Bisbal and Bengtson Starvation in early life stages of Paralichthys dentatus 



223 



Time (h) 



Figure 4 



Summer flounder, Paralichthys dentatus, 60-day-old juveniles. Morphometric, 

 gravimetric, and biochemical changes during ad libitum feeding ( ) or starva- 

 tion (•). (A) standard length; (B) dry weight; (C) eye diameter/head height ratio; 

 (D) pectoral angle; (E) RNA:DNA ratio; (F) total proteins. Symbols represent 

 the arithmetic mean of samples of 9-10 animals iStandard Error. Asterisks in- 

 dicate a statistically significant difference between fed and starved groups at a 

 particular sampling time. 



significant from the first sampling time in 16-day- 

 old larvae (f 18 =6.86, P<0.001, at 24 h), 33-day-old 

 larvae (f 18 =2.87, P=0.010, at 24 h), and in 60-day-old 

 juveniles U 10 =3.05, P=0.012, at 72 h; Fig. 7, D, F, and 

 H, respectively). In the case of 6-day-old larvae, these 

 differences were significant after 48 hours U 18 =10.49, 

 P<0.001; Fig. 7B). 



Discussion 



In summer flounder, the onset of mortality due to 

 starvation occurred later in older ontogenetic stages, 

 similar to observations made by Ivlev (1961) and 

 Wyatt ( 1972). Response to starvation may depend not 

 only on energy reserves stored in the liver, muscles, 

 and other body tissues but also on more efficient cata- 

 bolic capabilities attained during ontogenesis 

 (Ehrlich, 1974b). Yin and Blaxter ( 1987 ) argued that 



the relative tolerance to lack of food is the result of 

 reduced energy costs for metamorphosing flounder that 

 increasingly spend more time lying on the bottom. 



Morphometric, biochemical, and histological mea- 

 surements all showed significant differences between 

 starved and fed summer flounder at some point dur- 

 ing development. The question then becomes the fol- 

 lowing: Which individual measurement or combina- 

 tion is the most useful indicator of nutritional sta- 

 tus as development proceeds? We define usefulness 

 both in terms of ease and practicality of application. 

 Because of the relatively low resistance to starva- 

 tion in younger larvae, it is imperative to select an 

 indicator with the sensitivity to respond quickly to 

 changes in nutritional status. 



While mean length and dry weight of fed summer 

 flounder showed a steady increase, starving fish 

 shrank or did not grow. Only in 6-day-old larvae did 

 standard length decrease, presumably representing 



