An Introduction to the Concepts of Lake Management
Would you take your family to have a picnic at a park where the grass is green and the trees are magnificent but the lake smells unpleasant and looks stagnant? Of course not! There is no reason why a lake cannot be as beautiful as it surrounds. In this quick introduction to lake management we will explain the causes, problems and management of a lakes ecosystem. Every lake is different and has different factors contributing to it success or failure;sunlight/temperature, nutrients and oxygen are the most significant in terms of a lakes dynamics. Knowledge and management of these factors are the perfect starting point for any lakes well being. Sunlight is the lakes primary source of energy, it initiates photosynthesis(the release of oxygen by plants during the day and carbon dioxide at night) of the plants in the lake and its surrounds and determines such factors as algal and plant
growth and species of plant life present.
Temperature effectively relates to the “Thermal Stratification” of the lakes water column where the lake is separated into different thermal gradients or layers; as the sun warms the waters surface this layer become slighter trapping the cooler, denser water beneath it causing different temperature zones to be present. This layering effect can cause the different zones to not mix and the top, warmer layer can encourage detrimental algal growth.
The thermal stratification of a lake can also affect the amount of dissolved oxygen in the water body, the higher the temperature, the less dissolved oxygen it contains causing the organism sin these areas to die. Oxygen in the lake essentially comes from sources such as wind and wave action and photosynthesis of the plants in the lake as well as from artificial means such as aerators and fountains. Dissolved Oxygen (DO) has a critical effect on the lakes well being, a lack of DO can result in iron in the water being converted from an insoluble form to a soluble form which affects water quality, sulfide being converted to toxic hydrogen sulfide and waste materials being unable to be decomposed on the lakes bottom.
The amount of oxygen in a water body is unstable due to factors such as water temperature, amount of sunlight and photosynthesis etc. The addition of aerators and fountains can help overcome any oxygen deficiencies in a lake by mixing the thermal layers and directly adding oxygen to the water body. Photosynthesis indicates the importance of using aerators and fountains particularly at night as the oxygen levels in the lake decrease significantly at this time.
Nutrient levels can be related to the amount of aquatic weeds in the lake and algal growth, the more nutrient in the lake the more these undesirable organisms increase leading to a smelly,stagnant lake. Phosphate and nitrogen are found in commonly used garden and turf fertilizers and are the main chemicals looked to be present in the management of lakes as they are the main contributors affecting water quality. These can enter the lake system via run off from turf and lawns and incoming water sources such as storm water drains, creeks and tributaries flowing into the lake.
Dead and dying algae, plants and vegetation also add to the bio-load of the lake and contribute nutrients that are considered harmful to a lakes ecosystem. There are two types of naturally occurring bacteria present in ponds and lakes, these being: aerobic and anaerobic bacteria. These break down the nutrient load on the lake by feeding on organic nutrients breaking them down to non-organic compounds that aquatic plants and algae cannot access readily for food. Aerobic bacteria are the most effective and only exist where oxygen is present and are much more effective than aerobic bacteria in the breakdown of organic nutrient. Anaerobic bacteria as part of their consumption of nutrient produce harmful by-products that can be contributed to a lake being stagnant and unpleasant smelling.
Lakes can effectively be managed by the use of long term measures such as:
• Addition of aerators and fountains positioned correctly to gain maximum benefit form aeration and circulation.
• Reduction of nutrient to the water body.
• Addition of beneficial bacteria and enzymes such as Clearpond Pondzyme+ Concentrate.
Oxygen adding devices such as aerators and fountains can be broken down into two subsections: those that pump air into the water column such as pond aerators and those that pump water into the air such as lake fountains.
Aeration of the lake aids in impacting on the factors contributing to the problems found in large water bodies: oxygen, temperature and nutrient content. The addition of aeration encourages the growth of aerobic bacteria enabling the decomposition of organic waste and nutrient to increase, it also circulates the water breaking thermal stratification lowering the lakes overall temperature and also provides oxygen to the deeper areas of the lakes. The position in the lake of the fountains and aerators are crucial as the correct positioning helps prevent areas where “dead spots” are likely to occur as well as providing a visually spectacular feature.
The use of naturally occurring bacteria and enzymes in conjunction with aeration devices is exceptionally beneficial to the lake, these enzymes help speed up the breakdown of nutrients which in turn reduces the amount of sediment on the bottom of the lake, improves the lakes water clarity and eliminates odours. Essentially the bacteria makes nutrients such as phosphate and nitrogen unavailable to stimulate the growth of algae by competing with the algae and winning! Thorough water chemistry analysis is essential during the use of liquid bacteria and enzymes in a lake as favourable results will be achieved quicker and the product will be more effective if ideal water conditions are maintained. Initial doses of Pondzyme+ will need to be followed up with periodical doses to achieve a harmonious balance of the lakes ecology. In summary, with an understanding of a lakes aquatic ecosystem and help from Clearpond you will be able to achieve a lake you will be proud to take your family to have a picnic by!