Muriel Dunn

Muriel Dunn

I study ocean acoustics and fisheries sciences. I am interested in oceanographic instrumentation, physics and the ocean.

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Pages

Posts

The Arctic after dark: a secret world of hidden life

less than 1 minute read

Published:

Article about Deep Impact campaign in Svalbard in January 2023 published in Nature written by journalist, Randall Hyman. I was part of a large campaign studying the effects of the polar night on various arctic ocean species. My PhD research with mesocosm (AZKABAN/AFKABAN) is summarized.

portfolio

AZKABAN-light 2022

During my PhD I lead a field campaign, AZKABAN-light (Arrested Zooplankton Kept Alive for Broadband Acoustic Net light experiment) during which we built a purpose-built mesocosm species for acoustic experiments in Ny-Ålesund, Svalbard during the polar night in January 2022. Fieldwork collaboration with Chelsey McGowan-Yallop and Stig Falk-Petersen. Photo taken by Malin Daase.

Master’s fieldwork 1

The frame before being deployed for a month in the Bay of Fundy and the team who help deploy, prepare and build it. Grand Passage, September 2018. (Left to right: Len Zedel, Greg Trowse, Mark Downey, Muriel Dunn and Richard Cheel.)

Drifter fieldwork

Deploying eight drifters to study tidal currents and estuarine residence times in Grappler Inlet, Bamfield, BC during Bachelor final year project (February 2015). Left to right: Muriel Dunn and Mark Halverson.

publications

Development of acoustic Doppler fish monitoring for applications in high-energy tidal channels

Published in Underwater acoustics conference and exhibition, 2019

Detecting fish in ADCP measurements using coninciding incidences of high phase correlation and high intensity.

Recommended citation: Dunn, M., Zedel, L., Trowse, G. (2019). "Development of acoustic Doppler fish monitoring for applications in high-energy tidal channels". UACE2019-Conference Proceedings. https://www.uaconferences.org/docs/Past_Proceedings/UACE2019_Proceedings.pdf

Developments in fish detection using broadband acoustic doppler current profiler

Published in Memorial University of Newfoundland Library, 2019

This thesis presents results from a 600 kHz RD Instruments Workhorse ADCP alongside a 120 kHz BioSonics DTX Submersible Split-Beam Echosounder system and contrasts their capabilities in the context of fish monitoring in high-energy tidal channels.

Recommended citation: Dunn, M., 2019. Developments in fish detection using broadband acoustic doppler current profiler (Masters dissertation, Memorial University of Newfoundland). https://research.library.mun.ca/14340/1/thesis.pdf

Report - Data from the BREA-MFP and CBS-MEA research programs describing the Anguniaqvia niqiqyuam Marine Protected Area (ANMPA) ecosystem

Published in Canadian data report of fisheries and aquatic sciences, 2020

The conservation objectives of the Anguniaqvia niqiqyuam Marine Protected Area (ANMPA) focus on maintaining the integrity of marine habitats offshore of the Cape Parry Migratory Bird Sanctuary that support populations of key species, such as beluga whales, Arctic Char, and ringed and bearded seals. This report provides ecosystem-level scientific knowledge to support the development of monitoring objectives and activities.

Recommended citation: Niemi, A., Majewski, A., et al. (including Dunn, M.) (2020). Data from the BREA-MFP and CBS-MEA research programs describing the Anguniaqvia niqiqyuam Marine Protected Area (ANMPA) ecosystem. Can. Data Rep. Fish. Aquat. Sci. 1316: ix + 90 p. https://publications.gc.ca/site/eng/9.892324/publication.html

Inverse method applied to autonomous broadband hydroacoustic survey detects higher densities of zooplankton in near-surface aggregations than vessel-based net survey

Published in Canadian Journal of Fisheries and Aquatic Sciences, 2023

This paper presents the inverse method applied to broadband autonomous acoustic surveys. We conclude the inverse method can improve density estimates of epipelagic organisms by diminishing avoidance biases and increasing the spatio-temporal resolution of ship-based surveys.

Recommended citation: Dunn, M., Pedersen, G., Basedow, S.L., Daase, M., Falk-Petersen, S., Bachelot, L., Camus, L. and Geoffroy, M., 2022. Inverse method applied to autonomous broadband hydroacoustic survey detects higher densities of zooplankton in near-surface aggregations than vessel-based net survey. Canadian Journal of Fisheries and Aquatic Sciences. https://doi.org/10.1139/cjfas-2022-0105 https://cdnsciencepub.com/doi/abs/10.1139/cjfas-2022-0105

A Digital Twin of the Trondheim Fjord for Environmental Monitoring—A Pilot Case

Published in Journal of Marine Science and Engineering, 2024

This paper presents the results of a Water Quality DTO pilot located in the Trondheim fjord in Norway. This paper details the building blocks of DTO, specific to this environmental monitoring pilot.

Recommended citation: Vasilijevic, A., Brönner, U., Dunn, M., García-Valle, G., Fabrini, J., Stevenson-Jones, R., ... & Nepstad, R. (2024). A Digital Twin of the Trondheim Fjord for Environmental Monitoring—A Pilot Case. Journal of Marine Science and Engineering, 12(9), 1530. https://doi.org/10.3390/jmse12091530

Extreme mismatch between phytoplankton and grazers during Arctic spring blooms and consequences for the pelagic food-web

Published in Progress in Oceanography, 2024

we surveyed the pelagic ecosystem of the Barents Sea Polar Front in May of two consecutive years (2021 and 2022) to investigate the pelagic food-web from primary producers to planktivorous fish.

Recommended citation: Renaud, P. E., Daase, M., Leu, E., Geoffroy, M., Basedow, S., Inall, M., ... & Gradinger, R. (2024). Extreme mismatch between phytoplankton and grazers during Arctic spring blooms and consequences for the pelagic food-web. Progress in Oceanography, 229, 103365. https://doi.org/10.1016/j.pocean.2024.103365

Broadband acoustic classification of Atlantic cod, polar cod, and northern shrimp in in situ mesocosm experiments

Published in Fisheries Research, 2025

This paper presents machine learning classification of target strength spectra shape collected from mesocosm experiments for northern shrimp, Atlantic cod and polar cod.

Recommended citation: Muriel Dunn, Geir Pedersen, Malin Daase, Jørgen Berge, Emily Venables, Sünnje L. Basedow, Stig Falk-Petersen, Tom J. Langbehn, Jenny Jensen, Lionel Camus, Maxime Geoffroy, Broadband acoustic classification of Atlantic cod, polar cod, and northern shrimp in in situ mesocosm experiments, Fisheries Research, 286, 2025, 107388, https://doi.org/10.1016/j.fishres.2025.107388. https://doi.org/10.1016/j.fishres.2025.107388

talks

Sensor fusion for rapid biomass estimates of Calanus sound scattering layer.

Published:

Rapid and automated estimates of zooplankton biomass within a sound scattering layer could validate satellite observations, optimize catch potential for Calanus finmarchicus harvesters and provide an indicator for ocean health. Instruments commonly used for non-lethal monitoring of zooplankton in the ocean, namely acoustics and optical sensors, each have inherent strengths and weaknesses. Utilizing both methods together leverages the advantages of each whilst minimizing each sensor’s limitations. We developed a near real-time sound scattering layer (SSL) detector based on thresholding and mathematical morphology of echograms. A detected SSL triggers a submersible platform mounted with an optical sensor to investigate the SSL for a size and composition estimate of the particles. This data pipeline is instrument- and platform agnostic. We will present two case studies: the first with a marine observatory buoy with a profiling frame, and the second with an uncrewed surface vehicle and an autonomous underwater vehicle. We present results for the data pipeline tested for sound scattering layers dominated by Calanus finmarchicus where a sound scattering model is used to estimate the target strength of the average copepod detected for a rapid biomass estimate. The solution is planned to be leveraged in a Digital Twins of the ocean demonstrator for plankton monitoring.

Muriel Dunn, Ralph Stevenson-Jones, Emlyn Davies, Raymond Nepstad, Ute Brönner.

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teaching

Physics Lab Course - Teachers Assistant

Course, University of British Columbia, 2014

Teacher’s assistant for enriched physics lab classes for first-year bachelor students. The students explored physics and statistical analysis through experiments and coding. I insturcted and guided students to an understanding of physics through socratic questioning. I marked lab assignments and provided feedback.

Software Carpentries Shell/Git/Python

Workshop, University of Bergen (online), 2021

This 5-day workshop covered Git, Unix Shell and Plotting and Programming with Python I, II and III with hands-on teaching.