| Popis: |
A 60-day preliminary study was conducted to determine whether excessive temperature, bacterial infection, or heavy metals contamination contributed to spermatophore and sperm deterioration in laboratory-held Penaeus setiferus males. Three treatments were tested in which: 1) culture water temperature was held at 25–26°C; 2) males were inoculated with a killed Vibrio sp. bacterin; and 3) EDTA (ethylenediaminetetraacetic acid) was added to culture water at 25 ppm. These were compared with a control treatment at mean ambient temperature of 29.1°C. A combination of males from the primary offshore breeding population (mean weight 43.9 g ± 1.78 S.E.M.) and young-of-the-year males (mean weight 24.5 g ± 0.83) were used. Mean baseline values (± S.E.M.) established at initiation were, per male: sperm count, 38.7 × 106 ± 10.165 × 106; percent abnormal sperm, 5.0% ± 1.13; and spermatophore weight, 0.103 g ± 0.0215. At the midpoint 30-day samples, mean sperm counts were significantly lower in the ambient and EDTA treatments. The chilled and inoculated treatments showed no decline in sperm counts during the first 30-day period, but the percentage of abnormalities had increased from 5.0% ± 1.13 in the baseline to 16.3% ± 9.94 and 57.0% ± 9.64, respectively. At termination (60 days), only the chilled treatment contained any males bearing sperm (33% of males sampled from the treatment), but sperm abnormalities ranged from 53–72%. Results indicate that parameters tested did not prevent decline in male reproductive condition over time. |
