hydrothermal vents food web
Petroleum-derived organic matter contributed to vent food webs and was even one of the dominant food sources, especially in the vesicomyid assemblage where all organisms with the exception of vesicomyids may rely on this basal source. This distinct isotopic composition is rarely reported and is comparable with those speculated for free-living chemosynthetic bacteria in deep-sea hydrothermal vents [2,11,34,35]. Plankton and shrimp eat the microbes. . Institute of Biogeosciences, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan, Roles Using stable isotopes and quantitative community characteristics to determine a local hydrothermal vent food web D. Bergquist , J. Eckner , +4 authors C. Fisher Biology chemosynthetic bacteria and amphipods. Hydrothermal vent food webs are mainly based on local microbial chemosynthesis (Childress and Fisher, 1992), performed by free-living or/and symbiotic chemoautotrophic microorganisms that utilise the chemical energy released by the oxidation of reduced chemicals species (H2, H2S, CH4) present in the hydrothermal fluids (Childress and Fisher, 1992). The δ15N values of both surface and bottom POM showed large variations (2 to 4.3‰) among sampling sites (Table 1; Fig 2C and 2D). Discover a faster, simpler path to publishing in a high-quality journal. These are the major levels of an ecosystem, primary producers, primary consumers, secondary consumers, and tertiary consumers. The vent crab X. testudinatus, which is categorized as an omnivorous generalist [18,19,58], exhibited large individual variations in both δ13C and δ15N values, resembling the pattern of Xenograpsus ngatama, which inhabits the shallow hydrothermal vents off the South Tonga Arc . The mean δ13C values of zooplankton and epibenthic crustaceans were higher than those for averaged seawater POM by 2.4 and 3.5‰, respectively. Zooplankton and epibenthic crustaceans, as the fundamental consumers, exhibit δ13C and δ15N values ranging from −21.3 to −19.8‰ and +5.1 to +7.5‰, respectively, and can utilize the vent POM for 38–53% of their diets. Investigation, Among various amino acids, glutamic acid and phenylalanine have been widely accepted as the most useful pair to derive the precise estimation of trophic levels [29,30]. were collected, respectively. Yes The fact that δ15N values for a portion of the crab individuals were even lower than those of the macroalgae verified the limited contribution of macroalgae to the crab’s diet. This study aims to investigate a thorough spectrum of food source utilization, trophic structure, and energy flow in the KST ecosystem. The approach reduces the possible bias in the estimate of diet composition. (Eq 2) Bacterial mats in hydrothermal vent fields (sulfide oxidizing bacteria and other unidentified forms) have been widely and consistently characterized by low δ15N values (ca. The sea snails were generally present with patches of green macroalgae (C. catenata) with A. misera being more abundant than E. contractus. Investigation, Our results indicated that the chemosynthetic and photosynthetic productions contributed nearly equally to the food web. Decisions about food source selection were also influential in the modeling results and a fundamental knowledge of the system is a prerequisite for implementing the mixing model and interpreting the output data . https://doi.org/10.1371/journal.pone.0204753.g002, https://doi.org/10.1371/journal.pone.0204753.t001, https://doi.org/10.1371/journal.pone.0204753.t002. Our isotopic evidence combined with the modeling results demonstrated a widespread contribution of vent POM to the food web. The respective contributions of photosynthetic and chemoautotrophic primary production to benthic and even pelagic communities are poorly understood and a quantitative picture of energy transfer in such ecosystems is required. galatheid crabs and zoarcid fish. Aside from the ingestion of vent POM, the mixing model also indicated that epibenthic crustaceans play a vital role in the crab’s diet, coinciding with the existence of highly active chitinolytic enzymes in the crab’s midgut glands . 1‰ (Fig 3). Competing interests: The authors have declared that no competing interests exist. Species identification was mainly based on a previous survey . The bacteria are able to release the energy in hydrogen sulfide so it can be utilized by organisms living around the vent. The epibenthic crustaceans, which were mainly composed of amphipod, mysida, Euphausiacea, and unidentified species, had δ13C and δ15N values ranging from −20.0 to −19.8‰ and +5.6 to +6.5‰, respectively. Their δ13C values still fell in an extremely large range reported for worldwide marine macroalgae (−3.0 to −35‰) [52,53]. Nov. 21, 2020. The δ13C and δ15N values of green macroalgae (C. catenata) ranged from −22.8‰ to −17.3‰ and from +3.7‰ to +5.7‰, respectively. About half of the diet of epibenthic crustaceans was contributed by vent POM (52–53%) and seawater POM (47–48%) (Table 3). In a land ecosystem, most of the time the primary producers are photosynthetic plants or algae. No, Is the Subject Area "Zooplankton" applicable to this article? Their computed dietary composition was highly consistent across all transects, with equal ingestion of zooplankton and epibenthic crustaceans (ca. Although the green macroalgae sampled from some sites also exhibited high δ13C values, a previous study revealed common yet very limited use of the green algae Ulvophyceae by X. testudinatus, based on its 18S ribosomal DNA libraries of stomach and gut content . No obvious trend in the δ13C variation was observed for the bottom POM samples (Fig 2B). We would also like to thank the editors for their effort and support during the review process and the reviewers for their constructive comments. Corals and sea anemones, which are classified as carnivorous suspension feeders, exhibited comparable δ15N values yet obviously more depleted δ13C values (−19.9 to −20.3‰) than scavenger/detritivores. Detritivores revealed obviously large isotopic variations in terms of spatial scale. Due to the large intra-species isotopic variation (e.g., in crabs), the estimation of dietary compositions was performed for each individual rather than the population. The δ13C values of autotrophic organisms are strongly dependent on (1) isotopic fractionation during biosynthetic processes, and (2) the isotopic composition of inorganic carbon sources [31,36]. Only 5% of the ocean’s floor has been mapped—who know what else we might find down there. Overall, the interpretation of the origin of vent POM enriched in 13C and depleted in 15N is mutually coherent. Tags: Question 7 . Despite their unusual nature, faunas based on chemosynthesis are tied together by food webs similar to those of better-known communities. It is composed of andesitic rocks formed during the subduction of the Philippine Sea plate underneath the Eurasian continent and represents the most westward extension of volcanic activity within the Okinawa Trough  (Fig 1). The discharge of hot, reducing fluids into the cold, oxidized deep sea facilitates the generation of strong redox and temperature gradients, both of which favor the colonization of microbial communities possessing various physiological characteristics. were mainly distributed within 50 to 100 m from the vent center, except for one colony observed at a site 10 m from the vent center in the NW transect. All other life depends on primary producers, and they have the greatest biomass in the community. ~r9����ؙ�YrGEXO�W)��*��Ɯ >���=����&�hժU�A7�r��weM��#��3�蔕�r��;��aﲋ�c�xp��q�ʍ�7~�8����W]����Հ�?>�8|���7�z��͛7��0�z�ߍ?�ݻ�����y����yH. Besides, large differences between the isotope compositions of consumers and diets can further decrease the uncertainty introduced during the selection of specific TDFs . Formal analysis, Although the extent of chemosynthesis in surface water is rarely quantified, our results indicating substantial contribution of vent POM to the zooplankton diet (38 to 46%) strongly suggests that even the pelagic consumers can feed on chemosynthetic production discharged to surface water. This study provides the first quantitative evaluation of chemosynthetic and photosynthetic contributions to the shallow-water hydrothermal vent food web via a thorough isotopic survey of potential food sources and vent-related species with knowledge-based numerical modeling of mixed diets. Particularly, food chain length (FCL) has been suggested to lengthen with increasing productivity [70,71]. The seawater surrounding hydrothermal vents typically contains carbon dioxide , molecular hydrogen, hydrogen sulfide, and methane. Moreover, since zooplankton can be passively transported by currents and tides , lateral export of chemosynthetic energy from the venting area to the adjacent open ocean would be highly possible. Based on gut content analysis and field observations, a previous study concluded that the major dietary source for vent crabs is sunken zooplankton toxified by large amounts of hydrogen sulfide released during a period of strong venting . A total of 38–46% of the zooplankton’s diet was from vent POM. For more information about PLOS Subject Areas, click Department of Geosciences, National Taiwan University, Taipei, Taiwan, ROC, Roles Tube worms, mussels, and clams use the microbes to produce nutrients. The higher dietary consumption of vent POM for epibenthic crustaceans likely resulted from their greater access to the bacterial biomass associated with vent fluids. While zooplankton showed δ13C values distinct from those of crab (mean Δδ13C = 3.8‰, Fig 3), it contributed a proportion of 26 ± 9% to the crab’s diet on average (Fig 5). We used stable isotopes of carbon and nitrogen to examine the diversity of microbial populations consumed as foods at deep‐sea hydrothermal vents. What organisms form the base of the food web at a hydrothermal vent? The large bacterial mats that form actually attract various animals to the vents. Writing – review & editing, Affiliation Citation: Chang N-N, Lin L-H, Tu T-H, Jeng M-S, Chikaraishi Y, Wang P-L (2018) Trophic structure and energy flow in a shallow-water hydrothermal vent: Insights from a stable isotope approach. . For small epibenthic crustaceans, a light trap equipped with a 5-L plastic bottle and a light source was deployed overnight on the seabed of both venting and non-vent areas. The variations in the δ13C value for surface seawater POM decreased with distance from the vent center (Fig 2A). In addition, improved understanding of energy transfer through hydrothermal vent food webs is critical for constructing models of chemical fluxes … marking pens Procedures: 1. The only isotopic data for biofilms in the KST vent field showed an extremely low δ15N value (−1.2‰) but a mid-ranged δ13C value (−21.4‰) , which suggested it had little contribution to benthic consumers (with high δ13C and δ15N values). Hydrothermal Vents Food Web - Christian's Marine Science Page! In this lesson, we learned about what a food web is and what its levels are, and then conducted a food web of a hydrothermal vent. To obtain sufficient sample amounts for isotopic analysis, several individuals of zooplankton and epibenthic crustaceans, or muscle tissue from more than five individuals of sea snail A. misera at the same sites were pooled. Vent crab with mussels and worm tubes (NOAA image) The chemosynthetic vent bacteria are the base of the food chain at hydrothermal vents. The simple mass balance generates δ13C and δ15N values of −8.0‰ and −9.9.
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