Zooplankton community structure driven by vertebrate and invertebrate predators

Abstract

A zooplankton community was established in outdoor experimental ponds, into which a vertebrate predator (topmouth gudgeon: Pseudorasbora parva) and/or an invertebrate predator (phantom midge larva: Chaoborus flavicans) were introduced and their predation effects on the zooplankton community structure were evaluated. In the ponds which had Chaoborus but not fish, small- and medium-sized cladocerans and calanoid copepods were eliminated while rotifers became abundant. A large-sized cladoceran Daphnia longispina, whose juveniles had high helmets and long tailspines as anti-predator devices, escaped from Chaoborus predation and increased. In the ponds which had fish but not Chaoborus, the large-sized Daphnia was selectively predated by the fish while small-and medium-sized cladocerans and calanoid copepods predominated. In the ponds containing both Chaoborus and fish, the fish reduced the late instar larvae (III and IV) of Chaoborus but increased the early instar larvae (I and II). Small- and large-sized cladocerans were scarcely found. The former might have been eliminated by predation of the early instar larvae of Chaoborus, while the latter was probably predated by fish. Consequently, the medium-sized cladocerans, which may have succeeded in escaping from both types of predator, appeared abundantly. The results suggest that various combinations of vertebrate and invertebrate predators are able to drive various kinds of zooplankton community structure.

Population dynamics of Chaoborus flavicans and Daphnia spp.: effects on a zooplankton community in a volcanic eutrophic lake with naturally high metal concentrations (L. Monticchio Grande, Southern Italy)

“…Invertebrate predators, such as Chaoborus (Diptera) larvae, play a major role in structuring zooplankton communities in lakes by directly limiting prey populations (Hanazato & Yasuno 1989;Hanazato 1990) and altering the dynamics, size and structure of prey populations (Neill 1981;Mumm 1997;Riccardi et al 2002). The 'Chaoborus-Daphnia / predator-prey' system is very well studied.…”

Different life-history trade-offs of twoDaphniaspecies (Cladocera, Crustacea) under natural conditions as the response to predation and competition

“…The size structure of Daphnia in Lake Piaseczno could be Vertebrates eat selectively large-sized zooplankters whilst invertebrates typically select small or medium-sized prey. Hanazato and Yasumo (1989) found that in ponds where vertebrate (topmouth gudgeon) and invertebrate predators (phantom midge larva) occurred, small and largesized cladocerans were scarcely found. A similar phenomenon was observed in Lake Piaseczno.…”

Commentary on Effects of Anthropogenic and Natural Organic Chemicals on Development, Swimming Behavior, and Reproduction of Daphnia, a Key Member of Aquatic Ecosystems

“…The synergistic effect of both the kairomone and carbaryl (Table 4) reduced the population growth to half or less of that predicted from the separate effects of the two factors. Such a large reduction is particularly important to Daphnia, which typically requires a high rate of population growth to persist through periods of high mortality from predators (18,23,(48)(49)(50) (60); the more recent data are from samples taken by Dodson. by toxic xenobiotics may result in higher mortality due to both vertebrate and invertebrate predators. For example, an increase in swimming velocity will increase encounter rate with predators and therefore increase the rate of mortality (51).…”