Lecane (Rotifera: Lecanidae) community in psammon habitat in Central Coast Vietnam: Diversity and relation to environmental condition

Characteristics of the Lecane (Rotifera) community in psammon in Central Coast Vietnam were investigated. A total of 50 taxa were identified in samples collected at hygropsammon zones of temporary pools, contributing 4 new species to rotifers' record of Vietnam. Psammonxenic species accounted for the largest percentage of Lecane community with 82%, followed by psammophiles (12%) and psammonbionts (6%). Influences of some environmental factors on the distribution of psammic lecanids were also observed. This group of organisms showed a slight tendency towards sand with grain sizes larger than 125 µm. Besides, other abiotic factors including pH, total phosphorus (TP) and total dissolved solids (TDS) were also found to significantly related to the distribution of some common Lecane species

Species diversity of rotifers (Rotifera: Eurotatoria) of Phu Ninh Lake with five new records from Vietnam

A total of sixty-one taxa of rotifer, belonging to 15 families, 3 orders were identified from the Phu Ninh Lake, Vietnam. Of these, five species were recorded new to Vietnam Rotifera fauna, including Lecane acanthinula (Hauer, 1938), L. sola (Hauer, 1936), L. thailandensis Segers & Sanoamuang, 1994, L. pyriformis (Daday, 1905), and Mytilina bisulcata (Lucks, 1912). The result raised the total number of rotifers known from Vietnam to 227 species. Moreover, the results showed that the number of species recorded increased with the increase of sample size, which followed the equation y=12.85+14.12log(x) (R2 = 0.99). Based on the estimators, the α-diversity of rotifers in Phu Ninh Lake might be up to 67±4 taxa (according to the Bootstrap index), 71±8 taxa (according to the Chao index), or even up to 79 taxa (according to Jacknife 2 index)

Effects of potassium dichromate on the survival and reproduction of Moina micrura Kurz. 1875 (Cladocera: Moinidae)

Today, heavy metal pollution is an urgent problem in the world including Vietnam. An analytical approach is very important to identify, assess and forecast environmental risks from toxic components, in which ecotoxicology is considered to be the optimal tool. We conducted a study on M. micrura in order to contribute the creation of a biological basis for the use of zooplankton as an early warning of the risk of water pollution. The results showed that M. micrura was isolated from 29/3 Park Lake, Da Nang City, central Vietnam. The acute toxicity test of potassium dichromate on M. micrura showed LC 50 at 12, 24 and 48 hr were 0.26, 0.15 and 0.08 mg.l-1 K2Cr2O7, respectively. EC 50 was 0.015 mg.l-1 K2Cr2O7 for egg parameter and 0.009 mg.l-1 K2Cr2O7for neonate parameter. The results of acute and chronic toxicity tests showed that M. micrura was more sensitive than D. magna, D. pulex and C. cornuta.

M^2UNet: MetaFormer Multi-scale Upsampling Network for Polyp Segmentation

Polyp segmentation has recently garnered significant attention, and multiple methods have been formulated to achieve commendable outcomes. However, these techniques often confront difficulty when working with the complex polyp foreground and their surrounding regions because of the nature of convolution operation. Besides, most existing methods forget to exploit the potential information from multiple decoder stages. To address this challenge, we suggest combining MetaFormer, introduced as a baseline for integrating CNN and Transformer, with UNet framework and incorporating our Multi-scale Upsampling block (MU). This simple module makes it possible to combine multi-level information by exploring multiple receptive field paths of the shallow decoder stage and then adding with the higher stage to aggregate better feature representation, which is essential in medical image segmentation. Taken all together, we propose MetaFormer Multi-scale Upsampling Network (M$^2$UNet) for the polyp segmentation task. Extensive experiments on five benchmark datasets demonstrate that our method achieved competitive performance compared with several previous methods

Effects of cultural conditions on life history characteristics of the freshwater rotifer Brachionus calyciflorus

The effects of temperature, food concentration, and pH conditions on the life history characteristics of the freshwater rotifer, Brachionus calyciflorus, were investigated. The culture temperature (20, 25, and 30°C) had a significant relationship with life history parameters. At lower temperatures, there was a prolongation of the mean lifespan and juvenile period. The optimal temperature for the fecundity of this species was 25°C with an average quantity of 23.67±6.99 offspring female-1 across the entire lifespan of 6.7 days. No significant difference was found between the mean lifespan at different algae densities but the maximum fecundity (25.75±6.99 offspring female-1) was obtained at an algae density of 10x106 cells.ml-1. Brachionus calyciflorus could tolerate a broad range of pH (4-10) but preferred pH from 6-10. These results are critical for potential applications of this species in ecotoxicology, biomonitoring as well as in mass culture as live food for larval rearing in aquaculture

Rotifers from Thuy Tien lake and Nhu Y river in central Vietnam, with a description of Ploesoma asiaticum new species (Rotifera: Monogononta)

We surveyed Thuy Tien lake and Nhu Y river, Thua Thien Hue province, Vietnam, for rotifers from March to August 2010, and additionally in February 2012 in Thuy Tien lake. A total of 98 species-level taxa are identified, belonging to 31 genera and 21 families. Of there, 52 are first records for Vietnam, Filinia minuta (Smirnov, 1928) is new to the Oriental region and Ploesoma asiaticum n. sp. is new to science. These results increase the rotifer record for Vietnam from 122 to 174 taxa. In addition to describing the new taxon, we provide comparative illustrations including trophi scanning electron microscopy photographs of Ploesoma hudsoni (Imhof 1891)

Isolation of Some Microalgae Strains Belonging to the Family Scenedesmaceas (Chlorophyta) in Freshwater Bodies in Central Vietnam and Investigation Into Their Biological Characteristics

Seven microalgae strains from samples collected from freshwater lakes in Central Vietnam were isolated and cultivated in BBM medium for investigating their biological characteristics and their applicability. These strains were identified belonging to 6 species, 3 genera of the family Scenedesmaceae, division Chlorophyta. Their average growth rate was from 0.081 - 0.160 d-1, and the highest cell density of each strain reached from 2.6 x 106 - 60 x 106 cells/ml. The total content of pigments (including chlorophyll-a, chlorophyll-b, and carotenoid) of all strains was not too high (4.10 - 11.3 μg/mL), but the total lipid content exhibiting noticeably high levels, accounted for 16.6% - 74.1% of dry cell weight. Among isolated strains, Desmodesmusabundans and D.costato-granulatus were the most prominent with the highest growth rate and density in combination with remarkably high contents of lipids and pigments, and thus were identified as two potentially great candidates for biofuel production and chlorophyll and carotenoid extraction

Characteristics of microplastics in shoreline sediments from a tropical and urbanized beach (Da Nang, Vietnam)

International audienceMicroplastics in shoreline sediments were investigated from Da Nang beach for the first time. Sediment samples at the two depth strata (0-5 cm and 5-10 cm) at eight sites along the entire coast were collected for identifying the characteristics of microplastics, including their concentration, size, shape, color, and nature. The synthetic fiber was the predominant type of microplastics, accounting for 99.2% of the total items. Blue (59.9%) and white (22.9%) were the most common colors of the fibers. Synthetic fibers showed a homogenous distribution at all sampling sites with a mean concentration of 9238 ± 2097 items kg − 1 d.w. Meanwhile, the fibers tended to concentrate much more at the surface stratum than the deeper stratum. A large number of synthetic fibers (81.9%) were in the size range of 300-2600 μm, which might pose a threat to marine biota and human health

Species Diversity of Rotifers (Rotifera: Monogononta) in Freshwater Psammon with Three New Records to Vietnam

This study aims to evaluate the diversity of rotifers in psammon in the Central Coast of Vietnam. A total of 64 rotifer species belonging to 17 genera and 14 families were recorded in 10 samples collected at hygropsammon zones of freshwater lakes and ponds in Thua Thien Hue province. Lepadella cristata (Rousselet, 1893), Cephalodella tenuior (Gosse, 1886), and Lindia torulosa Dujardin, 1841 were new record to Vietnam rotifers fauna. Species from the families Lecanidae, Lepadellidae, and Trichocercidae are abundant (containing about 44%, 14%, and 12%, respectively) in the total rotifer species recorded. Psammonxenic species accounted for the largest percentage of the psammic rotifer community with 83%, followed by psammonphiles (11%) and psammonbionts (6%). Our study results enrich the data on the diversity and the ecology of rotifers in Vietnam