MEPS 622:49-65 (2019)  -  DOI: https://doi.org/10.3354/meps13053

ABSTRACT: Deep-sea hydrothermal vents host unique marine ecosystems that rely on organic matter produced by chemoautotrophic microbes together with phytodetritus. Although meiofauna can be abundant at such vents, the small size of meiofauna limits studies on nutritional sources. Here we investigated dietary sources of meio- and macrofauna at hydrothermal vent fields in the western North Pacific using stable carbon and nitrogen isotope ratios (δ¹³C, δ¹⁵N) and natural-abundance radiocarbon (Δ¹⁴C). Bacterial mats and Paralvinella spp. (polychaetes) collected from hydrothermal vent chimneys were enriched in ¹³C (up to -10‰) and depleted in ¹⁴C (-700 to -580‰). The δ¹³C and Δ¹⁴C values of dirivultid copepods, endemic to hydrothermal vent chimneys, were -11‰ and -661‰, respectively, and were similar to the values in the bacterial mats and Paralvinella spp. but distinct from those of nearby non-vent sediments (δ¹³C: ~-24‰) and water-column plankton (Δ¹⁴C: ~40‰). In contrast, δ¹³C values of nematodes from vent chimneys were similar to those of non-vent sites (ca. -25‰). Results suggest that dirivultids relied on vent chimney bacterial mats as their nutritional source, whereas vent nematodes did not obtain significant nutrient amounts from the chemolithoautotrophic microbes. The Δ¹⁴C values of Neoverruca intermedia (vent barnacle) suggest they gain nutrition from chemoautotrophic microbes, but the source of inorganic carbon was diluted with bottom water much more than those of the Paralvinella habitat, reflecting Neoverruca’s more distant distribution from active venting. The combination of stable and radioisotope analyses on hydrothermal vent organisms provides valuable information on their nutritional sources and, hence, their adaptive ecology to chemosynthesis-based ecosystems.

KEY WORDS: Meiofauna · Dirivultid copepods · Nematodes · Paralvinella · Neoverruca · Nutrition · Natural-abundance radiocarbon · Stable carbon and nitrogen isotope ratios

Full text in pdf format Supplementary material

Cite this article as: Nomaki H, Uejima Y, Ogawa NO, Yamane M and others (2019) Nutritional sources of meio- and macrofauna at hydrothermal vents and adjacent areas: natural-abundance radiocarbon and stable isotope analyses. Mar Ecol Prog Ser 622:49-65. https://doi.org/10.3354/meps13053 Export citation Share:    Facebook - - linkedIn