Evaluation of Mn and Fe in coral skeletons (Porites spp.) as proxies for sediment loading and reconstruction of 50 yrs of land use on Ishigaki Island, Japan
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Manganese (Mn) and iron (Fe) concentrations were measured in coral skeletons (Porites spp.) collected from the Todoroki River on Ishigaki Island, Japan, to reconstruct the history of land use in the river catchment area. We prepared (1) five bulk samples to investigate the present spatial distribution and (2) micro-samples from two long cores to study the temporal variability of sediment loading from the Todoroki River. The existing state of the elements Mn and Fe in bulk coral skeleton samples was examined by a chemical cleaning experiment. The results of the experiment suggested that Fe was not incorporated into the crystal lattice of the coral skeleton but that Mn was incorporated, as previously reported. The bulk sample data, with and without chemical cleaning, indicated that the spatial distribution of both elements in corals collected along a sampling line from the river mouth toward the reef crest was complex and most likely reflected salinity changes and the amount of suspended particulate matter. The temporal variation of Mn and Fe, in particular the variation of baseline/background levels, mainly reflected the history of land development on Ishigaki Island. In addition, Mn showed clear seasonal variability that appeared to be controlled by a combination of temperature, primary productivity, and precipitation. The results of the present study suggest that Mn may be a useful proxy for river discharge or biological activity depending on local marine conditions, if the specific behavior of Mn at the coral growth site is known.
KeywordsSediment loading Manganese Iron Coral skeleton Cleaning experiment
The authors thank Y. Yoshinaga for assisting in the preparation of subsamples. The research was funded by Grant-in-Aid for Scientific Research on Innovative Areas ‘Coral reef science for symbiosis and coexistence of human and ecosystem under combined stresses’ (#20121004) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) Japan.
- Ahrland S (1975) Metal complexes present in seawater. In: Goldberg ED (ed) The Nature of Seawater. Dahlem Konferenzen, Berlin, pp 219–144Google Scholar
- de Baar HJW, de Jong JTM (2001) Distributions, Sources and Sinks of Iron in Seawater. In: Turner DR, Hunter KA (eds) Biogeochemistry of Fe in Seawater. SCOR-IUPAC series, J Wiley, Baltimore, pp 123–253Google Scholar
- Felis T, Merkel U, Asami R, Deschamps P, Hathorne EC, Kölling M, Bard E, Cabioch G, Durand N, Prange M, Schulz M, Cahyarini SY, Pfeiffer M (2012) Pronounced interannual variability in tropical South Pacific temperatures during Heinrich Stadial 1. Nat Commun 3:965 [doi: 10.1038/ncomms1973]Google Scholar
- Hasegawa H (2011) The decline of coral reef conditions caused by the extensive land modification: a case study of the Shiraho Area on Ishigaki Island, Okinawa, Japan. J Remote Sensing Soc Japan 31:73–86. in JapaneseGoogle Scholar
- Kawahata H, Saito I, Suzuki A (1998) Terrestrial inputs potentially influence carbon cycle and metabolism in the Shiraho reef. Proceedings of Techno-Ocean 1998 International Symposium 381–384Google Scholar
- Lapworth DJ, Knights KV, Key RM, Johnson CC, Ayoade E, Adekanmi MA, Arisekola TM, Okunlola OA, Backman B, Eklund M, Everett PA, Lister RT, Ridgway J, Watts KJ, Kemp SJ, Pitfield PEJ (2012) Geochemical mapping using stream sediments in west-central Nigeria: Implications for environmental studies and mineral exploration in West Africa. Appl Geochem 27:1035–1052CrossRefGoogle Scholar
- Mishima M, Suzuki A, Nagao M, Ishimura T, Inoue M, Kawahata H (2010) Abrupt shift toward cooler condition in the earliest 20th century detected in a 165 year coral record from Ishigaki Island, southwestern Japan. Geophys Res Lett 37:L15609 [doi: 10.1029/2010GL043451]
- Moyer RP, Grottoli AG, Olesik JW (2012) A multiproxy record of terrestrial inputs to the coastal ocean using minor and trace elements (Ba/Ca, Mn/Ca, Y/Ca) and carbon isotopes (δ13C, Δ14C) in a nearshore coral from Puerto Rico. Paleoceanography 27:PA3205 [doi: 10.1029/2011PA002249]
- Nakasone K, Higa E, Omija T, Yasumura S, Nadaoka K (2001) Measurements of suspended solids in Todoroki River, Ishigaki Island. Annual Report of Okinawa Prefectural Institute of Environment and Health 35:93–102 in JapaneseGoogle Scholar
- Sarthou G, Bucciarelli E, Chever F, Hansard SP, González-Dávila M, Santana-Casiano JM, Planchon F, Speich S (2011) Labile Fe(II) concentrations in the Atlantic sector of the Southern Ocean along a transect from the subtropical domain to the Weddell Sea Gyre. Biogeosciences 8:2461–2479CrossRefGoogle Scholar
- Yamazaki A, Watanabe T, Tsunogai U (2011) Nitrogen isotopes of organic nitrogen in reef coral skeletons as a proxy of tropical nutrient dynamics. Geophys Res Lett 38:L19605 [doi: 10.1029/2011GL049053]