‐conserved profiles for isolates of D. fortii, D. ovum, and D. caudata were observed. Historical and recent data from various State and Tribal monitoring programs were compiled and compared, including maximum recorded cell abundances of Dinophysis spp., maximum concentrations of OA/DTXs recorded in commercial shellfish species, and durations of harvesting closures, to provide perspective regarding potential for DSP impacts to regional public health and shellfish industry.
  • Article
    Absolute probability estimates of lethal vessel strikes to North Atlantic right whales in Roseway Basin, Scotian Shelf
    (Ecological Society of America, 2012-10) van der Hoop, Julie ; Vanderlaan, Angelia S. M. ; Taggart, Christopher T.
    Vessel strikes are the primary source of known mortality for the endangered North Atlantic right whale (Eubalaena glacialis). Multi-institutional efforts to reduce mortality associated with vessel strikes include vessel-routing amendments such as the International Maritime Organization voluntary “area to be avoided” (ATBA) in the Roseway Basin right whale feeding habitat on the southwestern Scotian Shelf. Though relative probabilities of lethal vessel strikes have been estimated and published, absolute probabilities remain unknown. We used a modeling approach to determine the regional effect of the ATBA, by estimating reductions in the expected number of lethal vessel strikes. This analysis differs from others in that it explicitly includes a spatiotemporal analysis of real-time transits of vessels through a population of simulated, swimming right whales. Combining automatic identification system (AIS) vessel navigation data and an observationally based whale movement model allowed us to determine the spatial and temporal intersection of vessels and whales, from which various probability estimates of lethal vessel strikes are derived. We estimate one lethal vessel strike every 0.775–2.07 years prior to ATBA implementation, consistent with and more constrained than previous estimates of every 2–16 years. Following implementation, a lethal vessel strike is expected every 41 years. When whale abundance is held constant across years, we estimate that voluntary vessel compliance with the ATBA results in an 82% reduction in the per capita rate of lethal strikes; very similar to a previously published estimate of 82% reduction in the relative risk of a lethal vessel strike. The models we developed can inform decision-making and policy design, based on their ability to provide absolute, population-corrected, time-varying estimates of lethal vessel strikes, and they are easily transported to other regions and situations.
  • Article
    Abundance and diversity of ascidians in the southern Gulf of Chiriquí, Pacific Panama
    (Regional Euro-Asian Biological Invasions Centre (REABIC), 2011-07-04) Bullard, Stephan G. ; Carman, Mary R. ; Rocha, Rosana M. ; Dijkstra, Jennifer A. ; Goodwin, Anne M.
    Little is known about the ascidian fauna of Pacific Panama. Ascidian surveys were conducted in the southern Gulf of Chiriquí on the Pacific coast of Panama in January 2008 and 2009. Surveys along linear transects at 2-3 m depth (snorkel, 2008) and 5 and 12 m depth (SCUBA, 2009) were conducted at multiple sites within a chain of islands extending out from the mainland. Twelve different ascidian taxa were observed with mean densities of up to ~17 ascidians m-2. The most abundant species was Rhopalaea birkelandi. Two of the most abundant taxa (Ascidia sp., Pyura sp.) appear to represent previously undescribed species. Several species of didemnids were also abundant. Ascidians were most abundant near the coast of the mainland and were less abundant near the islands farthest offshore. These data on Panamanian ascidian communities provide a baseline of local biodiversity against which it will be possible to determine whether the communities change over time, if additional species become introduced to the region, or if native Panamanian species become invasive in other parts of the world.
  • Article
    Accelerating global ocean observing: monitoring the coastal ocean through broadly accessible, low-cost sensor networks
    (Marine Technology Society, 2021-05-01) Wang, Zhaohui Aleck ; Michel, Anna P. M. ; Mooney, T. Aran
    The global coastal ocean provides food and other critical resources to human societies. Yet this habitat, for which many depend, has experienced severe degradation from human activities. The rates of human-induced changes along the coast demand significantly improved coverage of ocean observations in order to support science-based decision making and policy formation tailored to specific regions. Our proposal envisions developing a global network of low-cost, easily produced and readily deployed oceanographic sensors for use on a wide variety of platforms in the coastal ocean. A substantially large number of these sensors can thus be installed on existing infrastructure, ships of opportunity, and fishing fleets, or even individually along the coast, particularly in vulnerable and disadvantaged regions. This would vastly increase the spatiotemporal resolution of the current data coverage along the coast, allowing greater equitable access. It would also offer significant opportunities for partnership with communities, NGOs, governments, and other stakeholders, as well as a wide range of commercial and industrial sectors to develop and deploy sensors in scalable networks transmitting data in near-real time. Finally, it presents a vastly lowered bar for participation by citizen scientists and other engaged members of the public to address location-specific coastal problems anywhere in the world.
  • Preprint
    Accelerator mass spectrometry 14C determination in CO2 produced from laser decomposition of aragonite
    ( 2008-08-29) Rosenheim, Brad E. ; Thorrold, Simon R. ; Roberts, Mark L.
    Determination of 14C in aragonite (CaCO3) decomposed thermally to CO2 using an yttrium‐aluminum‐garnet doped neodymium laser is reported. Laser decomposition accelerator mass spectrometer (LD‐AMS) measurements reproduce AMS determinations of 14C from conventional reaction of aragonite with concentrated phosphoric acid. The lack of significant differences between these sets of measurements indicate that LD‐AMS radiocarbon dating can overcome the significant fractionation that has been observed during stable isotope (C and O) laser decomposition analysis of different carbonate minerals. The laser regularly converted nearly 30% of material removed to CO2 despite being optimized for ablation, where laser energy breaks material apart rather than chemically altering it. These results illustrate promise for using laser decomposition on the front‐end of AMS systems that directly measure CO2 gas. The feasibility of such measurements depends on 1. the improvement of material removal and/or CO2 generation efficiency of the laser decomposition system and 2. the ionization efficiency of AMS systems measuring continuously flowing CO2.
  • Preprint
    Accounting for biological and physical sources of acoustic backscatter improves estimates of zooplankton biomass
    ( 2007-09-26) Warren, Joseph D. ; Wiebe, Peter H.
    In order to convert measurements of backscattered acoustic energy to estimates of abundance and taxonomic information about the zooplankton community, all of the scattering processes in the water column need to be identified and their scattering contributions quantified. Zooplankton populations in the eastern edge of Wilkinson Basin in the Gulf of Maine in the Northwest Atlantic were surveyed in October 1997. Net tow samples at different depths, temperature and salinity profiles, and multiple frequency acoustic backscatter measurements from the upper 200 meters of the water column were collected. Zooplankton samples were identified, enumerated, and measured. Temperature and salinity profiles were used to estimate the amount of turbulent microstructure in the water column. These data sets were used with theoretical acoustic scattering models to calculate the contributions of both biological and physical scatterers to the overall measured scattering level. The output of these predictions shows that the dominant source of acoustic backscatter varies with depth and acoustic frequency in this region. By quantifying the contributions from multiple scattering sources, acoustic backscatter becomes a better measure of net-collected zooplankton biomass.
  • Article
    Accounting for seasonal and composition-related variability in acoustic material properties in estimating copepod and krill target strength
    (Wiley, 2019-11-06) Sakinan, Serdar ; Lawson, Gareth L. ; Wiebe, Peter ; Copley, Nancy
    Estimation of abundance or biomass, using acoustic techniques requires knowledge of the frequency dependent acoustic backscatter characteristics, or target strength, of organisms. Target strength of zooplankton is typically estimated from physics‐based models that involve multiple parameters, notably including the acoustic material properties (i.e., the contrasts in density and sound speed between the animal and surrounding seawater). In this work, variability in the acoustic material properties of two zooplankton species in the Gulf of Maine, the copepod (Calanus finmarchicus) and krill (Meganyctiphanes norvegica), was investigated relative to changing season as well as, for the copepod, temperature and depth. Increases in the density and sound speed contrasts of these species from fall to spring were observed. Target strength predictions based on these measurements varied between fall and spring by 2‐3 dB in krill. Measurements were also conducted on C. finmarchicus lipid extract at changing temperature and pressure. The density contrast of the extract varied negatively with temperature, while the sound speed contrast changed by more than 10 % over the temperature and pressure ranges that the organism expected to occupy. C. finmarchicus target strength predictions showed that the combined effect of temperature and pressure can be significant (more than 10 dB) due to the varying response of lipids. The large vertical migration ranges and lipid accumulation characteristics of these species (e.g., the diapause behaviour of Calanus copepods) suggest that it is necessary for seasonal and environmental variability in material properties to be taken into account to achieve reliable measurements.
  • Article
    Accurate automatic quantification of taxa-specific plankton abundance using dual classification with correction
    (Inter-Research, 2006-01-11) Hu, Qiao ; Davis, Cabell S.
    Optical imaging samplers are becoming widely used in plankton ecology, but image analysis methods have lagged behind image acquisition rates. Automated methods for analysis and recognition of plankton images have been developed, which are capable of real-time processing of incoming image data into major taxonomic groups. The limited accuracy of these methods can require significant manual post-processing to correct the automatically generated results, in order to obtain accurate estimates of plankton abundance patterns. We present here a dual-classification method in which each plankton image is first identified using a shaped-based feature set and a neural network classifier, and then a second time using a texture-based feature set and a support vector machine classifier. The plankton image is considered to belong to a given taxon only if the 2 identifications agree; otherwise it is labeled as unknown. This dual-classification method greatly reduces the false positive rate, and thus gives better abundance estimation in regions of low relative abundance. A confusion matrix is computed from a set of training images in order to determine the detection and false positives rates. These rates are used to correct abundances estimated from the automatic classification results. Aside from the manual sorting required to generate the initial training set of images, this dual-classification method is fully automatic and does not require subsequent manual correction of automatically sorted images. The resulting abundances agree closely with those obtained using manually sorted results. A set of images from a Video Plankton Recorder was used to evaluate this method and compare it with previously reported single-classifier results for major taxa.
  • Preprint
    Acoustic and biological trends on coral reefs off Maui, Hawaii
    ( 2017-11) Kaplan, Maxwell B. ; Lammers, Marc O. ; Zang, Eden ; Mooney, T. Aran
    Coral reefs are characterized by high biodiversity and evidence suggests that reef soundscapes reflect local species assemblages. To investigate how sounds produced on a given reef relate to abiotic and biotic parameters and how that relationship may change over time, an observational study was conducted between September 2014 and January 2016 at seven Hawaiian reefs that varied in coral cover, rugosity, and fish assemblages. The reefs were equipped with temperature loggers and acoustic recording devices that recorded on a 10% duty cycle. Benthic and fish visual survey data were collected four times over the course of the study. On average, reefs ranged from 0 to 80% live coral cover, although changes between surveys were noted, in particular during the major El Niño-related bleaching event of October 2015. Acoustic analyses focused on two frequency bands (50–1200 Hz and 1.8–20.5 kHz) that corresponded to the dominant spectral features of the major sound-producing taxa on these reefs, fish and snapping shrimp, respectively. In the low-frequency band, the presence of humpback whales (December– May) was a major contributor to sound level, whereas in the high-frequency band sound level closely tracked water temperature. On shorter timescales, the magnitude of the diel trend in sound production was greater than that of the lunar trend, but both varied in strength among reefs, which may reflect differences in the species assemblages present. Results indicated that the magnitude of the diel trend was related to fish densities at low frequencies and coral cover at high frequencies; however, the strength of these relationships varied by season. Thus, long-term acoustic recordings capture the substantial acoustic variability present in coral-reef ecosystems and provide insight into the presence and relative abundance of sound-producing organisms.
  • Technical Report
    Acoustic and oceanographic observations collected during the Nomans Island experiment in Spring 2017
    (Woods Hole Oceanographic Institution, 2020-07) Johnson, Hansen D. ; Newhall, Arthur E. ; Lin, Ying-Tsong ; Baumgartner, Mark F.
    The Woods Hole Oceanographic Institution (WHOI) has developed a digital acoustic monitoring (DMON) instrument and low-frequency detection and classification system (LFDCS) to detect and classify baleen whales in near real-time from autonomous platforms. This document provides a detailed description of the data, sensors, and research activities pertaining to the Nomans Island experiment, which was designed to evaluate the range-dependent accuracy of the DMON/LFDCS on mobile and fixed platforms. The experiment took place over a 4-week period (28 Feb to 31 Mar) in the spring of 2017 at a shallow (30m) site approximately 15 km Southwest of Martha’s Vineyard, USA. A DMON/LFDCS-equipped Slocum glider was deployed alongside an extant DMON/LFDCS moored buoy to provide the means to compare system performance between platforms. Vertical and horizontal hydrophone line arrays were deployed in the same area to facilitate call localization. A short transmission loss trial was conducted shortly after the array deployments. The Slocum glider and several sensors mounted to the arrays provided environmental data to characterize variability in water column structure and sound speed during the study period.
  • Thesis
    Acoustic classification of zooplankton
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1998-02) Martin Traykovski, Linda V.
    Work on the forward problem in zooplankton bioacoustics has resulted in the identification of three categories of acoustic scatterers: elastic-shelled (e.g. pteropods), fluid-like (e.g. euphausiids), and gas-bearing (e.g. siphonophores). The relationship between backscattered energy and animal biomass has been shown to vary by a factor of —19,000 across these categories, so that to make accurate estimates of zooplankton biomass from acoustic backscatter measurements of the ocean, the acoustic characteristics of the species of interest must be well-understood. This thesis describes the development of both feature based and model based classification techniques to invert broadband acoustic echoes from individual zooplankton for scatterer type, as well as for particular parameters such as animal orientation. The feature based Empirical Orthogonal Function Classifier (EOFC) discriminates scatterer types by identifying characteristic modes of variability in the echo spectra, exploiting only the inherent characteristic structure of the acoustic signatures. The model based Model Parameterisation Classifier (MPC) classifies based on correlation of observed echo spectra with simplified parameterisations of theoretical scattering models for the three classes. The Covariance Mean Variance Classifiers (CMVC) are a set of advanced model based techniques which exploit the full complexity of the theoretical models by searching the entire physical model parameter space without employing simplifying parameterisations. Three different CMVC algorithms were developed: the Integrated Score Classifier (ISC), the Pairwise Score Classifier (PSC) and the Bayesian Probability Classifier (BPC); these classifiers assign observations to a class based on similarities in covariance, mean, and variance, while accounting for model ambiguity and validity. These feature based and model based inversion techniques were successfully applied to several thousand echoes acquired from broadband (-350 kHz - 750 kHz) insonifications of live zooplankton collected on Georges Bank and the Gulf of Maine to determine scatterer class. CMVC techniques were also applied to echoes from fluid-like zooplankton (Antarctic krill) to invert for angle of orientation using generic and animal-specific theoretical and empirical models. Application of these inversion techniques in situ will allow correct apportionment of backscattered energy to animal biomass, significantly improving estimates of zooplankton biomass based on acoustic surveys.
  • Thesis
    Acoustic communication in the North Atlantic right whale (Eubalaena glacialis)
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2003-09) Parks, Susan E.
    The focus of this thesis is the use of sound for communication by the North Atlantic right whale (Eubalaena glacialis). The surface active group (SAG) is the predominant social interaction in this species for which use of sound has been documented. Different group compositions in SAGs indicate that both potentially reproductive and non-reproductive groups have been combined under one labeL. Sound production in SAGs suggests that females form and maintain the groups by producing Scream calls. Males produce Upcalls to advertise their presence as they come into a group or when the female is on a dive. Males may use Gunshot sounds as threat signals to other males in the group or potentially as reproductive advertisement signals to the female. Some calves produce Warble sounds in SAGs. This may be limited to female calves. This description of acoustic activity in the groups adds to the picture of the SAGs as complex interactions between individuals, rather than simple groups with only one whale producing all the sounds to attract other whales to the group. Playback experiments demonstrate that right whales can use sounds from SAGs to locate the groups. Male right whales approached both North Atlantic and Southern right whale SAG playbacks. Female right whales only approached Southern right whale playbacks. Anatomical modeling resulted in a frequency range of hearing for the right whale (10 Hz - 22 kHz) that is consistent with the sounds that they produce and overlaps the frequency range of most anthropogenic noise sources. This combination of research provides a thorough description how North Atlantic right whales use sound in SAGs and how increasing levels of noise in the oceans may impact right whales in these groups.
  • Article
    Acoustic detection range of right whale upcalls identified in near-real time from a moored buoy and a Slocum glider
    (Acoustical Society of America, 2022-04-13) Johnson, Hansen D. ; Taggart, Christopher T. ; Newhall, Arthur E. ; Lin, Ying-Tsong ; Baumgartner, Mark F.
    The goal of this study was to characterize the detection range of a near real-time baleen whale detection system, the digital acoustic monitoring instrument/low-frequency detection and classification system (DMON/LFDCS), equipped on a Slocum glider and a moored buoy. As a reference, a hydrophone array was deployed alongside the glider and buoy at a shallow-water site southwest of Martha's Vineyard (Massachusetts, USA) over a four-week period in spring 2017. A call-by-call comparison between North Atlantic right whale upcalls localized with the array (n = 541) and those detected by the glider or buoy was used to estimate the detection function for each DMON/LFDCS platform. The probability of detection was influenced by range, ambient noise level, platform depth, detection process, review protocol, and calling rate. The conservative analysis of near real-time pitch tracks suggested that, under typical conditions, a 0.33 probability of detection of a single call occurred at 6.2 km for the buoy and 8.6–13.4 km for the glider (depending on glider depth), while a 0.10 probability of detection of a single call occurred at 14.4 m for the buoy and 22.6–27.5 km for the glider. Probability of detection is predicted to increase substantially at all ranges if more than one call is available for detection.
  • Article
    Acoustic differentiation of Shiho- and Naisa-type short-finned pilot whales in the Pacific Ocean
    (Acoustical Society of America, 2017-02) Van Cise, Amy M. ; Roch, Marie ; Baird, Robin W. ; Mooney, T. Aran ; Barlow, Jay
    Divergence in acoustic signals used by different populations of marine mammals can be caused by a variety of environmental, hereditary, or social factors, and can indicate isolation between those populations. Two types of genetically and morphologically distinct short-finned pilot whales, called the Naisa- and Shiho-types when first described off Japan, have been identified in the Pacific Ocean. Acoustic differentiation between these types would support their designation as sub-species or species, and improve the understanding of their distribution in areas where genetic samples are difficult to obtain. Calls from two regions representing the two types were analyzed using 24 recordings from Hawai‘i (Naisa-type) and 12 recordings from the eastern Pacific Ocean (Shiho-type). Calls from the two types were significantly differentiated in median start frequency, frequency range, and duration, and were significantly differentiated in the cumulative distribution of start frequency, frequency range, and duration. Gaussian mixture models were used to classify calls from the two different regions with 74% accuracy, which was significantly greater than chance. The results of these analyses indicate that the two types are acoustically distinct, which supports the hypothesis that the two types may be separate sub-species.