Deep-sea whale fall fauna from the Atlantic resembles that of the Pacific Ocean.

Paulo Y G Sumida,Koichi Ara,Yoshihiro Fujiwara,Joan M Alfaro-Lucas,Takashi Toyofuku,Hiroshi Kitazato,Jose A A Perez,Mauricio Shimabukuro,Andre O S Lima,Abilio Soares-Gomes

doi:10.1038/srep22139

Abstract

Whale carcasses create remarkable habitats in the deep-sea by producing concentrated sources of organic matter for a food-deprived biota as well as places of evolutionary novelty and biodiversity. Although many of the faunal patterns on whale falls have already been described, the biogeography of these communities is still poorly known especially from basins other than the NE Pacific Ocean. The present work describes the community composition of the deepest natural whale carcass described to date found at 4204 m depth on Southwest Atlantic Ocean with manned submersible Shinkai 6500. This is the first record of a natural whale fall in the deep Atlantic Ocean. The skeleton belonged to an Antarctic Minke whale composed of only nine caudal vertebrae, whose degradation state suggests it was on the bottom for 5–10 years. The fauna consisted mainly of galatheid crabs, a new species of the snail Rubyspira and polychaete worms, including a new Osedax species. Most of the 41 species found in the carcass are new to science, with several genera shared with NE Pacific whale falls and vent and seep ecosystems. This similarity suggests the whale-fall fauna is widespread and has dispersed in a stepping stone fashion, deeply influencing its evolutionary history.

Highlights

Whale carcasses are considered the largest organic inputs reaching the deep ocean floor in a single event
Separated by thousands of kilometers, this abyssal Southwest Atlantic whale fall is inhabited by many lineages previously only found in the Pacific chemosynthesis-based communities
The area was under the influence of the Antarctic Bottom Water (AABW)[37] with a temperature of 0.4 °C and salinity 34.7

Summary

Introduction

Whale carcasses are considered the largest organic inputs reaching the deep ocean floor in a single event. The “sulfophilic stage” occurs when anaerobic microbial degradation of organic-enriched sediments and the lipid-rich skeleton create high fluxes of reduced compounds, which allow the development of a chemosynthesis-based community[11,12,13,14,15] This stage shows faunal overlap with other deep-sea chemosynthetic communities, such as hydrothermal vents, cold seeps and wood falls[1,10,12,16,17,18,19,20]. Based on this faunal overlap, Smith et al.[16] theorized that whale falls may act as stepping-stones for faunal dispersal among different chemosynthetic communities, and could contribute to the colonization of new habitats separated by hundreds of kilometers (e.g. hydrothermal vents) The advancement in the understanding of these poorly known communities has been mainly due to time-series studies of artificially implanted whale carcasses on the seafloor[1,20,32,33,34,35,36]

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