Seasonal variability in food consumption, body composition and allometric relationships in the brown shrimp Farfantepenaeus aztecus (Ives, 1891) (Decapoda, Penaeidae) from Tamiahua Lagoon, Veracruz

Abstract

The effect of saUnity and temperature regimes, typical of most contrasting periods of the annual cycle (warm and cold) at Tamiahua lagoon, Veracruz, Mexico, on food consumption, body composition and allometdc relationships of juveniles of the brown shrimp Farfantepenaeus aztecus (Ives, 1891) were examined. The following morphometric and tissue composition parameters were measured: total length (TL), céphalothorax length (CL), wet weight (WW), dry weight (DW), % body water content, organic matter (OM), total minerals (TM) and energy content (EC). The digestive tract of shrimps collected from both warm and cold periods was analysed determining its composition, quantity, and caloric content of the ingested food. AUometric relationships were calculated among: DW-WW, WW-TL and CL-TL. OM and TM content were correlated with the shrimp's body weight. During the cold and warm seasons, salinity fluctuated between 24 and 36 psu and 12-36 psu, and average temperatures between 25 and 30°C, respectively. WW-TL and CL-TL relationships were statistically different among shrimps from both seasons. Body water content varied significantly, altering the DW-WW relationship, being higher in the warm season. No significant seasonal variation was detected in the shrimp's OM, TM and EC. A shift in shrimp feeding habits was distinguished in the two seasons examined. Carnivorous habits prevail in winter whilst herbivory is more frequently observed during the warm season. However, the food energy remained relatively stable in both seasons, indicating that shrimp consume available resources in the lagoon in order to compensate for the absence of other food components and thus to maintain a constant energy flow independent of the season.Se evaluó el efecto de los regímenes de salinidad-temperatura, propios de las épocas más contrastantes del ciclo anual (cálida-fría) de la laguna de Tamiahua, Veracruz, México, sobre la ingestión de alimento, composición corporal y relaciones alométricas de camarones juveniles de ambos sexos de la especie Farfantepenaeus aztecus (Ivés, 1891). Los índices morfométricos y de composición del tejido medidos fueron: longitud total (LT), longitud del cefalotórax (LC), peso húmedo (PH), peso seco (PS), % de agua corporal, materia orgánica (MO), minerales totales (MT) y contenido de energía (CE). Se analizó el tracto digestivo en camarones colectados en ambas épocas, midiendo el tipo, cantidad y contenido calórico del alimento ingerido. Se calcularon las relaciones alométricas: PS-PH, PH-LT y LC-LT. La MO y el contenido de minerales se correlacionaron con el peso corporal de los camarones. Durante la época fria la salinidad fluctuó entre 24-36 ups, en la época cálida se registró entre 12-36 ups, las temperaturas promedio de cada época fueron 25° y 30°C respectivamente. Las relaciones PH-LT y LC-LT, resultaron estadísticamente diferentes entre camarones de ambas épocas. El contenido de agua corporal varió significativamente, alterando la relación PS-PH, siendo superior en organismos de época cálida. La MO, MT y el CE d...

Aspects of the Life Cycle of Chirostoma jordani (Pisces: Atherinopsidae) in A Periurban Lake from Mexico City: An Ecophysiological Assessment

“…Subsequently, using the QO2 -dry weight relationship, the QO2/day of the average organism of the analyzed sample was calculated. Finally, the values obtained were converted into energy expenditure equivalents, through the use of the oxycaloric coefficient (Qox= 3.32 cal/mg O2, Bradfield and Solomon, 1972;Latournerié-Cervera, 2007), resulting in the fraction of energy used in aerobic metabolism. The "acclimatization" pattern of the fish was assessed considering the metabolic rate of organisms of similar size and body weight during the dry and rainy season, using a "Student's T" test under a H0 of no difference.…”

“…The body constituents of organisms are a reflection of the composition and availability of food supplies available in their habitat, as well as the interconversion processes of their intermediary metabolism to respond to proper functioning and to give continuity to the different phases of its life cycle, all of this is modulated by multiple intrinsic and extrinsic factors that, depending on the level at which they occur in the environmental mosaic of the habitat of the species, can act as limiting, masking, controlling factors and can even be lethal, due to the intensity of the factor and its possible interaction with other environmental entities (Fry, 1971;Latournerié-Cervera, 2007). In the present study (Table I), five indicators were analyzed: wet weight, dry weight, body water, N-total and energy content.…”