Aquatic Practicals Flashcards
Why are fish so sensitive to temperature?
- Poikilothermic
2. Water metabolism impacts presence of toxic compounds
What is the ideal temperature for tropical fish?
25-28 degrees Celsius to grow
What is the ideal temperature for cold water fish?
10-20 degrees to grow
What is the relationship between temperature and dissolved oxygen?
Oxygen and temperature are inversely proportional
What are some potential issues with a low pH?
- Decreased amount of dissolved organic phosphorous and CO2 available for photosynthesis
- Increase in solubilisation of toxic metals from sediments
What are the issues of high pH?
- Toxic form of ammonia more prevalent (NH3)
2. Phosphate which is commonly added as a fertiliser can precipitate
When is the pH going to be the least?
pH will be the least in the morning
Name the ways that pH can be lowered?
- phosphate can be added (it increases algal growth though)
- peat or reverse osmosis
- adding CO2
How can the pH be increased?
- adding baking soda, limestone and shells
What is meant by the term carbonate hardness?
- refers to the capacity of the water to neutralise acid - concentration of bicarbonate ions
What is meant by the term general hardness?
- measure of chemically bivalent ions (mainly Ca and Mg)
What should be the level of oxygen within a system?
- 70-100% saturated
What does chloride do?
causes gill necrosis
What is the difference between FAN and TAN?
- FAN (free ammonia nitrogen)= highly soluble toxic unionised ammonia (known as free ammonia nitrogen)
- TAN (total ammonia nitrogen) includes the less toxic forms
How can the effects of toxicity occur at the gills?
- the presence of high ammonia leads to increased water absorption
- To a large extent, ammonia is excreted across the gills via a concentration gradient
- Ammonia is a strong cell poison that can cause damage at concentration as small as 0.2-1.0 ppm FAN
