[en] Rationale:Stable isotope analysis is used to investigate the trophic ecology of organisms and, in order to use samples from archived collections, and it is important to know whether preservation methods alter the results. This study investigates the long-term effects of four preservation methods on sea stars isotopic composition and isotopic niche parameters.Methods:We assessed effects of preservation method (freezing, drying, formaldehyde, ethanol) and duration (0, 1, 3, 6, 9, 12 and 24 months) on the stable isotope ratios of carbon, nitrogen and sulfur of sea star tissues. Isotopic ratios were measured using CF-EA-IRMS. We also monitored the evolution ofcommonly used ecological metrics (isotopic niche parameters) throughout the experiment. Results:Clear changes of δ13C values were observed for samples stored in formaldehyde and ethanol. None of the preservation methods had significant or consistent effects on δ15Nvalues. Formaldehydeinduced a decrease of δ34S values. All these changes could be mitigated using correction factors.Isotopic niches parameters slightly changed over time when computed with δ13C and δ15N values, but inconsistent variations occurred when computed with δ13C and δ34S values.Conclusions: Overall, these results show that preservation may affect the stable isotope ratios of sea stars. Correction factors can be used to mitigate the effects of the preservation method on stable isotope ratios. Isotopic niches parameters are overall unchanged. Consequently, in most cases, museum samples are suitable to calculate isotopic niche parameters.
Hobson KA. Tracing origins and migration of wildlife using stable isotopes: A review. Oecologia. 1999;120(3):314-326. https://doi.org/10.1007/s004420050865
Michener RH, Kaufman L. Stable isotopes ratios as tracers in marine food webs: an update. In: Michener R, Lajtha K, eds. Stable Isotopes in Ecology and Environmental science. Oxford, UK: Blackwell Publishing; 2007:238-282 https://doi.org/10.1002/9780470691854.ch9.
DeNiro MJ, Epstein S. Influence of diet on the distribution of carbon isotopes in animals. Geochim Cosmochim Acta. 1978;42(5):495-506. https://doi.org/10.1016/0016-7037(78)90199-0
DeNiro MJ, Epstein S. Influence of diet on the distribution of nitrogen isotopes in animals. Geochim Cosmochim Acta. 1981;45(3):341-351. https://doi.org/10.1016/0016-7037(81)90244-1
Fry B, Scalan RS, Winters JK, Parker PL. Sulphur uptake by salt grasses, mangroves, and seagrasses in anaerobic sediments. Geochim Cosmochim Acta. 1982;46(6):1121-1124. https://doi.org/10.1016/0016-7037(82)90063-1
Machás R, Santos R. Sources of organic matter in Ria Formosa revealed by stable isotope analysis. Acta Oecol. 1999;20(4):463-469. https://doi.org/10.1016/S1146-609X(99)00122-8
Connolly RM, Guest MA, Melville AJ, Oakes JM. Sulfur stable isotopes separate producers in marine food-web analysis. Oecologia. 2004;138(2):161-167. https://doi.org/10.1007/s00442-003-1415-0
Kaehler S, Pakhomov EA. Effects of storage and preservation on the δ13C and δ15N signatures of selected marine organisms. Mar Ecol Prog Ser. 2001;219:299-304. https://doi.org/10.3354/meps219299
Sarakinos HC, Johnson ML, Vander Zanden MJ. A synthesis of tissue-preservation effects on carbon and nitrogen stable isotope signatures. Can J Zool. 2002;80(2):381-387. https://doi.org/10.1139/z02-007
Fanelli E, Cartes JE, Papiol V, Rumolo P, Sprovieri M. Effects of preservation on the δ13C and δ15N values of deep sea macrofauna. J Exp Mar Biol Ecol. 2010;395(1-2):93-97. https://doi.org/10.1016/j.jembe.2010.08.020
Carabel S, Verísimo P, Freire J. Effects of preservatives on stable isotope analyses of four marine species. Estuar Coast Shelf Sci. 2009;82(2):348-350. https://doi.org/10.1016/j.ecss.2009
Bosley KL, Wainright SC. Effects of preservatives and acidification on the stable isotope ratios (15N:14N, 13C:12C) of two species of marine animals. Can J Fish Aquat Sci. 1999;56(11):2181-2185. https://doi.org/10.1139/f99-153
Edwards MS, Turner TF, Sharp ZD. Short- and long-term effects of fixation and preservation on stable isotope values (δ13C, δ15N, δ34S) of fluid-preserved museum specimens. Copeia. 2002;2002(4):1106-1112. https://doi.org/10.1643/0045-8511(2002)002[1106:SALTEO]2.0.CO;2
Lau DCP, Leung KMY, Dudgeon D. Preservation effects on C/N ratios and stable isotope signatures of freshwater fishes and benthic macroinvertebrates. Limnol Oceanogr Methods. 2012;10(2):75-89. https://doi.org/10.4319/lom.2012.10.75
González-Bergonzoni I, Vidal N, Wang B, et al. General validation of formalin-preserved fish samples in food web studies using stable isotopes. Methods Ecol Evol. 2015;6(3):307-314. https://doi.org/10.1111/2041-210X.12313
Stallings CD, Nelson JA, Rozar KL, et al. Effects of preservation methods of muscle tissue from upper-trophic level reef fishes on stable isotope values (δ13C and δ15N). PeerJ. 2015;3:e874. https://doi.org/10.7717/peerj.874
Kim SL, Koch PL. Methods to collect, preserve, and prepare elasmobranch tissues for stable isotope analysis. Environ Biol Fishes. 2012;95(1):53-63. https://doi.org/10.1007/s10641-011-9860-9
Olin JA, Poulakisn GR, Stevens PW, DeAngelo JA, Fisk AT. Preservation effects on stable isotope values of archived elasmobranch fin tissue: Comparisons between frozen and ethanol-stored samples. Trans Am Fish Soc. 2014;143(6):1569-1576. https://doi.org/10.1080/00028487.2014.954055
Barrow LM, Bjorndal KA, Reich KJ. Effects of preservation method on stable carbon and nitrogen isotope values. Physiol Biochem Zool. 2008;81(5):688-693. https://doi.org/10.1086/588172
Bugoni L, McGill RAR, Furness RW. Effects of preservation methods on stable isotope signatures in bird tissues. Rapid Commun Mass Spectrom. 2008;22(16):2457-2462. https://doi.org/10.1002/rcm.3633
Kiszka J, Lesage V, Ridoux V. Effect of ethanol preservation on stable carbon and nitrogen isotope values in cetacean epidermis: Implication for using archived biopsy samples. Mar Mamm Sci. 2014;30(2):788-795. https://doi.org/10.1111/mms.12058
Javornik J, Hopkins JB III, Zavadlav S, et al. Effects of ethanol storage and lipids on stable isotope values in a large mammalian omnivore. J Mammal. 2019;100(1):150-157. https://doi.org/10.1093/jmammal/gyy187
Oczkowski A, Thornber CS, Markham EE, Rossi R, Ziegler A, Rinehart S. Testing sample stability using four storage methods and the macroalgae Ulva and Gracilaria. Limnol Oceanogr Methods. 2015;13(1):9-14. https://doi.org/10.1002/lom3.10002
Fleming NEC, Houghton JDR, Magill CL, Harrod C. Preservation methods alter stable isotope values in gelatinous zooplankton: Implications for interpreting trophic ecology. Mar Biol. 2011;158(9):2141-2146. https://doi.org/10.1007/s00227-011-1714-7
Syväranta J, Martino A, Kopp D, Céréghino R, Santoul F. Freezing and chemical preservatives alter the stable isotope values of carbon and nitrogen of the Asiatic clam (Corbicula fluminea). Hydrobiologia. 2011;658(1):383-388. https://doi.org/10.1007/s10750-010-0512-4
Umbricht J, Dippner JW, Fry B, et al. Correction of the isotopic composition (δ13C and δ15N) of preserved Baltic and North Sea macrozoobenthos and their trophic interactions. Mar Ecol Prog Ser. 2018;595:1-13. https://doi.org/10.3354/meps12543
Rennie MD, Ozersky T, Evans DO. Effects of formalin preservation on invertebrate stable isotope values over decadal time scales. Can J Zool. 2012;90(11):1320-1327. https://doi.org/10.1139/z2012-101
Krab EJ, Van Logtestijn RSP, Cornelissen JHC, Berg MP. Reservations about preservations: Storage methods affect d13C signatures differently even in closely related soil fauna. Methods Ecol Evol. 2012;3(1):138-144. https://doi.org/10.1111/j.2041-210X.2011.00126.x
Jesus FM, Pereira MR, Rosa CS, Moreira MZ, Sperber CF. Preservation methods alter carbon and nitrogen stable isotope values in crickets (Orthoptera: Grylloidea). PLoS ONE. 2015;10(9):e0137650. https://doi.org/10.1371/journal.pone.0137650
Feuchtmayr H, Grey J. Effect of preparation and preservation procedures on carbon and nitrogen stable isotope determinations from zooplankton. Rapid Commun Mass Spectrom. 2003;17(23):2605-2610. https://doi.org/10.1002/rcm.1227
Xu J, Yang Q, Zhang M, Zhang M, Xie P, Hansson LA. Preservation effects on stable isotope ratios and consequences for the reconstruction of energetic pathways. Aquat Ecol. 2011;45(4):483-492. https://doi.org/10.1007/s10452-011-9369-5
Layman CA, Arrington DA, Montaña CG, Post DM. Can stable isotope ratios provide for community-wide measures of trophic structure? Ecology. 2007;88(1):42-48. https://doi.org/10.1890/0012-9658(2007)88[42%3ACSIRPF]2.0.CO%3B2
Cucherousset J, Villéger S. Quantifying the multiple facets of isotopic diversity: New metrics for stable isotope ecology. Ecol Indic. 2015;56:152-160. https://doi.org/10.1016/j.ecolind.2015.03.032
Jackson AL, Inger R, Parnell AC, Bearhop S. Comparing isotopic niche widths among and within communities: SIBER – Stable isotope Bayesian ellipses in R. J Anim Ecol. 2011;80(3):595-602. https://doi.org/10.1111/j.1365-2656.2011.01806.x
Parnell AC, Inger R, Bearhop S, Jackson AL. Source partitioning using stable isotopes: Coping with too much variation. PLoS ONE. 2010;5(3):e9672. https://doi.org/10.1371/journal.pone.0009672
Quezada-Romegialli C, Jackson AL, Hayden B, Kahilainen KK, Lopes C, Harrod C. tRophicPosition, an R package for the Bayesian estimation of trophic position from consumer stable isotope ratios. Methods Ecol Evol. 2018;9(6):1592-1599. https://doi.org/10.1111/2041-210X.13009
Ribi G, Schärer R, Ochsner P. Stomach contents and size-frequency distributions of two coexisting sea star species, Astropecten aranciacus and A. bispinosus, with reference to competition. Mar Biol. 1977;43(2):181-185. https://doi.org/10.1007/BF00391266
Dearborn JH, Edwards KC, Fratt DB. Diet, feeding behavior, and surface morphology of the multi-armed Antarctic sea star Labidiaster annulatus (Echinodermata: Asteroidea). Mar Ecol Prog Ser. 1991;77:65-84. https://doi.org/10.3354/meps077065
Gale KSP, Hamel JF, Mercier A. Trophic ecology of deep-sea Asteroidea (Echinodermata) from eastern Canada. Deep Sea Res I. 2013;80:25-36. https://doi.org/10.1016/j.dsr.2013.05.016
Hedges JI, Stern JH. Carbon and nitrogen determinations of carbonate-containing solids. Limnol Oceanogr. 1984;29(3):657-663. https://doi.org/10.4319/lo.1984.29.3.0657
Coplen TB. Guidelines and recommended terms for expression of stable- isotope-ratio and gas-ratio measurement results. Rapid Commun Mass Spectrom. 2011;25(17):2538-2560. https://doi.org/10.1002/rcm.5129
R Core Team. R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. 2013. http://www.R-project.org/
Rice WR. Analysing tables of statistical tests. Evolution. 1989;43(1):223-225. https://doi.org/10.1111/j.1558-5646.1989.tb04220.x
Reid WDK, Sweeting CJ, Wigham BD, McGill RAR, Polunin NVC. Isotopic niche variability in macroconsumers of the east scotia ridge (Southern Ocean) hydrothermal vents: What more can we learn from an ellipse? Mar Ecol Prog Ser. 2016;542:13-24. https://doi.org/10.3354/meps11571
Von Endt DW. Spirit collections: A preliminary analysis of some organic materials found in the storage fluids of mammals. Collect Forum. 1994;10:10-19.
Sweeting CJ, Polunin NVC, Jennings S. Tissue and fixative dependent shifts of δ13C and δ15N in preserved ecological material. Rapid Commun Mass Spectrom. 2004;18(21):2587-2592. https://doi.org/10.1002/rcm.1661