Effect Of Different Densities Research Articles

Effects of mussel-phytoplankton interactions on the aquatic environment

A five-day in situ experiment was conducted in plastic enclosures to investigate the effects of different densities of the mussel Mytilus edulis, and sampling time on water variables, and phytoplankton community structure in Sanggou Bay (Shandong, China). The tested mussel densities were low (LD300: 300 g/m3), medium (MD600: 600 g/m3), high (HD900: 900 g/m3), and sampling times were at 6:00 and 17:00 h. The water variables analyzed as indicators were pH, dissolved oxygen, nutrients, carbonate system, pCO2, and chlorophyll-a (Chl-a). The results showed that density and sampling time had highly significant effects on all water parameters and phytoplankton abundance, except for dissolved oxygen (P<0.01). At the same sampling time, pH, c[CO32-] and Chl-a concentrations in the water column of LD300 treatment were much higher than those of MD600 and HD900 treatments, while c[HCO3-], c[CO2] and pCO2 were significantly lower than those of MD600 and HD900 treatments (P<0.01). Phosphate was the main limiting nutrient for phytoplankton growth. Chl-a concentrations increased and then decreased significantly in LD300 and MD600 treatments, while it diminished continuously in HD900 treatment. The higher M. edulis density showed higher correlation with picophytoplankton abundance and Chl-a concentrations. Not only the phytoplankton structure was affected, but also the condition index of the HD900 treatment was significantly reduced (P<0.05). The present study showed LD300 and MD600 treatments significantly promoted the growth of picophytoplankton. The selective filtration of M. edulis for microphytoplankton and nanophytoplankton were much higher than those for picophytoplankton. The combined decrease in competitors (micro- and nanophytoplankton) led to a substantial increase of picophytoplankton abundance in shellfish farming areas. The interactions between mussel and phytoplankton significantly affected the water environment. However, well designed integrated shellfish and algae aquaculture might mitigate the adverse impacts.

Effect of different density of lac insect (Kerria lacca) infestation on host plant Flemingia macrophylla growth and photosynthetic pigments

Effect of different density of lac insect (Kerria lacca) infestation on host plant Flemingia macrophylla growth and photosynthetic pigments

Effect of different density of lac insect (Kerria lacca) infestation on host plant Flemingia macrophylla growth and photosynthetic pigments

Effect of different density of lac insect (Kerria lacca) infestation on host plant Flemingia macrophylla growth and photosynthetic pigments

Feed conversion ratio and feed efficiency of giant gouramy (Osphronemus goramy) seed with different densities on biofloc media

This study aims to determine the effect of different densities on the feed conversion ratio and feed efficiency of giant gourami on biofloc media. This study used an experimental method using a completely randomized design. Giant gourami seeds were reared for 42 days with four treatments and three replications. K1 (control, non-biofloc, density of 100 fish/pond), K2 (control, non-biofloc, density of 150 fish/pond), P1 (treatment of biofloc with a density of 100 fish/pond), and P2 (treatment of biofloc with a density of 150 fish/pond)). The results showed that different densities had no significant effect on the feed conversion ratio and feed efficiency of giant gourami seeds on biofloc media (p>0.05). However, the lowest feed conversion ratio value was found in treatment P2 (1.17 ± 0.01), then followed by treatment P1 (1.28 ± 0.2), K1 (1.99 ± 1.02), and the highest value was in treatment K2. (2.11 ± 0.83). The highest feed utilization efficiency value was found in treatment P2 (85.78 ± 0.01%), then followed by treatment P1 (79.10 ± 0.11%), K1 (58.58 ± 0.24%), and the lowest value was found in treatment K2 (52.02 ± 0.18%).

Effect of Different Densities on the Rabbitfish (Siganus rivulatus) Performance and Health Status Under Biofloc System During the Nursery Phase

Effect of Different Densities on the Rabbitfish (Siganus rivulatus) Performance and Health Status Under Biofloc System During the Nursery Phase

Growth, survival, and myogenic gene expression in the post-larvae of Colossoma macropomum provisioned with Artemia nauplii.

Artemia nauplii are widely used as fish larvae feed due to its beneficial nutritional characteristics for larval development; however, efficient feeding strategies are needed to balance its high costs. Therefore, we evaluated the effects of different densities of Artemia nauplii (100, 250, 500, 750, and 1000 nauplii/post-larvae) on the growth, survival, water quality, and myogenic gene expression of tambaqui (Colossoma macropomum) post-larvae cultivated in a recirculating aquaculture system. After 2weeks of trial, there was a significant decrease in dissolved oxygen concentration with the increase in nauplii density, but it did not interfere with larval performance and survival. In the first week, larvae fed with fewer than 500 nauplii/post-larvae presented slower growth, while in the second week, larvae fed with 1000 nauplii/post-larvae had the highest final weight and length. Regression analysis suggests that the optimum feeding density of Artemia nauplii during the first week is 411 nauplii/post-larvae, while for the second week, the growth increased proportionally to the feeding densities. The relative expression of the myod, myog, and mstn genes was higher in larvae fed with fewer than 500 nauplii/post-larvae. Although low-growing larvae showed increased expression of myod and myog genes, responsible for muscle hyperplasia and hypertrophy, respectively, mstn expression may have played a significant inhibitory role in larval development. Further research is needed to better determine the effects of the live food on the zootechnical performance and the expression of the myogenic genes in the initial phase of the life cycle of the tambaqui post-larvae.

Effects of stocking density and diets on survival and growth of lavi-cultured slipper lobster (\(\textit{Thenus orientalis}\) Lund, 1793)

A study on the effect of different densities and feed when rearing phyllosoma larvae of slipper lobster (Thenus Orientalis) was conducted at Nha Trang Marine Research and Development Center, Institute of Aquaculture Research No. 3 from January to April 2020 to evaluate the effect of density and types of food on survival, growth (phase transition rate, phyllosoma larval size: CL and CW). In general, the impact of feed on phyllosoma larvae was recorded in such parameters as survival rate, stage transition rate, and larval size (CL and CW). The results showed that the survival rate of phyllosoma larvae depends on the density of rearing phyllosoma larvae, and the appropriate density when breeding is 15 fish/L. However, density does not affect the growth of phyllosoma larvae. Besides, the best feed formula for rearing phyllosoma larvae in this study was umbrella Artemia + (white clam) fresh meat for the first seven days, and newly hatched Artemia + white clam meat continued to be fed from day one, 8th to 24th day.

Effect of Different Density on Survival Rate of Gourami Fingerling (Osphronemus goramy) Razor Size on Closed Transportation System

The low survival rate of gourami fingerling transportation is a problem. Setting the expected amount can lead to death. This research aims to determine the exact amount of density in the razor-sized gourami fingerling transported during the treatment period and to analyze its effect on the survival of razor-sized gourami fingerling. This research was carried out from April to June 2022. This research method used in the Factorial Randomized Group Design (FRGD) experiment consisted of two factors, namely the density factor of 4 levels (10, 20, 30, 40 fish/2L) and the three-stage transport duration factor levels ( 3, 5 and 7 hours). The transportation system in this study is a closed system. The parameters observed were post-transportation life, post-maintenance life for 7 days and water quality in the form of temperature, ammonia, pH and DO. Based on the results of research showed that the effective density for the transportation of razor-sized gourami fingerling was 30 fish/2L with a transportation duration of 5 hours and the survival rate post-transportation was 97.8% and post-maintenance 7 days was 90.02%.

The Effect of Density and Resin Content on Oil Palm Trunk Particleboard

The physical (density and moisture content) and chemical properties of the oil palm trunk (OPT) were examined. The effect of different densities (500, 600, and 700 kgm-3) and different percentages of urea-formaldehyde (UF) resin content (8, 10, and 12%) on the single layer at the different portions of OPT particleboard were evaluated for mechanical and dimensional stability. The results showed that the bottom portion and near bark had a positive result on density and moisture content. Lignin, holocellulose, and alpha-cellulose of the OPT showed the highest content at the bottom portion. The density was found to effect all the board properties significantly at p &lt; 0.05 on the modulus of elasticity (MOE), modulus of rupture (MOR), internal bond (IB), thickness swelling (TS), and water absorption (WA) of the particleboards. For the resin content, all the board properties were effected except for the water absorption. The particleboards produced, from 700 kgm-3 densities and 10% resin content, met the minimum requirement for the particleboard (Type 18) stipulated in the Japanese Industrial Standard (JIS A 5908). The particleboard manufacturing from OPT particles as the replacement for wood is very promising.

Effects of different densities of beluga sturgeon (Huso huso) on growth indices and total organic matter in integrated system using the bioremediation activity of Nereis worm (Nereis diversicolor)

Effects of different densities of beluga sturgeon (Huso huso) on growth indices and total organic matter in integrated system using the bioremediation activity of Nereis worm (Nereis diversicolor)

High population density of bee pollinators increasing Camelina sativa (L.) Crantz seed yield: Implications on the potential risk for insect-mediated gene flow

New Camelina sativa genotypes have been genetically engineered (GE) to produce unique high-value chemical compounds and biofuel products. However, baseline information on predictive environmental risk assessment on this plant is urgently needed to establish guidelines for commercial large-scale production. Pollinating insects such as bees could facilitate the spread of transgenes into the ecosystem and raises ecological concerns on insect-mediated gene flow. Thus determination of the potential impact of pollinating insects on C. sativa pollination and gene flow becomes important. A 4-year experiment conducted in Connecticut, USA (2017) and Yangzhou, China (2019–2021) was carried out to determine the pollination effect of different densities of honey bees (Apis mellifera L.) populations on C. sativa seed yield and assess their involvement on C. sativa pollen dispersal. Insect cages experiments with presence or absence of honey bees showed that C. sativa seed yield was not affected by a relatively low population density of honey bees (20 honey bees m−2). However, at a higher density of honey bee population, Camelina sativa seed yield (0.23 g plant-1 and 73.3 g m−2) was statistically greater than those of the uncaged control (0.21 g plant-1 and 68.9 g m−2), caged C. sativa plants without honey bees (0.20 g plant-1 and 66.3 g m−2) or with 20 honey bees m−2 (0.21 g plant-1 and 66.9 g m−2), although C. sativa is commonly assumed to be self-pollinated. Principle coordinate analysis (PCoA) made from SSR markers revealed that honey bee and bumble bee are able to transfer C. sativa pollen from pollen source to adjacent flowers of other species (e.g., Brassica juncea, Brassica napus) up to 10−15 m beyond the field edge, raising ecological concerns on insect-mediated gene flow between adjacent C. sativa fields particularly if GE C. sativa cultivars are involved. The new information in this study will help to better understand C. sativa pollination biology, environmental risks associated with insect-mediated gene flow, and develop management strategies to reduce gene flow and facilitate coexistence between GE and non-GE C. sativa under natural agroecosystem.

Effects of Planting Density of Spring Soybean on Canopy Photosynthetically Active Radiation and Yield in Northeast China

Soybean is an important legume crop. Planting density of soybean directly affects the distribution of photosynthetically active radiation (PAR) in the canopy, which affects the physiological changes, such as photosynthesis of soybean, and leads to the change of yield. In this experiment, soybean variety Heinong 84 was adopted, and five planting densities were set as 200,000 plants/ha (D20), 250,000 plants/ha (D25), 300,000 plants/ha (D30), 400,000 plants/ha (D40) and 500,000 plants/ha (D50). The canopy PAR intensity was measured based on photosynthetically active radiation recorder, and the effects of different densities on soybean canopy PAR and yield were studied systematically. According to the results, with the extension of growth period, the PAR above and within the canopy of soybean decreased first and then increased, and the rules were consistent under different densities. During each growth period, PAR was above that of canopy &gt; growth point &gt; middle stem &gt; cotyledon scar and decreased with the increase of density. The growth point changed significantly, followed by middle stem, but no significant change happened in cotyledon scar. The absorption photosynthetically active radiation (FPAR) showed a unimodal trend with the increase of density at V4 and R2 and had an upward trend at R4 and R6. The number of effective pods per plant and 100 seed weight of D20 are the highest, and the yield of D25 is the highest.

Effects of Monochoria vaginalis density on yield losses, economic thresholds, and gross returns in paddy rice (Oryza sativa L.)

AbstractMonochoria vaginalis (Burm. f.) Kunth is an annual weed commonly found in paddy fields. Understanding the effects of M. vaginalis on the yield and economics of paddy rice (Oryza sativa L.) is essential for integrated weed management. Here, a field experiment was conducted over two consecutive years (2017–2018) to determine the effects of different densities of M. vaginalis (0, 1, 4, 8, 12, 16, 20, and 24 plants m–2) on yield losses, economic thresholds, and gross returns in paddy rice. The results showed that a higher density of M. vaginalis exhibited greater inhibitory effects on plant height, tiller number per plant, and adjusted gross returns in both early and late rice. The inhibitory effects on spike number per plant, filled grains per panicle, and 1,000‐kernel weight were also significant, although lesser than those observed on the other yield traits. The economic threshold of M. vaginalis under manual weeding varied from 2.80 to 4.44 plants m–2, whereas the threshold levels under herbicide application ranged between 0.71 and 1.03 plants m–2 in the 2 yr. Averaged across all other factors, the adjusted gross returns decreased by 45.0% with increasing M. vaginalis density from 0 to 24 plants m–2. Taking into account the economic thresholds and gross returns, irrational use of herbicides should be prevented for weed management in paddy fields. This study provides useful data for reducing the use of chemical herbicides, saving the costs of weed management practices, and protecting the environment of farmland ecosystems.

Evaluation of The Predatory Efficiency of Orius Albidipennis Reuter for Two Prey Species Myzus Persicae (Sulzer) and Thrips Tabaci Lind. on The Carrot Plant in Laboratory

The study aimed to investigate the effect of different densities of M.persicae and T. tabaci on the predatory ability of the predator O. albidipennis and determine the preference for one of the two prey, in addition to assessing the in vitro predator's efficiency in reducing the number of aphids on the carrot plant. The results indicated that the rates of predated adult and nymph thrips were significantly higher than that of predated aphids. The highest rate of predation for nymphs and adults thrips was 33.2 and 25 preys per day, respectively, at a density of 60prey/container, while the highest rate of predation of adults and nymphs of aphids was 19 and 13.2prey/day, respectively, at a density of 60prey/container. The food preference experiment showed that the adults of the predator O. albidipennis feed on the immature stages thrips and aphids when introduced together and have no clear preference for one of the prey. The results of evaluating the efficiency of predator adults on reducing different densities of aphids showed that the predator was effectively able to reduce the population increase of aphids when the insect densities were 10, 20 or 30 insect. however, the predator was not effective when introduced to aphids at starting density of 40, no significant difference was found due to predator presence or absence as the aphids population density were 118.4 and 135.2 insects/cage after four days, respectively.

Effects of Different Densities of Iron Fertilizer on Mung Bean Yield

Effects of Different Densities of Iron Fertilizer on Mung Bean Yield

Effects of Different Densities of Sea Grape Caulerpa lentillifera on Water Quality, Growth and Survival of the Whiteleg Shrimp Litopenaeus vannamei in Polyculture System

The integrated aquaculture-seaweed system has been identified as a bio-mitigation strategy to overcome environmental damage, improve the efficiency of nutrient use, maintain good water quality, and ensure the system’s sustainability. This study was conducted to determine the appropriate density of sea grape (Caulerpa lentillifera) in polyculture with whiteleg shrimp (Litopenaeus vannamei) in the same culture tank. Five treatments were randomly designed in triplicate tanks where shrimp was monocultured (without sea grape) as a control treatment and four polyculture treatments with different seaweed density levels (0.5, 1, 1.5, and 2 kg m−3) for 56 days. The results showed that polyculture of shrimp and sea grape significantly reduced the concentrations of total ammonia nitrogen (TAN), nitrite (NO2−), nitrate (NO3−), and phosphate (PO43−) in the rearing tanks and significantly improved (p &lt; 0.05) the growth rate (6.67–6.76% day−1), survival (73.3–78.5%), and production of shrimp (3.44–3.87 kg m−3) compared to monoculture (6.24% day−1, 54.8%, and 2.02 kg m−3, respectively). Applying shrimp and sea grape polyculture at a density of 1 kg m−3 provided a relatively better shrimp performance and feed conversion ratio than other seaweed densities, although not significantly different among polyculture treatments. The findings suggested that sea grape could be used at densities of 0.5–2 kg m−3 in polyculture with whiteleg shrimp, of which 1 kg m−3 resulted in higher production and feed efficiency.

Waste to wealth: A sustainable circular bioeconomy approach of chicken manure powder for increasing productivity of Lanchester’s freshwater prawn (Macrobrachium lanchesteri)

A biorefinery is ideal because it can combine many processes to produce multiple bio-products from organic solid waste. Moreover, in view of socially rising energy demands and biodiversity conservation, biorefinery contributed as a sustainable strategic tool for the emerging circular bio-economy. In this research objective was to study some techniques to increase the productivity of Lanchester’s freshwater prawn in earthen ponds. The experiment using a completely randomized design was conducted. In six Nattearthen ponds, different amounts of chicken manure were applied to produce different amounts of phytoplankton (green algae). The first pond was control, then, the 2nd to 6th ponds were applied with chicken manure in 30, 60, 90, 120 and 150 kg/rai/week, respectively. The prawns were fed twice daily with 5% of total body weight using 40% protein diet. The results of the study showed that feeding with different densities of phytoplankton (green algae) affected the productivity of Lanchester's freshwater prawn significantly. The highest productivity of Lanchester's freshwater prawn was 566.30 ±4.88 g from the pond applied with chicken manure of 120 kg/rai/week. The productivity of Lanchester’s freshwater prawn applied with 90, 30, 60, 150 and 0 kilograms/rai/week of chicken manure was 416.53 ± 9.89, 295.43 ± 5.46, 281.13 ± 4.63, 275.39±4.78 and 265.86 ±4.79 g, respectively. In conclusion, the effect of different densities of phytoplankton (green algae) increased the productivity of Lanchester's freshwater prawn (Macrobrachium lanchesteri).

Effectiveness of Erosion Control Structures in Reducing Soil Loss on Skid Trails

Forest operations can lead to increased runoff and soil loss on roads and skid trails. Best management practices (BMPs) aim to minimize erosion and water quality problems, but the efficacies of various BMP options such as water bars are not well documented. The aim of this study was to evaluate the effects of different densities of water diversion structures (water bars) on runoff volume and soil loss on different skid trail gradients on two soils with different textures in the Shenrood forest, Guilan province, northern Iran. The treatments included combinations of four densities of water bars (1, 2, 3 or 6 water bars per 150 m length of skid trail section [overland trail]), on two levels of trail gradient (≤20% and &amp;gt;20%) and two soil textures (clay loam and silt loam). Average runoff volume and soil loss per m2 of skid trail surface area were significantly greater (P≤0.05) on silt loam than on clay loam textured soils, and on slope gradients &amp;gt;20% (23–28%) than on gradients ≤20% (5–13%). Average runoff volume increased, and average soil loss decreased significantly (P≤0.05) with increasing density of water bars on both gradients and on both soil textures. On both soil textures, the lowest surface runoff volumes were observed with one water bar and the greatest volumes with six water bars installed. In contrast, the smallest amount of soil loss on both soil textures was observed with six water bars, and the greatest soil loss when only one water bar was installed. The installation of additional water bars led to significant differences in both responses at each level of density and led to reductions in soil loss of 77%, 57% and 27% in the clay loam, and 79%, 60% and 30% in the silt loam soil compared to the single water bar treatment. The reduced soil loss per unit of surface runoff volume is likely due to the reduced velocity of surface water runoff in the skid trail. The greater density of water bars appears to effectively divert more but slower flowing water from the skid trail, leading to reduced soil loss. While additional water bars thus better meet the objective of BMPs to minimize soil loss, managers need to balance the cost of the construction of additional water bars against the ecological benefits of reduced soil loss. An investment into additional water bars may be worthwhile if the additional structures are able to divert surface runoff more effectively to nearby vegetation and reduce the input of soil from skid trails to streams, thereby preventing the loss of water quality of these streams.

The Effect of Li2CO3 on Mechanical and Electrochemical Behavior of Li6.4La3Zr1.4Ta0.6O12 Solid-State Electrolyte

Li6.4La3Zr1.4Ta0.6O12 (LLZTO) is a very promising solid-state electrolyte for all solid-state battery. Due to its high ionic conductivity and chemical and electrochemical stability that can allow to use Li metal as anode with a high energy density as well as enhanced battery safety. However, there is little research to study the intrinsic mechanical properties of LLZTO which is a key factor that will influence the capacity fading and shortened lifetime of battery. In this study, we examine the effect of different densities on the elastic modules, hardness and toughness of Ta substituted LLZO solid-state electrolyte which will result the varieties of the mechanical and electrochemical performance. After annealing, the densities of the sample varied from 85% to 96% with the grain size from 3.5μm to 5.1μm. By introduction of the Li2CO3 additive, the grains become more connected and the number of pores at the grain boundaries becomes much smaller. The grain size rages from 3 to10μm. 5%-LLZTO has more strong grain boundary. It is suggested that the mechanical fracture happened during the Li plating process. Impedance of ion diffusion and electron transfer increase as density increase. Hardness decreases with increasing porosity and increasing grain size. The young’s modulus and the hardness increased from 121.9 to 138.8 Gpa and 4.54 to 11.26 Gpa for the 85% and 96% relative density samples, respectively. The results of this study reveal that the density of LLZTO was influenced by the amount of Li2CO3, so that the mechanical performance can be optimized through the selection of the microstructure, network, and properties of the active materials.

Optimizing Parasitoid and Host Densities for Efficient Rearing of Ontsira mellipes (Hymenoptera: Braconidae) on Asian Longhorned Beetle (Coleoptera: Cerambycidae)

Ontsira mellipes Ashmead is a gregarious larval ectoparasitoid of woodboring cerambycids. It is native to North America but can readily attack the exotic Asian longhorned beetle, Anoplophora glabripennis (Motschulsky). This study aimed to develop an efficient rearing system for this parasitoid, as a potential novel association biocontrol agent for the beetle, by investigating the effects of different densities of host (two, three, or four larvae) and parasitoid (one, two, three, four, five, six, seven, and eight female wasps) on Ontsira's parasitization efficiency and reproductive outcomes. Results showed that overall parasitism and total numbers of parasitized hosts or progeny produced increased with host and/or parasitoid densities, but the number of parasitized hosts or progeny produced per female parasitoid decreased with parasitoid density at each given host density. Nonlinear regression indicated a consistent pattern of mutual interference as parasitoid density increased. Additional experiments showed that superparasitism (indirect interference) did not occur probably because the parasitoid detects hosts through vibration cues from host feeding and attacked (thus paralyzed) hosts are no longer detectable. Thus, the interference probably results from direct or exploitative competition. Interestingly, female parasitoids responded to increased parasitoid density with a significant increase in clutch size. Overall, per capita parasitization efficiency or reproductive outcomes were optimized at a low parasitoid-host ratio but with large group size of hosts and parasitoids. Therefore, an optimal combination of exposing three or four parasitoids to four hosts is proposed for efficient mass-rearing of this parasitoid.