Hoving, Henk-Jan T. , Hauss, Helena , Freitas, Rui, Hissmann, Karen, Osborn, Karen, Scheer, Stella Luna, Merten, Veronique and Hans, Anna Christina (2019) The role of gelatinous macrozooplankton in deep-sea carbon transport in Cape Verde Cruise No. POS532. . GEOMAR, Kiel, Germany, 38 pp. DOI 10.3289/cr_pos532.

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Abstract

4/2/2019 – 24/2/2019,
Mindelo (Republic of Cape Verde) – Mindelo (Republic of Cape Verde)
DeepC-Jelly
We proposed to test the hypothesis that large gelatinous macrozooplankton (e.g. tunicates,
hydrozoans) are a significant carbon storage in midwater, and a vector for carbon from midwater
to the ocean floor in Cape Verde. To test this hypothesis, we studied 1) the distribution, diversity and abundance of gelatinous organisms in the epi-, meso-, and bathypelagic zone, 2) their role in transporting carbon through the pelagic foodweb to the seafloor and 3) their behavior and associations. We worked in the coastal deep sea off Santo Antão and Fogo as well as in the open ocean at the time series station CVOO and an eddy. A manned submersible was used for mesopelagic surveys, to document the behaviour and associations of deep-sea organisms and to collect living specimens. We performed pelagic video transects, discrete net sampling, and eDNA sampling down to 3000 m. ADCP and CTD transects allowed a detailed reconstruction of the effect of the islands on currents and productivity. To quantify the carbon flux of pelagic foodfalls, we also surveyed the seafloor. Sample and video analysis is still in progress, but first results indicate the impact of the pelagic tunicate Pyrosoma atlanticum, which is an upwelling-favored species largely absent from the oligotrophic open ocean, in the nearshore regions of Cape Verde as well as in the cyclonic eddy sampled. It was also observed on the seafloor and resembles a food source and a habitat in the water column and in the benthos. Specimens of pelagic fauna were collected that allow new species descriptions. New records and a new species for the region were also observed during benthic surveys. The cruise was documented in various outreach activities including national television in Cabo Verde.

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