| Popis: |
The metabolic rate of an organism is influenced by mass, temperature, and diet. Climate change is anticipated to increase ambient temperatures of aquatic systems and decrease the quality of food available to algivorous fish. We conducted a lab experiment and a field study to quantify the influence that temperature and diet have on standard and field metabolic rate of cichlids from Lake Tanganyika. The lab experiment demonstrated the effects of increased temperature and decreased food quality on the relative growth rate (RGR) and standard metabolic rate of an algivorous cichlid, Tropheus duboisi. We found that in all temperature treatments fish fed a high quality diet had significantly higher RGR than fish fed a low quality diet and that fish at the highest temperature (32 °C) grew at half of the rate of fish at the lower temperatures (26 °C and 29 °C). Neither food quality nor temperature significantly affected the standard metabolic rate of the fish. I conclude that the effects of decreased food quality on RGR from climate change will be a more immediate stressor than increased temperature on metabolic rate. I also measured the field metabolic rates of seven species of African cichlids from three trophic levels. Both mass-specific metabolic rate and gut-fullness scaled positively with activity level. The algivores had the highest metabolic rates, which may be a result of their higher levels of activity and increased gut-fullness relative to other trophic levels. |
