Echoview user stories
We are pleased to showcase the remarkable research and achievements of Echoview users around the world through our ‘In the Spotlight’ series. This series celebrates their expertise and innovations in hydroacoustics, providing valuable insights and knowledge for the wider Echoview community.
In our latest instalment, we were thrilled to catch up with Dr. Angelee Pavanee Annasawmy, a biological oceanographer currently working at the Fondation pour la Recherche sur la Biodiversité in France. With over 10 years of experience studying micronekton, small fish, crustaceans, and squids ranging from 2 to 20 cm in size that inhabit the deep ocean, Pavanee uses active acoustics as a key tool to investigate their distribution and vertical migration patterns.
Thank you, Pavanee, for giving us an insight into your work and sharing your story with us. We're excited to highlight how your use of Echoview is advancing our understanding of micronekton and their critical role in the ocean ecosystem.
Please describe your key research/project?
I started working with acoustics data during my Master’s 2 project at the University of Montpellier (France) and the University of Cape Town (South Africa). During my former postdoctoral position with John Horne (University of Washington), Christian Reiss (NOAA), George Cutter (NOAA) and Gavin Macaulay (IMR, Aqualyd Limited), I investigated krill distribution, aggregation types, and predatory-prey interactions in the Southern Ocean. I also compared the performance of Nortek Signature100 and Kongsberg SIMRAD EK80 WBAT echosounders fixed on moorings deployed in the Southern Ocean. I started working with Echoview during my postdoc with John Horne.
How has Echoview assisted your research?
I used Echoview for visual inspection of the data, and I used the SHAPES algorithm within Echoview to identify krill aggregations.
Echoview was central to the success and completion of my postdoc.
The krill aggregations were then classified in three clusters based on their echometric values and I used statistical modelling to investigate how the influence of several environmental variables such as current speed and direction and the presence of predators shape the density of these aggregations. The Echoview team was also incredibly helpful and available throughout my postdoc. For example, the team provided support in reading the Nortek Signature100 files for the first time in Echoview.
What have been your key findings?
Three publications have resulted from this project:
Annasawmy, P., Horne, J.K., Reiss, C.S., Cutter, G.R., Macaulay, G.J., 2024 Field comparison of Antarctic krill (Euphausia superba) backscatter and aggregation types using Nortek and SIMRAD echosounders. ICES Journal of Marine Science. fsae093.
https://doi.org/10.1093/icesjms/fsae093
Annasawmy, P., Horne, J.K., Reiss, C.S., Cutter, G.R., Macaulay, G.J., 2023a. Antarctic krill (Euphausia superba) distributions, aggregation structures and predator interactions in Bransfield Strait. Polar Biology. https://doi.org/10.1007/s00300-023-03113-z
Annasawmy, P., Horne, J.K., Reiss, C.S., Macaulay, G.J., 2023b. Characterizing Antarctic air-breathing predator dive patterns on a common prey base from stationary echosounders. Polar Science. 100974. https://doi.org/10.1016/j.polar.2023.100974
In Annasawmy et al. (2024) we showed that the Nortek Signature100 and Kongsberg SIMRAD WBAT have different abilities to detect krill, delineate aggregations, and have different sensitivities to system noise. Although both instruments can be used for autonomous deployment and sampling of krill over extended periods, there is a strong caveat for the use of the Signature100 due to significant differences in noise characteristics and krill detection. We then showed that krill aggregates into 3 distinct types ranging from high to low densities, evenness, and dispersion which are influenced by current velocities and direction (Annasawmy et al., 2023a).
On our echograms, we also saw predator dive profiles and the majority of these dives occurred over the aggregation type with highest krill densities. The heterogeneity of krill aggregations potentially impacts predator foraging strategies and predator–krill interactions in the hydrodynamically active Bransfield Strait.
I then developed a methodology to extract dive metrics from the predator dive profiles visible on our echograms to identify potential predators and their behavioural patterns (Annasawmy et al., 2023b). Dive profiles were classified into four types which could correspond to a wide range of species, including petrels, black-browed albatrosses, Adélie, gentoo, and chinstrap penguins, crabeater seals, and humpback whales showing travelling, exploring, and foraging predator behaviors. These findings were presented during WGFAST conferences in 2021 and 2022, and during lab meetings at the University of Washington.
Dr. Pavanee's innovative research not only deepens our understanding of micronekton and their vital role in marine ecosystems but also exemplifies the powerful ways Echoview can support scientific advancements around the world.
Echoview user story contribution
Do you have an Echoview user story, photo, or anecdote you wish to share? You can participate by emailing us at info@echoview.com.
