The stable isotopic composition of carbonate (C & O) and the organic matrix (C & N) in waterbird eggshells from South Florida: insights into feeding ecology, timing of egg formation, and geographic range

G. J. Mackenzie, F. C. Schaffner, Peter K Swart

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

In order to better understand the feeding ecology and timing of egg formation and regional geographic range of wading birds from South Florida, the δ13C and δ18O values of eggshells and the δ13C and δ15N values of the organic matrix, were measured in ~400 samples, representing nine species of waterbirds. Results reveal major differences between the eggshells of birds nesting in the Everglades versus Florida Bay, with the samples from the Everglades having lower δ13C, and more positive δ18O values, compared to specimens from Florida Bay. The differences in the δ13C values represent a fundamental difference in the δ13C of the organic material at the base of the food chains in the two areas. In the Everglades, the δ13C values are controlled by particulate organic material derived from terrestrial vegetation, while in Florida Bay δ13C values are controlled by seagrasses and other marine plants. The positive δ18O values from the Everglades reflect enrichment in 18O of the water as a result of evaporation in the Everglades compared to Florida Bay during the period of egg formation. All of the samples exhibited similar δ15N values and the absence of positive correlation between δ13C and δ15N suggests that either the birds are feeding at generally similar trophic levels, or that the δ13C and δ15N of the organic material in the eggshell are not an effective trophic indicator in these environments.

Original languageEnglish (US)
Pages (from-to)89-108
Number of pages20
JournalHydrobiologia
Volume743
Issue number1
DOIs
StatePublished - 2015

Keywords

  • Carbon isotope
  • Eggshells
  • Nitrogen isotope
  • Oxygen isotope
  • Waterbirds

ASJC Scopus subject areas

  • Aquatic Science

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