Updated: Jun 3, 2019
By Sonja Wixom • Photos: Kirstin Sandblom
I would love for my thesis to be all educational content, and most of it will actually be just that. But, for a Master of Science degree I have to have some testable data and draw conclusions from these data. So I started, in the beginning, sampling the waterbody as if it was a lake. Each week in my seminar course we would share how our sampling has been going – and it seemed everyone’s went waaaay smoother than my own. Earlier in the blog posts I have written I explain why this is – because it is a wetland. I just wanted to emphasize that I had been sampling Koinonia’s waterbody as if it were a lake for over a year! What did this consist of? I primarily used a YSI sonde that I would lower into the water and get readings for water quality. With this I measured oxygen levels, pH levels, temperature, and specific conductivity – every other week for an entire year! Typically lakes in the northeast are dimictic meaning they turn over twice a year, and this is when it is important to measure these parameters to find out what is happening in the lake! I’ll explain more…. In the summer the air and sun heat up the top layer of water, while the bottom of the lake doesn’t get any sunlight or heat. The wind also slows down in the summer so there isn’t as much mechanical mixing that is wind driven. The end result is the top layer becoming warm and less dense than the bottom – it will stay on top and now is not likely to mix because of how cold and dense the bottom water is. This separation of layers is referred to as stratification. During long periods of stratification the bottom water doesn’t get oxygen added to the water – this usually happens during strong winds that causes the water to become choppy and mechanically adding in oxygen. Oxygen is also added by primary producers such as plants, but because this is so deep there are no plants that can live in such conditions with low-light. Therefore after long periods of summer stratification oxygen in the bottom waters (aka hypolimnion) there are still organisms using up oxygen, like fish and decomposers, but no replenishment! It is important to monitor these parameters throughout the year incase the bottom waters become oxygen poor (hypoxic) or no oxygen (anoxic). Issues with no oxygen can include fish kills and release of substrate bound nutrients, possibly resulting in an algal bloom!
So this process that I have explained was summer specific, but the same situation is also possible in winter! I had stated that most lakes in the northeast mix or ‘turnover’ twice a year, therefore they also stratify twice a year – the pattern is stratification in the summer, mix in the fall, stratification in the winter, mix in the spring. Of course this is all weather dependent, some winters are not cold enough for long enough to get ice coverage and the water never really becomes stratified! This is why it is important when studying a lake to understand the water quality parameters specifically before the lake turns over – to try to predict and prevent anoxic/hypoxic conditions!
So why didn’t this kind of sampling work at Koinonia?
The bladderwort was one issue – it crowded the YSI sonde whenever I lowered it into the water… but, Koinonia’s waterbody is a different story and isn’t necessarily classified as a dimictic lake. If you take a look at google earth or google earth pro, you will notice that the old stream – Mill Brook, can still be seen – the water is still flowing! This mechanical mixing due to elevation gradient prevents the water from every really becoming stagnant and stratifying. This is good news when thinking about oxygen levels and fish health. The water in Koinonia is so shallow and because of the plant coverage can get really, really warm! Warm water holds less oxygen than cold water, so if Mill Brook wasn’t still running most of the year this would be more concerning for the organisms that live in the water.
Maybe a video would help??
A peer and myself created an educational video explaining some of these terms and concepts for the North American Lake Management Society (NALMS) student submission series. Ours won! Please follow the link below to watch! https://www.youtube.com/watch?v=klQ43No0y-A
So what kind of data am I collecting now for my thesis because the lake-style was a bust?
Wetlands are a little trickier to categorize in the sense of ‘worth’ or ‘condition’, however there are a few tools that are popular in scientific literature. The one I am using now is called the ‘Floristic Quality Index Assessment’. How it works is I went out and sampled a few locations for plants using a quadrat. A quadrat is just a square of set size used to define area more precisely. I chose sample spots and identified all the plants within these plots. After getting confirmation on my identification, I went online and found ‘values’ for all of the plant species. The way it works is each plant species is given a point value on a scale of 1 to 10. Rare or endangered species have a high value, where as common or nuisance species would have a low value. Invasive species do not get values – at first you can think this cant be right, but when you think that if the plot is completely taken over by invasive species, as they commonly do, then that plot would actually have a zero because no other plants are there. Does that make sense? So to evaluate the floristic quality index (FQI) of one area I had to sample until I was confident that I took enough data points to include most of the plant species present. After my list was complied I researched each plant species-specific number, called its ‘coefficient of conservatism’ of ‘C value’. These values were averaged and a FQI for that area was calculated.
Science doesn’t always allow you to do exactly what you set out to accomplish – I learned this the hard way! I chose my sample locations by evaluating the different types of wetlands on the wetland mapper… I later learned that these locations were impossible to get to! So I adapted my approach to be able to sample what I could. So for my analysis of wetland condition at Koinonia I am sampling the wetland between the dam and the road (Mud Pond Rd) and comparing it to the quaking bog area above Mud Pond. This will emphasize the importance of keeping Koinonia protected from development and high traffic – using the more disturbed location that has been altered by high traffic, impoundment, and the road construction – compared to the quaking bog that has been largely left untouched and wild! I will also be comparing these values to those generated by the species lists in the technical report I have already mentioned – Ecological Communities of New York State! This is to compare Koinonia to ‘pristine’ wetland community that is largely theoretical to see where the value falls on the scale. It is important to remember with FQI that a single number tells us nothing, but FQI is used to compare areas against each other regardless of type of wetland!
Stay tuned for the next post where I share my results!