Population dynamics of Bosmina longirostris (Crustacea: Cladocera) in Lake Kariba,Zimbabwe

The population dynamics of Bosmina longirostris in a large tropical reservoir, Lake Kariba, Zimbabwe, are described. Population density showed two peaks associated with periods of high nutrient fluxes. Fecundity was always low. Two eggs per female was the maximum ever recorded. Instantaneous rates of birth, death and population growth calculated from field data using the egg ratio method are discussed. The rate of biomass change fluctuated in a regular pattern, probably linked to food availability or predation by a clupeid, Limnothrissa miodon.     

Revision of the Genus BosminaBAIRD, 1845 (Crustacea,Cladocera)

The genus Bosmina can be differentiated into four subgenera: 1. Bosmina s. str. BAIRD , 1845, 2. Eubosmina SELIGO , 1900, 3. Neobosmina LIEDER , 1957, and 4. Sinobosmina LIEDER , 1957. Subgeneric discrimination is based upon several features of the females (postabdominal claw, serration of the mucro, patterns of the lateral head pores) and, mainly, upon certain differences in the morphology of the male (postabdomen and, according to LILLJEBORG 1900, BURCKHARDT 1924 and KOŘINEK 1971, the first leg). The distribution of the Bosmina subgenera throughout the world varies: Bosmina s. str. is distributed worldwide (except for Australia?), Eubosmina is holarctic, Neobosmina has been found in Africa, the neotropical zone, Australia and Oceania, and Sinobosmina occurs in East and South-East Asia.     

History of the community of planktonic Cladocera in Lake Glubokoe (Moscow Region)

A 128-centimeter sediment core of a forest lake in the Moscow Region, for which the recent zooplankton has been well studied, was analysed. The changes in the density and size of organisms in the core points to an important role of fish and interspecific competition in Cladocera and to a minor role of invertebrate predators in the historical development of the plankton. No substantial shifts in the lake trophy seem to have occurred during the last 600 years. A widely used technique of heating the sediment in a 10% KOH solution may account for 5–13-fold losses of planktonic cladocerans' remains.     

Stratigraphy of Cladocera (Crustacea) and Chironomidae (Insecta: Diptera) in Three Sediment Cores from the Central Baltic Sea as Related to Paleo-salinity

In three sediment cores from the Central Baltic Sea (Bornholm Basin, Gdansk Bay) corresponding horizons with maximum abundance of remains of a limnetic fauna (Cladocera, Chironomidae) were found. These associations indicate the existence of an oligotrophic freshwater lake. However, this horizon does not coincide with the Ancylus stage but is located in sediment layers from the very end of that period, or from the Mastogloia stage, which was a transitional brackish water phase.     

Occurrence of Cladocera (Crustacea) in subterranean waters in Yugoslavia

Contrary to some localities in France and Spain, Cladocera occur in hypogean waters in Yugoslavia very sporadically. Beside the stygobitic species, Alona hercegovinae from caves and Alona smirnovi from interstitial waters, particularly some other Chydoridae seem to be suited for hypogean life. Chydorus sphaericus, reputed as one of the most euryoecious cladocerans, occurs also the deepest in interstitial waters as well as in caves. Other species, found in hypogean waters are Simocephalus vetulus, Ilyocryptus sordidus, Eurycercus lamellatus, Chydorus ovalis, Leydigia leydigi, Acroperus harpae and Biapertura affnis.     

On the taxonomy of theDaphnia hyalina-galeata complex (Crustacea: Cladocera)

Populations of theDaphnia hyalina-galeata complex from Central, North and South Europe have been compared morphologically. The main purpose of this investigation is delimitation of the critical speciesDaphnia galeata, based on a thorough examination of the original materials from G. O. Sars' collection, and taking into account hitherto overlooked or insufficiently appreciated characters. According to their morphology and ecology,Daphnia hyalina, Daphnia galeata andDaphnia cucullata have to be treated taxonomically as separate species. In view of the short and high antennula mound and other morphological characteristics,Daphnia gracilis Hellich andDaphnia hyalina lacustris sensu Lilljeborg belong to the speciesDaphnia galeata. In the common range ofDaphnia galeata andDaphnia cacullata there occurs quite frequently an intermediary form, which according to genetic evidence is a hybrid of these two species. Although apparently this hybrid form is stabilized genetically to a large extent and is capable of identical reproduction, it should not be considered as a species in the usual sense.The present work intends to put the notoriously confused systematics of theDaphnia hyalina-galeata complex on a firm basis. It concludes with a key, which should enable also non-specialists to identify uniquely the three species and the hybrid form in question.     

Global diversity of cladocerans (Cladocera; Crustacea) in freshwater

Cladocera is a primarily-freshwater monophyletic group, an important component of the microcrustacean zooplankton. They inhabit most types of continental fresh and saline water habitats, occurring more abundantly in both temporary and permanent stagnant waters. Cladocera is an ancient group of Palaeozoic origin. About 620 species are currently known, but we estimate that the real number of species is 2–4 times higher. A number of currently-recognised widespread species can be expected to harbour extensive cryptic diversity. Guest editors: E. V. Balian, C. Lévêque, H. Segers & K. Martens Freshwater Animal Diversity Assessment     

Significance of head and carapace pores inCeriodaphnia (Crustacea,Cladocera)

Twelve species ofCeriodaphnia were examined by light and scanning electron microscopy for the presence of head and carapace pores. Rostral pores, similar to those in the Scapholeberinae (Dumont & Pensaert, 1983) were found in all species, situated just anterior to or between insertions of the antennules. With two exceptions, the pattern of reticulations around the pores was distinctive for each species. Oval ‘head pores’ or fenestrae occur consistently on the anterior surface of the cervical notch of juvenile and adultC. dubia, cf.dubia (from Australia),lacustris, andreticulata. The patterns of reticulations around a fenestra are unique to each species. It appears thatC. cornuta (s.l.) in the Americas has a fenestra, whereas AustralianC. cornuta (s.s.) has none. Minute pores often occur bilaterally anterior and posterior to the cervical notch in heavily reticulated individuals of several species but are not constant enough to be taxonomically useful. Well-defined small pores are situated within narrow reticulations just medial to the ventral and posterior valve margins ofC. dubia, lacustris, andreticulata. These open into carapace glands of unknown, perhaps secretory, nature. Similar glands have been observed in related taxa. Such glands and marginal pores occur only occasionally or not at all in otherCeriodaphnia. Other small pores sometimes occur among reticulations of the head, fornix, and lateral and antero-ventral surfaces of the valves. They are found more often in juvenile or heavily reticulated individuals. As yet no consistent pattern to their occurrence among species has emerged. Head and carapace pores inCeriodaphnia may be most useful in identifying species rather than in determining species groups or evolutionary patterns within the genus.     

Palaeolimnological investigations in Poland based on Cladocera (Crustacea)

The results of subfossil Cladocera analysis obtained from deposits of 26 lakes throughout Poland have been presented. For years throughout Poland a broad range of palaeolimnological studies have been conducted. Their aim is to discover the historical development of water basins and climatic changes in the course of the last 13,000 years and also to investigate the gradual influence of man on the ecosystem with particular emphasis on the last few decades. The hitherto obtained results of palaeolimnological studies, including the results of Cladocera analysis, have yielded information about the development of lakes and provided the basis for plans of certain reservoirs and their basins. Over the past years, analysis of subfossil Cladocera has become one of the leading palaeolimnological methods. The results of detailed qualitative and quantitative analysis of Cladocera remains from sediments of 15 lakes allowed for a reconstruction of the lakes' development. The littoral and limnetic regions, changing trophy, from oligotrophy to advanced eutrophication, changes in pH and fluctuation of water levels, as well as changes resulting from settlement — from Mesolithic and Neolithic through Medieval times until the present — have been reconstructed. For individual lakes, phases of Cladocera development and periods of eutrophication were indicated which partially correlated with certain pollen zones as well as periods of human impact and geochemical effects.     

甲壳动物的生殖量与环境关系：Ⅰ.枝角类

生殖量是生殖潜力(reproductivepotential)的一个主要标志,也是生态系统(含生产力)和种群生态学(含数量变动)的一个主要内容。它在很大程度上是由遗传因子(基因)决定的,表现在各类动物的生殖量有很     

Moina mukhamedievi n. sp. (Crustacea,Cladocera) from ricefields of Uzbekistan (central Asia)

A new species of Cladocera, Moina mukhamedievi from ricefields of Uzbekistan, is described. It is compared with the related species M. dubia, M. brachiata, M. oryzae. This revised version was published online in September 2006 with corrections to the Cover Date.     

Subgeneric differences in head shield and ephippia ultrastructure within the genus Bosmina Baird (Crustacea,Cladocera)

Seven samples of roach (Rutilus rutilus L.) fromthe Austrian section of the Danube river, the Drauriver and lake Wallersee were examined to studypossible population genetic effects of anthropogenichabitat modification and subdivision. Geneticvariability was assessed using electrophoreticvariation of 11 enzyme systems coded by 14 gene loci.Genetic variation of roach was remarkably high, andwas mainly located within samples while differencesbetween them were weak. Morphometric analyses ofconventional external measurements revealedconsiderable morphological variation within samples.Significant differences between samples mainlyinvolved body depth and fin size, but did not allowadaptive ecomorphological interpretations in severalcases. The comparison of morphological and geneticvariation showed no significant correlations but waslimited by the narrow range of heterozygosityestimates.     

Seasonal changes of Bosmina (Crustacea, Cladocera) in Frains Lake, Michigan: laboratory observations of phenotypic changes induced by inorganic factors

In Frains Lake, individuals of the species Bosmina longirostris decrease relative mucro and antennule lengths during the spring and summer, and increase them again during the fall. The cyclomorphosis involves both embryonic and post-embryonic events, since the relative sizes of parts in neonates and the relative growth rates of parts in later instars change seasonally. Antennules grow during winter, but may even regress during summer. Mucrones show an opposite pattern, growing maximally during late summer and fall. The kinds of cyclomorphotic changes in Bosmina suggest evolutionary adjustments to two principle types of predators: visual vertebrates and blindly grasping invertebrates. While laboratory experiments implicate temperature and turbulence as proximate factors in the cyclomorphotic changes, some unknown factor (or factors) also appears necessary to stimulate the magnitude of responses observed in nature.     

Phylogeny and adaptive radiation in the Onychopoda (Crustacea,Cladocera): evidence from multiple gene sequences

Members of the order Cladocera show remarkable morphological and ecological diversity. One of the most spectacular adaptive radiations in this group has involved species of the suborder Onychopoda, which have adopted a novel feeding strategy, predation, and have colonized habitats with a broad range of salinities. In order to evaluate the origins and systematics of this group, we derived a molecular phylogeny for its three component families including nine of 10 recognized genera based on three mitochondrial (mt) gene sequences: cytochrome c oxidase subunit I (COI), the ribosomal small and large subunits (12S and 16S) and one nuclear gene sequence: the small ribosomal subunit (18S). Maximum‐parsimony, maximum‐likelihood and neighbour‐joining phylogenetic analyses were largely congruent, supporting the monophyly of the suborder and each of its families. Comparative analyses of data based on total evidence and the conditional combination of the ribosomal genes produced relatively congruent patterns of phylogenetic affinity. By contrast, analyses of single gene results were inconsistent in recovering the monophyletic groups identified by the multigene analyses. Based on the reconstructed phylogeny, we discriminate among the existing hypotheses regarding the evolutionary history of the onychopods. We identify a prolonged episode of speciation from the Miocene to the Pleistocene with two pulses of diversification. We discuss our results with reference to the geological history of the Ponto‐Caspian basin, the region which fostered the onychopod radiation.     

Effect of food concentration on the carbon balance of Bosmina longirostris (Crustacea: Cladocera)

SUMMARY. 1. The carbon balance of the small cladoceran, Bosmina longirostris , was examined at four food concentrations (0,05, 0.10, 0.25, 2.50mg C 1-⁻¹) based on long-term growth experiments.
2. At birth, B. longirostris allocated about 60% of assimilation to body growth at all food concentrations. However, allocation to body growth decreased with age and was less than 5% after the fourth instar at the lowest food concentration. The proportion allocated to reproduction increased with increasing food concentration, but was relatively constant among different adult instars.
3. Assimilation rate increased with increasing food concentration and increasing body size: the mean rate from birth to 15 days was 6.6 times higher at the highest food concentration than at the lowest food concentration. However, with decreasing food concentration and increasing body size, a higher proportion of the assimilated carbon was lost as respiration. As a result, the net production rate reached a plateau at intermediate body size and was 9.1 times higher at the highest food concentration than at the lowest food concentration.
4. Comparison with previous studies revealed that B. longirostris is more efficient than Daphnia with regard to carbon production, especially at low food conditions, if the death rate is negligible.     

The late Holocene appearance of European Bosmina (Eubosmina) thersites (Crustacea, Cladocera) in lakes surrounding the Baltic Sea

This study shows the appearance of Bosmina (Eubosmina) thersites during the last millennium in two lakes in Northern Europe: Lake Charzykowskie (Poland) and Lake Lohja (Estonia). Cladocera remains collected from both lakes showed similar Bosmina species composition and changes during the late Holocene. Older sediment layers showed a prevalence of smaller Eubosmina species (B. (E.) longispina), indicating oligotrophic conditions of the lakes, while younger layers were dominated by larger species (B. (E.) coregoni and B. (E.) thersites), typically found in lakes with higher trophy. The presence of B. (E.) thersites has rarely been reported in paleolimnological research, and this is the first observance of its high abundance in lake sediments. More research is needed, however, to better understand the appearance, speciation driver, continental range, and ecological preferences of B. (E.) thersites.     

Temperature- and predator-induced phenotypic plasticity in Bosmina cornuta and B. pellucida (Crustacea: Cladocera)

SUMMARY 1. Clones of Bosmina cornuta and B. pellucida (B. longirostris species complex) were derived from samples collected from Scheuermühlenteich and Lake Windsborn(westernGermany). Experimental temperature change (to 10 °C and 20 °C) and exposure to Acanthocyclops vernalis copepods (12 L^?1) significantly altered external morphology in laboratory cultures of the two species. Morphological traits were derived from eight log₁₀‐transformed and standardised morphometric distances by factorial analysis: factor 1 represented body size, factor 2, size of appendages and factor 3, the head size. 2. Acclimation of clones to cold water (10 °C, >14 days) led to an increase in body, antennule and mucrone size in B. cornuta and B. pellucida. Moreover, at 10 °C, B. cornuta cultures usually collapsed within a few weeks. Compared to the trials at 10 °C, acclimation to 20 °C (the two species) and to 15 °C (B. pellucida only) left the size of body appendages unchanged. Individuals were unequivocally assigned to each species by discriminant functions. Conspecific individuals that were acclimated to different temperatures between 10 and 20 °C also differed in external morphology, but discriminant analysis yielded misclassification rates of 5.3–23.3%. 3. Morphological response to the presence of copepod predators was weaker than that caused by temperature change. Long‐term exposure of clones to copepod predators induced a significant increase in size of appendages in the two species but left body size unaffected. Again, species identification by discriminant functions could be made without any error, whereas conspecific controls and experimentals were misclassified at rates between 19.4 and 29.5%. 4. It is suggested that temperature is the main proximal cue for Bosmina cyclomorphosis. The distinct response to temperature of B. pellucida and B. cornuta may also account for seasonal differences in abundance observed in field.     

Genotypic succession in the cyclomorphosis of Bosmina longirostris (Cladocera)

SUMMARY. The pattern of cyclomorphosis of Bosmina longirostris was followed over a 21-month period in Lake Travis, Texas. Appreciable variation was observed in body size and in the lengths of antennules and mucrones. Electrophoresis of clonal isolates collected over the period of study showed a seasonal cycle in esterase phenotypes. A definite association was demonstrated between the esterase phenotypes and morphologies of these clonal isolates. Individuals of one esterase phenotype were usually large and long-featured, whereas individuals of the other esterase phenotypes were smaller, with short features. The association of morphology and esterase phenotypes from laboratory experiments corresponded to the association observed in field samples. These results support the hypothesis that the cyclomorphosis of Lake Travis Bosmina involves a succession of clones as well as phenotypic plasticity.     

Bosmina (Eubosmina) longicornis longicornis SCHOEDLER, 1866 (Crustacea,Cladocera: Bosminidae) from the Postglacial Sediments of the Neuendorfer See,East-Germany

Analyses were made of subfossil Eubosmina remains from the Lake Neuendorfer See, a lake in the middle part of the river Spree in the “Urstromtal” of Baruth situated in the eastern part of Germany. In addition to Bosmina (Bosmina) longirostris (O. F. M., 1785) Bosmina (Eub.) longicornis longicornis Schoedler, 1866 occured in the lake from the Boreal (sediment depth 15.85 m) to the recent surface layers of the core. Other eubosminids did not occur during the history of the Lake Neuendorfer See with the exception of few remains of B. (Eub.) longispina, which were detected in the lowermost layers of the core during the late Pleistocene. In the present-day plankton, Bosmina (Eub.) l. longicornis was the only eubosminid found in the Lake Neuendorfer See. During the long period between colonization during the Boreal to the present, no changes were detected in typical morphological features of B. (Eub.) l. longicornis. All remains of Eubosmina in the layers above 15.85 m belong undoubtedly to the same taxon. No signs of any morphological instability (other then ontogenetic and cyclomorphic formchanges) or “morphological transition” (Hofmann, 1977) to other taxa could be found. By using paleolimnological analyses, the named taxon has proven to be a “good” entity within the group of long-spined taxa of the subgenus Eubosmina.