Value of Ponds to a Community

by Dr. Adrian Lawler
(retired) Aquarium Supervisor (l984-l998) J. L. Scott Aquarium Biloxi, Ms 39530

Original to Aquarticles

A pond, if properly stocked with mosquitofish (Gambusia affinis) or maintained so larval mosquitoes are otherwise controlled, is a great asset to a community. Besides the obvious benefits of being pleasing to view, a recreational/fishing area for people, and a water reservoir for possible use in fire control, there are other reasons a pond has high value to a community.

Reproduction site for mosquito control animals + for garden insect control animals

The greatest value a pond has, in my opinion, is as a breeding/reproduction site for several species of animals that help control mosquitoes and other insects. Toads, tree frogs, bull frogs, leopard frogs, bronze frogs, etc. (in my area) use ponds for mating and places to lay their eggs. Insect predators as dragonflies (mosquito hawks) and damselflies also reproduce in ponds. The aquatic nymphs (also called naiads) of dragonflies and damselflies prey on larval mosquitoes and other small organisms; adult dragonflies and adult damselflies prey on adult mosquitoes and other insects.

The control of mosquitoes to lessen the infections of humans by various diseases (as: malaria, yellow fever, West Nile virus, encephalitis, Dengue fever, etc.) is a major endeavor throughout many parts of the world. Estimates range from about 1.5 to 2.7 million people that are killed by malaria alone each year; thus, mosquitoes can be considered the greatest human killer in world. It is not nice to be a victim of a mosquito-borne disease (author got West Nile virus in 2003 in Mississippi and still realizes some effects of it).

Some of the same animals that reproduce in a pond also are helpful in the control of garden and lawn insect pests. In my area they are toads, tree frogs, bull frogs, bronze frogs, and adult dragonflies and damselflies. Large numbers of dragonflies have also been observed feeding on swarming fire ants and swarming termites by the author. Dragonflies were observed catching swarming winged fire ants shortly after they took flight off stalks of grass, and other places higher than their nest.

Watering site for mosquito predators and other wildlife

Another value a pond has is as a watering place for other mosquito predators like bats, various swallows (including purple martins), swifts, lizards, etc.

To attract wildlife for food

In my area various predatory birds get various animals from ponds for food. Red foxes may catch frogs, ducks, geese, mice, etc. around ponds. Nutria frequent ponds for aquatic plants to eat. Raccoons get fish, tadpoles, frogs, crayfish, etc. from ponds. Turtles get tadpoles, snails, plants, etc. out of ponds. Snakes catch frogs, toads, tadpoles, fish, etc. from ponds. Ponds provide foods for many animals.

As watery compost pits

Organic material washed or falling into a pond decays under bacteria and fungal action. This organic pond muck can be used to enrich garden plots and other land.

To offset errors made by humans

Ponds combat poor engineering/construction by contractors, homeowners, and city work crews throughout the world when they make/clean drainage ditches LOWER than the drainage pipes under driveways, or install drainage pipes under driveways HIGHER than associated ditches, or install flexible drainage pipes with the downhill end turned up, etc., thus causing standing water upstream (Figures 1, 2, 3) of various pipes and causing the too deep ditches to breed mosquitoes.

This results in the unwanted, and apparently in many cases, unknown, promotion of a greatly INCREASED number of breeding areas for mosquitoes and thus an increase in mosquito-borne diseases, like West Nile Virus, in the populations of cities around the world. Most cities do not even address or are not aware of this problem; i.e., that whoever is making/cleaning their drainage ditches too deep and leading to ditches with standing water that breed mosquitoes, is causing a very serious health threat to city citizens. We would also not have to spend as much money on mosquito spraying if drainage ditches were properly sloped for total drainage after rains.

Drainage ditches should have sand bottoms (Figure 4), where the sand tends to fill low spots under water flow.

Whoever digs out ditches lower than drainage pipes should replace their procedures with those that periodically disperse sand to the low areas in the ditches. Any excess sand will be washed downstream in heavy rains, and tend to fill low areas of ditches. When excess sand just starts to enter drainage pipe, then one knows the contour is correct to prevent standing water and mosquito-breeding pools of water.

With the increased use of more flexible HDPE black drainage pipe, there is the added problem of not getting the pipe installed straight, or sloped downstream, and the ends can turn up, trapping water inside the pipe for mosquito breeding (Figures 2 & 3). Additionally, cars wrecking in ditches can push the ends of the pipes up, so the pipes then hold water.

Properly run ponds are needed to offset the drainage ditch errors made by producing the mosquito-eaters needed to control the mosquitoes raised in improperly-designed/maintained mosquito-breeding ditches found in cities throughout the world.

In crowded cities roof-top tanks can be utilized for rearing dragonflies and damselflies to help control mosquitoes; tanks should also be stocked with mosquitofish. Tree frogs may also be able to utilize roof tanks for reproduction; toads and various other frogs would not be able to get to roof-top tanks for reproduction. Tanks could be automatically filled by water from air-conditioning units.

To serve as holding area while water is being cleaned of toxins

Ponds, either on residential property or commercial property, serve as retention/holding ponds for street/parking lot/yard run-off waters that contain automobile pollutants (antifreeze, oil, transmission fluid, brake fluid, window washer fluid, etc.) and toxins from yard pesticides, etc., where toxins are broken down by bacteria into less toxic compounds. Water is partially cleaned in ponds prior to release and running to rivers or bayous and eventually to the ocean. Ponds thus serve to protect oceans from receiving the maximum pollution from direct land run-off. The longer the toxin is held in a pond, the more toxin bacterial break-down occurs, and the less toxin that reaches streams, and eventually the ocean.

As reservoirs to help recharge water table

Dirt ponds are needed in all drainage areas to slow down and hold water run-off flow to rivers and oceans and to help water seep down to replenish water tables. Many cities drain water off land as quickly as possible so water flow down drainage ditches is very fast, having little time to soak in to help replenish water tables. This is a very bad practice. Fast drainage also adds litter, sediment, toxins, organic debris, and fresh water at heavy rates with each rain to downstream bodies of water. Falling water tables in our cities result in constant land settling, which leads to the cracking/breaking of water lines and sewage lines and constant leaks and repairs.

Pond locations

Ponds should be located no more than twice the average distance that toads migrate away from their hatch pond in order to get good land coverage by toads and thus better insect control.

Ponds should be (at least) at regular intervals (this should be no greater than 2x the dispersal travel distance of toads away from their tadpole-stage pond)(e.g., if toads travel a quarter mile away from their home pond, then ponds should be less than a half-mile apart in a city) in order to:

---Get fairly uniform dispersal of mosquito predators throughout the city.
---Cut down on the mosquito insecticides sprayed.
---Cut down on garden pest insects.

Toad tadpoles recently turned to toads leave a pond enmasse and in several waves of tiny toads that spread outwards from a pond in all directions. The number of waves depends on the number of toad choruses (= mass matings) in spring, which can occur near times of rain.

See these articles also:

Water the mosquitoes……..http://www.aquarticles.com/articles/management/Lawler_Mosquitoes.html

Predatory birds and ponds……http://aquarticles.com/articles/ponds/Lawler_Predatory_birds.html

Copyright 2007 by Dr. Adrian Lawler, Author Copyright 2007 by Aquarticles, Internet Sponsor

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