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Effects of temperature on survival and growth of Paphia textile juveniles
WU Jiaying, DAI Mingshu, LIU Zhigang, LIU Xiaokun
, Available online  , doi: 10.12131/20220155
Abstract:
In this study, we observed the effects of temperature on the survival and growth of Paphia textile juveniles by using experimental ecological methods, so as to provide references for the selection of the intermediate breeding site of the juveniles. The results show that: 1) The 48 h semi-lethal low and high temperatures were 4.95 and 33.39 ℃, respectively; the semi-lethal low and high temperatures at 96 h were 8.68 and 32.49 ℃, respectively; the 15 d semi-lethal low and high temperatures were 12.09 and 31.02 ℃, respectively. 2) At 10 ℃, the juveniles all died on the 10th day, and at 32 ℃, the survival rate of the juveniles on the 15th day was only 16.67%. 3) Taking the high and low temperatures of 50% of individuals which survived stably within 15 d as the critical temperature for survival, we found that the suitable survival temperature range of the juveniles was 12.09–31.02 ℃. Based on the group or groups with the highest survival rate (No significant difference between groups), the most suitable survival temperature range of juveniles was 14–28 ℃. 4) Based on the high and low temperatures corresponding to the average daily growth of 30% of the optimal group, the suitable growth temperature range of juveniles was 16.62–31.14 ℃. Based on the group or groups with the highest average daily growth (No significant difference between groups), the most suitable growth temperature range of juveniles was 24–28 ℃, and the optimal growth temperature was obviously biased towards the high temperature side within the suitable survival temperature range. In conclusion, it is inferred that P. textile juvenile is suitable for underwater bottom sowing in the southern sea area with a subtidal water temperature below 31 ℃.
Effect of five factors on removing ammonia nitrogen and nitrite by Rhodococcus ruber HDRR2Y fermentation
XU Yu, HU Xiaojuan, ZHANG Song, XU Wujie, SU Haochang, WEN Guoliang, CAO Yucheng
, Available online  , doi: 10.12131/20220044
Abstract:
The bacteria Rhodococcus ruber is usually used in waste water and sewage treatment. In order to discuss the effect of environmental factors on R. ruber HDRR2Y's removing ammonia nitrogen and nitrite, we added the culture medium of R. ruber strain HDRR2Y to the aquaculture water containing high concentration of ammonia nitrogen (\begin{document}${\rm{NH}}_4^+ $\end{document}-N) and nitrite (\begin{document}${\rm{NO}}_2^- $\end{document}-N), and observed the changes of ammonia nitrogen and nitrite concentrations by the national standard method, so as to investigate the effect of the culture medium on the removal of ammonia nitrogen and nitrite. In addition, we carried out the Plackett-Burman experimental design according to five factors: temperature, rotating speed, salinity, inoculum amount, substrate (Ammonia nitrogen and nitrite) concentration, to explore the effect of these factors on the removal of ammonia nitrogen and nitrite by R. ruber. The results show that during the fermentation process, the mass concentration of strain HDRR2Y increased from 5×104 CFU·mL−1 to 4.08×109 CFU·mL−1 in the initial 36 h. After adding the culture medium, the mass concentration of ammonia nitrogen decreased from 15 mg·L−1 to 5.56 mg·L−1, with a removal rate of 62.96%, and that of nitrite decreased from 15 mg·L−1 to 6.95 mg·L−1, with a removal rate of 59.37%. Among the five factors, temperature and ammonia nitrogen concentration had the most significant effects on the removal of ammonia nitrogen by strain HDRR2Y (P<0.05) (Temperature>ammonia nitrogen concentration>rotation speed>biomass>salinity). Temperature and rotating speed were the two most significant factors affecting the removal of nitrite (P<0.05) (Temperature>rotating speed>salinity>nitrite concentration>bacterial count). It is showed that the culture medium of strain HDRR2Y is good for removing ammonia nitrogen and nitrite, and temperature is the most significant factor affecting the efficiency of HDRR2Y in removing ammonia nitrogen and nitrite.
Influence of statistical deviation of historical catch on stock assessment: a case study of western Atlantic Thunnus thynnus
FENG Ji, ZHU Jiangfeng, ZHANG Fan, LI Yanan, GENG Zhe
, Available online  , doi: 10.12131/20220037
Abstract:
Catch data, which is the most basic data required for stock assessment, is also most likely to cause reporting and statistical errors. Misreporting is one of the causes for statistical deviation of historical catch, which is currently prevalent in all types of fisheries worldwide. Analyzing the influence of statistical deviation of historical catch on stock assessment based on historical data helps to establish reasonable management objectives, and promote sustainable utilization of fishery resources. In this study, we selected western Atlantic bluefin tuna (Thunnus thynnus) as an example to evaluate the influence of statistical deviation of historical catch on its stock assessment. We carried out a stock assessment by using Age-Structured Assessment Program (ASAP), and investigated the effects of catch information inaccuracy on the assessment results by setting different levels of statistical deviation of historical catch. The results indicate that the estimated values of fishing mortality (F) and spawning stock biomass (SSB) changed in the same direction with the adjusted catch. With the increase of statistical deviation of catch, the relative difference of biological reference points also increased. The relative deviation rate of F-related biological reference points was less than 1% under all eight assumed statistical deviations of catch. When the statistical deviation of the historical catch was assumed as −20%, the maximum relative difference of SSB-related biological reference points was about 4%. The statistical deviation of catch had a more obvious impact on SSB-related biological reference points than F-related biological reference points. In conclusion, it is suggested to strengthen the source analysis of catch data quality issues, so that the scientific reconstruction of historical fishery data can be conducted to improve the accuracy and reliability of the stock assessment results.
Comparative analysis of nutritional composition of muscle from Siganus oramin living in different habitats
YANG Yukai, HUANG Xiaolin, SHU Hu, LIN Heizhao, WANG Lan, XUN Pengwei, YU Wei, HUANG Zhong, LI Tao
, Available online  , doi: 10.12131/20210345
Abstract:
To provide basic data for the production of Siganus oramin formula feed, we measured the general nutritional composition, amino acids and fatty acids in the muscle of S. oramin from industrial farming, high pond farming and the wild by means of biochemical analysis, investigated the effects of habitat on muscle the nutrition and quality of S. oramin. The results show that compared with the wild fish, the contents of crude protein and crude lipid were higher but those of ash and moisture were lower in the muscle of the farmed fish, and the crude fat content in the industrial farmed fish was significantly higher than that of the other groups (P<0.05). Moreover, there were 17 common amino acids in the three kinds of fishes. Among them the glutamate content was the highest. Among the essential amino acids (EAA), lysine had the highest content. The essential amino acid index (EAAI) was highest in high-pond farmed fish but lowest in the wild fish. Furthermore, there were 26 species fatty acids in the two kinds of farmed fish but only 24 species were found in the wild fish. The contents of polyunsaturated fatty acids (PUFA), n-6 series C18:2n6c were highest in the two farmed fishes, while those of the C22:6n3 (DHA) and C20:5n3 (EPA) of n-3 series were significantly higher in the wild fish. The ratio of n-3/n-6 and the content of DHA+EPA in the wild fish were significantly different from the two farmed fishes (P<0.05). Thus, it is revealed that the farmed S. oramin's nutrition and flavor are better than the wild ones, but they lack n-3 PUFA such as DHA and EPA.