Now showing items 1-2 of 2

    • Article

      Effect of salinity on hemolymph calcium concentration during the molt cycle of the prawn Penaeus monodon 

      FD Parado-Estepa, JM Ladja, EG de Jesus & RP Ferraris - Marine Biology, 1989 - Springer Verlag
      Prawns (Penaeus monodon) were obtained from ponds in Iloilo, Philippines, in 1984 and 1985 and maintained in salinities from 8 to 44‰. Total hemolymph calcium was largely affected by molt stage and less so by salinity. A sharp, transient increase in hemolymph calcium occurred 3 to 6 h postmolt, followed by an equally rapid decrease from 6 h postmolt to intermolt. This biphasis response was limited to prawns in 8, 20 and 32‰S; in 44‰S, hemolymph calcium remained the same throughout the sampling period. Peak concentrations of total calcium were greater in low (8 and 20‰S) than in high salinities. Salinity had no effect on the duration of molt cycle nor on time of occurrence of molt. Almost half of molting incidents occurred between 18.01 and 0.00 hrs, and one-third between 0.01 and 06.00 hrs.
    • Article

      Thyroid hormone surges during milkfish metamorphosis. 

      EG de Jesus - The Israeli Journal of Aquaculture-Bamidgeh, 1994 - Society of Israeli Aquaculture and Marine Biotechnology
      Both thyroxine (T4) and triiodothyronine (T3) were detected in fertilized eggs and larvae of milkfish. The concentration of T4 was lower than that of T3 only in fertilized eggs and newly-hatched larvae. The total body concentrations of both thyroid hormones decreased after hatching. The T4 concentration fluctuated at relatively low levels during the first week after hatching, increased gradually during the next 2 weeks and was highest in 4-week-old larvae. On the other hand, T3 was undetectable in samples taken between days 3 and 11, showed a gradual increase beginning on day 13 and was highest in 27 day old larvae. The concentrations of both T4 and T3 declined again in 31-day-old juveniles. The peak corresponds with the development of silver coloration in hatchery-reared milkfish and the inshore milkfish and the inshore migration of larvae in the wild, suggesting a role for thyroid hormones during early development of this species.