Datensatz

Zusammenfassung

We study cannibalism in the cyclopoid copepod Cyclops abyssorum (Sars). The functional response of predatory stages Of C. abyssorum on inter- and conspecific prey is determined. Methods are developed to calculate the impact of cannibalism on populations. Four whole-lake studies found in the literature provide sufficient data to apply the methods. For these populations we calculate: 1. The cannibalism induced naupliar death-rate, CID. 2. The probability that a nauplius falls victim to cannibalism before reaching the copepodite stage, P(cann). 3. The percentage of the total amount of food ingested by the predator which is due to cannibalism, PWIC.

P(cann) is on average 20% with a maximum of 80%. We conclude that cannibalism is an important factor in naupliar mortality. CID is on average 0.007 d-1 with a maximum of 0.026 d-1. PWIC shows a seasonal trend with minima in summer and maxima in winter. In winter conspecific nauplii constitute up to 45% of the total dry weight ingested by adult females. PWIC is smaller in lakes with larger alternative prey populations. Consequences for the dynamics of C. abyssorum populations are discussed.