water flea
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2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Young-Mi Lee ◽  
Hayoung Cho ◽  
Ryeo-Ok Kim ◽  
Soyeon In ◽  
Se-Joo Kim ◽  
...  

AbstractReal-time quantitative reverse transcription polymerase chain reaction (qRT-PCR), a primary approach for evaluating gene expression, requires an appropriate normalization strategy to confirm relative gene expression levels by comparison, and rule out variations that might occur in analytical procedures. The best option is to use a reference gene whose expression level is stable across various experimental conditions to compare the mRNA levels of a target gene. However, there is limited information on how the reference gene is differentially expressed at different ages (growth) in small invertebrates with notable changes such as molting. In this study, expression profiles of nine candidate reference genes from the brackish water flea, Diaphanosoma celebensis, were evaluated under diverse exposure to toxicants and according to growth. As a result, four different algorithms showed similar stabilities of genes for chemical exposures in the case of limited conditions using the same developmental stage (H2A was stable, whereas Act was fairly unstable in adults), while the results according to age showed a significantly different pattern in suite of candidate reference genes. This affected the results of genes EcRA and GST, which are involved in development and detoxification mechanisms, respectively. Our finding is the first step towards establishing a standardized real-time qRT-PCR analysis of this environmentally important invertebrate that has potential for aquatic ecotoxicology, particularly in estuarine environments.


2021 ◽  
Author(s):  
Qiutong Shen ◽  
Yihe Zhan ◽  
Xuanhe Jia ◽  
Bangping Li ◽  
Xuexia Zhu ◽  
...  

Abstract Spinetoram is one of the most worldwidely used pesticides for its high insecticidal efficacy and low human toxicity Following the large usage of spinetoram, the ecotoxicity and environmental risks to aquatic ecosystems have call for urgent study In the present study, we investigated the combined effects of spinetoram and the harmful alga Microcystis aeruginosa in freshwater, on survival and reproduction of Daphnia pulex Acute toxicity test of spinetoram resulted in negative effects on survival, with a 48h-LC50 value of 3771 µg L–1 Under the long-time exposure to environmentally relevant concentrations (018 and 035 µg L–1) of spinetoram and a low composition of Microcystis (30%) in the diet, D pulex showed both shorter longevity and lower fecundity, the time to first brood was also increased At population level, carrying capacity was highly decreased by spinetoram and Microcystis, whereas a significant decrease of intrinsic growth rate was observed at 035 µg L–1 spinetoram with 30% Microcystis as food The present study highlighted that pesticide spinetoram had highly toxic effects on D pulex and could reduce the tolerance of D pulex to M aeruginosa, causing great effects on D pulex population in natural waterbodies


Water ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 2589
Author(s):  
Dmitry P. Karabanov ◽  
Petr G. Garibian ◽  
Eugeniya I. Bekker ◽  
Rimma Z. Sabitova ◽  
Alexey A. Kotov

Most studies of water flea (Crustacea: Cladocera) invasions are concentrated on a few taxa with an obvious harmful influence on native ecosystems, while our knowledge of cases of anthropogenic introduction with not-so-obvious consequences, in most other taxa, is poor. We found in the Volga basin (European Russia) a population that contained D. curvirostris Eylmann, 1887 and its hybrids with D. korovchinskyi Kotov et al. 2021. The latter taxon is endemic to the Far East and it has appeared in the Volga basin as a result of past human-mediated transportation. The population from Bakhilovo is represented by two strongly different groups of the COI haplotypes belonging, respectively, to (1) D. curvirostris and (2) D. korovchinskyi. We detected SNPs in the position 60 of the HSP-90ex3 locus and in the 195 positions of 28S rRNA locus, which differentiate two species. Part of the specimens from Bakhilovo belonged to D. curvirostris s.str., demonstrating homozygote SNP sites in two loci, but two specimens had heterozygote SNP sites in both nuclear loci. They belong to D. curvirostris x korovchinskyi hybrids. Most morphological traits of the females were characteristic of D. curvirostris. We found in some specimens some characters which could suggest their hybrid status, but this opinion is a hypothesis only, which needs to be checked on more ample material. The exact hybrid system in this pond is not known. Moreover, we have no evidences of sexual reproduction of the hybrids; they could reproduce by parthenogenesis only as is known for hybrids of the D. pulex group, or continuously crossing with parents like some members of D. longispina group. However, poor parental D. korovchinskyi was not detected in the pond either morphologically or genetically. The exact vector of its past anthropogenic transportation to the Volga is unknown. Most probably, just ephippia of D. korovchinskyi were translocated replaced from the Khabarovsk Territory to the Samara Area somehow. This is the first report on hybrids within the D. curvirostris species complex. Here, we demonstrated that accurate studies with deep resolution increase the number of revealed cryptic invasions. We expect that the number of revealed cases of cryptic interspecific invasions will grow rapidly.


2021 ◽  
Author(s):  
Kyo Suwa ◽  
Chiho Takahashi ◽  
Yoshifumi Horie

Abstract We investigated the lethal toxicity of Shibukuro and Tama river water near the inflow of Tamagawa hot-spring water in Akita Prefecture, Japan. We first measured heavy metal concentrations in both rivers. We detected iron, arsenic, and aluminum; the concentrations of each tended to decrease from upstream to downstream. We next examined the influence of river water on zebrafish Danio rerio and water flea Daphnia magna. We observed lethal effects in both species, with Daphnia magna more sensitive to toxicity than Danio rerio. For both species, the toxic effects of river water decreased with increasing distance downstream from the inflow of hot-spring water. Our results show that the heavy metals discharged from Tamagawa hot spring have a negative effect on aquatic organisms.


2021 ◽  
Vol 13 (9) ◽  
pp. 19324-19337
Author(s):  
Nidhi Sharma ◽  
Sarbjeet Kour

Cladocera, commonly known as ‘water flea’ due to the jerky movements produced by their second antennae, form an important food component for planktivorous fishes and other aquatic invertebrates. The present investigation comprising a collection of zooplankton samples from a shallow pond located in the Bishnah tehsil of Jammu district has revealed the presence of 13 Cladocera species belonging to the families Daphniidae, Chydoridae, Moinidae, Sididae, and Macrothricidae. Three species of the family Sididae belonging to the genus Diaphanosoma, namely, senegal, sarsi and excisum are new species records to the cladoceran fauna of Jammu & Kashmir. Presently, a detailed morphological analysis has been made on all the three Diaphanosoma species. They have shown major differences in their body size with D. senegal being larger than D. sarsi and D. excisum. All three species have well observable variability with reference to their head size, eye size, shell duplicature, shape of posterior valve margin, and the number of denticles so present on posterior valve margin. All the three species have also shown coexistence with each other, but D. senegal was dominant in terms of population density.


Author(s):  
Nichole E. DeWeese ◽  
Elizabeth J. Favot ◽  
Donn K. Branstrator ◽  
Euan D. Reavie ◽  
John P. Smol ◽  
...  

AbstractThe spiny water flea (Bythotrephes cederströmii), a freshwater crustacean considered to be the world’s best-studied invasive zooplankter, was first recorded in North America in the Laurentian Great Lakes during the 1980s. Its arrival is widely considered to be the result of ocean-going cargo ships that translocated contaminated ballast water from Eurasia to the Great Lakes during the 1970–1980s. The subsequent first discovery of the species in inland lakes is consistent with the hypothesis that propagules dispersed initially from established Great Lakes populations. Here we present evidence of exoskeletal remains, including mandibles, tail spines, and resting eggs, in 210Pb-dated lake sediment cores, which suggests that B. cederströmii was already resident in four inland North American lakes (two in Minnesota, USA; two in Ontario, Canada) by at least the early 1900s. Densities of exoskeletal remains were low and relatively steady from first appearance until about 1990, after which time they increased in all cores. The earliest evidence that we found was a mandible at 33-cm depth (pre-1650) in the sediments of Three Mile Lake, Ontario, Canada. These unexpected findings challenge the current paradigm of B. cederströmii invasion, renew uncertainty about the timing and sequence of its colonization of North American lakes, and potentially question our ability to detect invasive species with traditional sampling methods. We attempted to eliminate errors in the dated stratigraphies of the exoskeletal remains that might have been introduced either methodologically (e.g., core-wall smearing) or naturally (e.g., bioturbation). Nonetheless, given the very low numbers of subfossils encountered, questions remain about the possible artifactual nature of our observations and therefore we regard our results as ‘preliminary findings’ at this time.


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