AB 23:201-208 (2015)  -  DOI: https://doi.org/10.3354/ab00621

ABSTRACT: Otolith carbon isotope δ¹³C values may provide temporally resolved diet proxies in fish. If otolith δ¹³C values reflect diet, isotope values from recent otolith and muscle tissue should correlate and known ontogenetic diet shifts should be reflected in comparisons between otolith material deposited during different life history stages. We analyzed paired otolith and muscle samples for δ¹³C from black rockfish Sebastes melanops to examine the potential of otoliths to reflect diet in small (200-299 mm fork length) and large (≥300 mm) fish. We found a significant positive regression between δ¹³C values from recent (~12 mo) otolith material and muscle in large fish, but not in small fish. Within individual otoliths, δ¹³C values were enriched by ~3‰ in recent otolith edge material compared to age-0 otolith core material and were consistent with known nearshore-offshore gradients in δ¹³C values at the base of the food web. Bulk otolith δ¹³C appeared to provide a broad indicator of dietary carbon sources, but variation in metabolism and dissolved inorganic carbon δ¹³C among and within individuals likely influences otolith δ¹³C as well and limits precision. Nevertheless, the results are promising and bulk otolith δ¹³C may be an appropriate tool to examine large trophic and ecosystem level shifts that have occurred concurrently with changes in habitat, commercial fishing, invasive species, climate change, and other direct or indirect human impacts using historic or ancient otoliths. Future studies should continue to consider the utility of bulk otolith δ¹³C to describe diet in other marine fish using this simple approach.

KEY WORDS: Food web · Carbon isotopes · Stable isotope · Nearshore · Kelp · Micromill

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Cite this article as: von Biela VR, Newsome SD, Zimmerman CE (2015) Examining the utility of bulk otolith δ13C to describe diet in wild-caught black rockfish Sebastes melanops. Aquat Biol 23:201-208. https://doi.org/10.3354/ab00621 Export citation Share:    Facebook - - linkedIn