POPULATION STRUCTURE AND HABITAT CONNECTIVITY OF Genidens genidens (SILURIFORMES) IN TROPICAL AND SUBTROPICAL COASTS FROM SOUTHWESTERN ATLANTIC

THAIS MACIEL; AVIGLIANO, ESTEBAN; MAICHAK DE CARVALHO, BARBARA; MILLER, NATHAN; MARCELO VIANNA

Workshop; II Workshop Latinoamericano de otolitos y otras estructuras calcificadas; 2019

We use otolith trace element-to-calcium element concentration ratios (Ba:Ca, Cu:Ca, Mg:Ca, Mn:Ca, Ni:Ca, Sr:Ca and Zn:Ca) and shape to evaluate habitat use pattern, the degree of segregation and presence of different nursery areas and fish stocks of Genidens genidens in the Brazilian coastal. Otolith core and edge element:Ca fingerprints (N= 89), as well as elliptic Fourier descriptors (N=147) were compared between four estuaries (Paraíba do Sul River, Guanabara Bay, Itapanhaú River and Paranaguá Bay). Several element:Ca ratios were significantly different between estuaries for core and edge (p<0.05). MANOVA, PERMANOVA, linear and quadratic discriminant analyses based on Fourier descriptors (12 harmonics) and microchemistry were effective for discriminating between all sampling sites (p<0.05), except Itapanhaú River and Paranaguá Bay (p>0.05). When otolith microchemistry and shape were combined, the jackknifed classification increased in relation to the separate methods, ranged from 89.5 to 100% (mean 95.2%). Otolith mean Sr:Ca suggests that G. genidens is a estuarine-resident species. However, biannual cyclical Sr:Ca oscillations indicate that oceanic incursions may occur, although, further investigations are required to verify the elements incorporation pattern into the this species otolith. The high degree of segregation in juvenile and adult stages between the estuaries is consistent with isolated nurseries and stocks, respectively, and advocates for estuary-specific management strategies.