Image 1. The lichen being soaked for around 20 minutes in order to rehydrate the data collected.

Image 2. Water after being filtered. This product was looked at under the stereoscope.

Summary:

We decided to study on how the proximity to a body of water may affect taxa composition (tardigrades, rotifers, and nematodes) of collected samples. After doing some research, we found that tardigrades prefer habitats with higher humidity (Northcote-Smith 2012). We hypothesized that there would be a higher abundance of taxa composition in moist environment. However, their reason for dispersal is still unknown. We have much to learn about their ecology.

Methods:

To ensure that we collected enough data for our research, we decided that each member would collect five samples of lichen from different trees. Two members were to collect lichen from trees near the Red Cedar River , designated as “moist” environment, while the other two were to collect samples from trees far from the Red Cedar River, the “dry” environment. These samples were collected from roughly between four to six feet off the ground. In the lab, the

lichen samples were rehydrated in tap water for about twenty minutes before the liquid was strained into an empty petri dish using two layers of cheesecloth. The strained liquid was observed under a microscope to count the number of live specimens of tardigrades, nematodes, and rotifers in each sample. After collecting all of our data, we performed a Chi-square Test of Independence and the Goodness of Fit Test to determine if there was a significant relationship between the gathered data.

Results:

The Chi-square Test of Independence rejects the null hypothesis and concluded that there is a significant relationship between the abundance of taxa (tardigrades, nematodes, and rotifers) and the environments of close and near proximity to water (p=0.3212) (Figure 1).

The Chi-square Goodness of Fit Test rejected the null hypothesis with a X2 value of 18.84 for the environment close to the proximity to water (df = 2, p<.001) (Figure 2), as well as for the environment with a far proximity to water with a calculated X2 value of 63.62 (df = 2, p<.001) (Figure 3). This concludes that there is a significant difference between the observed and expected value of both environments.

There were more tardigrades and nematodes found in environments close to water source and more rotifers found in environments far from a water source.

Discussion:

Many species of rotifers are parthenogenetic, meaning that the egg of female rotifers have the ability to reproduce without being fertilized by sperm. We hypothesize that this could be the reason why rotifers are more abundant than tardigrades and nematodes in dry environments. However, this requires more in depth research. Future research could use our data and results to explore the reason behind taxa’s (tardigrades, nematodes, and rotifers) dispersal.

References:

Tardigrade Tea Website.

Bagai A, Guruswamy V, Liu J, Rizki G. 2000. Introduction to the Rotifera.

Northcote-Smith E. 2012. The ecology of tardigrades. The Plymouth Student Scientist (5)2: 569-580.