Efeito do tempo de conservação dos espécimes sobre a qualidade dos microincrementos em otólitos sagittae de Anchoa tricolor (Agassiz) (Clupeiformes, Engraulidae). O número de microincrementos em otólitos sagittae de espécimes de pós-larvas de Anchoa tricolor (Agassiz, 1829) fixadas em formol 10% foram comparados em diferentes períodos de conservação (quatro dias versus quatro anos). Diferenças significativas foram encontradas no número de microincrementos para pós-larvas variando de 20-26 mm de comprimento total (CT), com médias de 18,6 microincrementos (± 0.75 erro padrão) para peixes preservados por quatro anos, e 35,3 microincrementos (± 1.28 erro padrão) para peixes preservados por quatro dias. Portanto, o número de microincrementos em otólitos de pós-larvas preservados por longos períodos pode não ser adequado para inferências de taxas de idade ou crescimento. Adicionalmente, não foram detectados ou extraídos otólitos em pós-larvas menores do que 20 mm CT devido a maior composição de matéria orgânica durante esta fase do ciclo de vida.
Phenotypic differentiation among fish populations may be used for management of distinct stocks and helps in conserving biodiversity. We compared morphometric and meristic characters of the anchovy Anchoa januaria from shallow semi-closed bays between the south-eastern (Tropical, 23°S) and southern (Subtropical, 25°S) Brazilian coast. We hypothesized that differences between habitats and environmental conditions result in morphological divergence between conspecific populations. Fish size did not differ significantly between the two areas. Significant differences in the meristic and morphological characters were detected for individuals between the two areas, with specimens from the Subtropical region having significant larger head height, pectoral fin length and eye diameter compared with those from the Tropical region. Conversely, specimens from the Tropical region had significantly larger maxillary length, mouth length and body height than those from the Subtropical region. The number of rays for the dorsal and pectoral fins were higher for the specimens from the Subtropical region, whereas for the anal fin was higher for individuals from the Tropical region. Different morphological groups between the two regions were depicted by principal component analysis and discriminant function analysis, which suggest that morphological divergence is occurring. Local environmental influences and the lack of genetic interchange are likely to be the causes of such divergence. This is facilitated by the low tolerance of this species to marine waters that prevents connectivity between these stocks/populations.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.