Joe Fletcher
No Longer a Member
I thought this might be of interest to some of you guys . Its from the Barbel Society face book page .... I assume they must know what they are talking about ?
I’ve read some ridiculous comments on DO recently so felt it only right that RC&C of the BS should put something definitive out on it.
Dissolved oxygen (DO) refers to microscopic bubbles of gaseous oxygen (O2) that are mixed in water and available to aquatic organisms for respiration - a critical process for almost all organisms.
Primary sources include the atmosphere and aquatic plants. Surface waters, which are in contact with the atmosphere, absorb oxygen from the air. Aquatic plants release oxygen into the water as a by-product of photosynthesis.
Oysters and other aquatic life are just as dependent on gaseous oxygen dissolved in the water as people are dependent on gaseous oxygen in the air. Aquatic organisms can only function properly within a certain range of DO concentrations.
1
DO concentrations that are too low may prevent organisms from growing, feeding, or reproducing properly, and lead to unhealthy and less biologically diverse communities.
Dissolved oxygen can be affected by both human and natural influences. Natural influences include: temperature and season, time of the day, salinity, suspended sediments and water turbulence. Human influences include nutrient pollution, thermal pollution and sediment pollution.
2
DO concentrations decrease as water temperature increases. This is because oxygen is less soluble in warm water than in cool water. A serious issue at this time.
Although DO concentration decreases as water temperatures increase, DO concentration is actually higher during the day than at night. During the day, aquatic plants release oxygen into the water through photosynthesis. During the night, photosynthetic activity ceases and oxygen continues to be consumed through respiration by aquatic plants and animals.
3
DO concentration decreases as salinity increases. Salinity refers to the amount of salts dissolved in water. Dissolved salts such as sodium chloride, occupy space in water that would otherwise be available for oxygen molecules to dissolve in. Thus, as the amount of salts dissolved in water increases, DO decreases (tidal Trent boys note!).
4
DO concentration can decrease as the concentration of suspended sediments in water increases. Suspended sediment refers to the amount of loose particles of clay, silt, and sand floating in the water.
This will be an issue when the rains come with the soil being so dry).
Suspended sediments make oxygen less soluble in water by absorbing heat and raising water temperature. They limit oxygen production in plants by interfering with sunlight needed for photosynthesis.
Water turbulence ( For those heading for weirs ) can affect DO concentration. Turbulence refers to water that is moving rapidly and irregularly due to physical forces caused by wind, tides, wave action and currents. Water turbulence may lead to an increase in DO concentration but can also increase the mixing with bottom waters which typically have low DO concentrations.
Water turbulence may also lead to a decrease in DO concentration by stirring up bottom sediments, increasing the concentration of suspended sediments. Increased bank erosion has the same effect.
5
DO concentrations are higher during the day when plants produce oxygen as a by-product of photosynthesis. At night, photosynthetic activity ceases, and oxygen continues to be consumed through respiration by aquatic plants and animals.
Nutrient pollution by man may lead to a decrease in DO concentration, particularly nitrogen and phosphorous which cause increases in growth of phytoplankton (tiny microscopic plants) and cause algal blooms.
Algal blooms are dense floating masses of phytoplankton that discolour the waters surface. When phytoplankton die, they are decomposed by bacteria that consume DO during the process.
Nutrient pollution can be classified into two types, point source and non-point source.
Point sources of nutrient include sewage treatment and industrial treatment plants. Non-point sources include nutrient pollution carried by storm water runoff and include fertilised agricultural lands, residential lawns and golf courses. Also livestock farms through animal waste.
Thermal pollution (man) cause DO concentrations to decrease. Thermal pollution increases water temperature. As water temperature increases, DO concentration decreases. Power plants routinely discharge heated wastewater into natural waters.
Sediment pollution can also be increases by humans through boating (erosion), dredging and development of land - removal of vegetation increases stormwater runoff and soil erosion.
Each of these (human influenced) pollution types has a unique way of lowering DO concentration.
So there you have it guys. Hopefully you all now have a better understanding of DO and the serious increased risks to our barbel during this period of extremely high temperatures. Add to this the human influences and you can see why the risks may be higher to some rivers than others.
The request from the BS to its members, indeed all barbel anglers, at this time is do not fish at all for the foreseeable month or so for barbel. If you need to go out, remember there are other species and venues. We also thank, and respect, those Clubs and Associations that are now closing their waters.
BS RC&C Sub-panel
I’ve read some ridiculous comments on DO recently so felt it only right that RC&C of the BS should put something definitive out on it.
Dissolved oxygen (DO) refers to microscopic bubbles of gaseous oxygen (O2) that are mixed in water and available to aquatic organisms for respiration - a critical process for almost all organisms.
Primary sources include the atmosphere and aquatic plants. Surface waters, which are in contact with the atmosphere, absorb oxygen from the air. Aquatic plants release oxygen into the water as a by-product of photosynthesis.
Oysters and other aquatic life are just as dependent on gaseous oxygen dissolved in the water as people are dependent on gaseous oxygen in the air. Aquatic organisms can only function properly within a certain range of DO concentrations.
1
DO concentrations that are too low may prevent organisms from growing, feeding, or reproducing properly, and lead to unhealthy and less biologically diverse communities.
Dissolved oxygen can be affected by both human and natural influences. Natural influences include: temperature and season, time of the day, salinity, suspended sediments and water turbulence. Human influences include nutrient pollution, thermal pollution and sediment pollution.
2
DO concentrations decrease as water temperature increases. This is because oxygen is less soluble in warm water than in cool water. A serious issue at this time.
Although DO concentration decreases as water temperatures increase, DO concentration is actually higher during the day than at night. During the day, aquatic plants release oxygen into the water through photosynthesis. During the night, photosynthetic activity ceases and oxygen continues to be consumed through respiration by aquatic plants and animals.
3
DO concentration decreases as salinity increases. Salinity refers to the amount of salts dissolved in water. Dissolved salts such as sodium chloride, occupy space in water that would otherwise be available for oxygen molecules to dissolve in. Thus, as the amount of salts dissolved in water increases, DO decreases (tidal Trent boys note!).
4
DO concentration can decrease as the concentration of suspended sediments in water increases. Suspended sediment refers to the amount of loose particles of clay, silt, and sand floating in the water.
This will be an issue when the rains come with the soil being so dry).
Suspended sediments make oxygen less soluble in water by absorbing heat and raising water temperature. They limit oxygen production in plants by interfering with sunlight needed for photosynthesis.
Water turbulence ( For those heading for weirs ) can affect DO concentration. Turbulence refers to water that is moving rapidly and irregularly due to physical forces caused by wind, tides, wave action and currents. Water turbulence may lead to an increase in DO concentration but can also increase the mixing with bottom waters which typically have low DO concentrations.
Water turbulence may also lead to a decrease in DO concentration by stirring up bottom sediments, increasing the concentration of suspended sediments. Increased bank erosion has the same effect.
5
DO concentrations are higher during the day when plants produce oxygen as a by-product of photosynthesis. At night, photosynthetic activity ceases, and oxygen continues to be consumed through respiration by aquatic plants and animals.
Nutrient pollution by man may lead to a decrease in DO concentration, particularly nitrogen and phosphorous which cause increases in growth of phytoplankton (tiny microscopic plants) and cause algal blooms.
Algal blooms are dense floating masses of phytoplankton that discolour the waters surface. When phytoplankton die, they are decomposed by bacteria that consume DO during the process.
Nutrient pollution can be classified into two types, point source and non-point source.
Point sources of nutrient include sewage treatment and industrial treatment plants. Non-point sources include nutrient pollution carried by storm water runoff and include fertilised agricultural lands, residential lawns and golf courses. Also livestock farms through animal waste.
Thermal pollution (man) cause DO concentrations to decrease. Thermal pollution increases water temperature. As water temperature increases, DO concentration decreases. Power plants routinely discharge heated wastewater into natural waters.
Sediment pollution can also be increases by humans through boating (erosion), dredging and development of land - removal of vegetation increases stormwater runoff and soil erosion.
Each of these (human influenced) pollution types has a unique way of lowering DO concentration.
So there you have it guys. Hopefully you all now have a better understanding of DO and the serious increased risks to our barbel during this period of extremely high temperatures. Add to this the human influences and you can see why the risks may be higher to some rivers than others.
The request from the BS to its members, indeed all barbel anglers, at this time is do not fish at all for the foreseeable month or so for barbel. If you need to go out, remember there are other species and venues. We also thank, and respect, those Clubs and Associations that are now closing their waters.
BS RC&C Sub-panel
