From lecithotrophy to planktotrophy: ontogeny of larval feeding in the Amazon River prawn Macrobrachium amazonicum

Abstract

During downstream transport from rivers to estuaries, early larval stages of the Amazon River prawn Macrobrachium amazonicum (Heller 1862) are likely exposed to planktonic food limitation. In the laboratory, we studied the effects of presence or absence of food on larval survival, moulting and biomass (dry mass, and content of carbon, hydrogen and nitrogen). Unfed larvae developed successfully from hatching of the Zoea I (Z I) to the third zoeal stage (Z III). Complete absence of starvation effects indicated obligatory lecithotrophy in Z I, while significantly delayed moulting and reduced biomass in unfed Z II proved that this stage is facultatively lecithotrophic. Although unfed Z III did not develop any further (obligatory planktotrophy), they still showed a high endotrophic potential, surviving for up to another 10 d (in total 2 wk from hatching), and utilizing about two-thirds of their initial biomass. Dramatically decreasing C:N ratios in unfed larvae suggest an almost complete metabolic degradation of internal lipid stores (visible as fat droplets in the hepatopancreas region), but little protein mobilization. Larvae obtained from 2 different females differed significantly in biomass at hatching and, correspondingly, also in maximum survival time, delay of moulting to the Z III and average rates of biomass utilization. In conclusion, the early larval stages of M. amazonicum depend very little on food, shifting from completely non-feeding behaviour (Z I) through facultative lecithotrophy (Z II), to planktotrophy (later stages). This ontogenetic pattern may be an adaptation to initial food limitation associated with larval export from limnic to estuarine environments.

Effect of salinity on the metabolism and osmoregulation of selected ontogenetic stages of an amazon population of Macrobrachium amazonicum shrimp (Decapoda, Palaemonidae)

“…Macrobrachium amazonicum have between 9 and 11 larval stages under laboratorial conditions in which salinity and temperature are kept, respectively, around at 10 and 29°C (Guest and Durocher, 1979;Vega Perez, 1984;Anger and Hayd, 2009). We observed in the present work an abbreviation of the larval stage once almost all zoeae VIII kept on brackish water of 6, 12 or 18 underwent metamorphosis directly to post-larvae.…”

Amphidromy in shrimps: a life cycle between rivers and the sea

“…Furthermore, Pantanal Zoea I larvae were facultativly lecithotrophic but Zoea III (and beyond) larvae completely planktotrophic. Amazonian estuarine larvae, which require salinity (optimally 10 ppt) to reach and continue into zoeal stages, can survive without food through Zoea III, occasionally molting to Zoea IV after which obligate planktotrophy begins (Anger & Hayd, 2009, 2010. The greater dependence on lecithotrophy in Amazonian larvae is likely an adaptation to the very long drift times in moving river water from upstream hatching sites to coastal estuaries.…”

Indicadores de condicion larvaria aplicados al camaron de rio del norte Cryphiops caementarius (Molina, 1782), en condiciones de cultivo controlado

“…Estos estudios, a nivel experimental y de cultivo, demuestran que su fisiología digestiva se relaciona con la estrategia de alimentación y desarrollo larvario, proporcionando información de base para adecuar los protocolos de alimentación en un cultivo comercial (Jones et al, 1997). Un ejemplo de ello corresponde a estudios realizados en estados tempranos de larvas de crustáceos de agua dulce del género Macrobrachium, en que se ha determinado que los primeros estados de desarrollo larvario, dependen muy poco del alimento externo, completando el estado de zoea 1 con la utilización sólo de las reservas vitelinas, mientras que el estado de zoea 2 presenta un comportamiento lecitotrófico facultativo, siendo completamente planctotróficas sólo en estados más avanzados (Roustain et al, 1999;Pereira & Valenti, 2003;Anger & Hayd, 2009). También, en estudios realizados con larvas de camarones peneidos, se ha observado que las protozoeas muestran mejor respuesta enzimática digestiva cuando se adiciona microalgas en la dieta, mejorando así su crecimiento y supervivencia.…”