Development of low‐lipid formulated feeds with different protein/energy ratios for Octopus vulgaris ongrowing

We studied the feeding and growth rates, feed efficiency and nutritional composition of subadult octopuses (689 ± 77 g) fed low‐lipid diets with two different protein/energy ratios (P/E): Medium P/E diet (30.5 g protein MJ^?1, 662 g kg^?1 protein dry weight (dw)) or High P/E diet (36.8 g protein MJ^?1, 843 g kg^?1 protein dw). Survival was 100% for the Medium P/E and 87.5% for the High P/E diet. The specific feeding rates were 1.91% and 1.67% body weight day^?1 for the Medium P/E and High P/E diet, respectively (P < 0.05). The specific growth rates (0.92% and 1.25% body weight day^?1), feed efficiency indices (47.3% and 72.7%), productive protein value (23.9% and 29.1%) and digestive gland index (5.6% and 6.4%) were significantly better in animals fed the High P/E than the Medium P/E diet (P < 0.05). The proximate composition of the digestive gland was similar for both diets, but the total lipid content of carcass was higher in animals fed the Medium P/E diet (P < 0.05). Our results suggest that the protein content of the feed could be a factor regulating feeding rates in octopus.     

All lives matter. An analysis of internationals' living conditions in Seoul,Korea, using an extended image–satisfaction–loyalty mechanism

We indirectly analyze the residential environment for long-staying internationals in Seoul, Korea, by extending the image–satisfaction–loyalty mechanism widely used in tourism, specifically by examining the internationals' satisfaction and loyalty. We consider residential difficulties, sociodemographics, and survey years along with image as exogenous variables and evaluate satisfaction not only in terms of its absolute but also its relative level, which is the difference between absolute satisfaction (AS) and previous expectation. Tourism studies have measured loyalty using individuals' intention to recommend to another and their own revisit intention, but we evaluate the revisit intention with place attachment/hometown perception, which is more suitable for long-staying residents. The variables are measured with 2016–2018 data from an annual quality of life survey for Seoul residents (n = 5279 individuals) and analyzed with structural equation modeling. Our results show that the conventionally used AS is associated only with recommendation intention, but the relative satisfaction (RS) both with recommendation intention and hometown perception. Regarding the exogenous variables, AS is substantially affected by image and RS is somewhat strongly influenced by residential difficulties. However, image is the principal determinant of loyalty level, whether recommendation intention or hometown perception. These findings confirm the applicability of the image–satisfaction–loyalty mechanism not only to short-staying inbound tourists but also to long-staying international residents.     

The corona blues according to daily life changes by COVID-19: A partial least squares regression model

This study identifies determinants of the variation in depression resulting from COVID-19, specifies in detail the changes to daily life, and then compares the determinants' magnitude. The determinants were combined into three groups: first, the unpredictability of the disease and side effects by its response measures (specifically, restrictions on the freedom of movement and strain on social relationships); second, (mis)information through social media, public authorities, and mass media; and third, income reductions and other sociodemographic factors. Daily life changes were divided into four categories: travel/mobility, time at home (alone and with family), domestic activities (remote work, online shopping, food deliveries, reading, and online networking), and conflicts (with family and neighbors). We measured the total 29 predictors using data from the 2020 Seoul Survey, which is based on face-to-face interviews with a probability sample of adult residents. We made our estimations using partial least squares regression, which can analyze all original variables regardless of collinearity. The regression model found that major stressors include declines in out-of-home offline networking and the rise of domestic activities—and subsequent conflicts with family—restrictions on mobility (specifically, those of leisure travel), and income reductions. In contrast, changes to working and shopping (to remote work and online shopping) rather than leisure increased uses of private transportation modes. Moreover, we found influences of all forms of communications and media to be insignificant. We shall also provide a discussion on policy and academic implications of the findings.     

Rearing equipment on the quality aspects and growth performance of Crassostrea gigas (Thunberg, 1793): Implications for marketability

Shell characteristics and consequent marketability of the oyster Crassostrea gigas are influenced by several factors, and most important of which are the rearing methods and gears. In this study, we investigated the effects of two different gears on the quality aspect (shell shape, weight meat percentage, backward shell shape, epibionts and blisters) and growth rate (weight and length) of C. gigas by adopting the innovative Ortac Oyster Farming System, during the field grow‐out phase of production. Aspect and growth of oysters farmed in Ortac and floating bags were compared. After 14 weeks, the aspect of the animals was influenced by the gear, resulting in a lower quality in the Ortac (i.e. worse shell shape, lower weight meat percentage, higher percentage of backwards and blisters) than in the floating bag, while the incidence of epibionts was less in the Ortac. Regarding the growth performance, total wet weight gained in the Ortac was lower (~28.3 g) than in the floating bag (~32.4 g; p < .05). These results highlight the efficiency of the floating bag as oyster rearing system in the Mediterranean basin and suggest the need to alter the Ortac gear to these environmental conditions.     

Effects of pulsed electric fields on the bioactive compound content and antioxidant capacity of tomato fruit

The effect of moderate intensity pulsed electric fields (MIPEF) on the bioactive compounds (total polyphenol, lycopene, and vitamin C content) as well as on the antioxidant capacity of tomato fruit was studied. The MIPEF treatment conditions were optimized to obtain tomato fruit with a high content of bioactive compounds. Tomato fruits were subjected to different electric field strengths (from 0.4 to 2.0 kV/cm) and number of pulses (from 5 to 30) and then immediately refrigerated at 4 °C for 24 h. A concentration of bioactive compounds higher than that of untreated tomatoes was obtained in MIPEF-treated tomatoes. A 44% increase in total polyphenol content was achieved under 30 pulses at 1.2 kV/cm. The hydrophilic antioxidant capacity was also enhanced by 44% applying 18 pulses at 1.2 kV/cm, and the lipophilic antioxidant capacity was increased by 37% under 5 pulses at 1.2 kV/cm. The maximum overall level of bioactive compounds and antioxidant capacity in the treated tomatoes was obtained under 16 pulses at 1 kV/cm. Therefore, MIPEF treatments could be considered an effective method to enhance the bioactive compound content and antioxidant potential of tomatoes.     

Effectiveness of a Full-Scale Constructed Wetland for the Removal of Metals from Domestic Wastewater

The mobility of fluorescein and bromide used as tracers in packed soil columns was investigated. Five different soils were used in two application methods: soil surface application and soil incorporation, both of which simulate accepted methods of soil application of termiticides to prevent structural infestation. The breakthrough of bromide and fluorescein in column eluates were measured. The absorbance of fluorescein at 492 nm was pH dependent, and proper adjustments were made after measuring the eluate pH. Although high recoveries of bromide from the soil columns were observed, the breakthrough was different among the soil types, indicating that bromide behaves differently in different soils. Recovery of fluorescein, a weak acid, varied depending upon the pH of the soil used, and was only observed in the eluates of two of the five soils tested. Soil treated with bromide and fluorescein followed by soaking extraction showed high recovery of bromide but low recovery of fluorescein, except for in the most alkaline of the soils tested. If fluorescein is used as a conservative tracer in pesticide soil mobility studies, mobility can be underestimated in acidic soils because the active ingredient might travel more quickly than does the fluorescein.     

The multi-functionality of paddy farming in Korea

The multi-functionality of paddy field and irrigation water has become a hot issue recently in Asian monsoon regions. Asian people know why they have to conserve the paddy farm where the sustainable functions have been historically inherited and maintain the rural community where the unique cultures have been traditionally created. But, the real value of multi-functionality has not been clearly highlighted as much worthy as it has. We should evaluate the characteristics of multi-functionality of paddy farming correctly and transmit them to the people of Western countries under quite different conditions of upland fields. In Korea, several studies on the multi-functionality of paddy farming have been performed with positive and negative viewpoints. This paper shows the results and the discussion of the researches to get global recognition on the multi-functionality of paddy farming.

Replacement of Artemia franciscana Nauplii by Microencapsulated Diets: Effect on Development,Digestive Enzymes,and Body Composition of White Shrimp,Litopenaeus vannamei,Larvae

The effects of two microencapsulated feeds were evaluated on development, growth, survival, proteolytic activity, and biochemical composition of white shrimp, Litopenaeus vannamei, larvae. The treatments were: (1) basal microcapsules (BM), (2) microcapsules containing krill hydrolysate (BMK), and (3) live food control (LFC: Artemia franciscana nauplii) with all treatments receiving algae (Chaetoceros ceratosporum and Tetraselmis chuii). No significant differences were found in development index and survival among larvae. Growth rate was significantly higher in larvae fed LFC (15 ± 0.06%/d) as compared with those offered the BM diet (7.5 ± 0.5%/d) with the BMK (11 ± 0.04%/d) treatment producing intermediate results. The activity of total proteases and chymotrypsin decreased significantly after Mysis I (M_I) in larvae fed LFC or BMK. Protein content of larvae increased significantly toward PL₁. The acylglycerides content in M_III fed on LFC (2.3 ± 0.2%/dw) was higher than that M_I fed BM (1 ± 0.01%/dw). No difference was observed in the cholesterol (CH) content of the larvae. The acylglycerides/protein and cholesterol/protein ratios showed a decreasing pattern between M_I and PL₁, indicating that these two ratios were related to ontogenetic shifts. These results demonstrate improvements in microparticulate diets when krill hydrolysates are included in the formulation.     

Effect of larval and prey density, prey dose and light conditions on first feeding common dentex (Dentex dentex L.) larvae

Initial larval stocking density, prey density, daily prey ration and light conditions (light intensity and photoperiod) were tested for common dentex larval rearing under experimental conditions. Experiments continued until the first peak of larval mortality. The best results in larval survival were obtained with an initial stocking density of between 10 and 40 larvae L^?1, fed with at least 10 rotifers mL^?1, maintaining ratios of 500–1000 rotifers larva^?1, with one or two adjustments of prey density per day. The use of more than 2000 rotifers larva^?1 or three daily adjustments of live prey density had negative effects on larval survival. The best light conditions for common dentex larval rearing were found using a photoperiod of 24 h L:0 h D and an intensity of at least 3.4 μmol m^?2 s^?1.