Final answer:
Research by Hairston et al. found that algal blooms were supported by the presence of one stickleback species due to more available dissolved organic matter, but not with two species due to their consumption of all essential nutrients.
Step-by-step explanation:
Hairston and colleagues investigated the dynamics between rotifers and their algal prey within lake microcosms and assessed the impact of predation on fish species. The research found that in the presence of one stickleback species, there was a greater availability of dissolved organic matter allowing for more algal blooms, which could support larger populations of rotifers.
However, with two stickleback species, they consumed all the nutrients required by the algae, preventing algal blooms and thus affecting the rotifer populations. This observation suggests that factors beyond predation, such as nutrient availability and competition for resources, are critical in accounting for population dynamics within these ecosystems.