WHOAS : Browsing Applied Ocean Physics and Engineering (AOP&E) by Title

Technical Report

The 17-meter flume at the Coastal Research Laboratory. Part I, Description and user's manual : technical report

(Woods Hole Oceanographic Institution, 1989-05) Butman, Cheryl Ann ; Chapman, Robert J.

The 17-Meter Flume, a recirculating, temperature-controlled, seawater channel, was recently constructed in W.H.O.I.'s Coastal Research Laboratory for studies of boundary-layer flows and sediment transport, and for interdisciplinary research where adequate simulation of the near-bed flow environment is required. The flume channel is 17.3-m long by 0.6-m wide and can be filled to a maximum depth of 0.3 m. The water is circulated by a centrifugal pump and is temperature controlled to ± 0.5°C over a range of about 4-30°C. Made of fiberglass , glass, plastics and high-grade stainless steel, all surfaces of the flume that come into contact with the water are noncorrosive and nontoxic to organisms. The flume is equipped with a computer-controlled, two-axis, laser-Doppler velocimeter (LDV) for detailed, accurate and precise measurements of flow characteristics anywhere along the flume channel. In addition to detailed descriptions and illustrations of all components of the flume, this report provides instructions for use of the flume and associated instrumentation. In Part II, flume flow characteristics measured with the LDV are illustrated and evaluated relative to theoretical and empirical expectations for open-channel flows.

Technical Report

The 17-meter flume at the Coastal Research Laboratory. Part II, Flow characteristics : technical report

(Woods Hole Oceanographic Institution, 1989-05) Trowbridge, John H. ; Geyer, W. Rockwell ; Butman, Cheryl Ann ; Chapman, Robert J.

This report summarizes the characteristics of the idealized one-dimensional turbulent channel flow for which the 17-Meter Flume was designed, and describes a measurement program designed to determine whether the flume can in fact produce such a flow. The measured quantities include mean velocities, Reynolds stresses, turbulence intensities and velocity spectra. Measured profiles of mean velocity, Reynolds stress and turbulence intensity are consistent with previous theoretical and empirical results. Measured spectra, although consistent with expectations over a wide range of frequencies, indicate a few unexpected features, including a constant spectral density at high frequencies (possibly due to aliasing or high-frequency noise) , motion at a few well-defined high frequencies of order 10 hz (possibly due to structual vibrations), oscillations with time scales of order 30 s (possibly due to low-mode standing surface waves) and irregular motions with time scales of several minutes (possibly due to fluctuations in pump performance) . The unexpected features indicated by the spectra at high and low frequencies do not have a significant effect on mean velocities and low-order statistics, but they may be important in some applications.

Technical Report

The 1998 WHOI/IOS/ONR internal solitary wave workshop : contributed papers

(Woods Hole Oceanographic Institution, 1999-07) Duda, Timothy F. ; Farmer, David M.

A workshop entitled "Internal Solitary Waves in the Ocean: Their Physics and Implications for Acoustics, Biology, and Geology" was held during October, 1998 in Sydney, British Columbia, Canada. It was jointly organized by the Woods Hole Oceanographic Institution (MA, USA), the Institute of Ocean Sciences, (Sydney, BC, Canada), and the U. S. Office of Naval Research. More than 60 scientists from seven countries attended. Participants contributed papers prior to the meeting which were published on the internet at the Woods Hole web site. Those papers are reproduced here.

Article

The 2005 Chios ancient shipwreck survey : new methods for underwater archaeology

(American School of Classical Studies at Athens, 2009-04) Foley, Brendan P. ; Dellaporta, Katerina ; Sakellariou, Dimitris ; Bingham, Brian S. ; Camilli, Richard ; Eustice, Ryan M. ; Evagelistis, Dionysis ; Ferrini, Vicki L. ; Katsaros, Kostas ; Kourkoumelis, Dimitris ; Mallios, Angelos ; Micha, Paraskevi ; Mindell, David A. ; Roman, Christopher N. ; Singh, Hanumant ; Switzer, David S. ; Theodoulou, Theotokis

In 2005 a Greek and American interdisciplinary team investigated two shipwrecks off the coast of Chios dating to the 4th-century b.c. and the 2nd/1st century. The project pioneered archaeological methods of precision acoustic, digital image, and chemical survey using an autonomous underwater vehicle (AUV) and in-situ sensors, increasing the speed of data acquisition while decreasing costs. The AUV recorded data revealing the physical dimensions, age, cargo, and preservation of the wrecks. The earlier wreck contained more than 350 amphoras, predominantly of Chian type, while the Hellenistic wreck contained about 40 Dressel 1C amphoras. Molecular biological analysis of two amphoras from the 4th-century wreck revealed ancient DNA of olive, oregano, and possibly mastic, part of a cargo outbound from Chios.

Article

3-D focused inversion of near-seafloor magnetic data with application to the Brothers volcano hydrothermal system, Southern Pacific Ocean, New Zealand

(American Geophysical Union, 2012-10-11) Tontini, F. Caratori ; de Ronde, Cornel E. J. ; Yoerger, Dana R. ; Kinsey, James C. ; Tivey, Maurice A.

We describe and apply a new inversion method for 3-D modeling of magnetic anomalies designed for general application but which is particularly useful for the interpretation of near-seafloor magnetic anomalies. The crust subsurface is modeled by a set of prismatic cells, each with uniform magnetization, that together reproduce the observed magnetic field. This problem is linear with respect to the magnetization, and the number of cells is normally greater than the amount of available data. Thus, the solution is obtained by solving an under-determined linear problem. A focused solution, exhibiting sharp boundaries between different magnetization domains, is obtained by allowing the amplitudes of magnetization to vary between a pre-determined range and by minimizing the region of the 3-D space where the source shows large variations, i.e., large gradients. A regularization functional based on a depth-weighting function is also introduced in order to counter-act the natural decay of the magnetic field intensity with depth. The inversion method has been used to explore the characteristics of the submarine hydrothermal system of Brothers volcano in the Kermadec arc, by inverting near-bottom magnetic data acquired by Autonomous Underwater Vehicles (AUVs). Different surface expressions of the hydrothermal vent fields show specific vertical structures in their underlying demagnetization regions that we interpret to represent hydrothermal upflow zones. For example, at focused vent sites the demagnetized conduits are vertical, pipe-like structures extending to depths of ~1000 m below the seafloor, whereas at diffuse vent sites the demagnetization regions are characterized by thin and inclined conduits.

Article

3D acoustic propagation through an estuarine salt wedge at low-to-mid-frequencies: Modeling and measurement

(Acoustical Society of America, 2019-09-30) Reeder, D. Benjamin ; Lin, Ying-Tsong

The estuarine salt wedge presents a dynamic and highly refractive waveguide, the acoustic propagation characteristics of which are controlled by the water column sound speed gradient and boundary interactions. Acoustically, the salt wedge consists of two isospeed layers separated by a thin, three-dimensional (3D), high-gradient layer. The behavior of a broadband (500–2000 Hz) acoustic field under the influence of an estuarine salt wedge in the Columbia River estuary is explored using two 3D acoustic propagation models: 3D rays and 3D parabolic equation. These model results are compared to data collected during the field experiment. Results demonstrate that the dominant physical mechanism controlling acoustic propagation in this waveguide shifts from 3D bottom scatter in a non-refractive waveguide (before the entrance of the salt wedge) to 3D acoustic refraction with minimal bottom interaction in a refractive waveguide (when the salt wedge occupies the acoustic transect). Vertical and horizontal refraction in the water column and out-of-plane scattering by the bottom are clearly evident at specific narrowband frequencies; however, these mechanisms contribute to, but do not account for, the total observed broadband transmission loss.

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.

Technical Report

4DGeoBrowser : a web-based data browser and server for accessing and analyzing multi-disciplinary data

(Woods Hole Oceanographic Institution, 2001-10) Lerner, Steven A. ; Maffei, Andrew R.

This report describes the 4DGeoBrowser software system. The GeoBrowser is a web-based application developed at the Woods Hole Oceanographic Institution by Steven Lerner and Andrew Maffei. It has been designed with the goal of creating, accessing, and analyzing repositories of oceanographic datasets that have been generated by investigators in differing scientific disciplines. Once the information is loaded onto a Geobrowser server the investigator-user is able to login to the website and use a set of data access and analysis tools to search, plot, and display this information. GeoBrowser servers are also capable of processing commands that are submitted remotely via HTTP URLs or email. Scientists are able to use this capability to make calls to the GeoBrowser server and generate click-able maps, tables of urls, and customized HTML pages. These can then be used to enhance websites associated with scientific projects. Examples of supporting scientific website functionality that includes time series plotting, data delivery by email, geo-spatial plotting of interdisciplinary data, map-based search capabilities and other functionality are presented in this report. The report includes examples of GeoBrowser application websites, a user manual, and a reference guide. In addition, the concept of Electronic Index Cards (EICs) is presented.

Article

A database of snow on sea ice in the central Arctic collected during the MOSAiC expedition

(Nature Research, 2023-06-22) Macfarlane, Amy R. ; Schneebeli, Martin ; Dadic, Ruzica ; Tavri, Aikaterini ; Immerz, Antonia ; Polashenski, Chris ; Krampe, Daniela ; Clemens-Sewall, David ; Wagner, David N. ; Perovich, Donald K. ; Henna-Reetta, Hannula ; Raphael, Ian ; Matero, Ilkka ; Regnery, Julia ; Smith, Madison M. ; Nicolaus, Marcel ; Jaggi, Matthias ; Oggier, Marc ; Webster, Melinda A. ; Lehning, Michael ; Kolabutin, Nikolai ; Itkin, Polona ; Naderpour, Reza ; Pirazzini, Roberta ; Hammerle, Stefan ; Arndt, Stefanie ; Fons, Steven

Snow plays an essential role in the Arctic as the interface between the sea ice and the atmosphere. Optical properties, thermal conductivity and mass distribution are critical to understanding the complex Arctic sea ice system’s energy balance and mass distribution. By conducting measurements from October 2019 to September 2020 on the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition, we have produced a dataset capturing the year-long evolution of the physical properties of the snow and surface scattering layer, a highly porous surface layer on Arctic sea ice that evolves due to preferential melt at the ice grain boundaries. The dataset includes measurements of snow during MOSAiC. Measurements included profiles of depth, density, temperature, snow water equivalent, penetration resistance, stable water isotope, salinity and microcomputer tomography samples. Most snowpit sites were visited and measured weekly to capture the temporal evolution of the physical properties of snow. The compiled dataset includes 576 snowpits and describes snow conditions during the MOSAiC expedition.

Article

A high‐resolution AUV navigation framework with integrated communication and tracking for under‐ice deployments

(Wiley, 2022-11-16) Randeni, Supun ; Schneider, Toby ; Bhatt, EeShan C. ; Víquez, Oscar A. ; Schmidt, Henrik

We developed an environmentally adaptive under‐ice navigation framework that was deployed in the Arctic Beaufort Sea during the United States Navy Ice Exercise in March 2020 (ICEX20). This navigation framework contained two subsystems developed from the ground up: (1) an on‐board hydrodynamic model‐aided navigation (HydroMAN) engine, and (2) an environmentally and acoustically adaptive integrated communication and navigation network (ICNN) that provided acoustic navigation aiding to the former. The HydroMAN synthesized measurements from an inertial navigation system (INS), ice‐tracking Doppler velocity log (DVL), ICNN and pressure sensor into its self‐calibrating vehicle flight dynamic model to compute the navigation solution. The ICNN system, which consisted of four ice buoys outfitted with acoustic modems, trilaterated the vehicle position using the one‐way‐travel‐times (OWTT) of acoustic datagrams transmitted by the autonomous underwater vehicle (AUV) and received by the ice buoy network. The ICNN digested salinity and temperature information to provide model‐assisted real‐time OWTT range conversion to deliver accurate acoustic navigation updates to the HydroMAN. To decouple the contributions from the HydroMAN and ICNN subsystems towards a stable navigation solution, this article evaluates them separately: (1) HydroMAN was compared against DVL bottom‐track aided INS during pre‐ICEX20 engineering trials where both systems provided similar accuracy; (2) ICNN was evaluated by conducting a static experiment in the Arctic where the ICNN navigation updates were compared against GPS with ICNN error within low tens of meters. The joint HydroMAN‐ICNN framework was tested during ICEX20, which provided a nondiverging high‐resolution navigation solution—with the majority of error below 15 m—that facilitated a successful AUV recovery through a small ice hole after an 11 km untethered run in the upper and mid‐water column.

Article

A marine heatwave changes the stabilizing effects of biodiversity in kelp forests

(Ecological Society of America, 2024-03-24) Liang, Maowei ; Lamy, Thomas ; Reuman, Daniel C. ; Wang, Shaopeng ; Bell, Tom W. ; Cavanaugh, Kyle C. ; Castorani, Max C. N.

Biodiversity can stabilize ecological communities through biological insurance, but climate and other environmental changes may disrupt this process via simultaneous ecosystem destabilization and biodiversity loss. While changes to diversity–stability relationships (DSRs) and the underlying mechanisms have been extensively explored in terrestrial plant communities, this topic remains largely unexplored in benthic marine ecosystems that comprise diverse assemblages of producers and consumers. By analyzing two decades of kelp forest biodiversity survey data, we discovered changes in diversity, stability, and their relationships at multiple scales (biological organizational levels, spatial scales, and functional groups) that were linked with the most severe marine heatwave ever documented in the North Pacific Ocean. Moreover, changes in the strength of DSRs during/after the heatwave were more apparent among functional groups than both biological organizational levels (population vs. ecosystem levels) and spatial scales (local vs. broad scales). Specifically, the strength of DSRs decreased for fishes, increased for mobile invertebrates and understory algae, and were unchanged for sessile invertebrates during/after the heatwave. Our findings suggest that biodiversity plays a key role in stabilizing marine ecosystems, but the resilience of DSRs to adverse climate impacts primarily depends on the functional identities of ecological communities.

Article

A model for community-driven development of best practices: The Ocean Observatories Initiative biogeochemical sensor data best practices and user guide

(Frontiers Media, 2024-04-03) Palevsky, Hilary I. ; Clayton, Sophie A. ; Benway, Heather M. ; Maheigan, Mairead ; Atamanchuk, Dariia ; Battisti, Roman ; Batryn, Jennifer ; Bourbonnais, Annie ; Briggs, Ellen M. ; Carvalho, Filipa ; Chase, Alison P. ; Eveleth, Rachel ; Fatland, Rob ; Fogaren, Kristen E. ; Fram, Jonathan Peter ; Hartman, Susan E. ; Le Bras, Isabela ; Manning, Cara C. ; Needoba, Joseph A. ; Neely, Merrie Beth ; Oliver, Hilde ; Reed, Andrew C. ; Rheuban, Jennie E. ; Schallenberg, Christina ; Walsh, Ian ; Wingard, Christopher ; Bauer, Kohen ; Chen, Baoshan ; Cuevas, Jose ; Flecha, Susana ; Horwith, Micah ; Melendez, Melissa ; Menz, Tyler ; Rivero-Calle, Sara ; Roden, Nicholas P. ; Steinhoff, Tobias ; Trucco-Pignata, Pablo Nicolas ; Vardaro, Michael F. ; Yoder, Meg

The field of oceanography is transitioning from data-poor to data-rich, thanks in part to increased deployment of in-situ platforms and sensors, such as those that instrument the US-funded Ocean Observatories Initiative (OOI). However, generating science-ready data products from these sensors, particularly those making biogeochemical measurements, often requires extensive end-user calibration and validation procedures, which can present a significant barrier. Openly available community-developed and -vetted Best Practices contribute to overcoming such barriers, but collaboratively developing user-friendly Best Practices can be challenging. Here we describe the process undertaken by the NSF-funded OOI Biogeochemical Sensor Data Working Group to develop Best Practices for creating science-ready biogeochemical data products from OOI data, culminating in the publication of the GOOS-endorsed OOI Biogeochemical Sensor Data Best Practices and User Guide. For Best Practices related to ocean observatories, engaging observatory staff is crucial, but having a “user-defined” process ensures the final product addresses user needs. Our process prioritized bringing together a diverse team and creating an inclusive environment where all participants could effectively contribute. Incorporating the perspectives of a wide range of experts and prospective end users through an iterative review process that included “Beta Testers’’ enabled us to produce a final product that combines technical information with a user-friendly structure that illustrates data analysis pipelines via flowcharts and worked examples accompanied by pseudo-code. Our process and its impact on improving the accessibility and utility of the end product provides a roadmap for other groups undertaking similar community-driven activities to develop and disseminate new Ocean Best Practices.

Article

A simple laboratory calibration method for mitigating seawater effects on soil moisture sensors

(Elsevier, 2023-09-01) Brilli, Nicola C. ; Stark, Nina ; Raubenhiemer, Britt ; Elgar, Steve ; Korka, Bennet

The importance of moisture content for sediment dynamics in coastal environments is well documented, particularly in reference to aeolian sediment transport (Davidson-Arnott, 2005). Tidally-induced changes in moisture content in partially saturated environments, such as beaches, cause significant changes in surface shear strength through the development of suction stresses, which can affect erodibility (Sassa and Watabe, 2007). Thus, the accurate measurement of moisture content in these environments is important for determination of strength properties and for predicting sediment transport. Most moisture sensors work by measuring dielectric permittivity, the ability to carry electric charge, of the substrate, which is proportional to the moisture content. However, most moisture sensors are not calibrated for seawater, which has a higher dielectric permittivity than freshwater, causing overestimation of the moisture content. Therefore, the goal of this study is to develop and demonstrate a laboratory calibration scheme to account for this overestimation, and thus to allow for more accurate measurements of moisture content in coastal environments.

Article

Abundance and distribution of sperm whales in the Canary Islands : can sperm whales in the archipelago sustain the current level of ship-strike mortalities?

(Public Library of Science, 2016-03-21) Fais, Andrea ; Lewis, Tim P. ; Zitterbart, Daniel P. ; Alvarez, Omar ; Tejedor, Ana ; Aguilar De Soto, Natacha

Sperm whales are present in the Canary Islands year-round, suggesting that the archipelago is an important area for this species in the North Atlantic. However, the area experiences one of the highest reported rates of sperm whale ship-strike in the world. Here we investigate if the number of sperm whales found in the archipelago can sustain the current rate of ship-strike mortality. The results of this study may also have implications for offshore areas where concentrations of sperm whales may coincide with high densities of ship traffic, but where ship-strikes may be undocumented. The absolute abundance of sperm whales in an area of 52933 km2, covering the territorial waters of the Canary Islands, was estimated from 2668 km of acoustic line-transect survey using Distance sampling analysis. Data on sperm whale diving and acoustic behaviour, obtained from bio-logging, were used to calculate g(0) = 0.92, this is less than one because of occasional extended periods when whales do not echolocate. This resulted in an absolute abundance estimate of 224 sperm whales (95% log-normal CI 120–418) within the survey area. The recruitment capability of this number of whales, some 2.5 whales per year, is likely to be exceeded by the current ship-strike mortality rate. Furthermore, we found areas of higher whale density within the archipelago, many coincident with those previously described, suggesting that these are important habitats for females and immature animals inhabiting the archipelago. Some of these areas are crossed by active shipping lanes increasing the risk of ship-strikes. Given the philopatry in female sperm whales, replacement of impacted whales might be limited. Therefore, the application of mitigation measures to reduce the ship-strike mortality rate seems essential for the conservation of sperm whales in the Canary Islands.

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.

Thesis

Accuracy bounds for normal-incidence acoustic structure estimation

(Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1977-08) Theriault, Kenneth B.

Determnation of the structure of a medium from normal-incidence acoustic reflection data is a basic problem in fields as diverse as medical technology and the earth sciences; this research examines the accuracy with which quantitative structure estimates can be made from noise-corrupted measurements of reflected energy. Two classes of simple physical models, which exclude geometrical spreading and attenuation, are developed: one in which the properties of the medium change continuously with depth, and one in which they change discretely. Given these reasonable models, estimation accuracy is studied by computing a statistical lower bound on estimator performance, the Cramer-Rao bound, for three cases of interest. (1) The bound is computed for the estimation of unknown, nonrandom reflection coefficients in a medium containing only discrete reflectors; special attention is given to the one- and two-reflector situations. The bound's ability to predict estimator performance is demonstrated, as is the inadequacy of a particular ad-hoc estimdtion method based on the Wiener- Levinson algorithm of stochastic filtering theory. (2) The bound is developed for estimation in a continuous medium whose structure (acoustic impedance, for exaiple) parametrized by a set of unknown, non-random coefficients, and for which the reflection response may be computed in closed form. The problem of estimating the parameters of a single, isogradient velocity layer of known depth is studied in detail. It is demonstrated that one can identify the parameters of such a layer from normal-incidence measurements given an appropriate source and experimenc geometry. (3) A unique extension of some known results in random process estimation is used to derive a pointwise bound for estimation in a continuous medium whose structure (reflection coefficient density) is a random process. Again we give special consideration to the problem of identifying a single isolated layer structure. We demonstrate that for a weakly scattering structure, estimation accuracy is independent of the mean or nominal structure.

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.

Article

Acidification reduced growth rate but not swimming speed of larval sea urchins

(Nature Publishing Group, 2015-05-15) Chan, Kit Yu Karen ; Garcia, Eliseba ; Dupont, Sam

Swimming behaviors of planktonic larvae impact dispersal and population dynamics of many benthic marine invertebrates. This key ecological function is modulated by larval development dynamics, biomechanics of the resulting morphology, and behavioral choices. Studies on ocean acidification effects on larval stages have yet to address this important interaction between development and swimming under environmentally-relevant flow conditions. Our video motion analysis revealed that pH covering present and future natural variability (pH 8.0, 7.6 and 7.2) did not affect age-specific swimming of larval green urchin Strongylocentrotus droebachiensis in still water nor in shear, despite acidified individuals being significantly smaller in size (reduced growth rate). This maintenance of speed and stability in shear was accompanied by an overall change in size-corrected shape, implying changes in swimming biomechanics. Our observations highlight strong evolutionary pressure to maintain swimming in a varying environment and the plasticity in larval responses to environmental change.

Technical Report

Acoustic and oceanographic observations and configuration information for the WHOI moorings from the SW06 experiment

(Woods Hole Oceanographic Institution, 2007-05) Newhall, Arthur E. ; Duda, Timothy F. ; von der Heydt, Keith ; Irish, James D. ; Kemp, John N. ; Lerner, Steven A. ; Liberatore, Stephen P. ; Lin, Ying-Tsong ; Lynch, James F. ; Maffei, Andrew R. ; Morozov, Andrey K. ; Shmelev, Alexey A. ; Sellers, Cynthia J. ; Witzell, Warren E.

This document describes data, sensors, and other useful information pertaining to the moorings that were deployed from the R/V Knorr from July 24th to August 4th, 2006 in support of the SW06 experiment. The SW06 experiment was a large, multi-disciplinary effort performed 100 miles east of the New Jersey coast. A total of 62 acoustic and oceanographic moorings were deployed and recovered. The moorings were deployed in a “T” geometry to create an along-shelf path along the 80 meter isobath and an across-shelf path starting at 600 meters depth and going shoreward to a depth of 60 meters. A cluster of moorings was placed at the intersection of the two paths to create a dense sensor-populated area to measure a 3-dimensional physical oceanography. Environmental moorings were deployed along both along-shelf and across-shelf paths to measure the physical oceanography along those paths. Moorings with acoustic sources were placed at the outer ends of the “T” to propagate various signals along these paths. Five single hydrophone receivers were positioned on the across shelf path and a vertical and horizontal hydrophone array was positioned at the intersection of the “T” to get receptions from all the acoustics assets that were used during SW06.

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.

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