Abstract
Ecotones can form hot spots of biodiversity by containing species from multiple ecosystems. Because biodiversity is often linked to ecological function, we posit that rates of key ecological functions are highest at ecotones and decline away from them. Here we test this hypothesis by measuring spatial decays in the function of carrion scavenging on a gradient ranging from ocean beaches upland into abutting coastal dunes. A large field experiment in Eastern Australia, at the ecotone formed by ocean beaches, employed multiple carrion placements and motion-triggered cameras to identify the animals consuming carcasses and the removal rates of necromass. Significantly more carrion was consumed by vertebrate scavengers at the beach interface (50–80% of total necromass removed) and declined significantly with distance (max. 350 m) into the abutting coastal dunes (20–25%). This marked cline was due to the consumption of carrion by both dune-dwelling and beach-dwelling animals at the beach–dune interface and a decline in scavenging activity by both groups farther upland. These spatial effects were consistent between sites, but the lower carrion removal away from the beach became less pronounced as the carcasses putrefied, suggesting that microbial actions can modify carrion suitability for vertebrate scavengers and hence change spatial patterns in ecological function. Our findings provide quantitative support for the widespread notion that ecological transition zones are hot spots of ecological functions and highlight the importance of managing functionally important species at ecotones.
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References
Andersson LC, Reynolds JD. 2017. Habitat features mediate selective consumption of salmon by bears. Can J Fish Aquat Sci 75(6):955–63.
Araujo MB. 2002. Biodiversity hotspots and zones of ecological transition. Conserv Biol 16(6):1662–3.
Baring RJ, Lester RE, Fairweather PG. 2018. Trophic relationships among animals associated with drifting wrack. Mar Freshw Res 69(8):1248.
Batary P, Baldi A. 2004. Evidence of an edge effect on avian nest success. Conserv Biol 18(2):389–400.
Bellwood DR, Hughes TP, Hoey AS. 2006. Sleeping functional group drives coral-reef recovery. Curr Biol 16(24):2434–9.
Bingham EL, Gilby BL, Olds AD, Weston MA, Connolly RM, Henderson CJ, Maslo B, Peterson CF, Voss CM, Schlacher TA. 2018a. Functional plasticity in vertebrate scavenger assemblages in the presence of introduced competitors. Oecologia 188(2):583–93.
Bingham EL, Gilby BL, Olds AD, Weston MA, Connolly RM, Henderson CJ, Maslo B, Peterson CH, Voss CM, Schlacher TA. 2018b. Functional plasticity in vertebrate scavenger assemblages in the presence of introduced competitors. Oecologia 188:583–93.
Blandford M, Katouli M, Gilby BL, O’Dea C, Olds A, Schlacher TA. 2019. Not all rotten fish stink: Microbial changes in decaying carcasses determine the potential health risks to animal scavengers. Estuar Coast Shelf Sci 227:106350. https://doi.org/10.1016/j.ecss.2019.106350.
Blandford MI. 2016. Microbial changes during decomposition of fish carcasses on an exposed sandy beach: Possible implications for toxicity and palatability of wave-cast carrion to vertebrate scavengers. BSc (Hons), University of the Sunshine Coast.
Bocher P, Robin F, Kojadinovic J, Delaporte P, Rousseau P, Dupuy C, Bustamante P. 2014. Trophic resource partitioning within a shorebird community feeding on intertidal mudflat habitats. J Sea Res 92:115–24.
Borland HP, Schlacher TA, Gilby BL, Connolly RM, Yabsley NA, Olds AD. 2017. Habitat type and beach exposure shape fish assemblages in the surf zones of ocean beaches. Mar Ecol Progress Ser 570:203–11.
Brown MB, Schlacher TA, Schoeman DS, Weston MA, Huijbers CM, Olds AD, Connolly RM. 2015. Invasive carnivores alter ecological function and enhance complementarity in scavenger assemblages on ocean beaches. Ecology 96(10):2715–25.
Clavel J, Julliard R, Devictor V. 2011. Worldwide decline of specialist species: toward a global functional homogenization? Front Ecol Environ 9(4):222–8.
Clements FE. 1907. Plant physiology and ecology. New York: Holt.
Fortin MJ, Olson RJ, Ferson S, Iverson L, Hunsaker C, Edwards G, Levine D, Butera K, Klemas V. 2000. Issues related to the detection of boundaries. Landsc Ecol 15(5):453–66.
Gamfeldt L, Roger F. 2017. Revisiting the biodiversity-ecosystem multifunctionality relationship. Nat Ecol Evolut 1(7):0168.
Gaston KJ, Rodrigues ASL, van Rensburg BJ, Koleff P, Chown SL. 2001. Complementary representation and zones of ecological transition. Ecol Lett 4(1):4–9.
Gosz JR. 1993. Ecotone hierarchies. Ecol Appl 3(3):369–76.
Harris RJ, Reed JM. 2002. Behavioral barriers to non-migratory movements of birds. Annales Zoologici Fennici. Finland: Finnish Zoological and Botanical Publishing Board.
Hoey AS, Bellwood DR. 2009. Limited functional redundancy in a high diversity system: single species dominates key ecological process on coral reefs. Ecosystems 12(8):1316–28.
Hoffmann AA, Blows MW. 1994. Species borders: ecological and evolutionary perspectives. Trends Ecol Evolut 9(6):223–7.
Howard GT, Norton WN, Stroot PG, Bailey KL, Watson EJ. 2012. Association of the genus acinetobacter with the decomposition of a swine carcass and the isolation and characterization of a novel strain of acinetobacter sp P4. Curr Microbiol 64(1):24–33.
Huijbers CM, Schlacher TA, McVeigh RR, Schoeman DS, Olds AD, Brown MB, Ekanayake KB, Weston MA, Connolly RM. 2016a. Functional replacement across species pools of vertebrate scavengers separated at a continental scale maintains an ecosystem function. Funct Ecol 30(6):998–1005.
Huijbers CM, Schlacher TA, Schoeman DS, Olds AD, Weston MA, Connolly RM. 2016b. Limited functional redundancy in vertebrate scavenger guilds fails to compensate for the loss of raptors from urbanized sandy beaches. Divers Distrib 21(1):55–63.
Huijbers CM, Schlacher TA, Schoeman DS, Weston MA, Connolly RM. 2013. Urbanisation alters processing of marine carrion on sandy beaches. Landsc Urban Plan 119:1–8.
Inger R, Per E, Cox DTC, Gaston KJ. 2016. Key role in ecosystem functioning of scavengers reliant on a single common species. Sci Rep 6:29641.
Leibold MA, Holyoak M, Mouquet N, Amarasekare P, Chase JM, Hoopes MF, Holt RD, Shurin JB, Law R, Tilman D, Loreau M, Gonzalez A. 2004. The metacommunity concept: a framework for multi-scale community ecology. Ecol Lett 7:601–13.
Lidicker WZ. 1999. Responses of mammals to habitat edges: an overview. Landsc Ecol 14(4):333–43.
Loreau M, Mouquet N, Gonzalez A. 2003a. Biodiversity as spatial insurance in heterogeneous landscapes. Proc Natl Acad Sci USA 100(22):12765–70.
Loreau M, Mouquet N, Holt RD. 2003b. Meta-ecosystems: a theoretical framework for a spatial ecosystem ecology. Ecol Lett 6(8):673–9.
Maxwell PS, Pitt KA, Olds AD, Rissik D, Connolly RM. 2015. Identifying habitats at risk: simple models can reveal complex ecosystem dynamics. Ecol Appl 25(2):573–87.
McClain CR, Schlacher TA. 2015. On some hypotheses of diversity of animal life at great depths on the sea floor. Mar Ecol 36(4):849–72.
Meager JJ, Schlacher TA, Nielsen T. 2012. Humans alter habitat selection of birds on ocean-exposed sandy beaches. Divers Distrib 18(3):294–306.
Mellbrand K, Lavery PS, Hyndes G, Hamback PA. 2011. Linking land and sea: different pathways for marine subsidies. Ecosystems 14:732–44.
Micheli F, Halpern BS. 2005. Low functional redundancy in coastal marine assemblages. Ecol Lett 8(4):391–400.
Olds AD, Frohloff BA, Gilby BL, Connolly RM, Yabsley NA, Maxwell PS, Henderson CJ, Schlacher TA. 2018a. Urbanisation supplements ecosystem functioning in disturbed estuaries. Ecography 41(12):2104–13.
Olds AD, Frohloff BA, Gilby BL, Connolly RM, Yabsley NA, Maxwell PS, Schlacher TA. 2018b. Urbanisation supplements ecosystem functioning in disturbed estuaries. Ecography 41:2104–13.
Olds AD, Pitt KA, Maxwell PS, Connolly RM. 2012. Synergistic effects of reserves and connectivity on ecological resilience. J Appl Ecol 49(6):1195–203.
Olds AD, Vargas-Fonseca E, Connolly RM, Gilby BL, Huijbers CM, Hyndes G, Layman CA, Whitfield AK, Schlacher TA. 2017. The ecology of fish in the surf zones of ocean beaches: a global review. Fish Fish 19(1):78–89.
Oliveira DL, Soares TF, Vasconcelos SD. 2016. Effect of bait decomposition on the attractiveness to species of Diptera of veterinary and forensic importance in a rainforest fragment in Brazil. Parasitol Res 115(1):449–55.
Peyras M, Vespa NI, Bellocq MI, Zurita GA. 2013. Quantifying edge effects: the role of habitat contrast and species specialization. J Insect Conserv 17(4):807–20.
Reid WV. 1998. Biodiversity hotspots. Trends Ecol Evolut 13(7):275–80.
Ries L, Fletcher RJ Jr, Battin J, Sisk TD. 2004. Ecological responses to habitat edges: mechanisms, models, and variability explained. Ann Rev Ecol Evolut Syst 35:491–522.
Ripple WJ, Beschta RL. 2007. Restoring Yellowstone’s aspen with wolves. Biol Conserv 138(3–4):514–19.
Risser PG. 1995a. Biodiversity and ecosystem function. Conserv Biol 9(4):742–6.
Risser PG. 1995b. The status of science examining ecotones. Bioscience 45(5):318–25.
Schlacher TA, Hutton BM, Gilby BL, Porch N, Maguire GS, Maslo B, Connolly RM, Olds AD, Weston MA. 2017. Algal subsidies enhance invertebrate prey for threatened shorebirds: A novel conservation tool on ocean beaches? Estuar Coast Shelf Sci 191:28–38.
Schlacher TA, Strydom S, Connolly RM. 2013. Multiple scavengers respond rapidly to pulsed carrion resources at the land–ocean interface. Acta Oecol 48:7–12.
Schlacher TA, Weston MA, Lynn D, Schoeman DS, Huijbers CM, Olds AD, Masters S, Connolly RM. 2015a. Conservation gone to the dogs: when canids rule the beach in small coastal reserves. Biodivers Conserv 24:493–509.
Schlacher TA, Weston MA, Schoeman DS, Olds AD, Huijbers CM, Connolly RM. 2015b. Golden opportunities: A horizon scan to expand sandy beach ecology. Estuar Coast Shelf Sci 157:1–6.
Sexton JP, McIntyre PJ, Angert AL, Rice KJ. 2009. Evolution and ecology of species range limits. Ann Rev Ecol Evolut Syst 40(1):415–36.
Sheaves M, Brookes J, Coles R, Freckelton M, Groves P, Johnston R, Winberg P. 2014. Repair and revitalisation of Australia’s tropical estuaries and coastal wetlands: opportunities and constraints for the reinstatement of lost function and productivity. Mar Policy 47:23–38.
Smith TB, Wayne RK, Girman DJ, Bruford MW. 1997. A role for ecotones in generating rainforest biodiversity. Science 276(5320):1855–7.
Somaweera R, Rhind D, Reynolds S, Eisemberg C, Sonneman T, Woods D. 2018. Observations of mammalian feeding by Australian freshwater crocodiles (Crocodylus johnstoni) in the Kimberley region of Western Australia. Rec West Aust Museum 33(1):103.
Spector S, Ayzama S. 2003. Rapid turnover and edge effects in dung beetle assemblages (Scarabaeidae) at a Bolivian neotropical forest-savanna ecotone. Biotropica 35(3):394–404.
Van Rensburg BJ, Levin N, Kark S. 2009. Spatial congruence between ecotones and range-restricted species: implications for conservation biogeography at the sub-continental scale. Divers Distrib 15(3):379–89.
Acknowledgements
We gratefully acknowledge funding for this project from SK House, the SeaWorld Research and Rescue Foundation, and the CRN-Water Science. A jolly band of students endured some particularly ‘charming’ mullet carcass smells and trekked with alacrity and determination through the dune vegetation; a very big ‘Thank You’ to Cassandra Duncan, Sarah Thackwray, Ellen Bingham, and Hayden Borland for their help and hard work in the field deploying copious volumes of odoriferous mullets in challenging terrains.
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Schlacher, T.A., Gilby, B.L., Olds, A.D. et al. Key Ecological Function Peaks at the Land–Ocean Transition Zone When Vertebrate Scavengers Concentrate on Ocean Beaches. Ecosystems 23, 906–916 (2020). https://doi.org/10.1007/s10021-019-00445-y
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DOI: https://doi.org/10.1007/s10021-019-00445-y