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Simulated green turtle grazing affects nutrient composition of the seagrass Thalassia testudinum

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Abstract

Before populations of green turtles (Chelonia mydas) were severely reduced by human overexploitation, the seagrass Thalassia testudinum was intensively grazed by green turtles in the Caribbean. To explore how nutrient composition of T. testudinum pastures responds to intense grazing pressure, we simulated green turtle grazing in 15 plots (each 3 m × 3 m) for 16 months in the central Bahamas. Comparisons of clipped plots with 15 adjacent control (unclipped) plots revealed that simulated grazing resulted in significantly higher energy, nitrogen, phosphorus, lignin, cutin, and condensed tannin content in blades in clipped plots, but sediment organic content was not affected. By continually re-cropping blades in grazing plots, turtles ingest young, actively growing blade tissue with higher energy, nitrogen, and phosphorus concentrations. Our 16-month clipping trial did not generate the expected decline in nutrient content in T. testudinum blades under intensive grazing. However, significant decreases in nitrogen and organic matter reserves in rhizomes, with declines apparent after 16 and 11 months, respectively, indicate that nutrient content of blades and/or blade productivity may decline under continued clipping.

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References

  • Ankom Technology Company (1998) Method for determining neutral detergent fiber (aNDF). Ankom Technical Manuals, Fairport

  • Ankom Technology Company (1999) Method for determining acid detergent fiber. Ankom Technical Manuals, Fairport

  • Arnold TM, Schultz JC (2002) Induced sink strength as a prerequisite for induced tannin biosynthesis in developing leaves of Populus. Oecologia 130:585–593

    Article  Google Scholar 

  • Arnold TM, Tanner CE, Hatch WI (1995) Phenotypic variation in polyphenolic content of the tropical brown alga Lobophora variegata as a function of nitrogen availability. Mar Ecol Prog Ser 123:177–183

    Article  CAS  Google Scholar 

  • Audubon MR (1897) Audubon and his journals, vol. 2. Books for Libraries Press, Freeport

    Google Scholar 

  • Balazs GH, Fujioka R, Fujioka C (1993) Marine turtle faeces on Hawaiian beaches. Mar Pollut Bull 26:392–394

    Article  Google Scholar 

  • Bjorndal KA (1979) Cellulose digestion and volatile fatty acid production in the green turtle, Chelonia mydas. Comp Biochem Physiol 63A:127–133

    Article  CAS  Google Scholar 

  • Bjorndal KA (1980) Nutrition and grazing behavior of the green turtle, Chelonia mydas. Mar Biol 56:147–154

    Article  CAS  Google Scholar 

  • Bjorndal KA (1982) The consequences of herbivory for the life history pattern of the Caribbean green turtle. In: Bjorndal KA (ed) Biology and conservation of sea turtles. Smithsonian Institution Press, Washington, pp. 111–116

    Google Scholar 

  • Bjorndal KA (1985) Nutritional ecology of sea turtles. Copeia 1985:736–751

    Article  Google Scholar 

  • Bjorndal KA (1997) Foraging ecology and nutrition of sea turtles. In: Lutz PL, Musick JA (eds) The biology of sea turtles. CRC, Boca Raton, pp. 199–231

    Google Scholar 

  • Bjorndal KA, Bolten AB, Chaloupka MY (2000) Green turtle somatic growth model: evidence for density dependence. Ecol Appl 10:269–282

    Google Scholar 

  • CARICOMP (1997a) Meteorological and oceanographic characterization of coral reef, seagrass and mangrove habitats in the Wider Caribbean. In: Lessios HA, MacIntyre IG (eds) Proceedings of the 8th international coral reef symposium, vol. 1. Smithsonian Tropical Research Institute, Balboa, Panama, pp. 657–662

  • CARICOMP (1997b) Variation in ecological parameters of Thalassia testudinum across the CARICOMP network. In: Lessios HA, MacIntyre IG (eds) Proceedings of the 8th international coral reef symposium, vol. 1. Smithsonian Tropical Research Institute, Balboa, Panama, pp. 663–668

  • Cipollini DF Jr (1997) Wind-induced mechanical stimulation increases pest resistance in common bean. Oecologia 111:84–90

    Article  Google Scholar 

  • Dawes CJ, Lawrence JM (1979) Effects of blade removal on the proximate composition of the rhizome of the seagrass Thalassia testudinum Banks ex Konig. Aquat Bot 7:255–266

    Article  Google Scholar 

  • Dawes CJ, Lawrence JM (1980) Seasonal changes in the proximate constituents of the seagrasses Thalassia testudinum, Halodule wrightii, and Syringodium filiforme. Aquat Bot 8:371–380

    Article  CAS  Google Scholar 

  • Dawes CJ, Andorfer J, Rose C, Uranowski C, Ehringer E (1997) Regrowth of the seagrass Thalassia testudinum into propeller scars. Aquat Bot 59:139–155

    Article  Google Scholar 

  • DeJaegher G, Boyer N, Gaspar T (1985) Thigmomorphogenesis in Bryonia dioica: changes in soluble and wall peroxidases, phenylalanine ammonia-lyase activity, cellulose, lignin content and monomeric constituents. Plant Growth Regul 3:133–148

    Article  CAS  Google Scholar 

  • Gallaher RN, Weldon CO, Futral JG (1975) An aluminum block digester for plant and soil analysis. Soil Sci Soc Am Proc 39:803–806

    Article  Google Scholar 

  • Goering HK, Van Soest PJ (1970) Forage fiber analyses: apparatus, reagents, procedures, and some applications. Agricultural Handbook No. 379, U.S. Dept Agric, Washington

  • Hambleton LG (1977) Semiautomated method for simultaneous determination of phosphorus, calcium and crude protein in animal feeds. J Assoc Off Anal Chem 60:845–852

    CAS  Google Scholar 

  • Heck KL Jr, Valentine JF (1995) Sea urchin herbivory: evidence for long-lasting effects in subtropical seagrass meadows. J Exp Mar Biol Ecol 189:205–217

    Article  Google Scholar 

  • Hemminga MA, Duarte CM (2000) Seagrass ecology. Cambridge University Press, Cambridge

    Book  Google Scholar 

  • Hily C, Bouteille M (1999) Modifications of the specific diversity and feeding guilds in an intertidal sediment colonized by an eelgrass meadow (Zostera marina) (Brittany, France). C R Acad Sci III 322:1121–1131

    Article  Google Scholar 

  • Jackson JBC (1997) Reefs before Columbus. Coral reefs 16(Suppl.):S23–S33

    Article  Google Scholar 

  • Jackson JBC, Kirby MX, Berger WH, Bjorndal KA, Botsford LW, Bourque BJ, Bradbury RH, Cooke R, Erlandson J, Estes JA, Hughes TP, Kidwell S, Lange CB, Lenihan HS, Pandolfi JM, Peterson CH, Steneck RS, Tegner MJ, Warner RR (2001) Historical overfishing and the recent collapse of coastal ecosystems. Science 293:629–638

    Article  CAS  Google Scholar 

  • Lee KS, Dunton KH (1999) Inorganic nitrogen acquisition in the seagrass Thalassia testudinum: development of a whole-plant nitrogen budget. Limnol Oceanogr 44:1204–1215

    Article  Google Scholar 

  • Maciá S, Lirman D (1999) Destruction of Florida Bay seagrasses by a grazing front of sea urchins. Bull Mar Sci 65:593–601

    Google Scholar 

  • Moore JE, Mott GO (1974) Recovery of residual organic matter from in vitro digestion of forages. J Dairy Sci 57:1258–1259

    Article  Google Scholar 

  • Moran KL (2003) Simulated green turtle grazing: effects on structure and productivity of seagrass (Thalassia testudinum) in the central Bahamas. PhD dissertation, University of Florida, Gainesville

  • Moran KL, Bjorndal KA (2005) Simulated green turtle grazing affects structure and productivity of seagrass pastures. Mar Ecol Prog Ser 305:235–247

    Article  Google Scholar 

  • Mortimer JA (1981) Feeding ecology of the West Caribbean green turtle (Chelonia mydas) in Nicaragua. Biotropica 13:49–58

    Article  Google Scholar 

  • Ogden JC (1980) Faunal relationships in Caribbean seagrass beds. In: Phillips RC, McRoy CP (eds) Handbook of seagrass biology. Garland Publishing Inc., New York, pp. 173–198

    Google Scholar 

  • Ogden JC, Robinson L, Whitlock K, Daganhardt H, Cebula R (1983) Diel foraging patterns in juvenile green turtles (Chelonia mydas L.) in St. Croix, U.S. Virgin Islands. J Exp Mar Biol Ecol 66:199–205

    Article  Google Scholar 

  • Pandolfi JM, Bradbury RH, Sala E, Hughes TP, Bjorndal KA, Cooke RG, McArdle D, McClenachan L, Newman MJH, Paredes G, Warner RR, Jackson JBC (2003) Global trajectories of the long-term decline of coral reef ecosystems. Science 301:955–958

    Article  CAS  Google Scholar 

  • Parr Instrument Co (1960) Oxygen bomb calorimetry and combustion methods. Tech Manual No. 130, pp. 1–56

  • Perneger TV (1998) What is wrong with Bonferroni adjustments. Br Med J 16:2529–2542

    Google Scholar 

  • Pitcher TJ (2001) Fisheries managed to rebuild ecosystems? Reconstructing the past to salvage the future. Ecol Appl 11:601–617

    Article  Google Scholar 

  • Radar LF, Grimaldi RS (1961) Chemical analysis for selected minor elements in Pierre shale. U.S. Geological Survey Professional Papers 391-A, 45 pp

  • Stevens CE, Hume ID (1995) Comparative physiology of the vertebrate digestive system, 2nd edn. Cambridge University Press, Cambridge

    Google Scholar 

  • Thayer GW, Engel DW, Bjorndal KA (1982) Evidence of short-circuiting of the detritus cycle of seagrass beds by the green turtle, Chelonia mydas L. J Exp Mar Biol Ecol 62:173–183

    Article  Google Scholar 

  • Thayer GW, Bjorndal KA, Ogden JC, Williams SL, Zieman JC (1984) Role of larger herbivores in seagrass communities. Estuaries 7:351–376

    Article  Google Scholar 

  • Tomasko DA, Dawes CJ (1989) Evidence for physiological integration between shaded and unshaded short shoots of Thalassia testudinum. Mar Ecol Prog Ser 54:299–305

    Article  Google Scholar 

  • Van Soest PJ (1982) Nutritional ecology of the ruminant. O & B Books, Corvallis

    Google Scholar 

  • Vicente VP, Arroyo-Aguilú JA, Rivera JA (1980) Thalassia as a food source: importance and potential in the marine and terrestrial environments. J Agric Univ Puerto Rico 64:107–120

    CAS  Google Scholar 

  • Walkley A, Black IA (1934) An examination of the Degtjareff method for determining soil organic matter and a proposed modification of the chromic acid titration method. Soil Sci 37:29–38

    Article  CAS  Google Scholar 

  • Williams SL (1988) Thalassia testudinum productivity and grazing by green turtles in a highly disturbed seagrass bed. Mar Biol 98:447–455

    Article  Google Scholar 

  • Zieman JC (1982) The ecology of the seagrasses of South Florida: a community profile. FWS/OBS-82/25. US Fish and Wildlife Service, Office of Biological Services, Washington

  • Zieman JC, Iverson RL, Ogden JC (1984) Herbivory effects on Thalassia testudinum leaf growth and nitrogen content. Mar Ecol Prog Ser 15:151–158

    Article  CAS  Google Scholar 

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Acknowledgments

We are grateful to A. Bolten, whose insights and discussions improved the quality of the study and whose assistance with logistics made this study possible. C. Chapman, L. Chapman, T. Frazer, and J. Ogden provided valuable advice. We thank T. Arnold for analyses of secondary compounds. P. Eliazar, R. Fethiere, J. Funk, L. Schwandes, L. Sollenberger, and the UF Forage Evaluation Support Laboratory assisted with lab analyses. R. Co, L. Conway-Cranos, C. Davis, J. Greenawalt, J. Hale, R. Kuo, P. Lamarque, B. Reardon, S. Schopmeyer, C. Ward-Paige, D. Winchester, and D. Wood were invaluable in data collection. This paper benefited from the participation of KAB in the Long-Term Ecological Records of Marine Communities Working Group supported by the National Center for Ecological Analysis and Synthesis (funded by U.S. National Science Foundation grant DEB-0072909, the University of California, and the University of California, Santa Barbara). The staff of the Caribbean Marine Research Center supplied logistical support and access to the field site. Financial support was provided by N. Thompson and the National Marine Fisheries Service, Southeast Fisheries Science Center; J. Marr, N. Langley, and the Caribbean Marine Research Center; Disney Wildlife Conservation Fund; National Fish and Wildlife Foundation; the PADI Foundation; Sigma Xi; and the American Museum of Natural History.

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Authors and Affiliations

  1. Archie Carr Center for Sea Turtle Research and Department of Zoology, University of Florida, P.O. Box 118525, Gainesville, FL, 32611, USA

    Kathleen L. Moran & Karen A. Bjorndal

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  1. Kathleen L. Moran
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  2. Karen A. Bjorndal
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Correspondence to Karen A. Bjorndal.

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Communicated by P.W. Sammarco, Chauvin

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Moran, K.L., Bjorndal, K.A. Simulated green turtle grazing affects nutrient composition of the seagrass Thalassia testudinum . Mar Biol 150, 1083–1092 (2007). https://doi.org/10.1007/s00227-006-0427-9

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