Effect of food quantity on growth and reproductive characteristics of Capitella sp. (Annelids: Polychaeta)

Summary

Effects of food quantity on growth, fecundity (defined as number of eggs deposited in the first spawning), egg size, egg energy content, and total reproductive output (total egg volume or total energy invested in spawned eggs) of Capitella sp. were examined in the laboratory. Results indicate that fecundity increased with increasing food quantity, whereas egg size and egg energy content decreased with increasing food quantity. These results suggest that there is a trade-off between fecundity and egg quality (in terms of egg size and egg energy content), thus supporting the hypothesis that, when food-limited, Capitella sp. produces fewer but higher quality offspring. Results further show that minor changes in food quantity (0.1 mg dry Ulva · worm⁻¹ · day⁻¹) can produce measurable changes in fecundity and egg size, suggesting that life history characteristics of this worm are flexible which enable it to adapt to a fluctuating environment.

Key words:

• Growth
• fecundity
• egg size
• egg energy content
• total reproductive out
• Capitella