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Influence of Food Supply on Postmetamorphic Growth and Survival of Hatchery-produced Lion's Paw Scallop, Nodipecten Nodosus (Linnaeus, 1758)

出版	2004
URL	http://books.google.com.hk/books?id=-bqJoAEACAAJ&hl=&source=gbs_api

註釋Poor growth and low survival are often reported in hatchery-reared scallops early after settlement and metamorphosis. The effects of algal deprivation, substrate biofilm, and two algal cell concentrations (ca. 4.7x10e3 and 4x10e4 cells mLe-1) on growth and survival were investigated during 9 days after settlement in experiment 1, and the effects of the two algal concentrations were examined for 16 days post-set in experiment 2. In experiment 1, the presence of biofilm on the collectors significantly enchanced postlarval settlement, but not growth. Five days after settlement, at a shell height of about 250 u.m, postlarvae fed a low algal concentration wwere significantly larger than postlarvae in the other treatments (unfed, biofilm-covered collectors and high algal concentration), which attained similar sizes. Nine days post-set, postlarvae fed at higher algal concentration were larger than postlarvae to which no suspended algae were supplied but were smaller than those cultured at low food concentration. Reserves accumulated during the larval stage were sufficient to sustain metamorphosis, limited shell growth, and high survival in the absence of exogenous food, giving no indications of food deprivation-induced mortality for at least 9 days post-set. In experiment 2, 10 days after settlement, postlarvae cultured at 4.7 x 10e3 cells mLe-1 were larger than postlarvae cultured at 4 x 10e4 cells mLe-1, but after 16 days post-set, postlarvae in both treatments attained similar shell height. Between 10 and 16 days after settlement (shell height ca. 300-400 u. m.), feeding demund of postlarval Nodipecten nodosus significantly increased, as demonstrated by a shap increase of gut pigment concentration, which was probably related to key events in the gill morphogenesis. Mortality, on the contrary, was higher at 4 x 10e4 cells mLe-1 than at 4.7 x 10e3 cells mLe-1. An alternative explanation to the high mortality of scallops often recorded early after metamorphosis in aquaculture settings, other than the depletion of endogenous reserves is proposed. Food demand of postlarval N. nodosus is less thant usually supplied in scallop hatcheries, and growth can be significantly increased early after settlement by adjusting the algal cell concentration.