Fin spines chemistry as a non-lethal alternative to otoliths for habitat and stock discrimination: comparison between structures for an endangered catfish species

AVIGLIANO, ESTEBAN

MARINE ECOLOGY PROGRESS SERIES

INTER-RESEARCH

Lugar: Oldendorf/Luhe; Año: 2019

0171-8630

Trace element:Ca(Ba:Ca, Mg:Ca, Mn:Ca and Sr:Ca) ratios in water and last growth intervals(outer 45 µm) of dorsal spine and otolith edges from Genidens barbus inthree study areas (Brazil, Argentina-Uruguay and Patagonia) were compared, tosee if the spine can provide a non-lethal natural marker alternative tootoliths for this endangered species. There was an association betweencalcified structures and the availability of some elemental:Ca ratios in water(all elements). Among the measured element:Ca ratios, a strongcorrelation in Ba:Ca between outer edges of fin spines and otoliths was found(r2 = 0.87, p = 0.0001), whereas Mg:Ca, Mn:Ca and Sr:Ca ratios wereweakly correlated between structures (0.09 < r2 < 0.20, 0.0006< p < 0.02). Several ratios were significantly different among sites forotolith and spine edge (p < 0.05). PERMANOVA (p < 0.05) and quadraticdiscriminant analysis (QDA) proved highly effective for characterizingdifferences in otolith and spine edge compositions between sampling sites(classification rates: 84.2 % and 90.1 % for otolith and spine edge,respectively) suggesting that both structures can be used as habitat markers.To identify the possible contribution of multiple stocks to the different areaswe performed QDA for the complete last year of a fish?s life. Classificationrates were high for both structures averaging 79.6 % and 81.2 % for otolith andspine, respectively, suggesting the existence of new stocks in Patagonianwaters. Spine chemistry seems to be an acceptable non-lethal advantage over otolith to studydifferent biological aspects of catfish.