Radiocarbon in otoliths of tropical marine fishes: Reference 14C chronology for north Caribbean waters

Abstract

Reef fishes support important fisheries throughout the Caribbean, but a combination of factors in the tropics makes otolith microstructure difficult to interpret for age estimation. Therefore, validation of ageing methods, via application of 14C is a major research priority. Utilizing known-Age otolith material from north Caribbean fishes, we determined that a distinct regional 14C chronology exists, differing from coral-based chronologies compiled for ageing validation from a wide-ranging area of the Atlantic and from an otolith-based chronology from the Gulf of Mexico. Our north Caribbean 14C chronology established a decline series with narrow prediction intervals that proved successful in ageing validation of three economically important reef fish species. In examining why our north Caribbean 14C chronology differed from some of the coral-based 14C data reported from the region, we determined differences among study objectives and research design impact 14C temporal relationships. This resulted in establishing the first of three important considerations relevant to applying 14C chronologies for ageing validation: 1) evaluation of the applicability of original goal/objectives and study design of potential 14C reference studies. Next, we determined differences between our 14C chronology and those from Florida and the Gulf of Mexico were explained by differences in regional patterns of oceanic upwelling, resulting in the second consideration for future validation work: 2) evaluation of the applicability of 14C reference data to the region/location where fish samples were obtained. Lastly, we emphasize the application of our north Caribbean 14C chronology should be limited to ageing validation studies of fishes from this region known to inhabit shallow water coral habitat as juveniles. Thus, we note the final consideration to strengthen findings of future age validation studies: 3) use of 14C analysis for age validation should be limited to species whose juvenile habitat is known to reflect the regional 14C reference chronology.