Biology subjects

Pham, H. Q.

Publications and source records attributed to Pham, H. Q..

3 recordsLinked to original sources

bioRxiv2023

Density effects on a tropical copepod Acartia sp.: implications as live feed in aquaculture

Calanoid copepod Acartia species are major live feeds for the early stages of economically important marine fish in hatcheries in Southeast Asian countries. However, rearing Acartia copepods at high densities to increase productivity remains a major challenge. To address the issue, we conducted two experiments on 1) Acartia sp. nauplii (1000, 3000, 6000, 9000, 12000, and 15000 individuals L-1) and 2) adults (1000, 1500, 2000, and 2500 individuals L-1). We assessed key parameters for biomass production: development, survival, and egg production. In general, increased density resulted in longer development time, and lowered survival and egg production, but did not affect the size of adult males and females. Despite survival to adulthood decreasing at higher stocking nauplii densities, the number of surviving adults was highest at a stocking density of 12000 ind L-1. Egg production was very low which may be the result of high egg predation. The total eggs harvested were highest at the lowest adult density. These results are essential for the biomass production of Acartia sp. in central Vietnam.

zoology↗

bioRxiv2022

Direct and delayed synergistic effects of marine heatwaves, metals and food limitation on tropical reef-associated fish larvae

Tropical fish are fast-growing and high energetic-demand organisms, which can be highly vulnerable to long-lasting effects of heat stress and pollution, particularly under food shortages. We tested this by assessing highly complex direct and delayed interactive effects of an extreme temperature (32{degrees}C) from a simulated marine heatwave (MHW), copper (Cu, 0, 100, 150 and 175 {micro}g L-1) and food availability (limited and saturated food) on larvae of a tropical, reef-associated seaperch (Psammoperca waigiensis). Cu, MHW, and food limitation independently reduced survival and growth, partly explained by reduced feeding. The negative effect of Cu on fish survival was more substantial under MHW, particularly under limited food. Delayed interactive effects of Cu, MHW, and food limitation were still lethal to fish larvae during the post-exposure period. These results indicate that reef-associated fish larvae are highly vulnerable to these dominant stressors, impairing their ecological function as predators in the coral reefs. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=101 SRC="FIGDIR/small/481600v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@1bc37aborg.highwire.dtl.DTLVardef@1eaedaeorg.highwire.dtl.DTLVardef@9a409eorg.highwire.dtl.DTLVardef@1087cc6_HPS_FORMAT_FIGEXP M_FIG C_FIG

ecology↗

bioRxiv2020

Although host-related factors are important for the formation of gut microbiota, environmental factors cannot be ignored

The gut microbiome is essential to human health. However, little is known about the influence of the environment versus host-related factors (e.g. genetic background, sex, age, and body mass) in the formation of human intestinal microflora. Here, we present evidence in support of the importance of host-related factors in the establishment and maintenance of individual gut assemblages. We collected fecal samples (n = 249) from 44 Korean naval trainees and 39 healthy people living in Korea over eight weeks and sequenced the bacterial 16S rRNA genes. The following hypotheses were tested: 1) microbiome function is linked to its diversity, community structure, and genetic host-related factors, and 2) preexisting host-related factors have a more significant effect on gut microbiome formation and composition than environmental factors. For each individual, the difference between the initial gut microbiota and that after eight weeks was negligible even though the 44 naval trainees lived in the same area and received the same diet, the same amount of exercise, and the same amount of physical stress during the study. This suggests that host-related factors, rather than environmental factors, is a key determinant of individual gut microflora. Moreover, eight weeks of physical training and experiencing the same environmental conditions resulted in an increase in the species Bifidobacterium, Faecalibacterium, and Roseburia in most trainees, suggesting a healthier intestinal environment. IMPORTANCEIn order to understand the role of human gut microbiome, it is important to know how individuals gut microbiota are formed. In this study, we tested the host-related factors versus environmental factors to affect gut microbiome and found that the former have a more association. However, we also found that the controlled environment give an effect on the gut microflora as well. This study provides preliminary evidence that differences in the formation and diversity of gut microbiota within a population could be determined by host-related factors rather than environmental factors.

microbiology↗