The Effect of Turbidity on the Abundance of Riffle Beetles

The Effect of Turbidity on the Abundance of Riffle BeetlesIntroduction: In this study, the goal is to determine the effect of turbidity on the abundance of riffle beetles. Those that are carrying out the experiment will learn what effects that low and high turbidity have on riffle beetle abundance. It is important to there to be research on this in order to know what the effects will be on riffle beetles because they are good detectors of pollution. This can help one to understand what level of turbidity will be ideal for a healthy wetland ecosystem. Turbidity is the independent variable in the experiment, while the abundance of riffle beetles is the dependent variable. The control variables in this experiment will be pH, temperature, the amount of food given to each organism, and the environment of each tank.

From this study, it will be possible for scientists to determine what the prime turbidity level is for riffle beetles in a wetland.Turbidity is a measure of how cloudy or clear a liquid, which is based on the light scattering through the water. The total suspended solids (TSS) are the cause of light being scattered and haziness of the water. When the scattered light is more intense, it indicates a higher level of turbidity. It is measured in Nephelometric Turbidity units (NTUs) or it could be measured in Jackson Turbidity Units (JTUs). For a less precise measurement of turbidity, one could use a Secchi Disk as well.Turbidity is a good indicator of the health of an ecosystem because higher turbidity can be caused by pollution. When the turbidity has a high measure of NTUs, it can be harmful to some species that are dependent on light. The sediment that causes turbidity can also allow for pollutants to attach on, increasing pollution in an area.

Some events that could cause pollution include sewage treatment chemicals place in the water, pesticide use, chemicals released from industrial plants, or overgrazing leading to loosened topsoil. Turbidity can also be caused by other events than just pollution. When a river has a faster flow, the water can potentially knock more sediment loose. More sediment being free can make the water cloudier and making the turbidity higher. Rainfall could also decrease turbidity levels because more water can dilute the water, making it appear less cloudy. Water can also knock sediment loose through erosion. Another contributor to turbidity is plant and microorganism life in the water, such as algae or plankton. The more plant growth and animal presence in an area, the greater the turbidity measurement would be.

In some bodies of water with plant life, the turbidity may vary with the seasons. In the spring, where there is typically greater sun presence and growth happening, the turbidity tends to be higher. The turbidity levels would then drop in the winter as growth decreases with the cooler temperatures. Turbidity impacts other environmental aspects in an ecosystem. It can affect the temperature underwater due to the suspended solids blocking sunlight. When the temperature of the water is colder, the dissolved oxygen present increases. The blocked sunlight also decreases some plant life, which may have provided food for other organisms. When the food isn’t present, there is less energy that can go to higher trophic levels in a community. When the amount of total suspended solids in an area is higher, streams and lakes can fill or even flood. For the organisms, like benthic macroorganisms, the higher turbidity can impact the habitats.

The sediment and solids in the water could later settle, leading to clogging the areas that could be used for homes or the suffocation of young macroorganisms on the bottom of the body of water. The riffle beetles (Optioservus ovalis) is in the family Elmidae. The species is small, with an adult being 2.2 to 2.6 millimeters long (Beaty 50). Riffle beetles are the most abundant of water beetles in North Carolina. Adult riffle beetles are black, shiny and are sometimes too covered in sediment to be identified. The beetles have long legs and claw that help them to clasp onto sediment in the flowing water of rivers and wetlands. They are covered in “hydrophobic hairs” that are used in order to trap air for gas exchange (Hammond). The bubble that forms around them acts as gills and is called a plastron (Brown 261). This allows them to be fully aquatic as both larvae and as an adult.Riffle beetles prefer to live in running freshwater, typically where the water flows quickly. They live up to the name “riffle beetle” because they are commonly found in the riffles of a body of water, such as a river.

In those riffles, the beetles live in areas with sand or gravel on the bottom.The water that they live in is shallow, never exceeding a depth of two meters. They prefer water with a high dissolved oxygen level as well. When the dissolved oxygen is too low, some larvae may allow themselves to drift in order to reach better conditions.Riffle beetles are first eggs, laid by adults in the riffle. The amount of eggs commonly laid by a riffle beetle is They spend a few months as eggs before hatching into larvae.. The larvae tend to be longer, harder, and flatter than adult riffle beetles. After about a year, the larvae can grow into the adult form. When they first hatch into their adult form, riffle beetles tend to be a lighter shade, darkening within a few days.The diet of riffle beetles includes detritus and miniscule algae. While some species may eat some live plants, the optioservus ovalis does not. There are very few known predators to the riffle beetles. Riffle beetles are known for being good indicators of an ecosystem’s health. The reason for this is because of the plastron that is necessary for their survival.

When there is pollution in the water, it can become more difficult for the riffle beetle to form the bubble of oxygen. This problem leads to the riffle beetles leaving their habitat for one that is healthier and beneficial.Wetlands are important ecosystems across the globe, forming . They are classified as “areas where water covers the soil, or is present either at or near the surface of the soil all year or for varying periods of time during the year, including during the growing season,” (EPA, What is a Wetland?). They are commonly found next to floodplains or other systems of waterways. Some types of wetlands include basins, floodplains, and prairie potholes. These wetlands help to prevent flooding in areas. This is because the ground holds a large amount of water, instead of letting it run through.

When the wetlands hold onto water, they can purify and filter is fluids before they are released. This is beneficial to help in the reduction of water pollution that occurs. Finally, wetlands are productive ecosystems, with a variety of species living there. Wetlands supply habitats and there is a food web present in each wetland community.The question proposed for the experiment is “What is the effect of turbidity on the abundance of riffle beetles?” The hypothesis is that if the turbidity of the water is above 150 NTUs, then the abundance of riffle beetles will decrease. This hypothesis was determined because riffle beetles are good indicators of water quality. When water is more turbid, it can be harmful to a creature’s habitat and make the environment seem less appealable.

Materials and Methods:Materials:21 5.5 gallon tanks with lids and dimensions of 43.2cm by 22.9 cm by 27.9 cm40 PVC pipe connectors1 ten-foot PVC pipe, cut into 10 cm length pieces with an inner diameter of 3 cm21 turbidimeters6 2.26 kilogram bags of blue aquarium rocks (.51 KG/AQUARIUM)21 aerators 21 thermometers42 5cm tall fake aquarium plants21 pine wood pieces, cut into 15cm by 7cm by 5cm dimensions4 2.23 kg bags of sand 231 liters of tap water 21 pH meters21 thermometers1 bottle of tap water conditioner1 bottle of pH UP1 bottle of pH DOWN21 aquarium heaters63 adult male riffle beetles (Optioservus ovalis) 441 oak leaves that are 5 centimeters in diameterMethods: Set up the 21 tanks with lids and cut a hole 7 cm from the base that will fit the diameter of the PVC pipe connectors. Insert the PVC pipe connectors into the holes and connect the tanks with PVC pipes.

Place 0.51 kilograms of blue aquarium rocks at the base of each tank.Place two 5 cm tall fake aquarium plants on the left side of the aquarium, along with one 15 centimeter piece of wood, being careful to not block the whole where the PVC pipe connector is attached.Fill each tank with 11 liters of tap water.Treat each tank with ¼ milliliter of tap water conditioner. Set them each to the pH of 7 by checking the pH meters. Adjust with pH UP and pH DOWN if it is necessary.Set each tank’s aquarium heater to a temperature of 25 degrees Celsius.Place an aerator in the bottom left corner of the aquarium.Place 384 grams of sand into each aquarium. Turn on each aerator. Set the aerators by turning them on and adjusting until the turbidimeter reads the needed turbidity for each tank. Set the tanks at these NTUs.