MEPS 229:195-205 (2002)  -  doi:10.3354/meps229195

How important are mangroves as a carbon source for decapod crustacean larvae in a tropical estuary?

Ralf Schwamborn1,*, Werner Ekau1, Maren Voss2, Ulrich Saint-Paul1

1Center for Tropical Marine Ecology (ZMT), Fahrenheitstraße 6, 28359 Bremen, Germany
2Baltic Sea Research Institute (IOW), Seestraße 15, 18119 Rostock-Warnemünde, Germany
*Present address: Departamento de Oceanografia, Universidade Federal de Pernambuco, 50 730-540 Recife, Brazil. E mail:

ABSTRACT: In order to evaluate the importance of mangrove leaf detritus as a food source for decapod crustacean larvae, stable isotopes (δ13C and δ15N) 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, δ13C 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 (δ13C: -26.8‰) to larval nutrition was generally negligible. Among decapod larvae, porcellanid zoeae showed relatively low δ13C values, while penaeid shrimp postlarvae showed the highest δ13C. 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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