The typology of temporary waterbodies and the influence of their parameters on the crustacean species composition of zooplankton

The typology of temporary waterbodies in Saratov oblast has developed with a similarity in the composition of zooplankton species that serve as its foundation. Seven waterbody groups have been distinguished: waterbodies of flood lands, river valley terraces, steppe watersheds, brackish lagoons, brackish lagoons connected to irrigation networks, excavated ponds, and puddles. The specificity of zooplankton species composition in different types of temporary waterbodies is shown. A significant influence of waterbody lifetime on the number of zooplankton species has been revealed, with the waterbody capacity and surface area in the period of maximal water level also being of great importance.     

Mean individual dry weight and length-weight regressions of some zooplankton of Lake Kariba

Individual dry weights of various crustacean zooplankton in Lake Kariba were determined. All the zooplankters were collected from pelagic waters. Regression equations relating dry weight to body length were computed for those species or groups in which size classes could be separated: Bosmina longirostris, Ceriodaphnia cornuta, and copepod copepodites and adults. The mean individual dry weights obtained for most of these zooplankters are similar to those reported in other studies.     

The influence of predation on horizontal distribution of zooplankton species

SUMMARY. 1. The horizontal distributions of Daphnia longispina and Bosmina tongispina in Lake Kvernavatn (Norway) were investigated twice in 1982. In late spring, when populations were small, the two species inhabited the same areas, and they were evenly distributed from the littoral to the pelagic. At high population densities, during midsummer, the species were spatially segregated, D. longispina being pelagic and B. longispina littoral in distribution.
2. The distribution and feeding of three-spined sticklebacks (Gasteros-teus aculeatus) were also studied. The sticklebacks were apparently forced into littoral areas by larger piscivorous predators in the pelagic and they were consequently restricted to foraging primarily on B. longispina, which formed dense swarms during daytime in summer.
3. We suggest that predation and competition influence the spatial distribution of zooplankton species. The feeding efficiency of fish foraging on high-density zooplankton populations can be reduced by spatial segregation of zooplankton species. Where high local densities occur, due to swarm formation, predation is changed from size-selective feeding to consumption of spatially isolated individuals.     

梁子湖浮游甲壳动物的生物多样性

基于2006年8月至2008年3月对梁子湖浮游甲壳动物的采样调查,记录了该湖区浮游甲壳动物22种,隶属9科18属,其中枝角类(Cladocera)16种,桡足类(Copepoda)6种,包括9属新记录.物种多样性季节性动态变化明显:枝角类优势种在春、夏和秋冬季依次为透明溞(Daphnia hyalina,优势度Y = 0.80±0.01),小栉溞(Daphnia cristata,Y = 0.50±0.03)和长额象鼻溞(Bosmina longirostris,Y = 0.58±0.04);而桡足类优势种在夏、秋和冬春季依次为长江新镖水蚤(Neodiaptomus yangtsekiangensis,Y = 0.41±0.01)、近邻剑水蚤(Cyclops vicinus,Y = 0.46)和特异荡镖水蚤(Neutrodiaptomus incongruens,Y = 0.65±0.18).浮游甲壳类个体密度以春季最高((292±85) ind/L),夏、秋、冬季渐低(依次为(169±104)、(140±53)、(120±0) ind/L).物种多样性冬春季较低(物种数S≤12,丰富度指数D = 0.77和0.71,香农-威纳指数H = 1.79和1.45),夏秋季较高(S≥17,D = 0.98和0.88,H = 1.78和1.83).梁子湖浮游甲壳类动物多样性年际差异不显著,表明湖区环境条件较为优越、稳定.     

Calcium content of crustacean zooplankton and its potential role in species distribution

SUMMARY 1. The occurrence and species composition of crustacean zooplankton in Norwegian lakes was related to ambient Ca concentrations, pH, total phosphorus and chlorophyll a , and to the presence/absence of other zooplankters and a planktivorous fish (roach: Rutilus rutilus ).
2. Ambient Ca concentrations appeared to influence the distribution of Daphnia species: Daphnia longispina often occurred in Ca-rich lakes with low fish-predation pressure while the smaller Daphnia cristata often occurred in opposite conditions.
3. Body Ca contents were measured in zooplankters from a wide range of localities, to examine Ca requirements and thus the potential for Ca-limitation of common species.
4. All Daphnia species had relatively high specific Ca contents [ranging from 0.8 to 4.4% Ca dry weight (DW)⁻¹] compared with other cladocerans and also copepods (ranging from 0.1 to 0.4% Ca DW⁻¹). Within the Daphnia genus, the specific Ca content increased with increasing body size of the species, and thus the large-bodied species had especially high Ca demands.
5. Because of their high Ca demands, species of Daphnia could be competitively disadvantaged in softwater lakes relative to less Ca-demanding species.     

富营养化对小型湖泊浮游甲壳动物群落结构及多样性的影响

2017年3月到2018年2月研究了临涣湖浮游甲壳动物群落结构的季节变化。临涣湖共记录浮游甲壳动物13种,其中枝角类8属8种,桡足类5属5种。短尾秀体溞(Diaphanosoma brachyurum)、广布中剑水蚤(Mesocyclops leuckarti)和象鼻溞(Bosmina sp.)等小型富营养种类是温暖季节的优势种,而近邻剑水蚤(Cyclops vicinus)是冬季的优势种。盔形溞(Daphnia galeata)等大型种类仅在少数月份中被观察到。临涣湖浮游甲壳动物的年平均密度和生物量分别为28.3个/L和0.33 mg/L。营养状态指数(TSI_M)的年平均值为62.6。浮游甲壳动物的Shannon指数、Pielou指数和Simpson指数的年平均值分别为0.86、0.74和0.49,且3种多样性指数均具有显著的季节差异。营养盐水平、营养状态指数和物种多样性指数均表明,临涣湖水体处于富营养化状态。冗余分析结果表明,水温、总磷浓度和叶绿素a浓度是影响临涣湖浮游甲壳动物群落结构变化的上行效应因子。鲢、鳙鱼的捕食压力是临涣湖浮游甲壳动物群落结构小型化的下...     

The crustacean zooplankton of Mali (West Africa)

48 species of Phyllopoda, 24 species of Copepoda, and a freshwater shrimp are reported from Mali. Morphologically noteworthy or little known species are figured. Daphnia barbata and D. dolichocephala are redescribed. Three West-African species of Tropodiaptomus were found. T. senegambiae is synonymised with T. banforanus. Thermodiaptomus yabensis is fully figured. The distribution of T. yabensis and the regional Tropodiaptomus is discussed. A general biogeographical discussion is not yet possible, because for many species, and particularly Cladocera, both taxonomical position and chorological records are fragmentary and uncertain. At least 29 species, however, seem to be restricted to Africa, and some even to West Africa.The water chemistry of the lakes of central Mali is characterized by a low mineral content, but seems not to be distributive to any of the numerous zooplankton species encountered.The zooplankton communities, especially in the lakes of the internal delta of the Niger, are typically composed of numerous species. Among copepods, it is usual to find three or four genera to co-occur, and each genus may be represented by up to three species. This indicates long-term instability of the communities, and suggests strong interspecies competition to be present. This is corroborated by an analysis of the ranges of some African endemics.It is shown that the Niger delta is part of the biological boundary of the Sahara as far as aquatic invertebrates are concerned. West African equatorial climate endemics (e.g. 3 Tropodiaptomus species, Thermodiaptomus yabensis), and arid to semi-arid climate endemics (Daphnia barbata, D. longispina, Metadiaptomus mauretanicus) meet and interpenetrate each others' ranges over a short distance.     

Surface spreading of synaptonemal complexes in three isopod crustacean species

The technique of whole mount spreading is used to investigate the SC of three species of Asellidae (isopod crustaceans), Asellus aquaticus, Proasellus coxalis and Proasellus meridianus, which display considerable differences in genomic DNA content.The three species, originally considered to belong to the same genus Asellus, were subsequently assigned to two separate genera: Asellus and Proasellus. The SCs of the three species differ in morphological details related to the shape of the centromere region, the attachments to the nuclear envelope, the width of the central region and the presence of twists of the lateral elements. Furthermore, they display some differences in the degree of compaction of genomic DNA in the mitotic chromosomes. The greatest differences are found between A. aquaticus and P. coxalis, while P. meridianus has several features in common with either species.     

The recovery of crustacean zooplankton from acidification depends on lake type

Acidification has harmed freshwater ecosystems in Northern Europe since the early 1900s. Stricter regulations aimed at decreasing acidic emissions have improved surface-water chemistry since the late 1980s but the recovery of biotic communities has not been consistent. Generally, the recovery of flora and fauna has been documented only for a few lakes or regions and large-scale assessments of long-term dynamics of biotic communities due to improved water quality are still lacking. This study investigates a large biomonitoring dataset of pelagic and littoral crustacean zooplankton (Cladocera and Copepoda) from 142 acid-sensitive lakes in Norway spanning 24 years (1997–2020). The aims were to assess the changes in zooplankton communities through time, compare patterns of changes across lake types (defined based on calcium and humic content), and identify correlations between abiotic and biological variables. Our results indicate chemical and biological recovery after acidification, as shown by a general increase in pH, acid neutralizing capacity, changes in community composition and increases in the total number of species, number of acid-sensitive species and functional richness through time. However, the zooplankton responses differ across lake types. This indicates that the concentration of calcium (or alkalinity) and total organic carbon (or humic substances) are important factors for the recovery. Therefore, assessment methods and management tools should be adapted to the diverse lake types. Long-term monitoring of freshwater ecosystems is needed to fully comprehend the recovery dynamics of biotic communities from acidification.     

Diurnal variation of metabolites in three individual participants

The circadian system influences virtually all biological functions. Understanding the impact of circadian variation on metabolism may provide insight into mechanisms of circadian-associated disorders and guide the implementation of chrono-therapy. Previous research has reported circadian variation in 7–20% of metabolites in human blood. In this study, untargeted metabolomics profiles were measured using blood of two healthy men and one healthy woman, collected every 2 h for up to 48 h under carefully controlled conditions. The pattern of variation of each metabolite over time was examined on each participant separately, using both one- and two-order harmonic models. A total of 100 of 663 metabolites, representing all metabolite categories, showed diurnal rhythmic concentrations that exceeded the Bonferroni threshold (P < 2.5 × 10^?5). Overall, peak times of many metabolites were clustered during the afternoon-midnight, including the majority of amino acids, all peptides, all lysolipids and all phospholipids, whereas the majority of steroids peaked in the morning. We observed substantial inter-individual variation for both peak times and amplitudes in these three subjects. In conclusion, at least 15% of blood metabolites, representing a broad group of biological pathways, exhibit diurnal variation in three participants. The average peak times of most of these metabolites are clustered in morning or afternoon-midnight. Further work is needed to validate and extend this work in more individuals.     

Effects of variation in individual growth on plant species coexistence

Abstract. Both size structure and variability (spatial heterogeneity, disturbance, stochasticity, variation in species attributes, etc.) are regarded as regulatory mechanisms of species coexistence. However, none of the models so far proposed consider both size structure and variability simultaneously. A size-structured variation model for plant-community dynamics is proposed, which is based on the diffusion model for growth dynamics of plant populations. This model has four functions: (1) mean growth rate of individuals of size x at time t, G(t, x) (species-specific mean traits, e.g. competitive ability); (2) variance in growth rate of individuals of size x at time t, D(t, x) (stochastic factors due to genetic variation, environmental heterogeneity, spatial variation of individuals, etc.); (3) mortality rate of individuals of size x at time t, M(t, x); and (4) recruitment rate at time t, R(t), as a boundary condition. The interference function for individuals of size x at time t, C(t, x), is introduced, which expresses the degree of interactions between individuals and hence averaged effects of local neighbourhood competition; the G(t, x), D(t, x), M(t, x) and R(t) functions are given in terms of C(t, x). These four functions describe the growth dynamics of individuals of each species in the plant community. Effects of the G(t, x), D(t, x), M(t, x) and R(t) functions on species coexistence in plant communities were evaluated by simulation and the relative importance of the D(t, x) function as well as size structure was shown for species coexistence especially in plant communities where competition among species is non-transitive or niche limitation does not work.     

The effect of herbivorous crustacean zooplankton on epilimnetic carbon and phosphorus cycling

Plastic limnocorrals (LCs; volume 70 m³) in oligo-mesotrophic Lake Lucerne, Switzerland were used to manipulate planktonic communities by (1) removing large zooplankton at the start of the experiment, and (2) adding phosphate during experiments of two weeks duration.Primary production (¹⁴C-assimilation), chlorophyll, standing crops and sedimentation of particulate organic carbon (POC) and of particulate phosphorus, as well as plankton composition were assessed simultaneously in two to four differently treated LCs. Carbon and phosphorus mass balances were calculated from assimilation, temporal change in standing crop of particulate matter, and sedimentation.A quick elimination of crustaceans by screening hardly increased primary production, but decreased sedimentation and mineralisation of particulate organic carbon, and thus significantly enhanced the standing crop of POC, but decreased POC turnover. The exclusion of crustaceans increased the mean residence time of total phosphorus by a reduced P loss by sedimentation.Increased grazing pressure during the experiment showed little grazing induced effect on plankton composition and primary production except at the very end.We conclude that in an oligo-mesotrophic lake, buffering mechanisms attenuate the impact of changing grazing pressures on primary production.     

Grazing by rotifers and crustacean zooplankton on nanoplanktonic protists

Predation on nanoflagellates by metazoan zooplankton was investigated using a radioactively labeled flagellate, Poterioochromonas malhamensis, as a tracer cell in laboratory incubations of freshly collected plankton assemblages. Experiments conducted in the fall, winter and spring indicated that rotifers dominated the grazing on nanoflagellates by metazoans in the winter (68%) and spring (92%). Rotifer grazing was not determined in the autumn. It is likely that the greater impact of rotifer grazing in the spring was due to the occurrence of abundant filamentous cyanobacteria and gelatinous colonial phytoplankton which selectively depressed feeding rates of crustaceans compared to rotifers. Crustacean predation on nanoflagellates was highest in the autumn when cladocerans (primarily Daphnia spp.) were abundant. Predation by metazoan zooplankton in this lake appeared capable of removing the total standing stock of heterotrophic and phototrophic nanoplankton in < 1 d. Impacts of ciliated protozoa on nanoplankton, calculated from abundances and literature feeding rates, ranged from approximately one-third to four times that of metazoan predation depending on season and method of calculation. The relative importance of the different groups of predators appears to vary seasonally which is expected to alter the transfer of energy, carbon and nutrients from bacteria to higher trophic levels.     

The influence of water exchange on zooplankton dynamics and species development in a south Norwegian fjord

During experiments in a south Norwegian fjord in March and April1979, distribution and development of zooplankton were investigatedin detail. Numbers of protozooplankton, meroplankton and holoplanktonwere determined as individual species. Strong water exchangecaused a high variability in plankton composition and biomass.Changes in salinity and temperature as well as numbers of planktonindividuals and in the percentage composition of the developmentalstages of the spring spawning Calanus finmarchicus revealedthat a wind-induced inflow of Skagerrak water along the southwestNorwegian coast also entered the Rosfjord. In contrast to theAtlantic water with low numbers of copepods from the hibernatinggeneration, in the Skagerrak water the spring generation ofC.finmarchicus had already developed up to the first and secondcopepodite stages. The Skagerrak water was already very richin phyto- and zooplankton organisms. Here, an increase in biomassover time mainly resulted from the development of younger toolder copepodite stages and from a considerable increase innumbers of the tintinnid, Leprotintinnus pellucidus. The verticaldistribution of plankton organisms and fecal pellets was closelyassociated with the occurrence and the stratification of watermasses coming into the Rosfjord.     

Effects of experimentally induced cyanobacterial blooms on crustacean zooplankton communities

SUMMARY 1. Large in situ enclosures were used to study the effects of experimentally induced cyanobacterial blooms on zooplankton communities. A combination of N and P was added to shallow (2 m) and deep enclosures (5 m) with the goal of reducing the TN : TP ratio to a low level (∼5 : 1) to promote cyanobacterial growth. After nutrient additions, high biomass of cyanobacteria developed rapidly in shallow enclosures reaching levels only observed during bloom events in eutrophic lakes.
2. In the shallow enclosures, particulate phosphorus (PP) was on average 35% higher in comparison with deep enclosures, suggesting that depth plays a key role in P uptake by algae. Phytoplankton communities in both deep and shallow enclosures were dominated by three cyanobacteria species – Aphanizomenon flos-aquae , Anabaena flos-aquae and Microcystis aeruginosa – which accounted for up to 70% of total phytoplankton biomass. However, the absolute biomass of the three species was much higher in shallow enclosures, especially Aphanizomenon flos-aquae . The three cyanobacteria species responded in contrasting ways to nutrient manipulation because of their different physiology.
3. Standardised concentrations of the hepatotoxic microcystin-LR increased as a result of nutrient manipulations by a factor of four in the treated enclosures. Increased biomass of inedible and toxin producing cyanobacteria was associated with a decline in Daphnia pulicaria biomass caused by a reduction in the number of individuals with a body length of >1 mm. Zooplankton biomass did not decline at moderate cyanobacteria biomass, but when cyanobacteria reached high biomass large cladocerans were reduced.
4. Our results demonstrate that zooplankton communities can be negatively affected by cyanobacterial blooms and therefore the potential to use herbivory to reduce algal blooms in such eutrophic lakes appears limited.     

浮游甲壳类定量采样计数方法评价

１引言浮游生物是养殖鱼类特别是滤食性鱼类的主要饵料,同时又是评价水生态系统质量优劣的重要指标．在大水面增养殖研究中,常常通过水体中浮游生物的采样分析,计算水体生物生产力．而在池塘生态系统中则又常常借助于浮游生物的采样分析来判定养鱼水质,决定增施饵肥料...     

A comparison of swimming structures and kinematics in three species of crustacean larvae

Crustacean larvae swim with paired rowing appendages that rotate around the body of the animal. The number of paired rowing appendages varies from one species of larvae to another. In addition, the size of the crustacean larvae is different between species and increases as they grow. The nature of the fluid forces changes as size increases, so the morphology and mechanics of swimming in these animals will change during increases in size. This article demonstrates the changing kinematics of locomotion between three species of crustacean larvae, which swim with one (Artemia franciscana), two (Carcinus maenas) or five (Homarus americanus) pairs of propulsive limbs. The relative change in the surface area and volume ratios of the locomotor structures are also demonstrated.     

A comparison of swimming structures and kinematics in three species of crustacean larvae

Crustacean larvae swim with paired rowing appendages that rotate around the body of the animal. The number of paired rowing appendages varies from one species of larvae to another. In addition, the size of the crustacean larvae is different between species and increases as they grow. The nature of the fluid forces changes as size increases, so the morphology and mechanics of swimming in these animals will change during increases in size. This article demonstrates the changing kinematics of locomotion between three species of crustacean larvae, which swim with one (Artemia franciscana), two (Carcinus maenas) or five (Homarus americanus) pairs of propulsive limbs. The relative change in the surface area and volume ratios of the locomotor structures are also demonstrated.     

Recreational boats as a vector of secondary spread for aquatic invasive species and native crustacean zooplankton

Recreational boats in tow between lakes are a known vector of the spread of aquatic invading species (AIS), but we have no test of the hypothesis that recreational boats are also a vector of secondary spread of AIS among freshwater ecosystems via in-water transport i.e., while boating between interconnected waterways. In this study, we surveyed recreational boaters travelling into Lake Simcoe (44°25′N, 79°20′W), Ontario, Canada, on their recreational activities, boat maintenance, and travel destinations, measured the degree of vessel fouling, and sampled all standing water and attached macrophytes associated with their vessels. A total of 321 zooplankton individuals comprising 15 different species were collected from the standing water in vessels, including veligers of the invasive zebra mussel Dreissena. The volume of water collected within the vessels significantly increased the number of zooplankton transported. Zooplankton species from pelagic habitats or with planktonic life stages were collected more frequently than species that occupy littoral or benthic habitats, likely reflecting the recreational activities of boaters. Patterns of boater activities, movements and hygiene habits, suggest recreational boating in the Lake Simcoe region is contributing to the spread of native and invasive species into nearby waterways. Our study validates the widespread assumption that recreational boats are an important in-water vector for the secondary spread of both native and invasive zooplankton species. Future management strategies to reduce the spread of AIS should be aimed at increasing awareness of boater hygiene practices, particularly the frequent draining of standing water.