科研之友
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摘要
Behavioral responses are important in zooplankton species exposed to invertebrate predators. In a Brazilian natural lake, the ostracod Physocypria schubarti Farkas, 1958 is abundant, despite the presence of predatory Chaoborus Lichtenstein, 1800 larvae. This is intriguing as this predator controls several microcrustacean populations in nature. Therefore, we analysed the interactions between fourth instar Chaoborus larvae and ostracods of two body sizes in laboratory. We evaluated (1) the behaviour of P. schubarti during Chaoborus attacks, (2) the probability of Chaoborus larvae ingesting them during such interactions and (3) the prey survival and predator ingestion rates after 24 h. When attacked, ostracods of both sizes frequently ceased to move and passively sank in the water column. This anti-predation strategy ("akinesis" or "dead-man response") was observed in over 80% of the interactions involving physical contact. Surprisingly the probability of Chaoborus larvae eating prey that exhibited, or not, this reaction was close or equal to zero. After 24 h, over 92% of the prey survived and the ingestion rate of the chaoborids was practically nihil. Our results suggest that, although akinesis is a very common behaviour, additional features of P. schubarti may be as or more important in explaining its low vulnerability when in high spatial overlap with Chaoborus larvae.
- 出版日期2017
