Effects of sudden salinity changes on the oxygen consumption and osmoregulatory parameters in the Senegales sole (Solea senegalensis Kaup, 1858)

Senegalese sole juveniles were held into flow-through respirometers and submitted to a sudden salinity change. Briefly, 40-50 g body weight fish were kept into chambers with initial salinity of 37.5 ppt (the same as in culture tanks) and, after an acclimation of 4 hours, the salinity was changed to 5 or 55 ppt. A control group did not experience any salinity alteration. Oxygen consumption was registered every 14 min and fish were sampled (gill biopsy and plasma) at different times (at t=4.5 h and t=7 h in order to determine gill Na+,K+- ATPase activity and plasma cortisol concentration. At t=4.5 h, oxygen consumption showed an inverse relationship with salinity, while gill Na+,K+- ATPase activity increased. Plasma cortisol levels presented a "U-shaped" relationship with salinity. At 7 h, oxygen consumption was higher in the control group, while cortisol and gill Na+,K+- ATPase activity varied in parallel to salinity. Our results suggest that sudden salinity changes evoked an acute stress situation (cortisol increased up to 15x over the basal level) which was slightly attenuate after 7 h. Fish quickly adapted its respiration rate to the new environmental conditions and this rate returned progressively to its normal values after the shock. Regarding enzyme activity, fish increased (55 ppt) or decreased (5 ppt) the ATPase activity depending on the salinity, as described in other studies.This work was supported by Interreg Project 0251_ECOAQUA_5_E, financed by the EDRF (European Regional Development Fund). www.juntadeandalucia.es/agriculturaypesca/ifapa/ecoaqua. &nbsp;Juveniles de lenguado senegal&eacute;s fueron mantenidos en respir&oacute;metros y sometidos a un cambio brusco de salinidad. Resumidamente, peces de 40-50 g se mantuvieron a una salinidad de 37.5 ppt y, despu&eacute;s de una aclimataci&oacute;n de 4 horas, la salinidad se vari&oacute; a 5 &oacute; 55 ppt. Un grupo control no experiment&oacute; ninguna alteraci&oacute;n. El consumo de ox&iacute;geno fue registrado cada 14 min y los peces fueron muestreados (plasma y branquias) a diferentes tiempos (t=4.5 h y t=7 h para determinar la actividad Na+,K+- ATPasa branquial la concentraci&oacute;n de cortisol en plasma). A t=4.5 h, el consumo de ox&iacute;geno fue inversamente proporcional con la salinidad, mientras que la actividad Na+,K+- ATPasa branquial creci&oacute;. El cortisol plasm&aacute;tico present&oacute; una curva en forma de "U" en funci&oacute;n de la salinidad. A t=7 h, el consumo de ox&iacute;geno fue mayor en el grupo control, mientras que la Na+,K+- ATPasa branquial vari&oacute; en paralelo con la salinidad. Nuestros resultados sugieren que un cambio brusco de salinidad provoca una situaci&oacute;n de estr&eacute;s agudo (cortisol aumenta 15 veces su valor basal), que se aten&uacute;a ligeramente despu&eacute;s de 7 h. Los peces r&aacute;pidamente adaptan su tasa respiratoria a esta nueva condici&oacute;n ambiental y luego var&iacute;a progresivamente a su valor inicial. Respecto a la actividad enzim&aacute;tica, los peces aumentaron (55 ppt) o disminuyeron (5 ppt) la actividad ATPasa en funci&oacute;n de la salinidad, como se ha descrito en previos trabajos.Este trabajo fue apoyado por el proyecto Interreg 0251_ECOAQUA_5_E , financiado por el FEDER (Fondo Europeo de Desarrollo Regional). www.juntadeandalucia.es/agriculturaypesca/ifapa/ecoaqua.</p

The importance of amphipods in diets of marine species with aquaculture interest of Andalusian coast

Los anfípodos son crustáceos con un alto valor nutricional y gran potencial para ser cultivados como alimento en especies de interés acuícola. Juegan un papel fundamental en el intercambio energético de la cadena trófica como recurso de muchos depredadores. Para evaluar la importancia de este grupo, se han revisado los estudios sobre alimentación de 10 especies (ocho peces y dos cefalópodos) del litoral andaluz cultivadas o con interés en acuicultura. Los anfípodos están presenten en la dieta de especies ya consolidadas en acuicultura como Sparus aurata, Dicentrarchus labrax y Solea senegalensis, aunque no se usan en ninguna de las fases de su cultivo intensivo. Existen otras muchas especies en las que los anfípodos podrían jugar un papel fundamental en su cultivo, como son Sepia officinalis, Octopus vulgaris, Solea solea, Mullus surmuletus y M. barbatus, además del género Hippocampus, de gran interés en acuariofilia. Es necesario intensificar la investigación de estos crustáceos para evaluar adecuadamente su importancia como presas en el medio natural y para cuantificar su valor nutricional como fuente alternativa de alimento.Amphipods are crustacean with high nutritional quality and great potential to be reared as food for species of aquaculture interest. They play a fundamental rol in energetic exchange of trophic chain as predators’ resource. To evaluate the importance of this group, the feeding habits of 10 species (eight finfish and two cephalopods) of Andalusian coast have been reviewed. Amphipods are present in diet of consolidated species in aquaculture like Sparus aurata, Dicentrarchus labrax and Solea senegalensis, althought they are not used in any production step. There are a lot of other species where amphipods could play an important rol in their intensive cultures, like Sepia officinalis, Octopus vulgaris, Solea solea, Mullus surmuletus and M. barbatus, in addition to the genus Hippocampus, with great interest in the field of fishkeeping. It is necessary to intensify research of these crustacean to evaluate correctly their importance as preys in the wild and to quantify their nutritional values as an alternative food source

Reproduction of the wedge sole (Dicologoglossa cuneata Moreau) in captivity: spawning parameters and influence of the natural temperature

In this work, the wedge sole (Dciologoglossa cuneata) spawning under natural thermocycle has been studied. The spawning parameters were similar to those of other flatfish in captivity, the relative fecundity being very high (1.7&plusmn;0.1 &middot;106 eggs Kg female-1 per spawning season). The percentage of floating eggs decreased in parallel to the time and was directly related to egg diameter, daily relative fecundity and fertilization rate. Nevertheless, the hatching rate variations were not correlated to any other spawning parameter. The temperature range during the spawning season was very wide (11-21 &ordm;C) though the largest spawns occurred between 12 and 16 &ordm;C . The natural temperature cycle influenced wedge sole egg production, the winter temperature minimum indicating the onset of spawning, but the variations in the reproductive season did not appear to affect the daily egg production. Future research should focus on the photoperiod and its interaction with temperature as key factor for spawning. This work was supported by Interreg Project 0251_ECOAQUA_5_E, financed by the EDRF (European Regional Development Fund). www.juntadeandalucia.es/agriculturaypesca/ifapa/ecoaqua.. &nbsp;El presente trabajo trata del estudio de las puestas de la aced&iacute;a (Dicologoglossa cuneata) en cautividad bajo condiciones naturales de temperatura. Los par&aacute;metros de puesta fueron similares a los de otros peces planos en cautividad, siendo la fecundidad relativa muy alta (1.7&plusmn;0.1 &middot;106 huevos Kg hembra-1 por estaci&oacute;n reproductora). El porcentaje de huevos flotantes disminuy&oacute; paralelamente con el tiempo y fue directamente proporcional al di&aacute;metro de huevos, fecundidad relativa diaria y tasa de fecundaci&oacute;n. Sin embargo, las variaciones de la tasa de eclosi&oacute;n no estuvieron correlacionadas con ning&uacute;n par&aacute;metro de puesta. El rango de temperatura durante la estaci&oacute;n de puesta fue muy amplio (11-21 &ordm;C), aunque las mayores puestas tuvieron lugar entre 12 y 16 &ordm;C. El ciclo natural de temperatura tuvo efectos sobre la producci&oacute;n de huevos de aced&iacute;a, con los m&iacute;nimos invernales indicando el comienzo de la puesta, aunque las variaciones dentro de la estaci&oacute;n de puesta no pareci&oacute; afectar a la producci&oacute;n diaria de huevos. Este trabajo fue apoyado por el proyecto Interreg 0251_ECOAQUA_5_E , financiado por el FEDER (Fondo Europeo de Desarrollo Regional).www.juntadeandalucia.es/agriculturaypesca/ifapa/ecoaqua.</p

Organogenesis and histological development of the wedge sole Dicologoglossa cuneata M. larva with special reference to the digestive system.

In this work, several features during the wedge sole larval development have been described. The newly hatched larva presented an acidophilic yolk with some oil drops. The digestive tract began to differentiate at 1 DAH, with a loop being discernible. The pancreas and liver were completely formed at 2 DAH, the former showing its typical basophilic acinar structure and acidophilic zymogen granules. The first supranuclear vesicles in enterocytes were seen at 3 DAH. At 4 DAH, yolk reserves were completely exhausted, the number of oesophagus and intestine mucous cells increased, and the heart was differentiated into four chambers: the venous sinus, atrium, ventricle, and arterious bulb. The development was fast and almost all organs were differentiated at 2 DAH. It is important to emphasize that gastric glands were not detected, a factor that should be considered when deciding diet formulation and feeding strategies for the rearing of this species. This work was supported by Interreg Project 0251_ECOAQUA_5_E, financed by the EDRF (European Regional Development Fund). www.juntadeandalucia.es/agriculturaypesca/ifapa/ecoaqua. &nbsp;La aced&iacute;a (Dicologoglossa cuneata) es un pez plano comercial objeto de investigaci&oacute;n en el IFAPA Agua del Pino. En este trabajo se describe su desarrollo larvario a nivel histomorfol&oacute;gico. La larva reci&eacute;n eclosionada presenta un saco vitelino con m&uacute;ltiples gotas de grasa, con el ano y la boca cerrados. A nivel histol&oacute;gico, se distingue el tubo digestivo como un segmento tubular recto situado por encima del vitelo. El h&iacute;gado y el p&aacute;ncreas ya est&aacute;n completamente formados a los 2-3 DDE (d&iacute;as despu&eacute;s de la eclosi&oacute;n), y el coraz&oacute;n se diferencia en atrio y ventr&iacute;culo. A los 4 DDE se reabsorbe el vitelo, la larva ya presenta pigmentaci&oacute;n y la boca y ano est&aacute;n abiertos; el tubo digestivo y el coraz&oacute;n se diferencian en 4 regiones, y se observa gran cantidad de t&uacute;bulos renales cerca de la vejiga natatoria. Este &oacute;rgano se insufla entre los 4 y 19 DDE y se atrofia a partir de 20 DDE, coincidiendo con el comienzo de la metamorfosis. El inicio de &eacute;sta se identifica por la transformaci&oacute;n de aleta tipo heterocerca a tipo homocerca, y por la migraci&oacute;n del ojo. La metamorfosis comienza a los 21-31 DDE y finaliza a los 25-37 DDE, por lo que existe una gran asincron&iacute;a.Este trabajo fue apoyado por el proyecto Interreg 0251_ECOAQUA_5_E , financiado por el FEDER (Fondo Europeo de Desarrollo Regional).www.juntadeandalucia.es/agriculturaypesca/ifapa/ecoaqua. &nbsp;</p

Organogenesis and histological development of the wedge sole Dicologoglossa cuneata M. larva.

In this work, several features during the wedge sole larval development have been described. The newly hatched larva presented an acidophilic yolk with some oil drops. The digestive tract began to differentiate at 1 DAH, with a loop being discernible. The pancreas and liver were completely formed at 2 DAH, the former showing its typical basophilic acinar structure and acidophilic zymogen granules. The first supranuclear vesicles in enterocytes were seen at 3 DAH. At 4 DAH, yolk reserves were completely exhausted, the number of oesophagus and intestine mucous cells increased, and the heart was differentiated into four chambers: the venous sinus, atrium, ventricle, and arterious bulb. The development was fast and almost all organs were differentiated at 2 DAH. It is important to emphasize that gastric glands were not detected, a factor that should be considered when deciding diet formulation and feeding strategies for the rearing of this species This work was supported by Interreg Project 0251_ECOAQUA_5_E, financed by the EDRF (European Regional Development Fund).www.juntadeandalucia.es/agriculturaypesca/ifapa/ecoaqua. &nbsp; La aced&iacute;a (Dicologoglossa cuneata) es un pez plano comercial objeto de investigaci&oacute;n en el IFAPA Agua del Pino. En este trabajo se describe su desarrollo larvario a nivel histomorfol&oacute;gico. La larva reci&eacute;n eclosionada presenta un saco vitelino con m&uacute;ltiples gotas de grasa, con el ano y la boca cerrados. A nivel histol&oacute;gico, se distingue el tubo digestivo como un segmento tubular recto situado por encima del vitelo. El h&iacute;gado y el p&aacute;ncreas ya est&aacute;n completamente formados a los 2-3 DDE (d&iacute;as despu&eacute;s de la eclosi&oacute;n), y el coraz&oacute;n se diferencia en atrio y ventr&iacute;culo. A los 4 DDE se reabsorbe el vitelo, la larva ya presenta pigmentaci&oacute;n y la boca y ano est&aacute;n abiertos; el tubo digestivo y el coraz&oacute;n se diferencian en 4 regiones, y se observa gran cantidad de t&uacute;bulos renales cerca de la vejiga natatoria. Este &oacute;rgano se insufla entre los 4 y 19 DDE y se atrofia a partir de 20 DDE, coincidiendo con el comienzo de la metamorfosis. El inicio de &eacute;sta se identifica por la transformaci&oacute;n de aleta tipo heterocerca a tipo homocerca, y por la migraci&oacute;n del ojo. La metamorfosis comienza a los 21-31 DDE y finaliza a los 25-37 DDE, por lo que existe una gran asincron&iacute;a. Este trabajo fue apoyado por el proyecto Interreg 0251_ECOAQUA_5_E , financiado por el FEDER (Fondo Europeo de Desarrollo Regional).www.juntadeandalucia.es/agriculturaypesca/ifapa/ecoaqua. &nbsp;</p

Influence of stocking density on tissue lipid composition in flatfish Scophthalmus rhombus

The effects of the stocking density on the tissue lipid composition and biometric features of the brill were studied. Fish were cultured at three different stocking densities: 1; 5 and 15 Kg m-2 (LSD, MSD and HSD) during 5 weeks. Survival and several biometric, feeding and tissue lipid composition were assessed. Although final weight and specific growth rate decreased in higher densities, there were not significant differences between MSD and HSD. Differences for survival rate, feed efficiency, conversion index and feed intake were not detected among treatments. The minimum HSI was found in the HSD treatment, and condition factor varied inversely regards to stocking density. In liver, no differences among treatments were registered for total neutral lipids (TNL), though total polar lipids (TPL) was significantly higher in HSD. Muscle TPL did not vary significantly between LSD and HSD, but TNL was significantly higher in HSD. This work was supported by Interreg Project 0251_ECOAQUA_5_E, financed by the EDRF (European Regional Development Fund).www.juntadeandalucia.es/agriculturaypesca/ifapa/ecoaqua. Se analiz&oacute; el efecto de la densidad de cultivo de parrachos en la composici&oacute;n lip&iacute;dica de diferentes tejidos de esta especie, as&iacute; como en la supervivencia y varios par&aacute;metros biom&eacute;tricos. Los peces se cultivaron durante 5 semanas a 3 densidades de cultivo: 1; 5 and 15 Kg m-2 (LSD, MSD y HSD). El peso final y la tasa de crecimiento espec&iacute;fica fueron menores en los cultivos a m&aacute;s densidad. Sin embargo no se observaron diferencias entre los grupos en supervivencia, eficiencia alimentaria, &iacute;ndice de conversi&oacute;n y tasa de ingesti&oacute;n. El &iacute;ndice hepatosom&aacute;tico fue menor los peces cultivados a m&aacute;s densidad. En el h&iacute;gado no se detectaron diferencias en los l&iacute;pidos neutros totales (TNL) entre los tratamientos, aunque la cantidad de l&iacute;pidos polares totales (TPL) fue mayor en HSD. En cambio los TPL fueron similares en el m&uacute;sculo en todos los tratamientos, mientras que los TNL fueron significativamente mayores en los peces cultivados a m&aacute;s densidad (HSD). Este trabajo fue apoyado por el proyecto Interreg 0251_ECOAQUA_5_E , financiado por el FEDER (Fondo Europeo de Desarrollo Regional).www.juntadeandalucia.es/agriculturaypesca/ifapa/ecoaqua.</p

Common and species-specific effects of phosphate on marine microalgae fatty acids shape their function in phytoplankton trophic ecology

The use of fatty acids (FA) to infer structure of phytoplankton assemblages and as indicators of microalgae nutritional value is acquiring relevance in modern phytoplankton ecology and new advances concerning factors influencing FA variability among microalgae are demanded. In this regard, the relationship between phosphorus and FA remains particularly little studied in marine phytoplankton. In the present study, we focus on phosphate effects on FA from a diversified set of marine microalgae and provide new insights into the applicability of FA in phytoplankton trophic ecology. Phosphate deprivation mainly induced monounsaturated FA production in eight out of nine microalgae and their changes were species-specific, with palmitoleic acid exhibiting extreme variation and discriminating between haptophyte classes. The important phosphate-induced and interspecific variability found for oleic acid was perceived as a concern for the current application of this FA as a trophic position indicator in grazers. Chloroplast C-16 and C-18 polyunsaturated FA were more affected by phosphate than C-20 and C-22 highly unsaturated FA (HUFA). The relative stability of stearidonic acid to phosphate in cryptophytes and haptophytes pinpointed this FA as a suited marker for both microalgae groups. Taken all species together, phosphate deprivation and taxonomy accounted for 20.8 and 50.7% of total FA variation, respectively. HUFA were minimally affected by phosphate indicating their suitability as indicators of phytoplankton trophic value. The asymptotic relationship between HUFA and phosphorus cell content suggested mineral composition (phosphorus) could be more important than HUFA content as attribute of marine microalgae nutritional value at the species level