Otters are semiaquatic mammals.
Table 1 shows the biomass of organisms at different trophic levels in a river ecosystem.
| Organism | Biomass (kg) |
|---|---|
| Algae | 600 |
| Water fleas | 90 |
| Brown trout | 15 |
| Otters | 0.6 |
Explain why the conversion of biomass from algae to water fleas is more efficient than the conversion of biomass from brown trout to otters.
