Thorhaugejohnston3969

The variations of life history traits have been observed for many fish species, which gains much concerns in the study of aquatic biology and ecology. In this study, the biological characteristics were explored for yellow croaker (Larimichthys polyactis) in the offshore waters of southern Zhejiang, based on 4920 individuals collected from 13 fishery-independent seasonal surveys from autumn 2015 to autumn 2018. Linear mixed effects models were used to estimate the growth, maturity characteristics, and their heterogeneity. The body length of yellow croaker samples ranged from 13 to 215 mm with the dominant body of 110 to 154 mm. click here The body weight ranged from 0.5 to 182.2 g, with the dominant body weight from 20 to 55 g. The results showed that the linear mixed effects models with random effects from season, gender, and year performed best for length-weight relationship, with the lowest AIC and RMSE values. The effects of season were much larger than those of genders and years. When the length exceeded 160 mm, the weight gain rate of yellow croaker was faster in spring and summer, lower in autumn and winter, while the male individuals gained more weight than the females with the same body length. Among 4841 individuals of specimens with gonadal data, the individuals at maturity Ⅱ stage occupied 50.4%, and the individuals at maturity stage contributed to 19.6%. The results from the best linear mixed effects model showed that season had the most significant influence on the maturity of yellow croaker. The 50% maturity length (L50%) was much lower in winter (124.6 mm) with no much difference between other seasons, indicating that yellow croaker matures earlier in winter. Our results indicated that linear mixed effect model could reflect the biological heterogeneity of yellow croaker conveniently and that the growth and maturity of yellow croaker had significantly sexual and temporal variations, which should be considered in the stock assessment and fishery management for yellow croaker.Bird strike accidents mainly occur in the airport area. Reducing bird activities through bird repeller equipment is one of the main measures to prevent bird strike. In this study, two bird species with high-risk, pigeon (Columba livia domestica) and kestrel (Falco tinnunculus), were selected as the subjects and the gas gun and directional acoustic bird repeller were selected as the evaluation objects in Shenyang Taoxian International Airport. This study aimed to examine the behavioral responses of birds at different distances during the normal operation of these equipment to explore their effective distance and effects. The results showed that the vigilant and escape behaviors of pigeons and kestrels at 10 m and 30 m away from the gas gun bird repeller which were significantly higher than those of the control, while the number of these behaviors at 50 m away was not significantly different from that of the control. Pigeons and kestrels at 50 m and 100 m away from the directional acoustic bird repeller could significantly increase their vigilant and escape behaviors, whereas the repeller could significantly cause kestrels to increase their vigilant behavior at 300 m away. We concluded that the effective bird expel distance of the gas gun was 30 m, and the directional acoustic bird repeller could effectively expel to 300 m, and that the effect of the directional acoustic bird repeller on birds was stronger than the gas gun. Our results could provide a reference for the introduction and rational use of bird expel equipment in the airports.In order to evaluate the effects of polystyrene microplastics (PS-MPs) on the growth, physiology, and biochemical characteristics of submerged plants, we exposed a typical submerged plant, Hydrilla verticillata, to a series of concentrations (i.e. 0, 5, 10, 30, 50, 100 mg·L-1) of 3 μm polystyrene microplastics (PS-MPs) and measured parameters including height, biomass, chlorophyll content, antioxidant enzyme activity, photosynthetic fluorescence. The results showed that the height of H. Verticillata significantly decreased at the high PS-MP concentrations (50 to 100 mg·L-1), while the fresh weight significantly increased at the low PS-MP concentration (5 mg·L-1). The fresh weight of H. verticillata gradually decreased with the increasing PS-MP concentration but the dry weight did not change. The total amount of chlorophyll, chlorophyll a, and chlorophyll a/b significantly decreased with the increases of the PS-MP concentrations, while the chlorophyll b did not change. PS-MPs affected the antioxidant enzyme aced at high concentrations (>30 mg·L-1). Our results provided basic information to better understand the eco-physiological effects of PS-MPs in the freshwater environment.To reconstruct the deposition rate of polychlorinated biphenyls (PCBs) in different historical periods and to examine the temporal and spatial trend of PCBs pollution, we analyzed the changes of PCBs concentration and deposition rate in peat cores and lake sediments, and evaluated the suitability of peat cores and lake sediments for studying PCBs deposition trend. Through the dating analysis of all samples, we found that peat bog could well record the historical sedimentation of PCBs. PCBs did not degrade in peat, and it was thus feasible to use peatland to examine the settlement of PCBs. In this study, the reconstruction time of ∑11PCBs in peat was from the beginning of 19th century to the beginning of 21st century. The mean inventory of ∑11PCBs in three peat cores of each bog changed between (37.0±5.4) and (47.2 ±27.8) μg·m-2, with the standard deviation between 14.9% and 58.9%. The highest concentration of ∑11PCBs was 6.8 ng·g-1DW, while the maximum deposition rate of reconstructed PCBs was up to 989.7 ng·m-2·a-1. The trend of deposition rate was first increasing and then decreasing. After the year 1980, the deposition rate was substantially decreasing, which was consistent with the prohibition of PCBs production in the United States in 1979. Meanwhile, the analysis of sediment samples in the lake near bog showed that concentration and maximum deposition rate of the lake sediment were comparable to those of the nearby bog. The concentrations of Di- to Hepta-PCB congeners were evenly distributed along the sediment profile. Therefore, lake sediments could not be used to analyze the historical sedimentary model of low order PCBs. This study reconstructed temporal and spatial variation of PCBs in atmospheric environment in different historical periods, which could provide basic data for the evaluation of regional environmental quality.