NOTE Booman et aL Responsiveness of starved Engrauhs mordax larvae to attacks by adult anchovy 



predation because of a decrease in encounter rates be- 

 tween predators and prey (Gamble and Fuiman 1987) 

 is not supported by our data. A decrease in encounter 

 rates does not seem to have occurred, since attack rates 

 on fed and starved larvae were the same. A change in 

 larval activity may, however, have a greater effect on 

 prey visibility among smaller larvae than larger ones. 

 Our scale of nutritional condition based on liver 

 characteristics could be used to assess the extent of the 

 interaction between starvation and predation in the 

 sea. The level of cell deterioration found in larvae 

 starved 4 days or more at 16°C most likely represents 

 the PNR, and the starvation-induced vulnerability to 

 predation could amplify the losses caused by starva- 

 tion only up to this point. A sharp decline in cholesterol 

 and polar lipid content was found in larval anchovy 

 after 5 days of starvation at 15.5°C (Hakanson 1989). 

 These lipids are cell membrane constituents. The high 

 vulnerability of larvae starved for periods longer than 

 4-5 days seems of less ecological consequence, since 

 nearly all such severely emaciated larvae would prob- 

 ably ultimately die of starvation. However, the increase 

 in vulnerability over the entire starvation period is of 

 interest, because it may affect estimates of starvation 

 rates in the sea and possibly estimates of natural larval 

 mortality. Clearly, rates of starvation based on daily 

 incidence of starvation classes (Theilacker 1986) may 

 underestimate the actual losses if starvation results in 

 an increase in the vulnerability to predators. In addi- 

 tion, our results may support the hypothesis of Isaacs 

 (1964) that daytime plankton samplers may be selec- 

 tive for weaker and less-responsive larvae. Such a 

 hypothesis requires vision to be the primary sensory 

 modality for the larval avoidance response. If this were 

 the case, the reduced responsiveness caused by star- 

 vation could result in daytime plankton catches con- 

 taining proportionately more starving larvae than 

 those taken at night. 



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