Saturday, August 2, 2008

Studying the River: The Importance of Looking Closely

I know it appears from the blog as though we've just been hanging out in our new home, cooking elaborate meals and celebrating birthdays, but we've actually been hard at work in between all the parties. Our river sampling began in earnest two weeks ago, and it has been keeping us quite busy. We have been choosing the reference sites which we will sample repeatedly over the coming year, and we just finished our first round of intensive macroinvertebrate sampling. "Macroinvertebrate" is the scientific name for the bugs that live in rivers, and they are great indicators of water quality, so we will be watching how their populations change over the wet and dry season this year. All of this has been quite a learning experience for us, so I thought I would share some about it here.


Of course, the first thing we had to learn was how to convince the hippos and crocs to allow us to sample for macroinvertebrates in these waters.




But we chose our sites carefully, and after watching the waters for 30 minutes, my trusty field assistant and I headed in.


We figured if the local ladies washing their clothes on the river banks could do it, why couldn't we?
It didn't hurt that we were also accompanied by an armed guard. Although he did admit upon questioning that, in the event of a croc attack, he would probably run away. But we appreciated his honesty:)

After kicking up the sediment in the river and collecting it with a net, we headed to the banks to sort out the bugs. You can see in the picture below the croc watching us from across the bank.
Here she is up close. What lovely animals!



And here is Chris with our driver and impromptu field assistant, carefully picking bugs out of the net.

Eventualy we decided to start sorting the bugs out at home in order to save time, but this had other unexpected benefits. In the field we were finding 20-30 bugs per sample, but once we got home and were able to pick through the samples more carefully, we were finding 100-200 bugs per sample! It's incredible how much life is in every inch of this river! The only downside is that this takes about 1-2 hours per sample, with about 12 samples per site. So we have spent a lot of time this week hunched over bowls with tweezers.

Our house is pretty small, so our laboratory, living room and kitchen are all the same. You can see in the picture below our bottles full of bugs, petri dishes to detect the presence of E. coli in the water, and our Bolivian coffee filter all hanging out on the counter together. I'm pretty sure this violates some health codes, but it's all in the name of science!



Now we will take our samples to an entomologist, who will identify the bugs and help us to characterize their sensitivity to water quality. By repeating this sampling every month, along with water quality analyses, we will learn a lot about how this important component of the ecosystem is affected by changes in the river. Of course, we'll also have a lot of fun along the way!
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