Cladoceran Leptodora Kindtii Research Articles

Size‐specific net avoidance behavior leads to considerable under‐estimation of the biomass of Leptodora kindtii during day time sampling

Diurnal variation in the density, biomass, and individual size of the predatory cladoceran Leptodora kindtii in Lake Vesijärvi (southern Finland) was studied. Day and night sampling was conducted in July and August at 16 different study stations with net hauls from the bottom to the surface. Independently on the month, estimated biomasses were more than two times higher at night than at day. This was due to both higher density and larger individual length at night. The day‐night differences could not be explained by vertical or horizontal migrations or by bottom‐dwelling behavior by Leptodora, but were attributed to net avoidance. When light was present, more Leptodora were able to avoid the net haul than in the darkness. The avoidance was more effective by large adult individuals (>5 mm) than by juveniles, which amplified the day‐night difference in the population biomass estimate. In order to evaluate the role of large pelagic invertebrate predators in aquatic food webs, nighttime sampling should be used.

The North American invasive zooplanktivoreBythotrephes longimanusis less hypoxia-tolerant than the nativeLeptodora kindtii

The predatory cladoceran Bythotrephes longimanus (spiny water flea) has been invading lakes and damaging food webs across the central part of North America since the early 1980s. To understand its niche and that of the taxonomically related and native predatory cladoceran Leptodora kindtii, we investigated species survival after 12 h exposures to low dissolved oxygen (DO) concentrations in the laboratory. Bythotrephes longimanus (n = 690) exhibited a hypoxia tolerance limit (LC50) of 1.65 mg·L−1DO (95% confidence interval: 1.59, 1.72 mg·L−1) and was significantly less tolerant of hypoxia than L. kindtii (n = 380), which exhibited an LC50of 0.58 mg·L−1DO (0.51, 0.65 mg·L−1). These lab-based physiological results are consistent with landscape-scale observations that B. longimanus successfully invades primarily mesotrophic and oligotrophic lakes, while L. kindtii inhabits a wider range of lakes that includes eutrophic ones. Climate change throughout the 21st century may increase the occurrence and severity of hypoxia in the hypolimnia of lakes and may provide a growing barrier to B. longimanus invasion.

Spatial distribution of brood-bearing females of limnetic species of Cladocera

In this study, the spatial distribution of brood-bearing females of five species of limnetic cladocerans (Daphnia cucullata, D. longispina, Bosmina coregoni, B. longirostris, Diaphanosoma brachyurum) in the deep mesotrophic lake in relation to the predation pressure of planktivorous fish (roach Rutilus rutilus, perch Perca fluviatilis, catfish Ictalurus nebulosus, white fish Coregonus albula, bleak Alburnus alburnus), and planktonic invertebrates (cyclopoids Mesocyclops leuckartii, Thermocyclops oithonoides, T. crassus, and cladoceran Leptodora kindtii) as well as some environmental variables was estimated. Most cladocerans showed apparent differences in horizontal distribution (ANOVA F=0.2–0.45, P<0.05) in the littoral zone and lack of such differences in the pelagic zone (F=0.07–0.13, P>0.05). Vertical distribution of most species, in turn, showed a clear pattern in the pelagic zone (F=0.31–0.39, P<0.05) and less regularities in the littoral zone (F=0.15–029, P>0.05). The differences in spatial distribution of non-predated and predated species suggest that predation pressure, but not predatory type, was an important factor structuring their distribution. Other factors that affected their distribution were conductivity, dissolved oxygen, TOC and macrophyte biomass; however, most of those variables better explained the distribution of brood-bearing cladocerans in the vertical than horizontal aspect.

The development and reproductive output of three species of Cladocera (Crustacea, Branchiopoda) with different size spectra as the result of vertebrate and invertebrate predation impact

Seasonal changes in development and reproduction of three species of Cladocera, Bosmina longirostris, Bosmina coregoni and Diaphanosoma brachyurum, were studied in regard to impact of vertebrate (planktivorous fish) and invertebrate (cladoceran Leptodora kindtii and cyclopoid copepods Mesocyclops leuckarti and Thermocyclops oithonoides) predators. Each of the cladocerans represented a different prey type. The population of the largest body-sized D. brachyurum was not affected by predators suggesting unidentified mechanisms of predation-avoidance. Diaphanosoma displayed low reproductive output coinciding with high density. Medium-sized B. coregoni, influenced by planktivorous fish, invested in reproduction and carried large egg-clutches resulting in gradual increase in population density. The population of small body-sized B. longirostris, that was influenced by invertebrate predators, displayed high density and reproductive effort in spring, followed by extreme collapse in abundance and reproduction during summer months. The results suggest that invertebrate predators may suppress populations of some Cladocera more strongly than planktivorous fish.

Abundance dynamics and functional role of predaceous Leptodora kindtii in the Curonian Lagoon

Abstract The abundance and distribution of predatory cladoceran Leptodora kindtii was investigated in the estuarine lagoon (Curonian Lagoon, SE Baltic Sea). Three hydrodynamically different parts of the lagoon were selected, representing transitory oligohaline, intermediate freshwater and stagnant freshwater sites. L. kindtii was least abundant at the oligohaline site, never occurring at salinities greater than 4 psu. At the two freshwater sites, the abundance of L. kindtii varied from a low of &lt;0.1 up to 2.2 indv. L−1 during peak abundance. Two peaks of L. kindtii abundance were observed with timing differences between stations: at the stagnant site the population of L. kindtii peaked two weeks earlier relative to the more hydrodynamically active sites, likely due to a 2°C higher May temperature. The small body size of L. kindtii in the lagoon (seasonal mean 2.68±0.6 mm) shows high fish predation pressure and predicts small cladocerans, juvenile copepods and rotifers being in the preferred prey size range. The calculated L. kindtii daily consumption during the population peak was as high as 100% of the daily zooplankton production, which implies high potential of this predator to shape the grazing zooplankton community in the lagoon.

Pleistocene‐driven diversification in freshwater zooplankton: Genetic patterns of refugial isolation and postglacial recolonization in Leptodora kindtii (Crustacea, Cladocera)

In this study we investigate the extent to which successive range fragmentations, postglacial expansions, and recolonizations influenced intraspecific genetic diversity and patterns of diversification in freshwater zooplankton. Specifically, we explore the global phylogeography of the Holarctic predatory cladoceran Leptodora kindtii Focke, 1844. Phylogenetic analyses based on the mitochondrial cytochrome c oxidase subunit I recover seven deeply divergent lineages (11.8–20.0%) comprising two sister clades within the Nearctic and east Palearctic and three related clades within the west Palearctic. Strong continental endemism was also supported by the nuclear 18S ribosomal gene. Intra‐continental divergence levels (&lt; 6%) suggest that many speciation events in Leptodora were initiated by glacial isolation. Demographic and network analyses indicate that in the Nearctic and west Palearctic, regions heavily affected by the Pleistocene glaciations, Leptodora persisted in both classic (e.g., Cascadia, Mississippi, southern Europe) and cryptic refugia (e.g., northeastern Europe, Carpathian basin). Strong signatures of late Pleistocene range expansions and secondary contact were observed in most clades. Deeper intraspecific phylogeographic structure occurs across much finer geographic scales in unglaciated regions of the east Palearctic than across glaciated Nearctic and west Palearctic regions. Leptodora's ecological and biological characteristics, such as a reliance on temperate, permanent lakes, weak dispersal ability, and specific geological settings likely shaped the complex pattern of diversification in this important planktonic predator. Our data suggest the Pleistocene glaciations were important in the diversification of Holarctic freshwater zooplankton.

Egg viability of the rotifer Brachionus urceolaris after ingestion by the predatory cladoceran Leptodora kindtii

Egg resistance against the digestive process of a predator is an effective strategy for zooplankton to compensate population loss due to predation. Parthenogenetic eggs of the rotiferan Brachionus urceolaris, which were ingested by the predatory cladoceran Leptodora kindtii, were expelled from the feeding basket of the predator without digestion. We found a negative correlation between the unconsumed ratio of eggs after ingestion and body length of the predator. As high as 75% of the unconsumed eggs successfully hatched and the hatch ratio was independent of body length of L. kindtii. Our results indicate that the rotifer has an effective strategy to maintain its population in the environment with abundant invertebrate predators.

Hypoxic zones as habitat for zooplankton in Lake Erie: Refuges from predation or exclusion zones?

Bottom hypoxia has reemerged as a prominent feature of Lake Erie's central basin during late summer. Similar to coastal marine systems, the impacts of hypoxia on pelagic organisms in Lake Erie remain largely enigmatic. During summer 2005 and 2007, we used pump sampling for mesozooplankton and fish acoustics to test the hypothesis that mesozooplankton use hypoxia as a refuge from predation. We explored species-specific diel vertical migration (DVM) of mesozooplankton and spatial overlap with planktivorous fishes at several offshore stations in the central basin of Lake Erie with similar thermal structure, but varying hypolimnetic dissolved oxygen (DO) concentrations (range: 0.3 to 4.6 mg l − 1). The tendency of a zooplankter to use the hypolimnion under normoxic conditions and its sensitivity to DO defined its DVM and overlap with fish, which were generally more sensitive to hypoxia than mesozooplankton. The diaptomids (calanoid copepods) and the predatory cladoceran Leptodora kindtii were largely unaffected by hypoxia, using the epilimnion during both day and night. Daphnia mendotae and the predatory cladoceran Bythotrephes longimanus, both of which migrated from the metalimnion and epilimnion to the hypolimnion during the day under normoxic conditions, avoided the hypolimnion at DO levels ≤ 2.0 mg l − 1 . Dissolved oxygen levels between 1.0 and 1.2 mg l − 1 were critical avoidance thresholds for most other mesozooplankton species, with the copepod Mesocyclops edax, a migrator between the epilimnion and hypolimnion, avoiding DO ≤ 1.2 mg l − 1 . By contrast the cool water, hypolimnetic copepod Diacyclops thomasi and Daphnia longiremis continued to use the hypolimnion during the day until DO became ≤ 1.0 mg l − 1 . These species aggregated in the metalimnion (primarily) and epilimnion (secondarily) at night. Only Bosmina was found in abundance in the hypolimnion at DO levels equal to 0.3 mg l − 1 . Hypoxia-intolerant species (e.g., D. mendotae, B. longimanus) that were compressed into the thin metalimnion during day likely faced high predation pressure from visual-feeding planktivorous fishes (e.g., rainbow smelt Osmerus mordax, emerald shiners Notropis atherinoides) as well as the predatory cladoceran, B. longimanus. By contrast, hypoxia-tolerant species (e.g., D. thomasi, D. longiremis, and B. longirostris) that remained in the hypolimnion may have found refuge in hypoxic areas with DO > 1.0 mg l − 1 , although fish were occasionally observed making feeding excursions into hypoxic waters.

The Predacious Cladoceran Leptodora kindtii as a Prey for the Cyclopoid Copepod Mesocyclops sp.: Laboratory Observations of Predator-Prey Interaction

ABSTRACT We observed the behavior of the cyclopoid copepod Mesocyclops sp. as it fed on the cladoceran Leptodora kindtii in the laboratory. The feeding efficiency (capture and ingestion successes) of Mesocyclops sp. was high for smaller L. kindtii (<2.5 mm in body size) but low for larger ones. Mesocyclops sp. ingested small L. kindtii whole, but often consumed parts of larger L. kindtii. The handling time increased as the L. kindtii body size increased, except when Mesocyclops sp. consumed only the second antennae. These laboratory observations suggest that Mesocyclops sp. may be a natural predator of small L. kindtii.

Feeding Habit of Pond Smelt (Hypomesus transpacificus nipponensis) and Its Impact on the Zooplankton Community in Lake Suwa, Japan

ABSTRACT We examined the feeding habit of pond smelt (Hypomesus transpacificus nipponesis) and its impact on the zooplankton community in Lake Suwa, Japan, from May to December 2001. Stomach contents were analyzed, and prey importance and the prey selectivity index were estimated from the stomach contents of fish and prey density in the lake. Results showed that herbivorous zooplankters the cladoceran Bosmina fatalis and the calanoid copepod Eodiaptomus jaonicus were the most important prey items, accounting for about 80% of the total prey biomass in the diet of the pond smelt. However, the selectivity index suggested that pond smelt preferred the predacious cladoceran Leptodora kindtii and the cyclopoid copepod Mesocyclops sp. In the lake, predation impact by pond smelt on the herbivorous zooplankton was not apparent, but the population dynamics of the large invertebrate predators L. kindtii and Mesocyclops sp. seemed to be affected by pond smelt by selective predation.

Diel Variations in the Vertical Distribution of Crustacean Zooplankton and Food Selection by Planktivorous Fish in a Shallow Turbid Lake

AbstractThe variations in the vertical migrations by zooplankton and food composition of fish in the shallow, clay‐turbid Mustionselkä basin of Lake Hiidenvesi were studied (water depth 3 m). Daphnids showed signs of reverse migration, their density in the surface layer being highest during the day. The reverse migration was probably due to predation threat by the predatory cladoceran Leptodora kindtii. Chydorus sphaericus, which was consumed especially by the day active bleak (Alburnus alburnus), showed normal vertical migration. Copepods showed no clear vertical movements. Leptodora kindtii, as well as the large herbivore Limnosida frontosa, showed no vertical migrations, but their overall abundance increased considerably during the night, indicating horizontal movement towards the open water at night. Due to the shallowness of the water, vertical migrations may not be a good predator‐avoidance strategy for the largest cladocerans, which may be able to perform horizontal migrations. (© 2004 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Morphological variation of the predatory cladoceran Leptodora kindtii in relation to prey characteristics.

The responses of invertebrate predators to changes in the morphology of their prey, and especially the responses for induced defences, are largely unexplored, compared with the vast amount of data on predator-induced defences. This study demonstrates that the size of the feeding basket, the anatomical structure used to capture prey by the predaceous freshwater cladoceran Leptodora kindtii, shows significant allometric changes with the average body size of the prey (herbivorous cladocerans) in six lakes of northeastern Poland. Prey density influences the basket size only in adult Leptodora individuals, whereas induced defences such as helmets of Daphniasp. seem to have no effect on Leptodora's morphology. In a feeding experiment it is shown that the increase in the feeding basket enables Leptodora to capture larger prey. The seasonal pattern of morphological change, and its measurable benefit suggest that the observed morphological variability of Leptodora is phenotypic plasticity.

Clutch size variation and morphology in a cyclomorphic Bosmina population

Clutch size, cyclomorphosis and allometric growth were analysed in a population of the humpbacked Bosmina (E.) coregoni gibbera. This species shows cyclomorphosis in antennule length and body height, traits that may reduce predation risk from Leptodora kindtii. Individuals with long antennule and extreme body height may pay a cost in terms of decreased reproductive capacity. On the other hand, increasing the body height may be a way to increase the brood chamber volume during periods of good food conditions. We tested these hypotheses by comparing the seasonal variation in clutch size with the seasonal variation in morphology. Antennule length and body height increased from mid-May to August and showed usually positive allometry at times with high population densities of the predatory cladoceran Leptodora kindtii. Clutch size decreased from spring to late summer contrary to the hypothesis that cyclomorphosis in height is caused by a seasonal variation in reproductive demand. However, within-dates antennule length was negatively related and body height was positively related to clutch size. We conclude that the long antennule may impose a cost that reduces the reproductive capacity. The hypothesis that carapace cyclomorphosis is driven by seasonally varying clutch sizes was rejected.

The evolutionary transformation of phyllopodous to stenopodous limbs in the Branchiopoda (Crustacea)--is there a common mechanism for early limb development in arthropods?

Arthropods and in particular crustaceans show a great diversity concerning their limb morphology. This makes the homologization of limbs and their parts and our understanding of evolutionary transformations of these limb types problematical. To address these problems we undertook a comparative study of the limb development of two representatives of branchiopod crustaceans, one with phyllopodous the other with stenopodous trunk limbs. The trunk limb ontogeny of a 'larger branchiopod', Cyclestheria hislopi ('Conchostraca') and the raptorial cladoceran Leptodora kindtii (Haplopoda) has been examined by various methods such as SEM, Hoechst fluorescent stain and expression of the Distal-less gene. The early ontogeny of the trunk limbs in C. hislopi and L. kindtii is similar. In both species the limbs are formed as ventrally placed, elongate, subdivided limb buds. However, in C. hislopi, the portions of the early limb bud end up constituting the endites and the endopod of the phyllopodous filtratory limb in the adult, whereas in L. kindtii, similar limb bud portions end up constituting the actual segments in the segmented, stenopodous, and raptorial trunk limbs of the adults. Hence, the portions of the limbs corresponding to the endites of the phyllopodous trunk limbs in C. hislopi (and other 'larger branchiopods') are homologous to the segments of the stenopodous trunk limbs in L. kindtii. It is most parsimonious to assume that the segmented trunk limbs in L. kindtii have developed from phyllopodous limbs with endites and not vice versa. This study has demonstrated at least one way in which segmented limbs have been derived from phyllopodous, multi-lobate limbs during evolution. Similar pathways can be assumed for the evolution of stenopodous, segmented and uniramous limbs in other crustaceans. Irrespective of the differences in the adult limb morphology, the early patterning of arthropod limbs seems to follow a similar principle.

A laboratory study of functional response of Leptodora kindtii to some cladoceran species and copepod nauplii

Feeding of the predatory cladoceran Leptodora kindtii was studied under laboratory conditions. Functional responses for two size classes of the predator to Rye prey taxa (Daphnia galeata, Diaphanosoma brachyurum, Ceriodaphnia pulchella, Bosmina coregoni and copepod nauplii) in five prey concentrations were determined and further analysed. Small juvenile Leptodora showed a Hollings' type I functional response in all five experiments, whereas large adult Leptodora showed in 3 out of 5 cases a Hollings' type II functional response. The possible significance of these differences is discussed. For all prey categories, the ratio of the basket length of Leptodora to the prey body length considerably influenced maximum predation rates. Prey taxa show different vulnerabilities for predation by Leptodora, hence, during periods of abundance this predator may have a significant structuring effect on the zooplankton community. [KEYWORDS: PREY SIZE, INVERTEBRATE PREDATORS, ZOOPLANKTON COMMUNITY, NEUSIEDLER-SEE, LAKE, BYTHOTREPHES, SELECTION, DENSITY, AUSTRIA]

Seasonal changes in the diets and relative abundances of perch and roach in the littoral and pelagic zones of a large lake

In the Enonselkä and Laitialanselkä basins of Lake Vesijärvi, perch Perca fluviatilis and roach Rutilus rutilus were abundant in the littoral and in the pelagic zones throughout the summer. In the littoral zone, roach was always more numerous than perch, while perch dominated in the open water. Intraspecific diet overlap values were higher than interspecific values. In the pelagic zone, perch &lt;155 mm fed mainly on the cladoceran Leptodora kindtii, while small bosminids were most important food items for roach. Large perch were piscivorous, feeding mainly on smelt Osmerus eperlanus. In the littoral zone small perch foraged on zooplankton and chironomid larvae and large perch on chironomids and fish (small perch). Small roach fed mainly on bosminids and detritus, while for roach &lt;185 mm macrophytes (Elodea Canadensis, Lemna trisulca) were also of importance. Detritus was more common in the food of roach in Laitialanselkä than in Enonselkä. The slower growth rate of roach in Laitialanselkä compared with Enonselkä was probably connected with this. However, considering the latitude of the lake, the growth rate of both roach and perch was relatively fast in both basins. The results indicated that in a large lake both perch and roach are able to utilize effectively the different habitats and diverse food resources. By segregation in food resource utilization they are able to co‐exist in large quantities, at the same time maintaining a relatively fast growth rate.

Seasonal changes in the diets and relative abundances of perch and roach in the littoral and pelagic zones of a large lake

In the Enonselkä and Laitialanselkä basins of Lake Vesijärvi, perch Perca fluviatilis and roach Rutilus rutilus were abundant in the littoral and in the pelagic zones throughout the summer. In the littoral zone, roach was always more numerous than perch, while perch dominated in the open water. Intraspecific diet overlap values were higher than interspecific values. In the pelagic zone, perch <155 mm fed mainly on the cladoceran Leptodora kindtii, while small bosminids were most important food items for roach. Large perch were piscivorous, feeding mainly on smelt Osmerus eperlanus. In the littoral zone small perch foraged on zooplankton and chironomid larvae and large perch on chironomids and fish (small perch). Small roach fed mainly on bosminids and detritus, while for roach <185 mm macrophytes (Elodea Canadensis, Lemna trisulca) were also of importance. Detritus was more common in the food of roach in Laitialanselkä than in Enonselkä. The slower growth rate of roach in Laitialanselkä compared with Enonselkä was probably connected with this. However, considering the latitude of the lake, the growth rate of both roach and perch was relatively fast in both basins. The results indicated that in a large lake both perch and roach are able to utilize effectively the different habitats and diverse food resources. By segregation in food resource utilization they are able to co-exist in large quantities, at the same time maintaining a relatively fast growth rate.

Cyclomorphosis in a population of Bosmina coregoni

A population of cyclomorphic Bosmina coregoni was studied in Lake Ostersjon, southwestern Sweden and results from field samples collected in 1988, 1989, 1990 and 1991 are presented. Animals collected in summer have remarkably higher carapace and prolonged antennule compared to what we call the normal morph. In 1991 the extreme morph reach its maximum body length, body height and antennule length in July to September. The occurrence of the extreme morph coincide with the hatching of the predaceous cladoceran Leptodora kindtii. The two morphs fluctuate in abundance and in relation to each other. In early spring only the normal morph occurred in the samples followed by a period of about two months when the two morphs were found together, in July only the extreme morph was found. In September the two morphs were again present in the lake. As has been shown for other cladoceran, the conspicuous carapace and antennule could be an adaptive response that decreases mortality due to invertebrate predation. Spectacular features like these are likely also accompanied by some sort of costs.

Conservation in equatorial Guinea: J. E. Fa, Oryx, 26(2), 1992, pp 87–94

In this study, the spatial distribution of brood-bearing females of five species of limnetic cladocerans (Daphnia cucullata, D. longispina, Bosmina coregoni, B. longirostris, Diaphanosoma brachyurum) in the deep mesotrophic lake in relation to the predation pressure of planktivorous fish (roach Rutilus rutilus, perch Perca fluviatilis, catfish Ictalurus nebulosus, white fish Coregonus albula, bleak Alburnus alburnus), and planktonic invertebrates (cyclopoids Mesocyclops leuckartii, Thermocyclops oithonoides, T. crassus, and cladoceran Leptodora kindtii) as well as some environmental variables was estimated. Most cladocerans showed apparent differences in horizontal distribution (ANOVA F = 0.2–0.45, P < 0.05) in the littoral zone and lack of such differences in the pelagic zone (F = 0.07–0.13, P > 0.05). Vertical distribution of most species, in turn, showed a clear pattern in the pelagic zone (F = 0.31–0.39, P < 0.05) and less regularities in the littoral zone (F = 0.15–029, P > 0.05). The differences in spatial distribution of non-predated and predated species suggest that predation pressure, but not predatory type, was an important factor structuring their distribution. Other factors that affected their distribution were conductivity, dissolved oxygen, TOC and macrophyte biomass; however, most of those variables better explained the distribution of brood-bearing cladocerans in the vertical than horizontal aspect.

The Occurrence of the Cladoceran Leptodora Kindtii in Colorado

The Occurrence of the Cladoceran Leptodora Kindtii in Colorado