Inter-Research
Marine Ecology Progress Series

ABSTRACT: In order to evaluate the importance of mangrove leaf detritus as a food source for decapod crustacean larvae, stable isotopes (d13C and d15N) were measured in the tissue of these larvae and other selected organisms. Decapod crustacean larvae and planktonic adult decapods, Lucifer faxoni and Acetes americanus, were sampled in the Itamaracá estuarine system, Brazil. For comparison with stable isotope values in the estuary, plankton and POM samples were also taken on the adjacent continental shelf. In the Itamaracá estuarine system, d13C of decapod larvae and the holoplanktonic decapods L. faxoni and A. americanus ranged from about -17 to -23‰ (mean: -19.8 ± 1.5‰). This indicates that the contribution of mangrove carbon (d13C: -26.8‰) to larval nutrition was generally negligible. Among decapod larvae, porcellanid zoeae showed relatively low d13C values, while penaeid shrimp postlarvae showed the highest d13C. Porcellanid zoeae were thus the only decapod larvae with a considerable percentage (13 to 40%) of mangrove carbon in their tissue. However, these low values may also be due to a negative isotope shift that occurs during embryogenesis. Feeding experiments with zoeae of Petrolisthes armatus (Anomura: Porcellanidae) and Sesarma rectum (Brachyura: Grapsidae) showed assimilatory shifts of up to 1.0 ± 0.2‰ for ¹³C and up to 1.4 ± 0.6‰ for ¹⁵N. Analysis of embryonic isotope fractionation for 5 decapod crustacean species, P. armatus, S. rectum, Aratus pisonii, Uca thayeri, and U. maracoani, showed that larval tissue was ¹³C-depleted by up to 3.8‰ and ¹⁵N-depleted by up to 2.3‰ in relation to parental tissue.

KEY WORDS: Decapod crustacean larvae · Stable isotopes · Mangrove estuaries · Detritus · Food webs

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Published in MEPS Vol. 229 (2002) on March 20
Print ISSN: 0171-8630; Online ISSN: 1616-1599. Copyright © Inter-Research, Oldendorf/Luhe, 2002