Biodiversity and trophic ecology of hydrothermal vent fauna associated with tubeworm assemblages on the Juan de Fuca Ridge
|Author(s)||Lelievre Yann1, 2, Sarrazin Jozee1, Marticorena Julien1, Schaal Gauthier3, Day Thomas1, Legendre Pierre2, Hourdez Stephane4, 5, Matabos Marjolaine1|
|Affiliation(s)||1 : IFREMER, Ctr Bretagne, REM EEP, Lab Environm Profond, F-29280 Plouzane, France.
2 : Univ Montreal, Dept Sci Biol, CP 6128,Succursale Ctr Ville, Montreal, PQ H3C 3J7, Canada.
3 : UMR 6539 9 CNRS UBO IRD Ifremer, Lab Sci Environm Marin LEMAR, BP 70, F-29280 Plouzane, France.
4 : Sorbonne Univ, Stn Biol Roscoff, UMR7144, F-29680 Roscoff, France.
5 : CNRS, UMR7144, Stn Biol Roscoff, F-29680 Roscoff, France.
|Source||Biogeosciences (1726-4170) (Copernicus Gesellschaft Mbh), 2018-05 , Vol. 15 , N. 9 , P. 2629-2647|
|WOS© Times Cited||7|
Hydrothermal vent sites along the Juan de Fuca Ridge in the north-east Pacific host dense populations of Ridgeia piscesae tubeworms that promote habitat heterogeneity and local diversity. A detailed description of the biodiversity and community structure is needed to help understand the ecological processes that underlie the distribution and dynamics of deep-sea vent communities. Here, we assessed the composition, abundance, diversity and trophic structure of six tubeworm samples, corresponding to different successional stages, collected on the Grotto hydrothermal edifice (Main Endeavour Field, Juan de Fuca Ridge) at 2196 m depth. Including R. piscesae, a total of 36 macrofaunal taxa were identified to the species level. Although polychaetes made up the most diverse taxon, faunal densities were dominated by gastropods. Most tubeworm aggregations were numerically dominated by the gastropods Lepetodrilus fucensis and Depressigyra globulus and polychaete Amphisamytha carldarei. The highest diversities were found in tubeworm aggregations characterised by the longest tubes (18.5 ± 3.3 cm). The high biomass of grazers and high resource partitioning at a small scale illustrates the importance of the diversity of free-living microbial communities in the maintenance of food webs. Although symbiont-bearing invertebrates R. piscesae represented a large part of the total biomass, the low number of specialised predators on this potential food source suggests that its primary role lies in community structuring. Vent food webs did not appear to be organised through predator–prey relationships. For example, although trophic structure complexity increased with ecological successional stages, showing a higher number of predators in the last stages, the food web structure itself did not change across assemblages. We suggest that environmental gradients provided by the biogenic structure of tubeworm bushes generate a multitude of ecological niches and contribute to the partitioning of nutritional resources, releasing communities from competition pressure for resources and thus allowing species to coexist.