Author(s): Sunardi; Takashi Asaeda
Linked Author(s): Takashi Asaeda
Keywords: Growth; Current velocity; Predation; Multiple dangers; Small planktivore
Abstract: Changes in rivers and streams caused by engineered structural have increased the habitat alteration of aquatic community and may cause small fish more vulnerable to high fluctuation of water discharge and predation. This study aimed to investigate the responses of a small fish, Pseudorasbora parva, inhabiting the streams faced with multiple dangers of high current and predation. The results showed that the small fish had a lowered growth as a result of being exposed to both the two stressors. Swimming energy expenditure and lost of feeding opportunities might be the main cause of lowered growth rate. Under such conditions, however, small fish might resolve the conflicting necessities by compromising costs and benefits associate with the growth. During the high risk of predation, fish shifted to the shallow part to avoid predation. The shallow part provided safer environment, nevertheless the cost was high in terms of low feeding opportunities and high swimming cost. During the low risk of predation, fish might migrate to deep part to compensate the feeding. After all, the results suggested that the failure of small planktivores to increase optimal body mass in such situation may occur as a cost of antipredatory behavior, which may be expected as a result of balancing conflicting demands. As an implication, the fish population in nature may have lower fitness following habitat invasion by predators and high current exposure.
Year: 2005