Acondicionamiento de reproductores y caracterización gonadal de Tawera gayi (Hupé, 1854) (Bivalva: Veneridae) bajo condiciones controladas de cultivo.

Abstract

El presente estudio describe el acondicionamiento de reproductores bajo sistema controlado del bivalvo Tawera gayi (Hupé, 1854), en el cual se caracterizó el estado de madurez gonadal en base a la presencia de células germinales masculinas y femeninas, estableciéndose su identificación mediante histología a través de microscopia óptica. Como metodología para el acondicionamiento se empleó una bandeja de 15,31 L de volumen útil donde fueron mantenidos 100 ejemplares de T.gayi. El sistema se mantuvo con agua de mar a 29-30 ppm con recambio de agua cada 3 días a temperatura promedio de 16 -18 °C. Con alimentación continua de una mezcla de microalgas de Isochrysis galbana y Chaetoceros muelleri. Los resultados obtenidos, ponen en manifiesto que Tawera es una especie dioica, sin dimorfismo sexual. Presenta fecundación externa, con un ciclo reproductivo continuo, asincrónico y sin reposo gonadal. Durante las primeras semanas de aclimatación los machos presentaron 100% de madurez máxima, mientras que las hembras demostraron un 71% de madurez avanzada y 29% de madurez máxima. Una vez acondicionadas y con alimento continuo, se logró 100% de evacuación parcial en hembras y 50% de evacuación parcial y total en machos, obteniendo desove en cautiverio. Palabras claves: Tawera gayi; acondicionamiento; caracterización gonadal; desove.

Broodstock conditioning, spawning, embryonic and early larval development of a novel baby clam species for aquaculture in the southeast Pacific: Tawera elliptica (Lamarck, 1818)

“…In turn, Le et al (2016) established a sperm: oocyte ratio equal to a range of 50–500:1 for optimal fertilization in Panopea zelandica , a value similar to the one used in this study, validating the good result in the percentage of embryos obtained in this clam versus the 10:1 ratio (sperm: oocyte) used by Trigo (2013). The first specimens to spawn were males, as mentioned by Trigo (2013); however, a longer period of motility was recorded in the sperm, which lasted up to 2 h.…”

“…Codakia orbicularis (Gros et al, 1997), which have a total diameter of 500 and 350 µm respectively (Table 5). Trigo (2013) records a total diameter of 108 µm for the juliana clam, a lower value for a hydrated oocyte than the one described in this study, being close to a newly evacuated oocyte without hydration (92 ± 5.88 µm). This size difference is probably related to the presence of hypotonated oocytes due to their immaturity.…”

“…The fertilization bioassay carried out by Trigo (2013) in T. elliptica was at a sperm: oocyte ratio of 10:1, a value lower than the one used in this experiment, where the ratio was 500:1. However, the number of embryos obtained in this study (405,000) was higher than the one obtained by Trigo (2013), who mentions that she only obtained a “low number” of embryos, so she could not obtain the type D veliger stage.…”

“…The survival of the T. elliptica specimens exceeded 97% during the 48 days of conditioning. Similarly, Trigo (2013) obtained a survival rate of 99% in conditioning adult T. elliptica , also under laboratory conditions. These results confirm that this clam adapts to laboratory conditions, achieving maximum maturity and evacuating its gametes.…”

“…The first spawning in a laboratory was carried out by Trigo (2013), which conditioned breeders for 18 days. However, a low number of embryos were obtained, and they did not reach the stage of type D veliger.…”