GDH activity and ammonium excretion during growth in the marine mysid, "Leptomysis lingvura"

[EN] Ammonium (NH4+) and nitrate (NO3-) are the main constituents of the inorganic nitrogen pool that supports primary production in marine systems. NH4+ release via glutamate deamination in heterotrophic organisms represents the largest recycled nitrogen source in the euphotic zone, supporting around the 80 % of the primary producers requirements (Harrison, 1992). Glutamate dehydrogenase (GDH) is the enzyme that catalyzes this process. This fact has lead to the use of GDH activity as an index, a proxy, for physiological NH4+ formation. The result is a measure of potential excretion that avoids incubation artefacts due to manipulation of the organisms. The relationship between GDH activity and NH4+ excretion in cultures of the marine mysid Leptomysis lingvura is analyzed here. With interspecific and environmental interferences minimized, the study shows that the relationship between GDH activity and NH4+ excretion in L. lingvura is similar to equivalent results measured on mixed assemblages of zooplankton.

Biología de la reproducción del cangrejo blanco Plagusia depressa (Fabricius, 1775) y cangrejo moro Grapsus grapsus (Linneus, 1758) en el litoral de Gran Canaria

[ES] La familia Grapsidae comprende el conjunto de cangrejos ecológicamente más diverso, dado que existen especies marinas, de agua salobre, dulceacuícolas, anfibias e incluso terrestres (Ruppert y Barnes, 1996). El presente trabajo se ha centrado en el estudio poblacional y reproductivo de dos especies de dicha familia: Grapsus grapsus y Plagusia depressa. Para ello se evaluaron las épocas de puesta, la proporción entre sexos y la fecundidad. Por último, se estudió el desarrollo embrionario para ambas especies. El objetivo de este trabajo fue la obtención de la información necesaria para realizar el cultivo en cautividad de las mismas. Bien para la utilización de las zoeas como presas vivas de otros cultivos, o bien para su producción, ya que estas dos especies de grápsidos poseen un gran potencial económico, dada su importancia marisquera, especialmente en el caso de Plagusia depressa, donde sus poblaciones naturales sufren graves retrocesos.

Infección del nemertino parásito, Carcinonemertes sp., sobre hembras ovadas de cangrejo blanco Plagusia depressa (Fabricius, 1775): Ciclo biológico y efecto sobre la puesta.

[ES] En el presente trabajo se describen los distintos estadíos del nemertino parásito, Carcinonemertes sp., hallado entre los huevos del braquiuro Plagusia depressa (Fabricius, 1775). Este organismo suele encontrarse en la puesta de distintas especies de cangrejos braquiuros, ejerciendo una depredación sobre la misma. Se comprobó que la presencia del parásito entre los huevos del cangrejo estaba relacionada con la época del año, ya que entre junio-septiembre no se detectó su presencia, mientras que a partir del mes de noviembre, todas las hembras ovadas de P. depressa estudiadas sufrían la acción parásita de Carcinonemertes sp. sobre sus huevos. El ciclo vital de Carcinonemertes sp. comienza en un estado de huevo, los cuales aparecen agrupados en forma de cordones entre los huevos del cangrejo; de estos huevos eclosionan larvas planctónicas ciliadas, que evolucionan a gusanos juveniles, los cuales se desarrollan en el interior de tubos mucosos secretados por ellos mismos, hasta alcanzar el estado adulto. Tras una reproducción de tipo sexual las hembras ponen los huevos cerrándose el ciclo.

Planktonic potential CO2 emission calculation: preliminary results by applying an adapted enzymatic methodology to marine ecosystems

[EN]Isocitrate Dehydrogenase (IDH) is a key enzyme in the Krebs cycle, being responsible for the production of one of the three CO2 molecules related to cellular respiration. In order to measure the potential CO2 production linked to the marine planktonic community we have adapted an enzymatic methodology. Preliminary results show that different proportions of autotrophs, heterotrophs and mixotrophs and their metabolic pathways, lead to different relationships between potential CO2 emission and potential O2 consumption during cellular respiration. Although more experiments need to be made, this methodology is leading to a better understanding of cellular respiration in marine samples and their impact on the food chain, vertical Carbon flux and the current sequestering capacity for anthropogenic CO2.

Obtención en cautividad de puestas naturales del pez de limon(Seriola dumerili), en la isla de Gran Canaria (España).

[EN]In the present study, natural spawning of a broodstock group of greater amberjack (Seriola dumerili) is described with regards to: date, number of spawns, and total number of eggs produced per spawn. Fish werecaught in 2011 in the Canary Islands, Gran Canaria (Canary Islands, Spain), and kept in captivity. At the end of May 2014, the broodstock group was formed by two females with a weight 9.81±1.08 kg, size 90.0±2.82cm, with oovocites > 800μ, and five males 9.46±2.04 kg, 86.75±5.43 cm, all fluent with sperm. Between the 1stof June and 18thof October 2014, a total of 25.60 million eggs were obtained in 23 spawns.

Comparación entre la calidad de puestas naturales e inducidas, mediante inyección e implante de GnRHa, del pez de limón (Seriola dumerili).

[EN]For this study, a total of 19 greater amberjack (Seriola dumerili) broodstock were used. Females with oocites bigger than 600μ, and fluent males with a mean weight of 10.72±1.22 kg, fameles, and 10.77±2.33 kg males. The experimental tanks were circular tanks of 40 m3 capacity. One of the tanks were not induced and the other two were with GnRHa, one with injections and the other by implants. Best results, in all parameters studied were with natural spawns, with a 84.37% of fertilization, 92.21% of viable eggs at 24 hours of spawn, 96.60% of hatching, 69.91% of larvae one day after hatching and 10.78% of 5 day life larvae.

Comparación entre puestas naturales e inducidas, mediante inyección e implante de GnRHa, en la producción de huevos del pez de limón (Seriola dumerili)

[EN]The number of eggs obtained in natural spawning (25.60 million) is higher than those obtained by injections (12.9 million) and implants (10.5 million). The number of eggs per female was 12.80 million, in natural spawning, and 4.30 and 3.51 million, in induced with injections and implants, respectively. In number of eggs per spawn, significant differences was observed, between natural spawns (1.11 million), and induced spawning’s (0.44 and 0.21 millions, injected and implants respectively). Significant differences was also found, in number of eggs per Kg female/spawn, between natural spawning’s (56,700 eggs), injection induced (37,200 eggs) and implants (25,200 eggs).

Obtención de puestas del pez de limón (Seriola dumerili) mediante GnRHa, comparación de la eficacia de la induccion con implante e inyección.

[EN]The three males and three females of tank 2 were induced with EV-500μg GnRHa implants, one implant (500μg) was used for the females and half that doses for males. The first injection was on the 3rd of June and the last one spawning’s the 21st of October, a total of 37 injections and 29 spawns were obtained. The first implant was introduced the 20th of June, the last spawn was on the 16th of October of the implant set the 14th, a total of 17 implants and 38 spawns were obtained. The number of spawns per induction was significantly higher (P < 0.01) in implanted females, no significant differences were found in latency period which was of 43-44 hours.

Eficacia de la inducción hormonal con GCH y GnRHa en reproductores de corvina (Argyrosomus regius).

[EN]Eighteen mature meagre (Argyrosomus regius) broodstock, born in captivity, were divided in 3 experimental groups in ratios of 3 ♀ and 3 ♂ each. One group was inducted by injections of hCG, the other with GnRHa and the last group with implants of GnRHa. In all three treatments all females responded positively to the hormonal treatment. Statistically differences were found, in the number of spawns per induction, of females induced with hCG with the GnRHa treatments. Latency period was longer in spawns from GnRHa implants, and showed statistically differences with the other two treatments.

Efecto del tipo de hormona y del metodo de aplicación, en las producciones de reproductores de corvina (Argyrosomus regius).

[EN]In the present study, the effect of three different hormonal treatments were tested (GnRHA and hCG injected and GnRHa implanted), in meagre (Argyrosomus regius) broodstock born in captivity, and their production. The highest productions per kg of female and spawn: number of eggs, fertilized eggs, hatched larvae, and larvae 3 days old after hatching, corresponds to the treatment of GnRHa injected. The number of viable eggs, hatched eggs and larvae 3 days with GnRha injected was significantly different from those treated with hGC. No significant differences were observed in production per kg female and induction in the different hormonal treatments,

Inducción de reproductores de corvina (Argyrosomus regius) nacidos en cautividad, mediante inyección con GCH y con GnRHa, esta aplicada además mediante implante. Efecto sobre la la calidad de las puestas

[EN]The best results in all quality parameters, were obtained in the spawns of the broodstock injected with GnRHa, having 98,7 + 1,4% of fertilized eggs, 62,24 ± 27,47 % viable eggs, 92,56 ± 17,19 % hatching and 92,73 ± 10,52 % 3 day old larvae after hatching. Percentage of viable eggs was lower in the spawns of the broomstick injected with hCG, and had significant differences when compared with GnRHa broodstock treatments. 3 day old larvae and hatchings, obtained from the broomstock injected with GnRHa showed significant differences to the rest of the hormonal treatments.