LMVP Celebrates 30th Birthday
Community scientists, and representatives from the University of Missouri, Missouri Department of Natural Resources, and the Missouri Department of Conservation met on Thursday, October 20 to celebrate 30 years of volunteer lake water quality monitoring in Missouri.
The Lakes of Missouri Volunteer Program (LMVP) began in 1992. Participants have since collected and processed over 18,000 water samples, all analyzed in the MU Limnology Lab at the University of Missouri. The LMVP now monitors 120 lake sites across the state up to 8 times each year for several water quality indicators including water clarity and algal toxins.
“What we have in Missouri is an impressive 30-year record of community-driven lake data that stands proudly alongside the best in the country,” said project manager Tony Thorpe.
Pat Market, director of the School of Natural Resources, gave opening remarks at the event. After dinner, attendants heard about the origins of LMVP from Jack Jones, Curators’ Professor Emeritus at MU’s School of Natural Resources and one of the LMVP’s founders. Robert Voss of the Missouri Department of Natural Resources spoke about the value of LMVP’s water quality data to the state of Missouri. Maryam Salehi, assistant professor of Civil and Environmental Engineering at MU, spoke about the pervasiveness of plastics in the environment.
Following the presentations, volunteers and professionals had the opportunity to mingle and chat, connecting those who collect the water samples with those who use the data.
The event was held at Waves Cider Company and catered by Pizza Tree. See more pictures here
National Lakes Assessment
by Jeremy Wease
The National Lakes assessment (NLA) is a general study conducted every five years by the EPA. The survey examines the current biological, chemical, physical, and recreational lake conditions across the US. This information will provide information about lake degradation on a national scale. The study is also designed to help identify which stressors are most associated with the degradation of biological conditions of lakes. Our lab at the University of Missouri previously participated in the study in 2007, 2012, and 2017.
Lakes are selected randomly using a survey designed to statistically represent the population of lakes in each ecological region (the geographic area in which climate, ecological features, and plant and animal communities are similar). The NLA sampling is comprised of natural lakes, ponds, and reservoirs across the lower 48 states. Starting with the NLA 2012, to be included in the survey a water body had to be a natural or man-made freshwater lake, pond, or reservoir, greater than 2.47 acres (1 hectare), at least 3.3 feet (1 meter) deep, and with a minimum quarter acre (0.1 hectare) of open water. The Great Lakes and the Great Salt Lake were not included in the survey, nor were commercial treatment and/or disposal ponds, brackish lakes, or ephemeral lakes.
Map showing sampling locations and ecoregions for the 2017 National Lakes Assessment effort.
The first step in the NLA survey is to visit the index site, located in the middle of the lake. Here we identify the photic zone of the lake by conducting a Secchi measurement. The photic zone is the top layer of water that receives sunlight. Sunlight is necessary for phytoplankton (algae and cyanobacteria, or bluegreen algae) to photosynthesize. Phytoplankton are important because they make up the base of the food web in lakes. Next, we use a YSI portable water quality sensor to measure dissolved oxygen, pH, and temperature at half meter increments from the surface to the bottom. Dissolved oxygen is essential for the survival of fish and aquatic invertebrates. After that we collect samples for analysis of chlorophyll , water chemistry, phytoplankton species composition, algal toxins, and atrazine.
With the water sampling at the index site complete, we next sample the zooplankton. The composition of the zooplankton community can indicate the presence of nutrient pollution in the lake. The zooplankton community varies with water quality as some species are more tolerant of poor water quality than others.
After sampling the index site we visit ten physical habitat stations, equidistant around the lake perimeter. Genetic material from various species should be found in the water. For example, a bass releases DNA into its surrounding environment from skin cells and feces. To measure the genetic material, we collect a littoral eDNA sample from the surface of the water. At each station we use a small bottle to suck up surface scums, films and dead bugs present, then combine the water in a 1L bottle. At each station we also collect a benthic macroinvertebrate sample. This sample is collected by dragging a fine-meshed net across the bottom of the lake for one meter. As with zooplankton, the benthic macroinvertebrate community is another indicator of lake health. Benthic macroinvertebrates live on the bottom of the lake. Many types feed on decaying material while others are predators that eat other macroinvertebrates. They are also a good source of food for the fish living in the water. At the final station we collect an enterococci sample. Enterococci are a group of gut bacteria and analysis of this sample will quantify fecal contamination at this station.
After collecting the samples at each station, we record multiple observations about the composition of the land and water near the shoreline. These observations will be checked against the data to help understand which physical characteristics are associated with good and bad water quality.
New to this year’s NLA sampling is fish tissue analysis. The fish tissue samples will be analyzed to determine which chemicals and toxins are found within the lake. This is important because throughout their life a fish’s tissue can slowly accumulate certain toxins. The fish we target are fish that people would typically consume, therefore any toxins found in the fish could be transferred to humans.
Results from the previous NLA effort are available by following the link below. Our lab at the University of Missouri was responsible for collecting Missouri's lake samples.
Leaf Litter and Water Quality
I was contacted by a gentleman whose neighborhood has a lake in need of attention. It was a pretty typical conversation, with complaints of decreasing clarity and water getting greener with each passing year. I was preparing to give my usual reply about the looking to the watershed and scrutinizing the landscape for possible runoff sources, when he told me that this lake is a retired quarry. It doesn’t have much of a watershed.
Apparently, limestone was mined from this site for railway construction. Mining was abandoned when the pit filled with water, forming the lake. Largely fed by groundwater, the lake has no inflowing or outflowing stream. With no outflow, any nutrients entering the lake will tend to cycle indefinitely. So how are nutrients entering the lake? This lake doesn’t drain any land and is surrounded by woods. It is possible that a broken sewer line is contributing nutrients to the groundwater feeding the lake. However, detecting such a problem is beyond what I can do right now, so I keep looking.
One other possible source of nutrients is leaf litter. A typical Ozark forest drops about 2.1 tons of leaf litter per acre each year. Based on a few estimates of the phosphorus content of leaf litter, that works out to be between 5.8 and 7 pounds of phosphorus per acre of forest each year. While this is a small, 1 acre lake, it has a long, skinny shape. As a result, it has more shoreline and more trees at its edge than a round lake with the same surface area.
Leaves in forested landscapes travel, on average, less than two feet after they fall. Drawing a two-foot-wide corridor around the lake gives an area of about a tenth of an acre. If we assumed (arbitrarily) that 30% of those leaves blew into the lake, we could be looking at around 0.15 pounds of phosphorus entering the lake each year. If this occurred each of the lake’s 60 years, it would yield a possible total of 9.12 pounds (or 4135 grams) of phosphorus. Assuming the lake to have an average depth of 10 feet, we get a total possible concentration of 335 micrograms of phosphorus per liter from leaf litter alone. That is a lot of phosphorus.
Measured phosphorus concentrations were an order of magnitude less, at only 44 micrograms per liter.
In reality, the amount of leaf litter entering the lake is probably considerably less. This is a neighborhood park, not an Ozark forest after all. Much of the leaf litter phosphorus that does enter the lake will settle to the bottom and remain there in particle form, meaning it won’t show up in water samples taken from the lake’s surface. Some phosphorus will be Incorporated into animal tissue. There is a community of shredding invertebrates in aquatic environments that break leaves and other organic material down into smaller pieces. These benthic (bottom dwelling) organisms feed larger animals like birds and fish, which can leave the lake or be harvested, taking nutrients with them.
The potential input of phosphorus from leaf litter is high. This potential is exacerbated by the quarry lake’s lack of flushing. This doesn’t mean that lake owners should chop down trees near their lake, however. The benefits of trees far outweigh the negatives. In addition to providing shade and beauty, trees retain phosphorus that otherwise might have entered the lake via runoff water.
The lake’s nutrient concentration has likely been stable over the last several decades. The surrounding homes are roughly 50 years old, so there haven’t been any new activities in the area. In the last 20 years, a trail has been added that allows its users to see the lake. Perhaps shade trees were cut down, allowing more sunlight to reach the lake.
The increased algal growth may be the result of top-down effects. Perhaps someone has been harvesting bass from the lake, and the fish that eat algae-grazing organisms are overpopulating. Also, this is a small lake, and small lakes tend to be very dynamic, with conditions changing quickly and often. Whatever has happened, monitoring the lake is a good place to start.