Freshwater Shrimp Research Articles

Brothers are better than nothing: first report of incestuous mating and inbreeding depression in a freshwater decapod crustacean

This study aimed at evaluating the effect of one generation of full-sibling mating on traits related to the fitness of the gregarious freshwater shrimp Neocaridina davidi, both under optimal and stressful (i.e. starvation) laboratory conditions. Females were maintained either with their brothers (Inbreeding treatment) or non-brothers (Outbreeding treatment), and the first and second broods were used to evaluate egg production and juvenile quality, respectively. The latter was analyzed in a 60-day period following hatching under optimal rearing conditions, and in a 20-day period following hatching under food deprivation conditions. All surviving females from both treatments mated and spawned, indicating that mating with brothers was as likely as mating with non-brothers. With respect to offspring production, inbreeding had no effect on fecundity and fertilization success, but negatively affected the number of hatched juveniles. These results suggest that egg loss was higher in inbred clutches, possibly due to lower embryonic survival. On the other hand, the effect of inbreeding on growth was absent for embryos and for juveniles under optimal rearing conditions, while it was significant for juveniles starved for 10 consecutive days following hatching. Inbreeding depression for survival was only detected in juveniles from stages S8-S9 under optimal rearing conditions. Overall, the present results show that N. davidi fitness decreases after one generation of full-sibling mating. The use of a potentially weak food deprivation protocol and/or the evaluation of only one inbred generation could explain the absence or subtle inbreeding depression for some of the evaluated traits. No evident relationship between life-history traits and the existence and magnitude of inbreeding was found when comparing our results with those previously reported in high-fecundity marine crustaceans and low-fecundity terrestrial crustaceans.

Lacustrine characteristics predict lipid contents of mysid shrimp (Mysis diluviana) populations

The freshwater mysid shrimp (Mysis diluviana) is a keystone species in many aquatic food webs. In this study, the lipid contents of mysid populations sampled from 19 lakes located in southern Ontario were determined to investigate the extent of interlacustrine variability in this characteristic, and examine potential relationships between mysid lipid content and other biotic and abiotic factors associated with lake trophodynamics. Individual mysid lipid contents ranged from 6.0 to 59.8 % (dry wt.) with average lipid contents across the sampled lakes ranging from 9.8 to 36.9 %. Principal components analysis demonstrated that mysid inhabited lakes could be differentiated using specific water chemistry, morphometric, and zooplankton population characteristics. Specifically, a subset of the study lakes was characterized by higher dissolved organic carbon concentrations, shallower Secchi depths, and significantly (p < 0.01) higher mysid lipid contents relative to other lakes included in the study. General linear modeling demonstrated that Secchi depth combined with lake maximum depth and benthic oxygen levels were significant (r2 = 0.69; p < 0.01) predictors of mysid lipid contents across the study populations with Secchi depth alone being a strong (r2 = 0.51) predictor of mysid population lipid contents. These results emphasize the importance of mysids as a lipid-rich macroinvertebrate and their contribution as a prey energy resource in freshwater food webs and demonstrate that easily quantifiable lacustrine characteristics such as Secchi depth can be indicators of energy accumulation in mysid populations.

Miniaturized QuEChERS based sample preparation method combined with gas chromatography–tandem mass spectrometry for the determination of selected polycyclic aromatic hydrocarbons in crustacean gammarids

The study presents a new miniaturized and low-cost sample preparation method combined with gas chromatography–triple quadrupole tandem mass spectrometry (GC–QqQ-MS/MS) analysis developed to determine selected polycyclic aromatic hydrocarbons (PAHs: (naphthalene – Nap, acenaphthene – Ace, anthracene – Ant, fluoranthene – Flu, and benzo[a]pyrene – BaP) in dried gammarid samples. The sample preparation involved modification of the so-called QuEChERS (stands for quick, easy, cheap, effective, rugged, and safe) method followed by use of a novel combination of dispersive liquid–liquid microextraction (DLLME) and treatment with H2SO4 solution, which allowed further purification and concentration of the extract and solvent exchange without the need for solvent evaporation. The QqQ-MS/MS detector operating in the pseudo-MRM mode was used to detect PAHs with increased sensitivity compared to the classical quadrupole MRM technique. The method was validated in terms of linearity and range, detection and quantification limits (LOD and LOQ), matrix effect, recovery and precision for the analysis of 200 mg samples of dried freshwater shrimps Gammarus pulex. The LOQs for the target PAHs ranged from 4.7 to 6.3 ng g−1 dw (dry weight) or after applying the conversion factor of 0.2 (dw/ww) from 0.94 to 1.3 ng g−1 ww (wet weight). The recovery for all the analytes was in the range 72–104% and repeatability (precision) expressed by relative standard deviation in the range 1–10%. The developed method has been shown to be suitable for the purpose of monitoring and controlling compliance with environmental quality standards (EQS, set by the EU) for Flu and BaP in surface water biota.

Comparative evaluation of the biofloc system versus the recirculation system with Macrobrachium amazonicum / Avaliação comparativa do sistema bioflocos versus o sistema de recirculação com Macrobrachium amazonicum

The aim of this study was to evaluate the efficiency of the biofloc system versus the recirculation system using the native Amazonian freshwater shrimp Macrobrachium amazonicum (Heller, 1862) as a cultivation organism. In this initial evaluation, the water quality parameters of each system were measured and the survival rate in the biofloc system showed similar values for M. amazonicum grown in a super-intensive recirculation system with averages values of 60%. The results indicated that both systems were within acceptable limits in terms of parameters (physical-chemical) and the survival rate of both systems showed similar values for M. amazonicum.

Morphological and phylogenetic characterization of a new microsporidium, Triwangia gracilipes n. sp. From the freshwater shrimp Caridina gracilipes (Decapoda: Atyidae) in China

A new microsporidian species was described from the freshwater shrimp Caridina gracilipes collected from Lake Luoma located in Northern Jiangsu province, East China. The infected shrimps appeared generally opaque due to the presence of white cysts located in the connective tissues of the surface of the hepatopancreas. The earliest developmental stages observed were diplokaryotic meronts which were in direct contact with the host cell cytoplasm. Multinucleate sporogonial plasmodia developed into uninucleate sporoblasts which were enclosed in sporophorous vesicles. The parasite developed synchronously within an individual sporophorous vesicle. Mature spores were pyriform and monokaryotic, measuring 5.45 ± 0.18 (5.12–5.82) µm long and 3.57 ± 0.17 (3.18–3.92) µm wide. Anisofilar polar filaments coiled 10–12 turns and arranged in one row. Phylogenetic analysis based on the obtained SSU rDNA sequence indicated that the present species clustered with Triwangia caridina with high support value to form an independent branch which was placed at the basal position of a large clade of containing microsporidia of fishes, crustaceans and amphipods. Based on the morphological characters and ultrastructural features, as well as SSU rDNA-inferred phylogenetic relationships, a new species was erected and named as Triwangia gracilipes n. sp. The taxonomic affiliation of Triwangia was also primarily explored.

Locomotor behavior of Neocaridina palmata: a study with leachates from UV-weathered microplastics.

Weathering of plastics leads to the formation of increasingly smaller particles with the release of chemical compounds. The latter occurs with currently unknown environmental impacts. Leachate-induced effects of weathered microplastics (MPs) are therefore of increasing concern. To investigate the toxicity of the chemical mixtures from such plastics, we exposed the freshwater shrimp Neocaridina palmata to enriched leachates from unweathered and artificially weathered (UV-A/B light) MPs (≤1 mm) from recycled low-density polyethylene (LDPE-R) pellets and from a biodegradable, not fully bio-based starch blend (SB) foil. We analyzed the individual locomotor activity (moved distance and frozen events) on day 1, 3, 7 and 14 of exposure to five leachate concentrations equivalent to 0.40–15.6 g MPs L−1, representing the upper scale of MPs that have been found in the environment. The median moved distance did not change as a function of concentration, except for the unweathered SB treatment on day 14 that indicated hyperactivity with increasing concentrations. Significant impacts were solely detected for few concentrations and exposure days. Generally, no consistent trend was observed across the experiments. We further assessed the baseline toxicity of the samples in the Microtox assay and detected high bioluminescence inhibitions of the bacterium Aliivibrio fischeri. This study demonstrates that neither the recycled nor the biodegradable material are without impacts on test parameters and therefore cannot be seen as safe alternative for conventional plastics regarding the toxicity. However, the observed in vitro toxicity did not result in substantial effects on the behavior of shrimps. Overall, we assume that the two endpoints examined in the atyid shrimp N. palmata were not sensitive to chemicals leaching from plastics or that effects on the in vivo level affect other toxic endpoints which were not considered in this study.

Extraction, purification and characterization of a thermally stable aspartic protease from freshwater shrimp Gammarus sp. with a high catalytic efficiency

In the curent study, a new aspartic protease is purified by pepstatin A affinity chromatography from freshwater amphipod Gammarus sp. The molecular weight of the enzyme was determined by SDS-PAGE which estimated to be 55 kDa. Optimal temperature and pH were 55 °C and 6, respectively. According to our results, calculated KM and Vmax for azocasein substrate were 0.05 μg mL−1 and 4.2 μmol min−1 while those of casein substrate were 0.006 μg mL−1 and 1.1 μmol min−1 respectively. The values of kcat constants for azocasein and casein substrates were calculated to be 2583 s−1 and 686 s−1 respectively. Moreover, the catalytic efficiencies (kcat/KM) for azocasein and casein substrates were 51,167 and 114,333 s−1 μg−1.ml respectively. The estimated ΔHD# , ΔGD# and ΔSD# were 4.221 kcal mol−1, 24.18 kcal mol−1 and 70 cal mol−1K−1respectively. The values of ΔGE−S# in the presence of azocasein and casein were −1.74 and 2.97 kcal mol−1 and those of ΔGE−T# for azocasein and casein were - 6.29 and - 6.76 kcal.mol−1respectively. Altogether, according to the obtained results, the new aspartic protease is thermally stable and catalytically efficient having a high affinity to milk casein as substrate and thus it has potential to be used in dairy industries for milk clotting.

Temporal and spatial variations in metals and arsenic contamination in water, sediment and biota of freshwater, marine and coastal environments after the Fundão dam failure

Temporal and spatial variabilities in concentrations of metals (Cd, Cr, Cu, Fe, Hg, Mn, Pb and Zn) and metalloid (As) associated with the Fundão dam tailings were evaluated in water, sediment and biota from freshwater (tributary, river, lakes and lagoons), marine and coastal (mangroves and beaches) ecosystems affected by the Mariana dam disaster (southeastern Brazil). In freshwater shrimps and fishes, temporal increases in the concentrations of most elements analyzed were observed. This finding was clearly associated with temporal increases in the concentrations of As and metals observed in both water and sediment. In turn, freshwater plankton showed only a temporal increase in Hg concentration, which was also associated with an increased concentration of this metal in the abiotic matrices. In marine fishes, temporal increases were only observed for Cu, Fe and Pb concentrations. Also, temporal increase was observed for Fe concentration in marine plankton (phytoplankton and zooplankton) and shrimps. Marine phytoplankton also showed a temporal increase in Hg concentration. All these findings were clearly associated with temporal increases in the concentrations of these metals in marine sediments. Mangrove crabs showed temporal increases in Hg and Cd, which were associated with temporal increases in water Hg and sediment Cd concentrations, respectively. In turn, beach crabs displayed temporal increases in Mn and Zn, which were associated with temporal increases in the concentrations of these metals in sediments, especially for Mn. In summary, all environmental matrices evaluated in the present study were shown to be contaminated with metals and metalloid associated with the Fundão dam tailings. Additionally, findings reported in the present study relative to the spatial variabilities observed in the whole aquatic area affected by the Fundão dam failure clearly reinforce the need of incorporating biological diversity in monitoring programs aiming to assess environmental health of aquatic systems, considering that patterns of metals and metalloid contamination levels may vary among taxa.

Can insecticide-free clean water regenerate the midgut epithelium of the freshwater shrimp after dimethoate treatment?

Insecticides such as dimethoate persist for a long time in freshwater environments, influencing the physiology of the animals inhabiting such environments. In aquatic organisms, toxic substances can enter the body through the epidermis and the digestive system. The midgut is part of this system in which intense processes constitute a barrier against the effects of toxic substances on the body. The aim of this study was to evaluate the toxic potential of dimethoate in the midgut epithelium of the freshwater shrimp Neocaridina davidi, emphasizing ultrastructural alterations. However, the additional and main purpose was to determine whether the midgut epithelium can regenerate after placing animals in insecticide-free clean water after various periods of exposure to dimethoate. N. davidi originates from Asia, but it has also been described in European rivers. This species is of particular interest among breeders worldwide due to its ease of breeding and reproduction. The animals were treated with dimethoate for 1, 2, and 3 weeks and then placed in clean water for 1, 2, and 3 weeks. The qualitative and quantitative analysis revealed different sensitivity of organs forming the midgut in freshwater crustaceans and the possibility for midgut regeneration after insecticide exposure. We concluded that different processes were triggered in the intestine and hepatopancreas to regenerate cells after damage, and mitochondria were the first organelles to respond to the appearance of a stressor in the living environment.

Association of the alga Cladogonium sp. with a multifactorial disease outbreak in dwarf shrimp (Neocaridina davidi).

This study outlines a multifactorial disease outbreak in a population of the freshwater shrimp Neocaridina davidi, with the focus on a rarely described parasitic alga. Within this multifactorial disease outbreak, low but consistent mortality was observed. During microscopic examination, an infection of the shrimp with bacterial and fungal-like agents was diagnosed. Furthermore, the green alga Cladogonium sp. was found in pleopodal regions. The alga compromised the body surface of the shrimp, and its rhizoids penetrated the chitin shell and reached into the subcutaneous tissue. This might be a first indication of a parasitic lifestyle. In addition to a morphological description, sequencing data are presented which allow the taxonomic classification of the organism within the order Trentepohliales.

К ИЗУЧЕНИЮ БИОЭКОЛОГИИ КРЕВЕТОК КАСПИЯ

Only two species of shrimps live in the Caspian Sea: Palaemon elegans and P. adspersus (Crustacea, Decapoda: Palaemonidae), which were introduced to the Caspian Sea in 1931-1934 during the introduction of mullets. Data on the biology of these species of shrimps are reflected only in the works by E.N. Kudelina (1950) and M.P. Marochkina (1980). This determines the relevance of research on the current state of the Caspian shrimp population. The material was collected in various areas of the Middle Caspian Sea in the summer-autumn period. Both species live up to five meters deep. P. elegans prefer coastal underwater objects with dense thickets, P. adspersus - open shallow waters with sandy-muddy soil. To the north of Makhachkala, P. elegans predominates, to the south, the number of both species is the same, and to the east, P. adspersus dominates. The characteristics of breeding females are presented, and the dependence of fecundity on the length of egg-bearing females is revealed. The absolute fecundity increased with the increase in the size of the females. Regression equations reflecting the relationship between fecundity and length of egg-bearing females of P. elegans and P. adspersus are calculated, expressed by power equations, respectively: E = 0.044947 · L265356 and E = 2.323 · L17.4, where: E - fecundity, L-length. In October 2017, in May and October 2018, several specimens of the subtropical freshwater shrimp Macrobrachium nipponense were found downstream of the Terek River. Probably, in the near future, the species composition of the Caspian shrimp will be replenished with another species.

Consumption of Calcium and Knowledge About Calcium Sources and Nutrition Labels Among Lower Secondary School Students in Thailand.

ObjectiveA three study research program was conducted to identify high calcium products available in the market (study I), identify high calcium products that were known or consumed by lower secondary school students in the last three months (study II), and identify the amount and sources of calcium that students had consumed in the prior 24 hours, their knowledge about sources of high calcium and how to interpret calcium information on nutrition labels of food packages (study III).MethodsIn study I, a cross-sectional market survey was employed. In studies II and III, a school-based cross-sectional survey was employed. The survey population was students enrolled in grades 7–9 (11–14 years old) in a medium-sized lower secondary school in semi-urban Khon Kaen, Thailand. A total of 309 students were invited, with 168 and 209 students participating in studies II and III, respectively. Data were collected with self-administered questionnaires.ResultsNinety-three high calcium products were identified. Only 49 were known or consumed by students in the last three months. The median amount of calcium consumed in the previous 24 hours was 410 mg (IQR: 160, 983). Only 31.1% of students (65/209) consumed more than the Thai recommended daily intake (TRDI) of calcium (800mg) in the previous 24 hours. Their main source of calcium was milk. Other high calcium items that were consumed were malt drink, minnow, canned fish, calcium fortified soy milk and Chinese kale. The overall average knowledge score was 6.5±2.4 out of a maximum of 17. The average knowledge scores for high calcium food sources and for interpreting the calcium information on a sample nutrition label were 4.6+1.8 (out of 12), and 1.9±1.2 (out of 5), respectively.DiscussionStudents should be introduced to high calcium products in their community such as hard tofu, minnow, and small freshwater shrimp. Educational programs on nutrition label interpretation are needed.

Age‐Structured Interactions among Reintroduced Sockeye Salmon, Resident Kokanee, Invasive Mysids, and their Zooplankton Prey in Skaha Lake, British Columbia

AbstractIn 2004, after an 85+ year absence, Sockeye Salmon Oncorhynchus nerka were reintroduced into Skaha Lake, British Columbia. Prior to this, the lake’s planktivore community was dominated by kokanee (lacustrine Sockeye Salmon) and an invasive freshwater shrimp Mysis diluviana, and British Columbia fisheries managers were concerned that reintroduced Sockeye Salmon fry might reduce the abundance of zooplankton prey and negatively affect the abundance and size of kokanee available for the recreational fishery. We looked for possible adverse effects by introducing contrasting densities (0–2,309 fish/ha) of marked, hatchery‐origin Sockeye Salmon fry to Skaha Lake over 12 years (2005–2017). During each year, we monitored state change indicators of lake flushing, water temperature, nutrients, phytoplankton, microzooplankton, M. diluviana, kokanee, and Sockeye Salmon. Zooplankton consumption by Sockeye Salmon, kokanee, and M. diluviana was estimated via bioenergetics models. We found that (1) average densities of pelagic fish gradually increased above premanipulation densities and (2) survival (egg to winter) of kokanee fry was variable but positively associated with increased abundances of Sockeye Salmon fry. Average survival of age‐0 to age‐3+ kokanee in Skaha Lake exhibited no significant trends. We also found that (3) growth rates for age‐0 Sockeye Salmon fry and kokanee were stable during 2005–2013, despite moderate increases in fish abundance, but declined in 2017. This decline was associated with record‐high biomasses of kokanee and M. diluviana, record rates of zooplankton loss from predation and lake flushing, and reduced zooplankton production. We found that (4) bioenergetics data showed that, on average, 1.8% of annual zooplankton prey consumption was attributable to hatchery‐origin Sockeye Salmon fry, 2.8% to Lake Whitefish Coregonus clupeaformis, 13.9% to older kokanee, and 79.6% of the zooplankton was consumed by M. diluviana. We concluded that during 2005–2015 consumption by planktivores never exceeded production by zooplankton, but in 2017, when lake flushing rates were exceptionally high, consumption by planktivores exceeded lake‐carrying capacity for pelagic fish. Sockeye Salmon fry played virtually no part in these events.

Comparison of different solvents for extraction of oils from by‐products of shrimps Penaeus vannamei and Procambarus clarkia

The effects of different extraction solvents on the extraction yield and chemical composition of oils from by-products of marine shrimp Penaeus vannamei (Pv) and freshwater shrimp Procambarus clarkia (Pc) were investigated. Our results indicated that the ethanol and n-hexane mixture (4:1, v/v) was suitable solvent for simultaneous extraction of phospholipid and nonpolar lipids. By contrast, the ethanol and n-hexane mixture (4:1, v/v) and single ethanol were suitable solvents for the extraction of polyunsaturated fatty acids-rich (36.10%–42.78% of total fatty acids for Pv and 23.57%–25.58% of total fatty acids for Pc) and phosphatidylcholine-rich (66.22–67.09 mol% of total phospholipids for Pv and 55.01–58.68 mol% of total phospholipids for Pc) oils, but acetone was suitable solvent for the extraction of astaxanthin-rich oil (436.19 μg/g oil for Pv and 799.27 μg/g oil for Pc). The findings will provide relevant information that can be used to improve the production of nutritional oils from shrimp by-products. Practical applications This study provides a theoretical basis for creating proper extraction processing to recover nutritional oils from shrimp by-products. For example, the ethanol and n-hexane mixture (4:1, v/v) was a suitable solvent for simultaneous extraction of phospholipid and non-polar lipids. By contrast, both of the ethanol and n-hexane mixture (4:1, v/v) and single ethanol were suitable solvents for the extraction of polyunsaturated fatty acids (PUFA)-rich and phosphatidylcholine-rich oils, but acetone was a suitable solvent for the extraction of astaxanthin-rich oil. Therefore, the oils extracted from shrimp by-products are rich in phospholipid, PUFA, and astaxanthin, which may be used as new functional food ingredients.

Determination of Toxic Elements and Arsenic Species in Salted Foods and Sea Salt by ICP-MS and HPLC-ICP-MS.

Toxic elements (Cd, Pb, and As) accumulate into the environment by industrialization and natural phenomena and then pass to organisms. Analysis of toxic elements in food must be accurately carried out on a regular basis so as to avoid any adverse impact. Salted foods are difficult samples and accurate analysis of As is not easy due to salt interference. In this study, analysis of As was carried without influence of salts in three types of salted foods via an analytical method, which was validated using spiking recovery experiments and by analyzing certified reference materials. As a result, toxic elements were detected in all samples but none of these exceeded the World Health Organization recommended limits. Among the As species, arsenobetaine (AsB) was the most abundant, while inorganic As was below the detection limit in all samples. All the analyzed salted food samples appeared to be safe for consumption. In addition, the analysis of sea shrimp, freshwater shrimp, and seawater verified As bioaccumulation in these organisms from the environment.

Comprehensive Multiphase NMR Probehead with Reduced Radiofrequency Heating Improves the Analysis of Living Organisms and Heat-Sensitive Samples

Comprehensive multiphase (CMP) NMR, first described in 2012, combines all of the hardware components necessary to analyze all phases (solid, gel, and solution) in samples in their natural state. In combination with spectral editing experiments, it can fully differentiate phases and study the transfer of chemical species across and between phases, providing unprecedented molecular-level information in unaltered natural systems. However, many natural samples, such as swollen soils, plants, and small organisms, contain water, salts, and ionic compounds, making them electrically lossy and susceptible to RF heating, especially when using high-strength RF fields required to select the solid domains. While dedicated reduced-heating probes have been developed for solid-state NMR, to date, all CMP-NMR probes have been based on solenoid designs, which can lead to problematic sample heating. Here, a new prototype CMP probe was developed, incorporating a loop gap resonator (LGR) for decoupling. Temperature increases are monitored in salt solutions analogous to those in small aquatic organisms and then tested in vivo on Hyalella azteca (freshwater shrimp). In the standard CMP probe (solenoid), 80% of organisms died within 4 h under high-power decoupling, while in the LGR design, all organisms survived the entire test period of 12 h. The LGR design reduced heating by a factor of ∼3, which allowed 100 kHz decoupling to be applied to salty samples with generally ≤10 °C sample heating. In addition to expanding the potential for in vivo research, the ability to apply uncompromised high-power decoupling could be beneficial for multiphase samples containing true crystalline solids that require the strongest possible decoupling fields for optimal detection.

Species diversity of freshwater shrimp in Henan Province, China, based on morphological characters and COI mitochondrial gene.

Freshwater shrimp are a rich species group, with a long and problematic taxonomic history attributed to their wide distribution and similar morphological characteristics. Shrimp diversity and species identification are important cornerstones for fisheries management. However, identification based on morphological characteristics is a difficult task for a nonspecialist. Abundant freshwater shrimp species are distributed in the waters of Henan Province, but investigations of freshwater shrimp are limited in this region, especially concerning molecular features. Here, we combined morphology and DNA barcodes to reveal the species diversity of freshwater shrimp in Henan province. A total of 1,200 freshwater shrimp samples were collected from 46 sampling sites, and 222 samples were chosen for further microscopic examination and molecular delimitation. We used tree‐based methods (NJ, ML, and bPTP) and distance‐based methods (estimation of the paired genetic distances and ABGD) to delimit species. The results showed that there were nine morphospecies based on morphological characteristics; all could effectively be defined by molecular methods, among which bPTP and ABGD defined 13 and 8 MOTUs, respectively. The estimation of the paired genetic distances of K2P and the p‐distances had similar results. Mean K2P distances and p‐distances within species were both equal to 1.2%. The maximum intraspecific genetic distances of all species were less than 2%, with the exception of Palaemon modestus and M. maculatum. Various analyses have shown that P. modestus and M. maculatum have a large genetic differentiation, which may indicate the existence of cryptic species. By contrast, DNA barcoding could unambiguously discriminate 13 species and detect cryptic diversity. Our results demonstrate the high efficiency of DNA barcoding to delimit freshwater shrimp diversity and detect the presence of cryptic species.

Description of one new species of freshwater shrimp of the genus Caridina (Crustacea: Decapoda: Atyidae) from two karst caves of Northern Vietnam.

A new species of atyid freshwater shrimp is described from two caves of Bac Kan Province, Northeast Vietnam, namely Caridina namdat sp. nov. This species can be distinguished from its congeners by a suite of morphological characters such as reduced eyes with short eyestalk, very short and unarmed rostrum, slender second pereiopod, elongated endopod of male first pleopod, and long appendix interna of the male second pleopod. Molecular phylogenetic data from the mitochondrial cytochrome oxidase subunit I (COI) and 16S ribosomal RNA genes also support the distinctiveness of the new species from all other examined species.

Transcriptome analysis of five ovarian stages reveals gonad maturation in female Macrobrachium nipponense

BackgroundMacrobrachium nipponense is an economically important species of freshwater shrimp in China. Unlike other marine shrimps, the ovaries in adult female M. nipponense can mature rapidly and periodically during the reproductive period, but the resulting high stocking densities and environmental deterioration can negatively impact the harvest yield and economic benefits. To better understand ovary development in female M. nipponense, we performed systematic transcriptome sequencing of five different stages of ovarian maturation.ResultsWe obtained 255,966 Gb of high quality transcriptome data from 15 samples. Of the 105,082 unigenes that were selected, 30,878 were successfully annotated. From these unigenes, we identified 17 differentially expressed genes and identified three distinct gene expression patterns related to different biological processes. We found that cathepins, legumains, and cystatin were enriched in the lysosome pathway, and they are related to vitellogenin hydrolysis. Additionally, we found that myosin heavy chain 67 participated in oocyte excretion.ConclusionsWe provide the first detailed transcriptome data relating to the ovarian maturation cycle in M. nipponense. Our results provide important reference information about the genomics, molecular biology, physiology, and population genetics of M. nipponense and other crustaceans. It is conducive to further solve the problem of M. nipponense rapid ovarian maturation from the aspects of energy supply and cell division.

Multigene phylogeny and taxonomic revision of American shrimps of the genus Cryphiops Dana, 1852 (Decapoda, Palaemonidae) implies a proposal for reversal of precedence with Macrobrachium Spence Bate, 1868.

The freshwater shrimp genus Cryphiops Dana, 1852 has a disjunct distribution in North (Mexico) and South (Brazil, Chile) America, and is composed of only six species. The current classification of genera in the Palaemonidae is controversial, based on variable morphological characters, and still far from a clear definition. Cryphiops differs from the speciose genus Macrobrachium Spence Bate, 1868 only by the absence of the hepatic spines on the carapace. Previous studies with a limited dataset suggested the necessity to link morphology and phylogeny to create an internal rearrangement in the genus to resolve the paraphyletic status. Through a molecular phylogenetic approach, the evolutionary relationships are inferred based on four (mitochondrial and nuclear) genes, among all recognized species of Cryphiops and, in combination with a taxonomic revision, a rearrangement in the systematics of the genus is suggested. The absence of hepatic spines on the carapace, the only character used to separate the genus Cryphiops, is subjective and should be considered as a homoplasy. This implies that Cryphiops and Macrobrachium are subjective synonyms and, because the latter genus is much more diverse and widely known, with several economically important species, to avoid confusion and disturbance in nomenclatural stability and keep universality, a proposal for the priority of the older synonym (Cryphiops) to be partially suppressed in favor of maintaining the prevailing use of the younger synonym (Macrobrachium) is presented. As the species of Cryphiops should be accommodated in the genus Macrobrachium, new names to replace three preoccupied specific names that, by this action, resulted to be secondary homonyms are offered.