The overall goal of this procedure is to establish a monitoring station that can continuously monitor the hydrology and water quality of a vernal pond. This method can provide insight to the functionality of vernal ponds, such as how human activities are impacting these sensitive aquatic ecosystems. The main advantage of this technique is that allows us to know at a high temporal resolution what the major water quality parameters are that maybe influencing contaminant fate and transport.
Though This method can provide insight into vernal pond ecosystem and it can also be applied to other systems such as lakes or streams. Visual demonstration of this method is helpful as the setup and installation steps can be confusing when under this equipment. This video focuses on the installation of the vernal monitoring pond monitoring system.
Details on surveying a vernal pond morphology and calculation of a pond's state storage curve are both provided in the text protocol. The sensors for this study this include a pressure transducer, a dissolved oxygen sensor, an oxidation reduction probe, an electrical conductivity probe, a pH probe, and a tipping bucket rain gauge. They should all be calibrated prior to the field installation.
Apart from the rain gauge, secure all of their sensors to a cinder block or a wooden stake so they will stay at the bottom of the pond, or at a depth of interest. To accomplish this use hose clamps or zip ties. When doing so be sure to attach the dissolved oxygen sensor at an angle at which oxygen will diffuse across its membrane.
Also, install the pressure transducer upright, so it measures the pressure of the water column above it. Position the sensors toward the center of the pond where they are unlikely to get dry during the study period. Measure and note the distance between the sensors in the deepest part of the pond, as this figure is needed for some calculations.
The sensor wires are vulnerable to mice or other animals that may chew on them such as when the water level is low. So run the wire through a PVC pipe for protection. Extend the pipe to end of the pond where the wires will engage with the data-logger.
Next set up the data-logger. To set up the data-logger install a tripod near the pond's edge and secure it to the ground using stakes. Attach a radio antennae if the data needs to be transmitted wirelessly.
Then onto the tripod attach the data box for the data-logger and a 12 volt battery with voltage regulator. Be sure to leave room on the tripod to mount a solar panel. Next attach a 10 watt solar panel to the top of the tripod, and angle it towards the sun;use a solar angle calculator to optimize the angle.
Now if there is there is room on the tripod attach a rain gauge, otherwise attach it to a wooden stake or metal pole near the edge of the pond. The rain gauge should be under the same amount of tree cover as the bulk of the pond surface area. Now set up the central data-logger, program it to record data on 15 minute intervals, feed all the sensor and solar panel wires into the enclosure box through the hole at the bottom of the box.
Then connect all sensors to the wiring panel in accordance with the sensor's instructions or the wiring diagram. Next, connect the solar panel wires to the 12 volt battery to recharge the battery. Now, connect the battery to power input panel.
Then place a desiccant pack inside the enclosure box to reduce the likelihood of moisture damage to the electronics. If possible test the system connected to a field laptop using the serial cable and use the software to ensure that the sensor network is working properly. Then plug the gap in the wire hole with clay to keep out insects and water.
Finally, close the enclosure box. If security is a concern close the box with a padlock. Going forward visit the site frequently and follow the manufacturer's recommendations for periodic sensor calibration, which can be weekly.
Vernal ponds can exhibit a wide range of morphology with profiles ranging from convex, to straight-slope, to concave. Precipitation, evapotranspiration, and ground water flow are important factors in determining the hydrology of vernal ponds. A study of three ponds was conducted during the breeding and metamorphosis period of wood frogs in the Northeastern United States.
The ponds were selected because their water levels changes are caused by rainfall and by waste water irrigation events. The sensors were placed at the bottoms of the ponds. In general, the temperature of the ponds increased over the study period but decreased in response to effluent irrigation events.
The pH was relatively consistent for the majority of the study period and as expected. The electrical conductivity of the ponds increased over the course of the study period likely due to higher electrical conductivity of waste water compared to rain water. Dissolved oxygen concentration and oxidation reduction potential generally followed a similar trend.
Dissolved oxygen followed a common trend of being inversely related to temperature, which related to mats of duckweed that grow on these ponds during this time of year. Once mastered, this type of thing can be done in four to six hours if performed properly. Plan to spend at least half the day in the field.
It's important to remember when you're doing this kind of research to secure the proper permits or landownership permissions, depending on whether you're doing on private or public property. Also don't forget that work with electricity can be extremely hazardous and that all the equipment must be properly grounded. Following this procedure, other methods like collecting ground water samples, can be performed in order to answer additional questions, like how the reflex conditions in the pond may affect the persistence of emerging contaminants and potentially, the metamorphosis of amphibians.
