Food partitioning of leaf-eating mangrove crabs (Sesarminae): Experimental and stable isotope (13C and 15N) evidence
Kristensen, D.K.; Kristensen, E.; Mangion, P. (2010). Food partitioning of leaf-eating mangrove crabs (Sesarminae): Experimental and stable isotope (13C and 15N) evidence. Est., Coast. and Shelf Sci. 87(4): 583-590. dx.doi.org/10.1016/j.ecss.2010.02.016 In: Estuarine, Coastal and Shelf Science. Academic Press: London; New York. ISSN 0272-7714; e-ISSN 1096-0015, more |  |
| Keyword | | | Author keywords | Sesarmid crab; mangrove; food source; stable isotopes; mixing model |
| Authors | | Top | - Kristensen, D.K.
- Kristensen, E.
- Mangion, P., more
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| Abstract | The feasibility of mangrove leaves as a full diet for sesarmid crabs has been questioned for decades. Since these leaves are nitrogen-poor, sesarmids probably obtain nitrogen from other sources to sustain growth. The aim of this study was to assess the food partitioning of the sesarmid species Neoepisesarma versicolor with emphasis on nitrogen allocation. The preference for animal tissue when crabs were pre-fed diets of different nitrogen content was determined in the laboratory. Furthermore, the possible in situ diet composition of N. versicolor was established from carbon and nitrogen stable isotope signature (d13C and d15N) of freshly caught individuals and their potential food sources, using a concentration-dependent mixing model. N. versicolor showed significantly higher feeding preferences for fish meat when pre-fed leaf material without than with access to meat, indicating that this crab species can meet its nitrogen demand by ingesting animal tissue. The stable isotope mixing model based on in situ materials suggests that the diet of N. versicolor consists of similar to 60% leaves in terms of biomass, leaving similar to 40% for other sources such as animal tissue and benthic microorganisms. The biomass contribution from animal tissues, in form of e.g. other crustaceans and fish carcasses, was found to account for similar to 15%. Despite the relative low biomass fraction, animal food sources may contribute with up to half of the nitrogen in the diet of N. versicolor. The quantity of ingested sediment most likely exceeds that of animal tissues. However, due to the low concentration of assimilable microalgae and other microorganism, we propose that sediment associated sources are less important as a nitrogen source for N. versicolor than hitherto presumed. |
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