Choked storage pond
Keeping the undesirables out can help safeguard your water resources
Report by Languard’s PAUL CAWOOD AquaticWEEDS
Water forms a vital part of managing our green spaces. Whether it’s the most prestigious golf course with beautifully proportioned showcase water features or a humble municipal pay and play that has a feature pond, water is crucial in providing the aesthetics we desire whilst ensuring the grass we play on is in top form. Recent years have seen extremes in water availability from wet winters that have caused drainage to be pushed to the limit to dry summers that have parched fairways. In some cases last year municipal football and rugby pitches were closed as they had dried to the point where they were unsafe to use. Water shapes the landscape and creates the spaces we enjoy as well as being the essential ingredient in ensuring the health of the grass.With the recent swings in rainfall it is a resource that is under growing pressure. Last year saw increased restrictions on licences to abstract water for irrigation use. Some areas, notably in the south east, imposed bans on irrigation using mains water. As rainfall becomes less predictable managing water stocks and the equipment that stores it is crucial. So what happens when you get unwelcome visitors in the form of aquatic weeds in your ornamental lake or irrigation pool? How do they get there? How can they be managed? There are some aliens out there that you should be aware of as they will dominate our aquatic environment with little or no resistance.
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AQUATIC weeds spread from some reliable sources. Plant fragments are the most likely form of spread from either mechanical sources (cutting and dredging) to spread by water foul. Many releases to the wild of non native undesirable species are by the public simply dumping foreign ornamentals in the wild.
Most unwelcome aquatic weeds are non native that have no place in our natural indigenous aquatic environment. Most of these invaders are escapees from domestic fish tanks that were used to oxygenate the water. They were sold by garden centres as both oxygenators for aquaria and features for garden ornamental ponds. As sometimes happens, when people tire of their aquarium, they free the fish in the local pond or river - and the plant life too. As with all alien invaders of the plant kind they are released into an environment where they have none of the natural controls that exist in their indigenous environment. There are no diseases, invertebrates that feed on them, or fish that can graze them to keep them in check. Without this natural restriction on their growth they literally spread unopposed in an environment that isn’t equipped to cope with them. The consequences are often profound. Pools and ponds that have slow flowing water can be completely consumed by these fast growing invasive species. If your pool is the centrepiece of your course, or you have a storage lagoon for the summer’s valuable irrigation water, then beware.
These green invaders can get a foothold and become embedded very quickly and have a profound effect on both the appearance of your lake and the ability of your pumping equipment to work.
SOLVING the problem of aquatic weeds is specialist work that requires the expert touch. Here are just a few of the common problems that unwanted aquatic vegetation can bring. Many courses use streams and balancing ponds to supply and replenish their irrigation water if it is not from a bore hole or the mains. This is an ideal system but careful maintenance is needed to ensure that aggressive fast growing weeds do not get in. The problems that occur if they do are clear:
• Water flows will be reduced
• Overflows can occur due to reduced flow rates
• The available volume for water storage will be reduced due to plant matter
• Pumping equipment will get fouled due to plant fragments
• Native plant species do not compete and die off
• The quality of the aquatic habitat is reduced
• Available oxygen levels are reduced affecting fish and invertebrate life
• Anaerobic conditions can be created resulting in ‘foul’ water
So who are the invaders and how are they stopped? They key culprits are Parrots Feather (Myriophylum aquaticum),
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