Trophic importance of meiofauna to polychaetes in a seagrass (Zostera marina) bed as traced by stable isotopes

Stable carbon and nitrogen isotope ratios of benthic invertebrates and their potential food sources, such as suspended particulate organic matter (POM), benthic microalgae, attached algae and seagrass, were identified in Dong-dae Bay during the winter. The carbon stable isotope ratios demonstrate that filter feeders, such as oysters (−19.5 ± 1.0‰), use benthic microalgae (−21.2 ± 0.2‰) as a major food, and polychaetes such as Glycera spp. (−14.0 ± 0.6 ‰) preferentially use meiofauna, such as nematodes (−14.0 ± 0.4‰) and copepods (−13.3 ± 1.0‰). These meiofauna may feed on mixed resources (including bacteria) with the isotope ratios between benthic microalgae (−21.2 ± 0.2‰) and seagrass (−9.3 ± 01.0‰). These findings are consistent with the trophic enrichment in the nitrogen isotope ratios (by 3–4‰) between consumers and food sources. Moreover, the results of the MixSIR model based on the observed isotope ratios suggest a large seagrass contribution to the food sources of benthic organisms such as meiofauna (~53.7–62.6%) and macrobenthos (~41.1–68%) through the food web. This model additionally suggests a relatively large contribution of benthic microalgae to the food sources of filter feeders (i.e. 26.4% for oysters).

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Stable-isotope and electron-microscopic evidence that cyamids (Crustacea: Amphipoda) feed on whale skin

Canadian Journal of Zoology ◽

10.1139/z99-249 ◽

2000 ◽

Vol 78 (5) ◽

pp. 721-727 ◽

Cited By ~ 13

Author(s):

Donald M Schell ◽

Victoria J Rowntree ◽

Carl J Pfeiffer

Keyword(s):

Stable Isotope ◽

Food Source ◽

Nitrogen Isotope ◽

Isotope Ratios ◽

Observational Evidence ◽

Food Sources ◽

Stable Carbon ◽

Electron Microscopic ◽

Carbon And Nitrogen ◽

Trophic Enrichment

Cyamids (Crustacea: Amphipoda) are found only on whales. Observational evidence and the morphology of the mouthparts have indicated that whale skin is the primary food for these organisms. It has also been suggested, however, that the cyamids may be feeding on epidermal diatoms and meiofauna associated with the skin or using the whales as transport to regions of high zooplankton densities, where small pelagic organisms are captured while the whales feed. Here we report electron-microscopic and isotopic evidence that whale skin was ingested and assimilated by cyamids. Stable carbon and nitrogen isotope ratios of cyamids and whale skin from six species of whales were compared with those of zooplankton from the regions through which the whales migrate, to infer the most likely food sources. In all cases, cyamid isotope ratios closely matched those of the whale skin and not those of the zooplankton, again indicating that whale skin was the predominant food source. Unlike most other carnivorous organisms, cyamids do not show a trophic enrichment of δ15N, a trait also found in other species of Amphipoda.

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TRANSFER EFFICIENCY FROM PRIMARY PRODUCERS TO RUDITAPES PHILIPPINARUM ON AN INTERTIDAL FLAT IN HIROSHIMA BAY, JAPAN

Proceedings of International Conference "Managinag risks to coastal regions and communities in a changinag world" (EMECS'11 - SeaCoasts XXVI) ◽

10.31519/conferencearticle_5b1b93b4af8c32.73166623 ◽

2017 ◽

Author(s):

Sosuke Otani ◽

Akira Umehara ◽

Haruka Miyagawa ◽

...

Keyword(s):

Stable Isotope ◽

Secondary Production ◽

Isotope Ratios ◽

Ruditapes Philippinarum ◽

Transfer Efficiency ◽

Food Sources ◽

Stable Isotope Ratios ◽

Primary Producers ◽

Nitrogen Stable Isotope ◽

Carbon And Nitrogen

Fish yields of Ruditapes philippinarum have been decreased and the resources have not yet recovered. It needs to clarify food sources of R. philippinarum, and relationship between primary and secondary production of it. The purpose on this study is to reveal transfer efficiency from primary producers to R. philippinarum and food sources of R. philippinarum. The field investigation was carried out to quantify biomass of R. philippinarum and primary producers on intertidal sand flat at Zigozen beach in Hiroshima Bay, Japan. In particular, photosynthetic rates of primary producers such as Zostera marina, Ulva sp. and microphytobenthos were determined in laboratory experiments. The carbon and nitrogen stable isotope ratios for R. philippinarum and 8 potential food sources (microphytobenthos, MPOM etc) growing in the tidal flat were also measured. In summer 2015, the primary productions of Z. marina, Ulva sp. and microphytobenthos were estimated to be 70.4 kgC/day, 43.4 kgC/day and 2.2 kgC/day, respectively. Secondary production of R. philippinarum was 0.4 kgC/day. Contribution of microphytobenthos to R. philippinarum as food source was 56-76% on the basis of those carbon and nitrogen stable isotope ratios. Transfer efficiency from microphytobenthos to R. philippinarum was estimated to be 10-14%. It was suggested that microphytobenthos might sustain the high secondary production of R. philippinarum, though the primary production of microphytobenthos was about 1/10 compared to other algae.

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