Intra-species variability in isotopic niches, specifically isotopic total niche width (ITNW), isotopic individual niche width (IINW), and isotopic individual specialization (IIS), was studied using an innovative approach without sacrificing the vertebrates. Stable isotopes (δ13C, δ15N) in four body tissues differing in isotopic half-life were analyzed from four freshwater fish species representing different trophic positions. ITNW was widest for the apex predator (European catfish) and narrowest for the obligate predator (Northern pike). IINW exhibited a polynomial trend for the European catfish, Northern pike, and Eurasian perch (mesopredator), decreasing with body mass and increasing again after exceeding a certain species-dependent body mass threshold. Thus, for ectotherms, apex predator status is linked rather to its size than to the species. In herbivores (rudd), IINW increased with body mass. The IIS of predators negatively correlated with site trophic state. Therefore, eutrophication can significantly change the foraging behavior of certain species. We assume that the observed trends will occur in other species at similar trophic positions in either aquatic or terrestrial systems. For confirmation, we recommend conducting a similar study on other species in different habitats.

Biology Centre of the Czech Academy of Sciences Institute of Hydrobiology Na Sádkách 7 37005 České Budějovice Czech Republic

Faculty of Science University of South Bohemia in České Budějovice Branišovská 31 37005 České Budějovice Czech Republic

See more in PubMed

Owen-Smith N., Fryxell J.M., Merrill E.H. Foraging theory upscaled: The behavioural ecology of herbivore movement. Philos. Trans. R. Soc. Lond. B Biol. Sci. 2010;365:2267–2278. PubMed PMC

DeSantis L.R.G., Pardi M.I., Du A., Greshko M.A., Yann L.T., Hulbert R.C., Louys J. Global long-term stability of individual dietary specialization in herbivorous mammals. Proc. R. Soc. B. 2022;289:20211839. doi: 10.1098/rspb.2021.1839. PubMed DOI PMC

Van Valen L. Morphological Variation and Width of Ecological Niche. Am. Nat. 1965;99:377–389. doi: 10.1086/282379. DOI

Urton E.J.M., Hobson K.A. Intrapopulation variation in gray wolf isotope (δ15 N and δ13C) profiles: Implications for the ecology of individuals. Oecologia. 2005;145:317–326. PubMed

Woo K.J., Elliott K.H., Davidson M., Gaston A.J., Davoren G.K. Individual specialization in diet by a generalist marine predator reflects specialization in foraging behaviour. J. Anim. Ecol. 2008;77:1082–1091. doi: 10.1111/j.1365-2656.2008.01429.x. PubMed DOI

Roberts P., Stewart B.A. Defining the ‘generalist specialist’ niche for Pleistocene Homo sapiens. Nat. Hum. Behav. 2018;2:542–550. doi: 10.1038/s41562-018-0394-4. PubMed DOI

Quevedo M., Svanbäck R., Eklöv P. Intrapopulation niche partitioning in a generalist predator limits food web connectivity. Ecology. 2009;90:2263–2274. doi: 10.1890/07-1580.1. PubMed DOI

Matich P., Heithaus M.R., Layman C.A. Contrasting patterns of individual specialization and trophic coupling in two marine apex predators. J. Anim. Ecol. 2011;80:294–305. doi: 10.1111/j.1365-2656.2010.01753.x. PubMed DOI

Vejřík L., Vejříková I., Blabolil P., Eloranta A.P., Kočvara L., Peterka J., Sajdlová Z., Chung S.H.T., Šmejkal M., Kiljunen M., et al. European catfish (Silurus glanis) as a freshwater apex predator drives ecosystem via its diet adaptability. Sci. Rep. 2017;7:5970. doi: 10.1038/s41598-017-16169-9. PubMed DOI PMC

Kapuscinski K.L., Farrell J.M., Wilkinson M.A. Feeding patterns and population structure of an invasive cyprinid, the rudd Scardinius erythrophthalmus (Cypriniformes, Cyprinidae), in Buffalo Harbor (Lake Erie) and the upper Niagara River. Hydrobiologia. 2012;693:169–181.

Vejříková I., Vejřík L., Syväranta J., Kiljunen M., Čech M., Blabolil P., Vašek M., Sajdlová Z., Chung S.H.T., Šmejkal M., et al. Distribution of herbivorous fish is frozen by low temperature. Sci. Rep. 2016;6:39600. doi: 10.1038/srep39600. PubMed DOI PMC

Bolnick D.I., Ingram T., Stutz W.E., Snowberg L., Lau O.L., Paull J. Ecological release from interspecific competition leads to decoupled changes in population and individual niche width. Proc. R. Soc. B Biol. Sci. 2010;277:1789–1797. doi: 10.1098/rspb.2010.0018. PubMed DOI PMC

Vander Zanden H.B., Bjorndal K.A., Reich K.J., Bolten A.B. Individual specialists in a generalist population: Results from a long-term stable isotope series. Biol. Lett. 2010;6:711–714. PubMed PMC

Pyke G.H., Pulliam H.R., Charnov E.L. Optimal Foraging: A Selective Review of Theory and Tests. Q. Rev. Biol. 1977;52:137–154.

Barabás G., D’Andrea R. The effect of intraspecific variation and heritability on community pattern and robustness. Ecol. Lett. 2016;19:977–986. doi: 10.1111/ele.12636. PubMed DOI

Araújo M.S., Bolnick D.I., Layman C.A. The ecological causes of individual specialisation. Ecol. Lett. 2011;14:948–958. doi: 10.1111/j.1461-0248.2011.01662.x. PubMed DOI

Belovsky G.E., Jordan P.A. The time-energy budget of a moose. Theor. Popul. Biol. 1978;14:76–104. doi: 10.1016/0040-5809(78)90006-0. PubMed DOI

Schoener T.W. Theory of feeding strategies. Annu. Rev. Ecol. Evol. Syst. 1971;2:369–404. doi: 10.1146/annurev.es.02.110171.002101. DOI

Sol D., Elie M., Marcoux M., Chrostovsky E., Porcher C., Lefebvre L. Ecological mechanisms of a resource polymorphism in Zenaida Doves of Barbados. Ecology. 2005;86:2397–2407. doi: 10.1890/04-1136. DOI

Stephens D.W., Krebs J.R. Foraging Theory. Princeton University Press; Princeton, NJ, USA: 1986.

Araújo M.S., Gonzaga M.O. Individual specialisation in the hunting wasp Trypoxylon (Trypargilum) albonigrum (Hymenoptera, Crabronidae) Behav. Ecol. Sociobiol. 2007;61:1855–1863. doi: 10.1007/s00265-007-0425-z. DOI

Svanbäck R., Persson L. Individual diet specialisation, niche width and population dynamics: Implications for trophic polymorphisms. J. Anim. Ecol. 2004;73:973–982.

Svanbäck R., Eklöv P., Fransson R., Holmgren K. Intraspecific competition drives multiple species resource polymorphism in fish communities. Oikos. 2008;117:114–124. doi: 10.1111/j.2007.0030-1299.16267.x. DOI

Knudsen R., Amundsen P.A., Primicerio R., Klemetsen A., Sorensen P. Contrasting niche-based variation in trophic morphology within Arctic charr populations. Evol. Ecol. Res. 2007;9:1005–1021.

Bolnick D.I., Amarasekare P., Araújo M.S., Bürger R., Levine J., Novak M., Rudolf V.H., Schreiber S.J., Urban M.C., Vasseur D.A., et al. Why intraspecific trait variation matters in community ecology. Trends Ecol. Evol. 2011;26:183–192. PubMed PMC

Prati S., Henriksen E.H., Smalås A., Knudsen R., Klemetsen A., Sánchez-Hernández J., Amundsen P.A. The effect of inter- and intraspecific competition on individual and population niche widths: A four-decade study on two interacting salmonids. Oikos. 2021;130:1679–1691.

Eklöv P., Svanbäck R. Predation risk influences adaptive morphological variation in fish populations. Am. Nat. 2006;167:440–452. doi: 10.1086/499544. PubMed DOI

Jacobson P.C., Stefan H.G., Pereira D.L. Coldwater fish oxythermal habitat in Minnesota lakes: Influence of total phosphorus, July air temperature, and relative depth. Can. J. Fish. Aquat. 2010;67:2002–2013.

North R.P., North R.L., Livingstone D.M., Koster O., Kipfer R. Long-term changes in hypoxia and soluble reactive phosphorus in the hypolimnion of a large temperate lake: Consequences of a climate regime shift. Glob. Chang. Biol. 2014;20:811–823. PubMed

Kerches-Rogeri N., Niebuhr B.B., Muylaert R.L., Mello M.A.L. Individual specialization in the use of space by frugivorous bats. J. Anim. Ecol. 2020;89:2584–2595. doi: 10.1111/1365-2656.13339. PubMed DOI

Sheppard C.E., Inger R., McDonald R.A., Barker S., Jackson A.L., Thompson F.J., Vitikainen E.I., Cant M.A., Marshall H.H. Intragroup competition predicts individual foraging specialisation in a group-living mammal. Ecol. Lett. 2018;21:665–673. doi: 10.1111/ele.12933. PubMed DOI PMC

Robbins C.T., Felicetti L.A., Sponheimer M. The effect of dietary protein quality on nitrogen isotope discrimination in mammals and birds. Oecologia. 2005;144:534–540. PubMed

Hette-Tronquart N. Isotopic niche is not equal to trophic niche. Ecol. Lett. 2019;22:1987–1989. doi: 10.1111/ele.13218. PubMed DOI

Vejřík L., Vejříková I., Kočvara L., Blabolil P., Peterka J., Sajdlová Z., Jůza T., Šmejkal M., Kolařík T., Bartoň D., et al. The pros and cons of the invasive freshwater apex predator, European catfish Silurus glanis, and powerful angling technique for its population control. J. Environ. Manag. 2019;241:374–382. PubMed

Bartoň D., Brabec M., Sajdlová Z., Souza A., Duras J., Kortan D., Blabolil P., Vejřík L., Kubečka J., Šmejkal M. Hydropeaking causes spatial shifts in a reproducing rheophilic fish. Sci. Total Environ. 2022;806:150649. doi: 10.1016/j.scitotenv.2021.150649. PubMed DOI

Vejříková I., Eloranta A.P., Vejřík L., Šmejkal M., Čech M., Sajdlová Z., Frouzova J., Kiljunen M., Peterka J. Macrophytes shape trophic niche variation among generalist fishes. PLoS ONE. 2017;12:e0177114. doi: 10.1371/journal.pone.0177114. PubMed DOI PMC

Stephen M.T., Crowther T.W. Predicting rates of isotopic turnover across the animal kingdom: A synthesis of existing data. J. Anim. Ecol. 2015;84:861–870. PubMed

Vašek M., Vejřík L., Vejříková I., Šmejkal M., Baran R., Muška M., Kubečka J., Peterka J. Development of non-lethal monitoring of stable isotopes in asp (Leuciscus aspius): A comparison of muscle, fin and scale tissues. Hydrobiology. 2017;785:327–335.

France R.L. Critical examination of stable isotope analysis as a means for tracing carbon pathways in stream ecosystems. Can. J. Fish. Aquat. 1995;52:651–656.

Anderson C., Cabana G. Estimating the trophic position of aquatic consumers in river food webs using stable nitrogen isotopes. J. N. Am. Benthol. Soc. 2007;26:273–285.

Post D.M. Using stable isotopes to estimate trophic position: Models, methods, and assumptions. Ecology. 2002;83:703–718.

Vander Zanden M.J., Shuter B.J., Lester N., Rasmussen J.B. Patterns of food chain length in lakes: A stable isotope study. Am. Nat. 1999;154:406–416. PubMed

Olsson K., Stenroth P., Nyström P., Granéli W. Invasions and niche width: Does niche width of an introduced crayfish differ from a native crayfish? Freshw. Biol. 2009;54:1731–1740.

Layman C.A., Arrington D.A., Montaña C.G., Post D.M. Can stable isotope ratios provide quantitative measures of trophic diversity within food webs? Ecology. 2007;88:42–48. PubMed

Jackson A.L., Inger R., Parnell A.C., Bearhop S. Comparing isotopic niche widths among and within communities: SIBER – Stable Isotope Bayesian Ellipses in R. J. Anim. Ecol. 2011;80:595–602. PubMed

Bolnick D.I., Svanbäck R., Fordyce J.A., Yang L.H., Davis J.M., Hulsey C.D., Forister M.L. The Ecology of Individuals: Incidence and Implications of Individual Specialization. Am. Nat. 2003;161:1–28. PubMed

Bolnick D.I. Ind Spec1. Center for Population Biology Store Hall University of California; Davis, CA, USA: 2002.

Bates D., Maechler M., Bolker B., Walker S. Fitting Linear Mixed-Effects Models Using lme4. J. Stat. Softw. 2015;67:1–48.

R Core Team . A Language and Environment for Statistical Computing. R Foundation for Statistical Computing; Vienna, Austria: 2021. [(accessed on 7 August 2023)]. Available online: https://www.R-project.org.

Allouche O., Kalyuzhny M., Moreno-Rueda G., Pizarro M., Kadmon K. Area–heterogeneity tradeoff and the diversity of ecological communities. Proc. Natl. Acad. Sci. USA. 2012;109:17495–17500. doi: 10.1073/pnas.1208652109. PubMed DOI PMC

Forsman A., Tibblin P., Berggren H., Nordahl O., Koch-Smidth P., Larsson P. Pike Esox lucius as an emerging model organism for studies in ecology and evolutionary biology: A review. J. Fish. Biol. 2015;87:472–479. PubMed PMC

Prugh R.L., Stoner C.J., Epps C.W., Bean W.T., Ripple W.J., Laliberte A.S., Brashares J.S. The rise of the mesopredator. BioScience. 2009;59:779–791.

Ripple W.J., Estes J., Beschta R., Wilmers C., Ritchie E., Hebblewhite M., Berger J., Elmhagen B., Letnic M., Nelson M.P. Status and ecological effects of the world’s largest carnivores. Science. 2014;343:1241484. PubMed

Kozlowski J., Uchmanski J. Optimal individual growth and reproduction in perennial species with indeterminate growth. Evol. Ecol. 1987;1:214–230. doi: 10.1007/BF02067552. DOI

Brooker R.M., Munday P.L., Brandl S.J., Jones G.P. Local extinction of a coral reef fish explained by inflexible prey choice. Coral Reefs. 2014;33:891–896. doi: 10.1007/s00338-014-1197-3. DOI

Orr H.A., Unckless R.L. Population extinction and the genetics of adaptation. Am. Nat. 2008;172:160–169. PubMed

Foote A.D., Newton J., Piertney S.B., Willerslev E., Gilbert M.T.P. Ecological, morphological and genetic divergence of sympatric North Atlantic killer whale populations. Mol. Ecol. 2009;18:5207–5217. doi: 10.1111/j.1365-294X.2009.04407.x. PubMed DOI

Werner E.E., Gilliam J.F. The ontogenetic niche and species interactions in size-structured populations. Annu. Rev. Ecol. Evol. Syst. 1984;15:393–425. doi: 10.1146/annurev.es.15.110184.002141. DOI

Rosenblatt A.E., Nifong J.C., Heithaus M.R., Mazzotti F.J., Cherkiss M.S., Jeffery B.M., Elsey R.M., Decker R.A., Silliman B.R., Guillette L.J. Factors affecting individual foraging specialization and temporal diet stability across the range of a large “generalist” apex predator. Oecologia. 2015;178:5–16. PubMed

Nurminen L., Horppila J., Lappalainen J., Malinen T. Implications of rudd (Scardinius erythrophthalmus) herbivory on submerged macrophytes in a shallow eutrophic lake. Hydrobiology. 2003;506–509:511–518. doi: 10.1023/B:HYDR.0000008577.16934.a9. DOI

Elton C.S. Animal Ecology. Sidgewick & Jackson; London, UK: 1927.

Matthews B., Marchinko K.B., Bolnick D.I., Mazumder A. Specialisation of trophic position and habitat use by sticklebacks in an adaptive radiation. Ecology. 2010;91:1025–1034. PubMed

Hughes A.R., Inouye B.D., Johnson M.T.J., Underwood N., Vellend M. Ecological consequences of genetic diversity. Ecol. Lett. 2008;11:609–623. doi: 10.1111/j.1461-0248.2008.01179.x. PubMed DOI

Heady W.N., Moore J.W. Tissue turnover and stable isotope clocks to quantify resource shifts in anadromous rainbow trout. Oecologia. 2013;172:21–34. PubMed

Wakefield E.D., Cleasby I.R., Bearhop S., Bodey T.W., Davies R.D., Miller P.I., Newton J., Votier S.C., Hamer K.C. Long-term individual foraging site fidelity—Why some gannets don’t change their spots. Ecology. 2015;96:3058–3074. doi: 10.1890/14-1300.1. PubMed DOI

Říha M., Gjelland K.O., Děd V., Eloranta A.P., Rabaneda Bueno R., Baktoft H., Vejřík L., Vejříková I., Draštík V., Šmejkal M., et al. Contrasting structural complexity differentiate hunting strategy in an ambush apex predator. Sci. Rep. 2021;11:17472. PubMed PMC

Long-lines for research monitoring and efficient population regulation of an invasive apex predator, European catfish (Silurus glanis)

A non-lethal stable isotope analysis of valued freshwater predatory fish using blood and fin tissues as alternatives to muscle tissue