Laboratory interactions of Bosmina and Ceriodaphnia, the influence of algae and bacteria on the outcome of competitive and non-competitive encounters
Jung, Thomas E.
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Laboratory investigations of interactions between the cladocerans, Ceriodaphnia reticulata and Bosmina longiros- tris. were performed in order to determine whether competition for food is important in determining their abundances. Two algae, Ankistrodesmus sp. and Chlamydomonas reinhard- tii. and two bacteria, Pseudomonas fluorescens and Serratia liauefaciens. were offered as food sources in various combinations and concentrations to the cladocerans under control and competition conditions. Once competition was demonstrated, attempts were made to manipulate these food sources in order to change the outcome of competition and/ or produce coexistence. The results of the competition experiments indicate the food regime is an important factor determining survival or death of Bosmina or Ceriodaphnia as well as the result of competitive interactions. Resource utilization showed important overlap such that Ceriodaphnia was able to out- compete Bosmina in two competition experiments. Ankistrodesmus. Pseudomonas, and Serratia as a food resource spectrum limits the growth of Ceriodaphnia but not Bosmina. The extent of this limitation on Ceriodaphnia depends upon the relative concentrations of the various foods such that results of competition experiments on this food regime range from extinction of Ceriodaphnia to coexistence of both animals.