Parâmetros hematológicos e alterações histopatológicas em bijupirá (Rachycentron canadum Linnaeus, 1766) com amyloodiniose

O objetivo do trabalho foi descrever os parâmetros hematológicos e as alterações histopatológicas em bijupirás infectados por Amyloodinium ocellatum. Um grupo de 27 peixes foi anestesiado para coleta de amostras de sangue e eutanasiados para coleta de muco e fragmentos de tecido cutâneo e branquial. Foram avaliadas a prevalência e a intensidade parasitária da infecção, assim como os valores de parâmetros hematológicos e alterações histopatológicas. A prevalência parasitária nas brânquias foi de 100% e no muco foi de 80,8% e as intensidades parasitárias médias foram de 683,5 nas brânquias, e 67,1 no muco cutâneo. Os valores médios dos parâmetros hematológicos foram: eritrócitos 4,3x10(6)µL; VG 26%; VGM 64,2fL; proteína plasmática 5,8mg/dL; trombócitos 5,2 x10³/µL e leucócitos 3,6 x10³/µL. Além disso, foram verificadas hiperplasia do epitélio respiratório acompanhada de fusão lamelar, descolamento do epitélio, dilatação do seio venoso, formação de aneurisma, ruptura do epitélio lamelar, hemorragia, necrose, reação inflamatória linfocítica. O parasito foi observado nas lamelas branquiais, o VMA variou do grau discreto ao severo e o IAH foi de 76,8. A pesquisa assume importância por se tratar dos primeiros estudos em Rachycentron canadum, um peixe que se destaca com potencial ao cultivo

Effects of tank colour on larval survival and development of mud crab Scylla serrata (Forskal)

Hatchery culture of mud crabs has not yet achieved commercial viability despite decades of research efforts. Further research is therefore needed to better understand larval culture requirements of the crab. Based on anecdotal observations, an experiment was carried out to test whether the background colour of the culture vessel affected larval culture success. Newly hatched larvae of Scylla serrata were reared in culture vessels of five colours, i.e., black, dark green, maroon, sky blue and white. Larval survival and development were monitored daily until all of them either moulted to the first crab stage or died. The results showed clear effects of background colour on larval survival. A general tendency of higher larval survival in darker-coloured backgrounds was evident. In particular, overall zoeal survival for larvae reared in black vessels was significantly higher than those reared in white ones. Background colour also appeared to affect larval development. Larvae reared in darker backgrounds generally had shorter development times and more synchronized moulting. A significant delay in zoeal development was observed in larvae reared in white vessels. Dark backgrounds possibly facilitated more efficient feeding, reduced settlement of larvae at the bottom of the vessels as well as minimized stress. This result appears to be the first to demonstrate that background colour can significantly affect larval survival and development of a crustacean species.\u