Stable isotope ratios indicate differential omnivory among syntopic rocky shore suspension-feeders

Richoux, Nicole B; Vermeulen, Ilke; Froneman, P William

Title: Stable isotope ratios indicate differential omnivory among syntopic rocky shore suspension-feeders
Creator: Richoux, Nicole B
Creator: Vermeulen, Ilke
Creator: Froneman, P William
Date Issued: 2014
Date: 2014
Type: text
Type: article
Identifier: http://hdl.handle.net/10962/68261
Identifier: vital:29224
Identifier: https://doi.org/10.1007/s00227-013-2358-6
Description: Publisher version
Description: We utilised stable isotope ratios to assess differences in diet among three indigenous and syntopic rocky shore suspension-feeders (mussels Perna perna, barnacles Tetraclita serrata, and polychaetes Gunnarea gaimardi). We also determined the spatial and temporal variability in the suspension-feeder diets by collecting specimens on two occasions from two regions adjacent to hydrologically distinct river mouths (i.e. one with larger annual freshwater throughput than the other). The results showed that the isotopic niches (used as proxies for trophic niches) of the three species did not overlap and that the barnacles occupied a trophic position (3.4) well above those of the mussels (2) and polychaetes (2.6). We ascribed the interspecific differences primarily to the disparate feeding mechanisms used by the species. Large-scale regional (~50 km) differences in suspension-feeder diets were apparent, but not small-scale (up to a few km north and south of each estuary mouth). The regional differences in diet resulted from the increased availability of estuarine-origin suspended particulate matter (SPM) and zooplankton in the region adjacent to the river with relatively larger freshwater output, although overall incorporation of zooplankton versus mixed SPM into consumer diets was relatively consistent between regions and through time. Temporal shifts in suspension-feeder diets were apparent from stable carbon isotope ratios in the consumers. Our results showcase the measurable effects of regional-scale processes that can alter the food sources for dominant primary consumers in the rocky intertidal, thus potentially affecting entire food webs through bottom-up processes. The clear evidence for trophic niche partitioning offers valuable insights into how potentially strong competitors can coexist.
Format: 14 pages
Format: pdf
Publisher: Springer Berlin Heidelberg
Language: English
Relation: Marine Biology
Relation: Richoux, N.B., Vermeulen, I. and Froneman, P.W. (2014) Stable isotope ratios indicate differential omnivory among syntopic rocky shore suspension-feeders. Marine Biology, 161: 971. https://doi.org/10.1007/s00227-013-2358-6
Relation: Marine Biology volume 161 number 5 971 984 2014 1432-1793
Rights: Springer-Verlag Berlin Heidelberg
Rights: Use of this resource is governed by the terms and conditions of the National Library of South Africa Copyright Act (http://www.nlsa.ac.za/downloads/Copyright Act.pdf)

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Richoux, Nicole Bertine (Assoc Prof)

Froneman, Pierre William (Prof)

RU Department of Zoology and Entomology

SDG 14. Life Below Water

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