Spawning and fecundity of king weakfish, Macrodon ancylodon, in the Río de la Plata estuary, Argentina–Uruguay

2004 ◽  
Vol 84 (2) ◽  
pp. 443-447 ◽  
Author(s):  
M.I. Militelli ◽  
G.J. Macchi
Keyword(s):  
Histological Analysis ◽  
Rio De La Plata ◽  
Río De La Plata ◽  
La Plata ◽  
Spawning Frequency ◽  
Multiple Spawner ◽  
Hydrated Oocyte ◽  
Gonadal Index ◽  
Second Peak ◽  
Female Weight

The reproductive biology of the king weakfish, Macrodon ancylodon, inhabiting the estuarine waters of the Río de la Plata (Argentina–Uruguay), was studied using macroscopic and histological analysis of the gonads. The samples were collected from commercial landings and from three research cruises carried out between 1999 and 2001. King weakfish is a multiple spawner with indeterminate annual fecundity. Spawning of this species extends from October to March with two main peaks of gonadal index in November and March. Based on the incidence of females with new postovulatory follicles, the evening near sunset was the estimated time of spawning for M. ancylodon. Spawning frequency, determined using the percentages of females with postovulatory follicles, was about 17% during March 2001, indicating that females spawn once every six days at the second peak of the reproductive season. Batch fecundity ranges from 12,400 to 225,700 hydrated oocytes and was fitted to a linear function of total length and ovary-free female weight. The number of hydrated oocytes decreased at the end of the spawning season. In addition, a decline in hydrated oocyte size and weight was also observed during this period.

Spawning and fecundity of Jenyns's sprat, Ramnogaster arcuata, a winter spawner in the temperate waters of the Río de la Plata estuary, Argentina–Uruguay

2008 ◽  
Vol 88 (2) ◽  
pp. 423-429 ◽  
Author(s):  
Karina A. Rodrigues ◽  
Gustavo J. Macchi ◽  
Eduardo M. Acha ◽  
María I. Militelli
Keyword(s):  
Dry Weight ◽  
Total Body Weight ◽  
Female Size ◽  
Rio De La Plata ◽  
Batch Fecundity ◽  
Río De La Plata ◽  
La Plata ◽  
Spawning Frequency ◽  
Multiple Spawner ◽  
Total Body

The reproductive biology of the Jenyns's sprat Ramnogaster arcuata in the Río de la Plata area was studied using macroscopic and histological analysis of ovaries. Samples were collected during two research surveys carried out in June 1998 and June 1999. In addition monthly occurrences of this species from historical data were analysed. Jenyns's sprat specimens were mainly observed in open waters of the estuary during winter months. Most of the females collected during June 1998 and 1999 were in the spawning stage. This pattern differs from fish that reproduce in the estuarine waters of the Río de la Plata, which spawn during spring and summer. These results suggest that conditions of productivity and larval retention in the estuary also remain during winter months. This characteristic might be useful for R. arcuata larvae in avoiding competition with other estuarine spawners. Jenyns's sprat is a multiple spawner with indeterminate annual fecundity. A preliminary estimate of spawning frequency (N = 220) indicated a daily percentage of females with postovulatory follicles of 17.35%, which suggests that this species spawns on average once every six days. Batch fecundity, estimated from counts of hydrated oocytes from 40 females, ranged from 669 to 2026 hydrated oocytes in 1998 and from 570 to 1830 hydrated oocytes in 1999. Batch fecundity was fitted to a linear function of total body weight (without ovary) in 1999. Mean relative fecundity was 234 hydrated oocytes per female gram (ovary free) in 1998 and 155 hydrated oocytes per female gram (ovary free) in 1999, and no significant relationship was observed between this parameter and female size. The dry weight of 100 hydrated oocytes ranged between 3.9 and 6.3 mg, these values being significantly higher than those estimated for other species of the Río de la Plata estuary.

Acido delta-aminolevulínico dehidrasa (ALA-D) como biomarcador de exposición a plomo en peces

2008 ◽  
Author(s):  
◽  
Paula Edith Lombardi
Keyword(s):  
Cyprinus Carpio ◽  
Buenos Aires ◽  
Rio De La Plata ◽  
Río De La Plata ◽  
Prochilodus Lineatus ◽  
La Plata ◽  
Del Rio

La actividad de la enzima ácido δ-aminolevulínico dehidrasa (ALA-D) es un reconocido biomarcador específico de exposición a plomo. Debido a sus características ha sido utilizado en estudios de monitoreo ambiental para evaluar la exposición a plomo en diversos organismos, entre ellos peces. El principal objetivo del presente trabajo de tesis fue validar un método de evaluación general de riesgo ecotoxicológico por exposición a plomo en poblaciones naturales de peces. Para tal fin se seleccionaron tres especies recolectadas del río de la Plata: Prochilodus lineatus (sábalo), Leporinus obtusidens (boga) y Cyprinus carpio (carpa). Las zonas de muestreo elegidas fueron: Berazategui y Berisso ubicadas cerca de las emisiones de residuos cloacales provenientes de las ciudades de Buenos Aires y La Plata. La tercera, Atalaya, libre de emisiones cloacales, pero sujeta a emisiones diversas, todas ellas, de origen antropogénico. Los muestreos se realizaron entre junio de 2002 y mayo de 2004. En primera instancia se caracterizaron diversos parámetros de la enzima ALA-D en muestras de sangre y de tejido hepático. Los resultados obtenidos mostraron características similares en la enzima sanguínea de todas las especies estudiadas. Lo mismo se observó para la enzima hepática. La comparación entre tejidos mostró diferencias en el valor de Km, siendo menor para la enzima hepática. Posteriormente, se procedió a validar el uso de la enzima como parámetro biomarcador de exposición a plomo en estudios de campo.

Sign in / Sign up

Export Citation Format

Share Document