scholarly journals Variation in environmental characteristics of waters among Amazon coast oyster culture units

2020 ◽  
Vol 50 (4) ◽  
pp. 295-304
Author(s):  
Dioniso de Souza SAMPAIO ◽  
Maria de Lourdes Souza SANTOS ◽  
Claudia Helena TAGLIARO ◽  
Colin Robert BEASLEY
Keyword(s):  
Seasonal Variation ◽  
Dissolved Oxygen ◽  
Dry Season ◽  
Wet Season ◽  
Environmental Characteristics ◽  
Oyster Culture ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Tidal State ◽  
Management And Conservation

ABSTRACT Oyster culture has benefited traditional coastal communities along the Amazon macrotidal mangrove coast of Pará state in Brazil since 2006. Currently, seven oyster culture units in five municipalities are expanding production, but with no environmental monitoring, which is important for the control of the impacts of oyster culture on waters as well as for oyster management and conservation. Seasonal variation in environmental characteristics of the water was evaluated at all oyster culture units in Pará, from September to November 2013 (dry season) and February to April 2014 (wet season), to generate baseline data to evaluate future impacts and aid strategic planning, such as diversifying seed production. Salinity, dissolved oxygen, pH, oxidation-reduction potential, depth, temperature, and chlorophyll-a concentration were measured during flooding and ebbing tides, and compared between seasons and among culture units using uni- and multivariate statistics. All variables were significantly higher in the dry season, except depth, which was significantly greater in the wet season. Mean salinity, which varied from 2.4 to 46, explained most of the variation among culture units in relation to season, sampling date within each season and tidal state. However, dissolved oxygen, pH and depth were also important. Oyster culture units in Pará may be suitable for sustainable harvesting of seed/spat from the wild (lower salinity and pH), or for on-growing (higher salinity, higher pH, and greater depth). Seasonal variation is sufficient to allow both activities at most units at appropriate times of the year, which would help increase oyster production in Pará.

Experimental considerations on monitoring ORP, pH, conductivity and dissolved oxygen in nitrogen and phosphorus biological removal processes

2001 ◽  
Vol 43 (11) ◽  
pp. 197-204 ◽  
Author(s):  
A. Spagni ◽  
J. Buday ◽  
P. Ratini ◽  
G. Bortone
Keyword(s):  
Dissolved Oxygen ◽  
P Uptake ◽  
Biological Nutrient Removal ◽  
Effective Control ◽  
Monitoring And Control ◽  
Nitrogen And Phosphorus ◽  
Ph Variation ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Removal Processes

An experimental study on monitoring Oxidation Reduction Potential (ORP), pH, Conductivity and Dissolved Oxygen (DO) in an Enhanced Biological Nutrient Removal process has been carried out. In the anaerobic phase, while ORP and conductivity were not reliable in monitoring simultaneously denitrification and P-release, pH showed the best performances. A significant relationship between P-released and pH variation was found. During the aerobic phase both ORP and pH were able to monitor successfully the nitrification, even though pH was much more reliable. pH can be also used for monitoring and control enhanced P-uptake. It has been concluded that, for a reliable and effective control of biological N and P removal processes a more sophisticated control system seems to be necessary.

scholarly journals Seasonal variation in quality of Louhajong river water, Tangail

2016 ◽  
Vol 28 (1) ◽  
pp. 9-16
Author(s):  
Md Rakib Hasan Sarker ◽  
Asadul Islam ◽  
Ariful Islam ◽  
Md Mahbubul Hoque ◽  
Shimul Roy
Keyword(s):  
Seasonal Variation ◽  
River Water ◽  
Water Samples ◽  
Dry Season ◽  
Fish Culture ◽  
Chemical Parameters ◽  
Wet Season ◽  
Physico Chemical ◽  
Standard Level

Water samples were collected from three points of Louhajong river (Dighulia, Kagmari Bridge and Oloa) to see the seasonal variation in physico-chemical parameters. The results revealed that some of the parameters such as TDS, alkalinity and acidity have exceeded the standard level in dry season in all of the points, which are unsuitable for different purposes including fish culture. During dry and wet seasons the highest concentrations of BOD was recorded as 2.0 and 0.8 ppm at Kagmari Bridge (point-2) respectively. DO ranged from 1.4 to 3.1 and 2.4 to 3.8 ppm during dry and wet seasons. Maximum and minimum EC was recorded as 890 and 130 ?s/cm at Dighulia (point-1) during dry and wet seasons. The results suggest that at wet season Louhajong river may be suitable for fish culture and other purposes.Bangladesh J. Sci. Res. 28(1): 9-16, June-2015

scholarly journals THE EFFECT OF SEASONAL VARIATION ON PERFORMANCE OF EGG TYPE POULTRY: A Case Study of Mitchell Farms, Mosogar, Delta State, Nigeria

2021 ◽  
Vol 24 (2) ◽  
pp. 101-105
Author(s):  
E. E. Guobadia
Keyword(s):  
Seasonal Variation ◽  
Feed Intake ◽  
Egg Production ◽  
Management Practices ◽  
Secondary Data ◽  
Dry Season ◽  
Wet Season ◽  
Egg Hatchability ◽  
Significant Difference

The study was designed to find out the effect of seasonal variation on poultry in Delta State of Nigeria. The variables considered were mortality rate, feed intake, egg production and egg hatchability in the wet and dry seasons of the year. Secondary data were also collected from records kept in the farm. Sites 4AHI-BLK,5AKI-BLK, 9H/BF and 10H/BF were used for the study with each having an average of 2,500-3,500 birds of the same breed and sex aged 1-9 weeks and 21-52weeks. The records were grouped into dry season (October-March) and wet season (April-September) covering three years, 1991-1994. The analysis of the result showed that seasonal variation does not have any significant effect (P < 0.05) on mortality and feed intake in the two seasons. However percentage egg production and egg hatchability revealed a significant difference (P < 0.05) between the two seasons, with a mean % egg production and hatchability of 74±.03 and 80.6 in the wet season and 53.67±0.01 and 55.9 respectively in the dry season. Recommendation is therefore made for proper planning which ensures the utilization of wet and dry season management practices to reduce the effect of high humidity and embient temperature on production.

scholarly journals The Cost of Reproduction in a Cooperatively Breeding Mammal: Consequences of Seasonal Variation in Rainfall, Reproduction, and Reproductive Suppression

2021 ◽  
Vol 12 ◽  
Author(s):  
Paul Juan Jacobs ◽  
Daniel William Hart ◽  
Tobias Suess ◽  
Andries Koch Janse van Vuuren ◽  
Nigel Charles Bennett
Keyword(s):  
Oxidative Stress ◽  
Seasonal Variation ◽  
Cost Of Reproduction ◽  
Dry Season ◽  
Breeding Period ◽  
Wet Season ◽  
Reproductive Suppression ◽  
Mole Rat ◽  
Cooperatively Breeding ◽  
The Cost

Biological investments, such as reproduction, are influenced by both biotic and abiotic factors and their interactions. The trade-off between reproduction and survival has been well established. Seasonally breeding species, therefore, may exhibit variations in these trade-offs, but there is a dearth of knowledge concerning this. This study investigated the physiological cost of reproduction (measured through oxidative stress) across seasons in the cooperatively breeding highveld mole-rat (Cryptomys hottentotus pretoriae), one of the few seasonal breeding mole-rats. Oxidative stress indicates elevated reactive oxygen species (ROS) levels, which can overwhelm antioxidant defences resulting in damaged proteins, lipids and DNA, which overall can reduce longevity and compromise reproduction. Oxidative markers such as total oxidant status (TOS-measure of total peroxides present), total antioxidant capacity (TAC), oxidative stress index (OSI), and malondialdehyde (MDA) are utilised to measure oxidative stress. In this study, breeding and non-breeding male (NBM) and female mole-rats were captured during the dry season (breeding period) and wet season (non-breeding period). There was an apparent cost of reproduction in the highveld mole-rat; however, the seasonality pattern to the cost of reproduction varied between the sexes. Breeding females (BFs) had significantly higher MDA during the breeding period/dry season in comparison to the non-breeding period/wet season; this is possibly a consequence of bearing and nursing offspring. Contrastingly, breeding males (BMs) showed increased oxidative damage in the non-breeding/wet season compared to the breeding/dry season, possibly due to increased activities of protecting their mating rights for the next breeding/dry season, but this was not significant. Interestingly, during the non-breeding period/wet season, non-breeding females (NBFs) are released from their reproductive suppression, which resulted in increases in TOS and OSI, which again indicated that just the mere ability to be able to breed results in a cost (oxidative stress). Therefore we can speculate that highveld mole-rats exhibited seasonal variation in redox balance brought about by variation in abiotic variables (e.g., rainfall), physiology and behaviour. We conclude that physiological changes associated with reproduction are sufficient to induce significant acute oxidative stress in the plasma of female highveld mole-rats, which become alleviated following transition to the non-breeding season/wet period suggesting a possible hormetic effect.

scholarly journals Distribution characteristics of dissolved oxygen and stable isotope compositions of shallow groundwater in the vicinity of an inland nuclear power plant, HK, China

2019 ◽  
Vol 98 ◽  
pp. 09035
Author(s):  
Jinjing Zan ◽  
Yihui Dong ◽  
Weimin Zhang ◽  
Weidong Xu ◽  
Jiale Li ◽  
...  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Dissolved Oxygen ◽  
Nuclear Power ◽  
Atmospheric Precipitation ◽  
Shallow Groundwater ◽  
Jiangxi Province ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Hydrogen And Oxygen Isotope

The hydrochemical and stable hydrogen and oxygen isotope compositional characteristics of surface and shallow groundwaters in the vicinity of HK nuclear power plant in Jiangxi Province of China. Dissolved oxygen (DO) contents of shallow groundwaters range between 1.75 to 19.40 mg/L, with variations related to well depth, groundwater level, and oxidation-reduction potential. Respective ranges of δD and δ18O (‰ VSMOW) in shallow groundwaters are -40.7 to -24.9 and -6.71 to -5.40, with average values of -31.8 and -5.87. The δD-δ18O relationship for the study area is δD = 8.3δ18O +16.8, indicating that atmospheric precipitation is the major recharge source of shallow groundwaters.

Inhibitors of Tyrosinase

1955 ◽  
Vol 32 (3) ◽  
pp. 468-484
Author(s):  
M. G. M. PRYOR
Keyword(s):  
Methylene Blue ◽  
Dissolved Oxygen ◽  
Inhibitory Effect ◽  
Tyrosinase Activity ◽  
Aromatic Substrate ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Low Concentrations ◽  
Sulphydryl Groups

1. It has been reported that if Drosophila larvae are ground to a fine paste with sand, the homogenate shows little tyrosinase activity, but that if the larvae are allowed to blacken in chloroform vapour before grinding, activity is increased. 2. This has been interpreted as showing the effect of an intracellular inhibitor, set free by rupturing the cells, but destroyed by chloroform. This inhibitor has been identified by previous authors as a dehydrogenase. 3. It is here suggested that the lack of activity of Drosophila extracts prepared with sand is due to destruction of tyrosinase as it oxidizes naturally occurring aromatic substrates. 4. It is shown that tyrosinase is destroyed by oxidizing the aromatic substrate present in the cuticle of Calliphora larvae, or by very low concentrations of homocatechol. 5. The aromatic substrate of Calliphora larvae is concentrated in the cuticle, and would be set free by fine grinding. 6. Drosophila or Calliphora larvae yield a more active extract when ground with sand than when simply crushed, provided that they are tested soon after grinding. 7. The tyrosinase activity of such extracts is not increased by chloroform or methanol. 8. The compound between o-quinones and amino-acids is capable of oxidizing ascorbic acid or excess amino-acid without the aid of an enzyme, and of simultaneously reducing methylene blue. 9. This reaction, rather than the activity of dehydrogenases, is probably responsible for most of the ability of damaged insect tissue to bleach methylene blue. 10. The blood of insects normally contains dissolved oxygen in equilibrium with the air. 11. The reaction involved in the blackening of insect blood may consume all the dissolved oxygen. 12. Previous observations on fluctuations in the oxidation-reduction potential of the blood of Calliphora larvae with age are probably due to changes in the rate at which oxygen is consumed by the blood after it is shed. 13. There does not therefore appear to be any valid evidence that tyrosinase is inhibited in vivo by the action of dehydrogenases. The absence of tyrosinase activity in undamaged tissue is probably due to the structure of the cytoplasm, which keeps enzyme and substrate apart. 14. Instances of the inhibition of tyrosinase reported in Crustacea and Echinodermata seem to be susceptible of the same explanation as in insects. 15. The supposed inhibitory effect of sulphydryl groups reported for vertebrate melanophores is shown to be due to the combination of sulphydryl groups with o-quinones, which prevents the formation of melanins.

Seasonal variation in foraging behaviour of plains zebra (Equus quagga) may alter contact with the anthrax bacterium (Bacillus anthracis)

2014 ◽  
Vol 92 (4) ◽  
pp. 331-337 ◽  
Author(s):  
Zepee Havarua ◽  
Wendy C. Turner ◽  
John K.E. Mfune
Keyword(s):  
Seasonal Variation ◽  
Bacillus Anthracis ◽  
Foraging Behaviour ◽  
Dry Season ◽  
Wet Season ◽  
Contact Rates ◽  
Bacterium Bacillus ◽  
Environmental Pathogens ◽  
Host Foraging ◽  
Plains Zebra

Pathogens transmitted via the environment are often aggregated in space, and seasonal variation in wildlife foraging behaviour may alter contact rates with environmental pathogens. The soil-borne bacterium Bacillus anthracis Cohn, 1872 causes anthrax, and herbivores acquire gastrointestinal anthrax by ingesting spores. Therefore host foraging behaviour could be a fundamental component of anthrax epidemiology. This study investigated seasonal changes in bite density and diet of plains zebras (Equus quagga Boddaert, 1785) in relation to anthrax seasonality in Etosha National Park, Namibia, where most zebra anthrax cases are observed in wet seasons. The diet of zebras shifted from more short grasses during the wet season to more tall grasses in the dry season, suggesting a greater potential for soil ingestion in wet seasons. Zebras also foraged most intensively in the wet season with the number of bites/step declining through the dry season. This higher bite density in wet seasons may lead individuals to ingest greater concentrations of the pathogen if foraging in a localized infectious area. Although sex and reproductive state affected bite density, no sex difference in anthrax occurrence was observed. This study demonstrates how considering variation in host foraging behaviour may enhance our understanding of disease seasonality for pathogens with foraging-dependent transmission.

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