Feeding in spatangoids: the case of Abatus cordatus in the Kerguelen Islands (Southern Ocean)

• Published in: Polar Biology
• Main Authors: Pascal, Pierre-Yves, Reynaud, Yann, Poulin, Elie, de Ridder, Chantal, Saucède, Thomas
• Other Authors: Institut de Systématique, Evolution, Biodiversité (ISYEB ), Muséum national d'Histoire naturelle (MNHN)-École Pratique des Hautes Études (EPHE), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Institut Pasteur de la Guadeloupe, Réseau International des Instituts Pasteur (RIIP), Laboratorio de Ecología Molecular, Departamento de Ciencias Ecológicas, Universidad de Chile = University of Chile Santiago (UCHILE)-Universidad de Chile = University of Chile Santiago (UCHILE), Laboratoire de Biologie Marine (LBM), Université libre de Bruxelles (ULB), Biogéosciences UMR 6282 (BGS), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Program PROTEKER (No. 1044) of the French Polar Institute, LTSER Zone ATelier Antarctique (ZATA, France), and support of the National Nature Reserve of the French Southern Territories and its staff and from Chilean PIA CONICYT ACT172065., Metabarcoding sequencing performed at Biomics Platform, C2RT, Institut Pasteur, Paris, France, supported by France Génomique (ANR-10-INBS-09-09) and IBISA.
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: Irregular sea urchin; Selectivity; Deposit feeding; Ingestion rate; Meiofauna; Nematode; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; [SDV.AEN]Life Sciences [q-bio]/Food and Nutrition; [SDV.BA.ZI]Life Sciences [q-bio]/Animal biology/Invertebrate Zoology; Antarctic; Southern Ocean; Kerguelen; Kerguelen Islands; Antarc*; Polar Biology
• Online Access: https://hal.science/hal-03235875; https://hal.science/hal-03235875/document; https://hal.science/hal-03235875/file/POBI-S-20-00089-2.pdf; https://doi.org/10.1007/s00300-021-02841-4

14 pages International audience Irregular urchins exclusively live in marine soft bottom habitats, dwelling either upon or inside sediments and selectively picking up sediment grains and organic particles, or swallowing bulk sediment to feed on the associated organic matter. The exact food source and dietary requirements of most irregular echinoids, however, remain incompletely understood. The schizasterid species Abatus cordatus (Verrill, 1876) is a sub-Antarctic spatangoid that is endemic to the Kerguelen. The feeding behaviour of A. cordatus was investigated using simultaneously metabarcoding and stable isotope approaches. Comparison of ingested and surrounding sediments by metabarcoding revealed a limited selective ingestion of prokaryotes and eukaryotes by the urchin. Compared to surrounding sediments, the gut content had (i) higher carbon and nitrogen concentrations potentially due to selective ingestion of organic matter and/or the sea urchin mucus secretion and (ii) δ15N enrichment due to the selective assimilation of lighter isotope in the gut. Feeding experiments were performed using 13C and 15 N-enriched sediments in aquariums. The progression of stable isotope enrichment in proximal and distal parts of the digestive track of A. cordatus revealed that all particles are not similarly transported likely due to siphon functioning. Ingestion of water with associated dissolved and particulate organic matter should play an important role in urchin nutrition. A. cordatus had a gut resident time fluctuating between 76 and 101 h and an ingestion rate of 36 mg dry sediment h−1 suggesting that dense populations of the species may play a key ecological role through bioturbation in soft bottom shallow-water habitats of the Kerguelen Islands.