Life beneath the ice: jellyfish and ctenophores from the Ross Sea, Antarctica, with an image-based training set for machine learning

Abstract

Southern Ocean ecosystems are currently experiencing increased environmental changes and anthropogenic pressures, urging scientists to report on their biodiversity and biogeography. Two major taxonomically diverse and trophically important gelatinous zooplankton groups that have, however, stayed largely understudied until now are the cnidarian jellyfish and ctenophores. This data scarcity is predominantly due to many of these fragile, soft-bodied organisms being easily fragmented and/or destroyed with traditional net sampling methods. Progress in alternative survey methods including, for instance, optics-based methods is slowly starting to overcome these obstacles. As video annotation by human observers is both time-consuming and financially costly, machine-learning techniques should be developed for the analysis of in situ /in aqua image-based datasets. This requires taxonomically accurate training sets for correct species identification and the present paper is the first to provide such data. In this study, we twice conducted three week-long in situ optics-based surveys of jellyfish and ctenophores found under the ice in the McMurdo Sound, Antarctica. Our study constitutes the first optics-based survey of gelatinous zooplankton in the Ross Sea and the first study to use in situ / in aqua observations to describe taxonomic and some trophic and behavioural characteristics of gelatinous zooplankton from the Southern Ocean. Despite the small geographic and temporal scales of our study, we provided new undescribed morphological traits for all observed gelatinous zooplankton species (eight cnidarian and four ctenophore species). Three ctenophores and one leptomedusa likely represent undescribed species. Furthermore, along with the photography and videography, we prepared a Common Objects in Context (COCO) dataset, so that this study is the first to provide a taxonomist-ratified image training set for future machine-learning algorithm development concerning Southern Ocean gelatinous zooplankton species.

Optical observations and spatio-temporal projections of gelatinous zooplankton in the Fram Strait, a gateway to a changing Arctic Ocean

“…Namely, B. bouilloni, which is a true deep-sea Arctic species, was found in the lowest temperature conditions and deeper depths. In contrast, S. bitentaculata, which is a cosmopolitan species (although it has been suggested it may be actually composed of multiple cryptic species; (Lindsay et al, 2017;Verhaegen et al, 2021), was found across a wider temperature and depths ranges.…”

Vertical structure characterization of acoustically detected zooplankton aggregation: a case study from the Ross Sea

“…The A4 area sub-system was different from the other areas showing a completely different arrangement of chemicals and biological variables (Bolinesi et al, 2020). Zooplankton is the most important factor in regulating food web dynamics and ecological interactions in the Ross Sea (Hopkins, 1987;Saino and Guglielmo, 2000;Ainley et al, 2010;Ainley et al, 2015;Minutoli et al, 2017;Smith et al, 2017;Kiko et al, 2020) with gelatinous zooplankton, comprising jellyfish, ctenophores and chordate tunicates (Pagès, 1997), showing a ubiquitous behavior (Richardson et al, 2009;Schaub et al, 2018;Verhaegen et al, 2021). Nonetheless, zooplankton abundance varies greatly over the continental shelf and its assemblages, beyond copepods, are mainly composed by fish larvae, euphausiids, hyperiid and gammarid amphipods, pteropods, chaetognaths, and ostracods (Guglielmo et al, 1990;Guglielmo et al, 1992;Hecq et al, 1992;Hunt et al, 2008;Stevens et al, 2015;Smith et al, 2017;Granata et al, 2022;Kim et al, 2022).…”

Accelerating ocean species discovery and laying the foundations for the future of marine biodiversity research and monitoring

“…the deep sea; Glover et al, 2018;Hughes et al, 2021; or polar marine ecosystems; e.g. Brandt et al, 2007;Verhaegen et al, 2021;Ramirez-Llodra et al, 2022). Only small fractions of many deep-sea ecosystems have been explored by biologists (Ramirez-Llodra et al, 2011;Rogers, 2015); with the deep pelagic being a particular challenge (Webb et al, 2010) because of its size, remoteness and the fragile nature of the organisms that inhabit it making them difficult to sample (e.g.…”