How do visible and UV light affect the structure and function of leaf-associated aquatic fungal communities polluted by TiO2 nanoparticles?

We assessed the phototoxicity of TiO2 nanoparticles on fungal structure and function. The fungal diversity was reduced by long-term exposure. However, the leaf decomposition rate was not inhibited rather than promoted under natural photoperiod.

Whole-Genome Resequencing of Wild and Cultivated Cannabis Reveals the Genetic Structure and Adaptive Selection of Important Traits

Background: Cannabis is an important industrial crop, whose bast fiber, seed, flowers and leaves are widely used by humans，especially cannabinoids extracted from plants as medicine is a hot spot in recent years. China is one of the origins of cannabis, where it has been cultivated and utilized for more than 6000 years, with the largest planting area of industrial hemp at present. China is rich in cannabis germplasm resources covering different latitudes (23 to 51°N) and is one of the few countries with wild cannabis resources. However, the genetic structure of Chinese cannabis populations and the adaptive selection of important traits remain unclear.Results: We identified the main morphological and physiological characteristics of wild cannabis and defined the genetic structure and relationships among wild and cultivated Chinese cannabis accessions and foreign representatives. This suggested that wild resources in Xinjiang have played an important role in the process of cannabis domestication. Adaptive selection analysis revealed that cultivated cannabis has undergone selective evolution or adaptation in flowering, growth and stress tolerance, and many functional genes were identified. Flowering characteristics analysis implied that wild cannabis is native to high latitudes and possesses the typical characteristic of early flowering, while cultivated cannabis has undergone a process of adaptive evolution to adjust to natural photoperiod conditions in different latitudes through regulation of FT-like expression.Conclusion: This study clarifies the genetic structure of Chinese cannabis and provides insight into adaptive selection and breeding in cannabis.

Morphoanatomy of Pangasionodon hypopthalmus Reared Under Controlled Photoperiod

Fish morphoanatomy is affected by environmental condition such as photoperiod duration. A research on the effects of shortened photoperiod on the morphoanatomy of Pangasionodon hypopthalmus has been conducted. There were 3 treatments applied, namely, 24 hours dark (24D), 18 hours dark (18D) and natural photoperiod (control). The fish, 8 cm total length (TL) and 4 gr body weight (BW) were reared in circular plastic tanks filled with 100 L freshwater and completed with aerators and circulation pumps, 30 fishes/tank. The fish was reared for 8 weeks and fed with commercial fish feed pellets, twice/day, at satiation. The dark condition was created by placing the tanks under dark tarp tents. Morphoanatomy data were studied by the end of experiment. Results shown that the survival of fish was 100%. The growth of fish reared in 24D and 18D was better, more than 20 cm TL and 85 gr BW, while that of the control was 18 cm TL and 72 gr BW. The condition factor as well as the liver condition of fish in all treatment was not different, it was around 1.2. The liver was reddish brown color, smooth and oily in which hepatosomatic index (HSI) value 0.023 in 24D; 0.027 in 18D and 0.048 in control. The visceralsonatic index (VSI) was 0.090 in 24D; 0.70 in 18D and 0.161 in control. In most of fishes reared in 24D and 18D, the gonad were in the 1st maturity stage (gonadosomatic index; GSI 0.0058 to 0.0068), while the gonad of some control fishes were in the 2nd maturity stage (GSI 0.0080). Data obtained shown that the morphoanatomical data (HSI, VSI and GSI) of the fish reared in lengthened dark were lower, but the growth data (TL and BW) was higher than those of the control, indicated that the fish reared in dark condition may allocated more energy for growing.

Dusky Grouper Epinephelus marginatus Growth and Survival When Exposed to Different Photoperiods

Photoperiod is considered an environmental factor that influences reproduction and the growth processes of fish throughout the year. In the present study, we subjected dusky grouper Epinephelus marginatus to different photoperiods in order to evaluate growth and survival. Juvenile dusky grouper were randomly distributed in twelve 100 L tanks containing four fish per aquarium. The fish were exposed to continuous light, normal photoperiod or continuous darkness for 50 days. Fish were fed 3% of their total biomass, twice a day, and the diet consisted of ground commercial dry pellets (42% crude protein, 12% humidity, 9% ether extract, 15% mineral matter, 4% crude fiber, 3.5% calcium and 3% vitamin C, in accordance with the manufacturer’s instructions). There was no mortality during the experiment. After 50 days, the best performance was found for exposure to continuous light (24 h artificial light). The final weight of the fish reared under continuous light was significantly higher than that of the fish exposed to continuous darkness. The specific growth rate of the fish exposed to continuous light was significantly higher than that of the fish exposed to the natural photoperiod and to continuous darkness. Modifications to the photoperiod can be a key factor in increasing the efficacy of current production and the improvement of current aquaculture protocols.

Sexual Maturation in Farmed Atlantic Salmon (Salmo salar): A Review

The sexual maturation of Atlantic salmon Salmo salar is a multifactorial process in which fish acquire somatic characteristics to reproduce. In salmon farming has been described a high variability in the trait age at maturation derived from wild reproductive strategies. Early maturation is a phenotype that generates serious economic repercussions on both, sea cage and on land-based aquaculture systems. In view of the challenges of this problem for the global salmon farming industry, it is essential to thoroughly understand the influencing factors of early and late maturation to find efficient alternatives for managing the phenomenon. This review briefly describes sexual maturation in S. salar, its variability in cultures, and the factors influencing the maturation age trait at the physiological, genetic and environmental levels. The control of early maturity through changes to the natural photoperiod and through the use of genetic markers are discussed.

Survival and growth of Pangasianodon hypophthalmus cultured under controlled photoperiod

Changing in photoperiod duration may affects the physiology of nocturnal fish such as Pangasianodon hypophthalmus. A study aims to understand the effects of controlled photoperiod towards survival and growth of P. hypophthalmus has been conducted from June to August 2020. There were 3 treatments applied, namely natural photoperiod, 18 hours dark (18D), and 24 hours dark (24D) with 3 replications in each treatment. The rearing tanks used in this study were 100 L circular plastic tanks. In 24D treatment, the tanks were placed under dark colored tarp tent continuously. For the 18D treatment, the tanks were placed under dark tarp tent, but the tent was opened for 6 hours/ day (the tanks were in dark condition for 18 hours/ day), while the control tanks were positioned under natural photoperiod. P. hypophthalmus fingerlings, 6-8 cm TL and 4-5 g BW were used in this study. Thirty fishes were reared in each rearing tank, they were feed with commercial pellets, 2 times/day, at satiation. Fish survival was monitored every day, while samplings for fish growth were conducted weekly for a 8 weeks period. Results indicate that the survival of fish was 100% in each treatment applied. Fish growth, however, shown differences. The growth of fish reared in 24D and 18D was better than that of the control. By the 9th week, the fish in 24D was around 70.71g BW with 19.27 cm TL (daily growth rate 9.35%), while those of the 18D was 69.41 g BW, 18.77 cm TL and 9.29% daily growth rate. The fish reared under natural photoperiod was around 61.95 g BW with 18.19 cm TL and 7.33% of daily growth rate. Data obtained indicate that the application of longer dark is positively improve the growth of P. hypophthalmus.Keywords:Nocturnal FishLight Dark Catfish

Water quality and growth of juvenile specimens in giant freshwater prawn Macrobrachium rosenbergii (De Man, 1879) cultures applied in recirculation and biofloc systems

Biofloc research commenced in the late 1970s, with the white shrimp Litopenaeus vannamei and the Nile tilapia Oreochromis niloticus the most commonly studied species. The present study evaluated M. rosenbergii cultures in recirculation and biofloc systems by comparing the water quality and productive performance of juveniles in both systems. The study was based on a simple randomized experimental design with a recirculation and biofloc treatment, each conducted in triplicate. The initial length and weight of the organisms was 1.04 cm and 0.31 g (recirculation) and 1 cm and 0.30 g (biofloc), respectively, while the bioassay, which lasted nine weeks, was undertaken in a salinity of 5 ppm with a natural photoperiod (12:12). The present study monitored basic variables corresponding to the water, survival, growth (in weight), and the composition of the plankton.The basic variables of the water (temperature, salinity, and pH) were kept within the recommended range for the culture. Of the plankton observed in the biofloc, nematodes, rotifers, cyanobacteria, ciliates, heliozoa, and dinoflagellates predominated. The organisms grown in the recirculation system reached 5.35 cm in length and 1.28 g in weight, while those grown in the biofloc reached 5.18 cm and 2 g, with significant differences in individual weight observed. Survival in the recirculation and biofloc systems was 73% and 60%, respectively, with significant differences observed. It is concluded that, although the survival rate was higher in the recirculation system, the weight of individual organisms was higher in the biofloc treatment.

Flexibility and Control of Circadian Activity, Migratory Restlessness and Fueling in Two Songbird Migrants

Juvenile songbirds rely on an endogenous program, encoding direction, distance, fueling, and timing of migration. Migratory distance is species-specific, expressed as a period of migratory restlessness, for which the length is correlated with distance, while fueling is modified to meet anticipated flight distances controlled by geomagnetic cues and amount of day-light available for foraging. How daylength affect onset and level of migratory activity and fueling decisions in wild birds have so far received limited attention. Here we study how photoperiod controls onset, level and extent of autumn migratory activity and fueling in juvenile diurnally migrating dunnocks, and nocturnally migrating European robins by experimentally increasing daylength. For both species, we kept a control group indoors at the location of capture in southern Sweden exposed to the natural photoperiod, and an experimental group with increased and advanced photoperiod by 2 h in the morning. Dunnocks initiated migratory activity at sunrise (or artificial sunrise) in both groups, demonstrating a highly responsive and flexible component for the onset of migration triggered by light. Experimental robins anticipated the end of nocturnal migratory activity predicting the earlier sunrise immediately after the time-shift and expressed this behavior already under darkness, supporting a fast-resetting mechanism to the new diel period. Timing of end of morning activity was not affected by the earlier sunrise in both species, suggesting a fixed endogenous control that persisted throughout the 13-day study period. Experimental dunnocks expressed higher overall activity and lower fuel loads than controls, while robins did not change their overall activity and fuel load in response to the shifted and increased photoperiod. These results reveal important adaptations for circadian timekeeping including both a flexible onset open to fast modifications and a more rigid end, with differential effects by the treatment on migratory activity and fueling in the two species.

Effect of Photoperiod Manipulation on Spawning Time and Performance of Turbot (Scophthalmus maximus)

Temperature and photoperiod are known as the main stimuli of seasonal reproduction in fish. Turbot (Scophthalmus maximus) is a spring spawning teleost fish species with a promising aquaculture potential and high market value. This study was conducted to assess the effect of photoperiod manipulation on spawning time and spawning performance of turbot. A total of 28 mature turbots from the Black Sea population were subjected to manipulated photoperiod (a photoperiod regime that fish would naturally receive three months later) and natural photoperiod for almost a year. While the fish exposed to natural photoperiod spawned in May, the fish exposed to manipulated photoperiod spawned almost three months earlier compared to the natural photoperiod group. Reproductive and hatchery performance of the manipulated photoperiod and natural photoperiod groups were similar. It can be emphasized that photoperiod play an important role in accelerating maturation and spawning. The findings of this study could be implemented in the turbot aquaculture industry to advance production.