Bisbal and Bengtson: Starvation in early life stages of Paralichthys dentatus 



225 



A 



pi 



LU 



LU W X 



Jf 



S 



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Figure 6 



Histological comparisons of well-fed and starved summer flounder, Paralichthys dentatus. larvae. (A) 19 days after hatching 

 (DAH), intestinal mucosae at the intestinal valve, ad-libitum-fed control (bar=50 urn). (B) 19 DAH, intestinal mucosae at the 

 intestinal valve, after 72 hours of starvation (bar=60 |im). The arrows indicate the mucosal height in each intestinal segment. 

 (C) 16 DAH, detail of enterocytes showing absorptive inclusions, ad-libitum-fed control (bar=35 urn). (D) 19 DAH, detail of 

 enterocytes showing cellular sloughing into the lumen, after 72 hours of starvation (bar=20 pm). Abbreviations: AI=anterior 

 intestine, IV=intestinal valve, LU=lumen, PI=posterior intestine. The arrows indicate the mucosal height in each intestinal segment. 



shrinkage of the larvae after yolk absorption. Shrink- 

 age of starved early stage larvae has been reported 

 in herring (Ehrlich et al., 1976) and striped bass 

 (Eldridge et al., 1981). Additionally, large variation 

 in the extent of shrinkage has been reported in pre- 

 served larvae as a consequence of capture and fixa- 

 tion (Theilacker, 1980; Hay, 1981). The time of sam- 

 pling must also be considered to account for changes 

 in dry weight associated with the diurnal rhythms of 

 visual feeders (Arthur, 1976 ). The dry weight of a larva 

 with a full digestive tract will obviously be greater than 

 that of the same larva with an empty digestive tract. 

 Because extensive calibration between laboratory and 

 field experiments is necessary to compare small larvae 

 at the same developmental stage, length and dry 

 weights are not useful indicators of nutritional status. 



The pectoral angle accurately identified the nutri- 

 tional condition of earlier larval stages. The variabil- 

 ity within each group was low and significant differ- 

 ences were established early in the sampling proto- 

 col. However, these attributes progressively vanished 

 at later stages. The eye length to head diameter ra- 

 tio was not a good indicator of the feeding condition 

 at any stage because of large variability within each 

 group. Ehrlich et al. (1976) found the pectoral angle 

 to be a good indicator of starvation in both herring, 

 Clupea harengus, and plaice, Pleuronectes platessa , 

 but the eye:head ratio was a good indicator in her- 

 ring only. 



Morphological characteristics are relatively simple 

 to measure, inexpensive, and require little time, but 

 the validity of laboratory-derived criteria is uncer- 



