Three-dimensional ecological niche modelling of midwater jellyfish
Final Report Abstract
The ocean’s midwater (between the euphotic zone and seafloor) is the largest continuous biome on our planet and is drastically under-sampled. As pelagic ecosystems are being widely acknowledged for their relevance in ecosystem services, our knowledge gap of the midwater is becoming an increasing problem as it hampers our ability to predict how it will be affected by global change and anthropogenic pressures. Gelatinous zooplankton dominate the midwater trophic web, playing important roles, e.g., as filter feeders and predators. Thus, during this project, we used ecological niche modelling in three dimensions (3D) to answer fundamental questions regarding their ecology, distribution, diversity, and differentiation processes. The main difficulty of the project was the time invested in collecting occurrence data of midwater jellyfish from analysing underwater videos or from online biogeographic databases. This resulted in a trade-off between the number of species investigated vs. the size of the studied regions. Therefore, on a global scale, ecological niche models were only conducted for one narcomedusa genus, Solmissus, whereas models restricted to the Arctic Ocean allowed for the investigation of multiple gelatinous zooplankton taxa. We found that the relative importance of the limiting environmental factors where highly depending on the taxa, but also on the geographical region considered. As hypothesised, temperature, salinity, and depth were important drivers in the distribution of midwater gelatinous zooplankton. However, on a global scale, dissolved oxygen was the main limiting factor in the distribution of the widespread genus Solmissus, with high occurrence probabilities found at low dissolved oxygen values. These results suggested that Solmissus spp. will likely come out as climate change winner by expanding its distribution when facing ocean deoxygenation. By coupling the models with near-future projections, we also found that arctic midwater gelatinous zooplankton communities would become more abundant but less diverse. Regarding differentiation processes, our phylogenetic analyses confirmed that S. incisa represented a complex of several cryptic species. By running separate ecological niche models for the “S.incisa” morphotypes “less than 28 tentacles” and “more than or equal to 28 tentacles”, we found two different niches along a vertical gradient. Thus, depth was considered as a driver in differentiation and speciation processes within midwater jellyfish. Recent efforts to characterise marine pelagic biogeographic regions took place, however we found the distribution of Solmissus morphotypes to be widespread, and to encompass multiple of the mesopelagic ecoregions. Furthermore, all these marine ecoregions, have been delimited on a 2D global scale, and no characterization for the rest of the midwater, under the mesopelagic zone, exist. As we found depth to be a main driver in the distribution of different morphotypes and species, to understand biogeographic midwater processes and highlight biodiversity hotspots, we highly suggest that future midwater ecoregions are delimited as 3D spaces. To conclude, our project showed the importance of including the third dimension when investigating the ecology, distribution, and differentiation processes of midwater gelatinous zooplankton. We further showed the value of ecological niche modelling in 3D coupled to online biogeographic databases including imagery and videography to study the vast and hard-to-sample midwater ecosystem.
Publications
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Life beneath the ice: jellyfish and ctenophores from the Ross Sea, Antarctica, with an image-based training set for machine learning. Biodiversity Data Journal, 9.
Verhaegen, Gerlien; Cimoli, Emiliano & Lindsay, Dhugal
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“11. FRAMJELLY – Gelatinous zooplankton in the gateway to the Arctic: advanced methods to study their diversity, distribution, and role in the Fram Strait food web.” In: Soltwedel, T. (Ed.) The Expedition PS126 of the Research Vessel POLARSTERN to the Fram Strait in 2021. Reports on Polar and marine Research 757, 137 pp.
Havermans, C.; Dischereit, A.; Hampe, H.; Merten, V.; Pantiukhin, D.; Verhaegen, G. & Hoving, H-J.
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“5. Marine biology: characterizing jellyfish diversity, distribution, and trophic role across a latitudinal gradient and in underexplored regions of the Southern Ocean (So-Jelly).” In: Gohl, K. (Ed.) Expedition Programme PS134, Expeditionsprogramm Polarstern, 43 pp.
Verhaegen, G.; Soto Àngel, J. J.; Ruiz, M. & Havermans, C.
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Drivers behind the diversity and distribution of a widespread midwater narcomedusa. Limnology and Oceanography, 68(9), 2088-2107.
Verhaegen, Gerlien; Sangekar, Mehul Naresh; Bentlage, Bastian; Hoving, Henk‐Jan; Collins, Allen G. & Lindsay, Dhugal
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Optical observations and spatio-temporal projections of gelatinous zooplankton in the Fram Strait, a gateway to a changing Arctic Ocean. Frontiers in Marine Science, 10.
Pantiukhin, Dmitrii; Verhaegen, Gerlien; Kraan, Casper; Jerosch, Kerstin; Neitzel, Philipp; Hoving, Henk-Jan T. & Havermans, Charlotte
