The use of morphological and histological features as nutritional condition indices of Pagrus pagrus larvae

Abstract

Morphometrical and histological techniques were employed to characterize Pagrus pagrus larvae nutritional condition. Larvae were reared in laboratory under controlled conditions with the main objective of testing whether these methodologies allowed finding differences between larvae from different feeding treatments. Once yolk was consumed (three days after hatching) larvae were assigned to a feeding treatment: starved during the whole experiment; delayed feeding, starved during three days; fed during the entire experiment. Algae (Nannochloropsis oculata) and rotifers (Brachionus plicatilis) were provided to larvae for feed treatments. Larvae were fixed daily; for morphometrical purposes in 5% formaldehyde solution, and in Bouin for histological sections. Results herein obtained showed that both methodologies are sensitive enough to distinguish larvae characterized by different nutritional condition states obtained from the feeding treatments. Consequently, these methodologies could be employed in wild red porgy larvae in order to asses their nutritional condition. These techniques could also be employed to check larval quality obtained with aquaculture purposes to estimate the effects of changes in rearing protocols or kind of food supply and thus, to guaranty a higher survival of early developmental stages of reared larvae.Con el objeto de determinar si las técnicas morfométricas e histológicas permiten diferenciar larvas en estado de inanición de las sometidas a tratamientos de alimentación, ejemplares de Pagrus pagrus fueron criados en laboratorio bajo condiciones controladas. Una vez que el vitelo fue consumido (tres días luego de la eclosión) las larvas fueron sometidas a diferentes tratamientos de alimentación: completamente privadas de alimento, privadas de alimento durante tres días y luego alimentadas, y alimentadas durante todo el experimento. Algas (Nannochloropsis oculata) y rotíferos (Brachionus plicatilis) fueron proporcionados a las larvas de los tratamientos de alimentación. Diariamente se fijaron ejemplares de los tres tratamientos en formol 5% para estudios morfométricos y en Bouin para estudios histológicos. Los resultados obtenidos dan evidencias de que las metodologías presentadas son suficientemente sensibles para determinar diferencias en la condición de larvas sometidas a los tratamientos de alimentación. Por lo tanto, podrían ser empleadas para determinar la condición nutricional de las larvas de besugo recolectadas en el mar. Por otra parte, éstas metodologías podrían ser empleadas para determinar la calidad de larvas producidas en acuicultura y evaluar los efectos de modificaciones introducidas en los protocolos de crianza o en el tipo de alimento suministrado con el objeto de mejorar la supervivencia de los estadios tempranos de desarrollo.

Morphological and biochemical approaches to assess the nutritional condition of the Argentine hake Merluccius hubbsi larvae from two different nursery areas

“…According to Diaz (2010), Diaz et al . (2013), and Diaz and Macchi (2014), the variables were (Figure 1): standard length ( L S ), length from the snout to the anus (LSA), head depth (HD), body depth at the anus (BDA) and eye diameter (ED). ED was determined as the average between the maximum and minimum diameters.…”

Ontogenetic shift in the energy allocation strategy and physiological condition of larval plaice (Pleuronectes platessa)

“…Slices were observed under optical microscope and a grade of condition was attributed to each larva. Grades were defined based on an extensive review of the literature describing for fish larvae the patterns of histological degradations of criteria commonly used for intestine (midgut and hindgut), pancreas and liver [35,37,70–76]. three grades of condition were then defined as follows:…”

Investigating environmental influence and temporal changes in sole (Solea solea) larvae condition using histology

“…Food deprivation in fish larvae can be assessed using condition indices (Ferron and Leggett, 1994). Many indices are available to highlight the effects of starvation J o u r n a l P r e -p r o o f on growth and nutritional condition (Buckley, 1979;Clemmesen, 1994;Diaz et al, 2018), energy reserves (Fraser, 1989;Giraldo et al, 2011) or tissue integrity (Diaz et al, 2013;O'Connell, 1976;Theilacker, 1978). The latter is an integrative approach of the level of starvation and can be evaluated using histology.…”

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“…In contrast, literature regarding the early life history of larval red porgy reared in intensive culture conditions is scarce, either fragmentary or related to the internal morphology of a few individuals caught in the wild (Alarcon and Alvarez, 1999), morphological and histological features (Diaz et al, 2013) and/or limited to yolk-sac larvae and larval development under captivity (Mihelakakis et al 2001). Therefore, the objective of this study was to describe the ontogeny of the early stages of development of red porgy larvae with focus on the age and size in the morphological and functional development under intensive culture conditions using ambient temperature regime.…”