Autochthony and isotopic niches of benthic fauna at shallow-water hydrothermal vents

Abstract

The food webs of shallow-water hydrothermal vents are supported by chemosynthetic and photosynthetic autotrophs. However, the relative importance of these two basal resources for benthic consumers and its changes along the physicochemical gradient caused by vent plumes are unknown. We used stable carbon and nitrogen isotopes (i.e., δ13C and δ15N) and Bayesian mixing models to quantify the dietary contribution of basal resources to the benthic fauna at the shallow-water vents around Kueishan Island, Taiwan. Our results indicated that the food chains and consumer production at the shallow-water vents were mainly driven by photoautotrophs (total algal contribution: 26–54%) and zooplankton (19–34%) rather than by chemosynthetic production (total contribution: 14–26%). Intraspecific differences in the trophic support and isotopic niche of the benthic consumers along the physicochemical gradient were also evident. For instance, sea anemone Anthopleura sp. exhibited the greatest reliance on chemosynthetic bacteria (26%) and photoautotrophs (66%) near the vent openings, but zooplankton was its main diet in regions 150–300 m (32–49%) and 300–700 m (32–78%) away from the vent mouths. The vent-induced physicochemical gradient structures not only the community but also the trophic support and isotopic niche of vent consumers.

Shallow-water hydrothermal vent system as an extreme proxy for discovery of microbiome significance in a crustacean holobiont

“…Similar results were reported for water and sediment samples collected from the Kueishan Island vent area, which were dominated by Sulfurovum (Wang et al, 2015;Yang et al, 2016;Wang et al, 2017). According to stable isotope analysis, the bacteria samples from the vent crab's carapace and the surrounding water did not differ in 13 C and 15 N levels, which might be potentially cognate (Wang et al, 2022). Additionally, plenty of white-colored biofilms are growing on the biotic (crab carapace, gastropod shell, algae) and abiotic surfaces (sediment, rock, or artificial fragment) in the underwater environments of Kueishan Island, which are usually fed by HV metazoans, including X. testudinatus.…”

“…Furthermore, the occurrence of photosynthesis in shallow-water HV systems may result in additional primary productivity, and higher species diversity than that found in deep-sea HV systems (Tarasov et al, 2005). Algae are one of the common species found in the Kueishan Island shallow-water HV system, which may also serve as an important energy source, followed by bacterial chemosynthesis (Chan et al, 2016;Wang et al, 2022). Additionally, 13 species of mollusks inhabit the vent area, the majority of which are grazers that feed on algae and biofilms (Chen et al, 2018a).…”

Differential feeding habits of the shallow-water hydrothermal vent crab Xenograpsus testudinatus correlate with their resident vent types at a scale of meters

“…In 2014, crabs from one vent influenced by both WV and YV and three peripheral sites (150-300 m) presented a wide range of δ 13 C (-20.5 to -14.3 ‰) and δ 15 N (3.2 to 9.8 ‰) values (Wang et al, 2022). Insignificant differences were found in both δ 13 C and δ 15 N values of vent crabs among the four sites.…”

“…In YV, it only had periphyton for 77 %. Chan et al (2016) and Wang et al (2022) reported along a 50 m transect line from two sites near vent mouths of WV and YV, only 5 % of the substrate was covered with encrusting red algae Hildenbrandia spp. and three red turf algae.…”

“…A trophic study by δ 13 C and δ 15 N analysis reveals that dead zooplankton killed by sulfur plumes (as plankton-derived production) is essential to scavengers and carnivores (Chang et al, 2018;Wang et al, 2014;Wu et al, 2021). The importance of dead zooplankton to vent crabs decreases from vent center to periphery accordingly (Wang et al, 2022). Furthermore, vent crabs collected from YV had significantly more depleted δ 13 C and δ 15 N values than those in WV (Wu et al, 2021).…”