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Caribbean coral reefs are undergoing massive degradation, with local increases ofmacroalgae and reduction of architectural complexity associated with loss of reefbuildingcorals. We explored whether reef degradation affects the feeding ecology oftwo co-occurring spiny lobsters: Panulirus guttatus, which is an obligate reef-dweller,and Panulirus argus, which uses various benthic habitats including coral reefs. Wecollected lobsters of both species from the back-reef zones of two large reefs similarin length (1.5 km) but differing widely in level of degradation, at the Puerto MorelosReef National Park (Mexico). We measured the carapace length (CL) and weight (W) oflobsters, estimated three condition indices (hepatosomatic index, HI; blood refractiveindex, BRI; and W/CL ratio), and analyzed their stomach contents and stable isotopevalues (d15N and d13C). All lobsters tested negative for the presence of the virus PaV1,which can affect nutritional condition. Stomach contents yielded 72 animal taxa, mainlymollusks and crustaceans, with an average of 35 taxa per species per reef, but withmuch overlap. In P. guttatus, CL, HI, BRI, and W/CL did not vary with reef, but meanisotopic values did. The isotopic niche of P. guttatus showed little overlap between reefs,reflecting differences in local carbon sources and underlining the habitat specialization ofP. guttatus, which exhibited a higher trophic position on the more degraded reef. Overall,the trophic position of P. guttatus was higher than that of P. argus. In P. argus, none ofthe variables differed between reefs and the isotopic niche was wide and with greatoverlap between reefs, reflecting the broader foraging ranges of P. argus compared toP. guttatus. Additional isotopic values from 16 P. argus caught at a depth of 25 m inthe fore reef suggest that these larger lobsters forage over different habitats and have ahigher trophic position than their smaller conspecifics and congeners from the back reef.The feeding ecology of P. argus appears to be less influenced by coral reef degradationthan that of P. guttatus, but our results suggest a buffering effect of omnivory againsthabitat degradation for both lobster species.

Palabras clave: Caribbean Sea; habitat degradation; nutritional condition; omnivory; Panulirus argus; Panulirus guttatus; Stable isotope analyis; stomach content

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