TY - JOUR
T1 - Elucidating carbon sources of hydrothermal vent animals using natural 14C abundances and habitat water temperature
AU - Nomaki, Hidetaka
AU - Chen, Chong
AU - Ogawa, Nanako O.
AU - Miyairi, Yosuke
AU - Ohkouchi, Naohiko
AU - Makabe, Akiko
AU - Kawagucci, Shinsuke
AU - Yokoyama, Yusuke
AU - Shimanaga, Motohiro
N1 - Publisher Copyright:
© 2024 The Authors. Limnology and Oceanography published by Wiley Periodicals LLC on behalf of Association for the Sciences of Limnology and Oceanography.
PY - 2024/5
Y1 - 2024/5
N2 - Deep-sea hydrothermal vents host exceptional ecosystems with lush animal communities primarily relying on organic matter (OM) produced by chemoautotrophic microbes. Though energy sources and food webs at vents have been extensively studied, the exact carbon sources of chemosynthetic primary production, such as methane (CH4) and carbon dioxide (CO2) in the vent fluid or bottom water, have not been elucidated quantitatively across spatial scales. Here, we investigate carbon and nitrogen sources of 12 vent animal species at the Iheya North field, Okinawa Trough inhabiting different distances from the central venting area and with various feeding ecologies using natural-abundance radiocarbon (Δ14C) in combination with conventional stable carbon and nitrogen isotope ratios (δ13C and δ15N). Our results show that generally, animals living closer to vent orifices were more depleted in 14C, indicating they assimilate more carbon from vent fluid CO2. Those relying on methanotrophs, however, exhibited low Δ14C values regardless of distance due to the lack of methane in the non-vent-influenced bottom water. Organisms with low Δ14C values also tend to exhibit low δ15N values, implying NH4+ assimilation into biomass in environments with high NH4+ concentrations. Our results demonstrate that 14C can clearly distinguish between chemoautotrophically fixed carbon originating from the vent fluid and detrital OM derived from surface primary production, and also discriminate between CO2- and CH4-based chemoautotrophy. Although vent animals rely on vent fluid energetically, our results highlight that the dependency on vent fluids as carbon source varies greatly depending on habitat, as well as carbon fixation pathways of microbial primary producers.
AB - Deep-sea hydrothermal vents host exceptional ecosystems with lush animal communities primarily relying on organic matter (OM) produced by chemoautotrophic microbes. Though energy sources and food webs at vents have been extensively studied, the exact carbon sources of chemosynthetic primary production, such as methane (CH4) and carbon dioxide (CO2) in the vent fluid or bottom water, have not been elucidated quantitatively across spatial scales. Here, we investigate carbon and nitrogen sources of 12 vent animal species at the Iheya North field, Okinawa Trough inhabiting different distances from the central venting area and with various feeding ecologies using natural-abundance radiocarbon (Δ14C) in combination with conventional stable carbon and nitrogen isotope ratios (δ13C and δ15N). Our results show that generally, animals living closer to vent orifices were more depleted in 14C, indicating they assimilate more carbon from vent fluid CO2. Those relying on methanotrophs, however, exhibited low Δ14C values regardless of distance due to the lack of methane in the non-vent-influenced bottom water. Organisms with low Δ14C values also tend to exhibit low δ15N values, implying NH4+ assimilation into biomass in environments with high NH4+ concentrations. Our results demonstrate that 14C can clearly distinguish between chemoautotrophically fixed carbon originating from the vent fluid and detrital OM derived from surface primary production, and also discriminate between CO2- and CH4-based chemoautotrophy. Although vent animals rely on vent fluid energetically, our results highlight that the dependency on vent fluids as carbon source varies greatly depending on habitat, as well as carbon fixation pathways of microbial primary producers.
UR - http://www.scopus.com/inward/record.url?scp=85191164932&partnerID=8YFLogxK
U2 - 10.1002/lno.12570
DO - 10.1002/lno.12570
M3 - Article
SN - 0024-3590
VL - 69
SP - 1270
EP - 1284
JO - Limnology and Oceanography
JF - Limnology and Oceanography
IS - 5
ER -