Daphnia Cucullata Research Articles

Some aspects in the costs of cyclomorphosis in Daphnia cucullata

Some aspects in the costs of cyclomorphosis in <i>Daphnia cucullata</i>

Predator-induced helmet formation in Daphnia cucullata(SARS)

Predator-induced helmet formation in Daphnia cucullata(SARS)

Evaluation ofChaoborus predation on natural populations of herbivorous zooplankton in a eutrophic lake

The effect of Chaoborus predation on natural zooplankton communities was tested in enclosure experiments during June, July and August in the eutrophic Frederiksborg Slotsso, Denmark. Natural densities of Chaoborus larvae in enclosures reduced the abundance of copepod nauplii and Chydorus sphaericus with up to 60% and 80%, respectively, compared with controls. In contrast, Chaoborus was not able to suppress populations of Eudiaptomus graciloides and Daphnia cucullata. Predation was strongest during June and decreased thereafter as Chaoborus pupae emerged. Laboratory experiments showed that a considerable part (20–30% of the population day −1) of Chaoborus larvae emerged as pupae at 18–20 °C in July and August. Chaoborus larvae occurred in the lake as migratory individuals from May to September with mean population densities of about 100 larvae m−2. Results from the enclosure experiments suggest that the populations of herbivorous zooplankton in Frederiksborg Slotsso during June, July and August are not controlled by natural populations of Chaoborus larvae.

Effectiveness of phytoplankton control by large-bodied and small-bodied zooplankton

Employingin situ enclosures containing inocula of the lake zooplankton (mainlyDaphnia galeata, Daphnia cucullata andBosmina spp.) from a moderately eutrophic Lake Ros (Northern Poland) or large-bodiedDaphina magna, the following observations on succession of phytoplankton were made: 1) whereasD. magna could control the density of all the photoplankton size classes, the lake zooplankton could not suppress the large-sized phytoplankters or net phytoplankton; 2) the lake zooplankton was able to control the density of small algae (< 50µm), but its effect on large algae may be opposite: a promotion of net phytoplankton growth by removing small-sized algae which can out-compete net phytoplankton for limited PO4-P resources (<5µg P l−1).

The effect of Daphnia body size on filtering rate inhibition in the presence of a filamentous cyanobacterium.

We tested the hypothesis that shifts in the size structure of daphnid assemblages may be caused by differing sensitivities of particular species to interfering filamentous cyanobacteria. Three Daphnia species of different size were fed the green alga Scenedesmus and filtering rates were measured in the presence and absence of straight filaments of the cyanobacterium Cylindrospermopsis raciborskii. Cylindrospermopsis was not lethally toxic to Daphnia, but was inadequate as the sole food. The filtering rates of all three Daphnia species were reduced in the presence of the filaments. The larger Daphnia pulicaria and Daphnia hyalina were more affected than the smallest, Daphnia cucullata, and within the size range of each species larger individuals were more affected than smaller ones. Our results are consistent with field observations that body size is an important factor determining the competitive success of Daphnia species in the presence of cyanobacterial filaments.

The lack of vertical migration in Daphnia: the effect of homogenously distributed food

Neither Daphnia hyalina, Daphnia cristata, nor Daphnia cucullata vertically migrated in Lake Mikolajskie and Lake Majcz. We suggest that even under strong fish predation pressure there is no reason to migrate when seston is relatively homogenously distributed throughout the water column.

Zooplankton grazing on [methyl‐3H]thymidine‐labeIled natural particle assemblages: determination of filtering rates and food selectivity

SUMMARY. 1. The grazing of [methyl‐3H]thymidine‐labelled bacteria by zooplankton was studied in Lake Norrviken. Sweden.2. Animals did not ingest bacteria attached to large colonies of the cyanobacterium Microcystis wesenbergii Kom. but small aggregates of hacteria and free bacteria were readily consumed.3. Diaphanosoma brachyurum (Liévin). Daphnia cucullata Sars. and Daphnia galeata Sars grazed free bacteria more quickly than aggregates, but Endiaptomus gracilis (Sars), Chydorus sphaericus Müll. and Bosmi‐ na coregoni s.l. Baird grazed the aggregates more readily.4. Filtering rate determinations varied from LA to 123 μl ind. −1h − 1for various species.

Differential feeding behaviour of the dominant cladocera as an explanation of zooplankton community structure in the Loosdrecht Lakes

The zooplankton of Loosdrecht Lakes is dominated byBosmina longirostris in the Spring period but is replaced by the largerB.coregoni in early summer at a time when phytoplankton populations, dominated by filamentous cyanophytes, are rapidly increasing. Throughout the summerB.coregoni coexists with the longer, but more slender,Daphnia cucullata.

Population genetic investigations onDaphnia cucullatain the Schöhsee at Plön

Population genetic investigations on<i>Daphnia cucullata</i>in the Schöhsee at Plön

Are there allelopathic interactions in zooplankton? Laboratory experiments with Daphnia.

Daphnia hyalina and Daphnia cucullata were kept in flow-through chambers in lake water (I), water from mass cultures of D. hyalina (II) and water from mass cultures of D. cucullata (III). A good correlation between body length and clutch size of the Daphnia was found in all cases. The regression lines of the different treatments were compared with respect to different slopes and different intercepts. D. hyalina showed the same reaction to medium II and III, but a lower regression coefficient and higher intercept in medium I. In contrast D. cucullata showed the same reaction to medium I and II, but a higher regression coefficient in medium III.

Estimating Competition in Cladocerans Using Data on Dynamics of Clutch Size and Population Density

AbstractNegative correlations between clutch size and population density are proposed to be considered as indices of intra‐ and interspecific competition in cladocerans if they are revealed while analyzing population dynamics and clutch size and time lags are taken into account. The proper correlation analysis of summer populations of Diaphanosoma brachyurum, Bosmina coregoni, Daphnia cucullata and D. galeata from mesotrophic Lake Glubokoye (Moscow Region) in 1975, 1978, and 1979 indicates the important role of competition of both types for the community studied. High niche overlap in food and space in the four populations was also observed.

The filtration apparatus of Cladocera: Filter mesh-sizes and their implications on food selectivity.

The filtering apparatus of eleven Cladoceran species was studied. The distances between the setulae, which act as filters, were measured. Among adult individuals, they vary from 0.2 μm in Diaphanosoma brachyurum to 4.7 μm in Sida crystallina. Species can be grouped according to the mesh-sizes, as "fine mesh filter-feeders": Diaphanosoma brachyurum, Ceriodaphnia quadrangula, Chydorus sphaericus, Daphnia cucullata and Daphnia magna; "medium mesh filter-feeders": Daphnia galeata, D. hyalina. D. pulicaria, Bosmina coregoni, and "coarse mesh filter-feeders": Holopedium gibberum and Sida crystallina. In Daphnia hyalina, the distances between setulae increase from 0.3-0.4 μm in small juveniles, to 0.8-2.0 μm in adults. In Daphnia magna, the mesh-size of the filter does not increase significantly with growth. There is good evidence that the relative abundance of the filter-feeding types varies with the trophic state of the lake. In oligotrophic lakes the "coarse mesh filter-feeders" usually dominate throughout the year. The seasonal succession of zooplankton species in eutrophic lakes can be interpreted as a succession of feeding types; during winter "coarse mesh filter-feeders" dominate, while "fine mesh filter-feeders" are most abundant during summer phytoplankton blooms. Our results support the hypothesis that the species composition of filter-feeding zooplankton is strongly influenced by the amount of suspended bacteria which are available as food only for filter-feeding species with fine meshes.

Effect of temperature in laboratory studies on development and growth of Cladocera and Copepoda from Tjeukemeer, The Netherlands

SUMMARY. The effects of temperature on development and growth are described for the common Cladocera and Copepoda in Tjeukemeer. Eight cladoceran species and five copepod species have been investigated: Daphnia hyalina, Daphnia cucullata, Bosmina coregoni, Bosmina longirostris, Chydorus sphaericus, Ceriodaphnia pulchella, Diaphanosoma brachyurum, Leptodora kindtii, Acanthocyclops robustus, Mesocydops leuckarti, Diacyclops bicuspidatus, Cyclops vicinus vicinus and Eurytemora affinis. Growth is expressed as length increment per size class (cladocerans) or instar (copepods) per week and as the relationship between time and length. The curvilinear logarithmic equation: In D = In a + b (In T)2 is fitted to the development times of eggs, combined naupliar instars and combined copepodite instars, as well as to the longevity of the adults. The results are compared with those found in the literature and differences are discussed.

Reproducibility of short-term and reproduction toxicity experiments with Daphnia magna and comparison of the sensitivity of Daphnia magna with Daphnia pulex and Daphnia cucullata in short-term experiments

Short-term toxicity tests with Daphnia magna are reasonably reproducible. The sensitivity of Daphnia pulex, Daphnia cucullata and Daphnia magna proved to be about the same in short-term tests with 15 different chemical compounds.

Circulation of water as a main factor influencing the development of helmets in Daphnia cucullata Sars

1. The problems concerning the development of helmets in Daphnia cucullata SARS were studied. The height of the head was expressed in per cent of the total length of Daphnia. The relative length of head was used as a measure characterising the size of helmet 2. In relatively deep small ponds with surface area less than 1 hectar the relative height of head in adult specimens reaches its maximum in autumn i.e. at the beginning of circulation. 3. The relative height of the head in neonata instar at 20°C is different in different populations. In the clones from 3 ponds with surface area more than 15 hectare the relative height of the head in neonata instar at 20° C is greater than in 4 clones from small ponds the surface of which is less than 1 hectar. 4. Populations possessing under natural conditions a low helmet were cultivated in the laboratory; their adult descendants did not develop the helmet at all. In the descendants of populations with high helmets a reduction of helmet could be observed after 5–10 generations cultivated in vessels in laboratory. 5. In the descendants of specimens which under laboratory conditions ceased to develop helmets in adult instars this ability is renewed when a water circulation is produced in the cultivation vessels by means of air bubbles. In this way we obtained higher helmets under laboratory conditions than could be ever found in populations under natural conditions. 6. According to our observations the function of the helmet can be interpreted as an adaptation to resist more easily the water current. 7. The role of fishes as selective factor is discussed.