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Published: August 8th 2012
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Piecing it together
All of the parts were purchased in the US and Sabah, and assembled at camp. One of the main things I’m working on this year is getting primary productivity measures of each of my 8 study streams. This is something I’ve never done before, and the methods and details are still very new to me. For those non-nerdy types, primary productivity is basically a measure of the amount of energy (food) in an area—primary producers are things like plants that convert sunlight to energy, and in turn provide energy to all the other life in a system. So primary productivity is often used to predict how much biodiversity should be in a given area—the more production (food), the more life an area can support.
I learned about stream primary productivity measures from a grad student at Alabama a few months before I left, and spent months (in between teaching) reading up on the methods, gathering equipment, and trying to figure out how to do this at my field site. I think the data will be GREAT to have, and very valuable, but in many ways it has been a series of constant challenges to get everything working.
Challenge 1: constructing chambers. In retrospect, this was probably the easiest part,
but at the time it felt as if this project would end before it began. I purchased most of the components in the US, but had shipping delays and delivery issues with at least two of my orders, and I was assured that customer service departments generally just don’t care that your field season may be in jeopardy when a website lists shipping as “3-5 days” but fails to mention at the time of purchase that there will be an additional week or so for them to get around to actually shipping your order so that the equipment won’t arrive until after you’ve moved out of your stated shipping address and are in a foreign country in another hemisphere. Hai yai yai…
Ultimately, I acquired all the components I needed and managed to jerry-rig what I couldn’t get. I spent a couple of days both constructing the chambers, and running around town getting final bits and pieces, and by the start of June I had what looked to be excellent productivity chambers. Now I just needed a few dry days to get clear stream water.
Challenge 2: getting them to work. According to my data
The productivity gear
All this is lugged to the streams by us--and it makes the hike considerably more challenging! book, the first actual attempt at getting my chambers to work was on 6 June. I can tell you now that I didn’t get a usable day of data until 23 June, and even that was fraught with challenges.
One aspect of getting the measurements I need is to run the measurement in full sunlight, and again in complete darkness. I was told to use a bucket to cover the chamber for the dark measure, but didn’t realize until I was ready to put the bucket on my first chamber on the 6
th that the wires connecting the fan to the battery would not extend underneath a bucket. Back to town to buy copper wire to lengthen the distance between the fan and the batteries.
The next day, someone asked me if my buckets would fit over my chambers. I said yes, I had measured them and tested them. Then he asked if they would fit over the chambers when they had the clamps attached. Back to the drawing board.
With limited supplies and limited muscles to carry equipment along the trails to my study streams, we decided to try black plastic bags instead of buckets. After
Chamber in Action
Rock inside chamber, chamber filled with water, oxygen probe inserted--and it's off! a few trials on the best method of ensuring complete darkness, we now have a great method, and one that seems easier than the original suggestion of buckets.
On 12 June I made a second attempt at primary productivity measures, only to discover that for some reason my fans would often stop working or not run at all in the first place. The problem seemed to be water getting into the mechanism, but after much trial and error, we realized that essentially the fan had to be elevated slightly higher above the chamber in order to avoid the drag induced by the stir bar on the underside of the lid. So simple a solution, but one that took weeks for us to realize what exactly was going on.
With this final adjustment, we were ready to start taking actual data on 21 June, when we got measures for two rocks on our LFE stream before it started raining—we need three in a single day for the data to be usable. Finally, on 23 June we had our first day of official data.
Challenge 3: getting the data. Once we had most of the kinks worked out, we dove headlong into getting the measures before I moved on to Danum Valley (our other field site). I figured that now that our major issues were sorted, we’d have no problems. Oh, how naïve I was…
At least once a day all week I forgot to put the stir bar inside the chamber before affixing all the clamps, essentially wasting about 20 precious minutes each time. This may not seem like a lot of time in the grand scheme of things, but keep in mind that our travel time to each stream is about 2-3 hours, and that it’s almost impossible to get a car to leave camp before 8am, meaning we can’t start collecting data until about 10 or 11 am—leaving precious few hours of good sunlight, especially when each rock can take 2 hours to measure.
On 23 June, we discovered after running a chamber for the full 2 hours that we never had a stir bar inside at all, making those data completely useless. We also managed to run out of time and didn’t finish our 5
th & final measure because a) it was getting dark and b) we had at least an hour’s hike back to where we were meeting the car picking us up.
On 24 June, our batteries started dying and although we carted 3 sets of batteries into the field, we had to run only one chamber at a time because we didn’t have enough to power two chambers simultaneously. Amazingly, we managed to get all 5 measures we needed for this stream. But just to keep my ego in check, one of the chambers was broken (the 2
nd one to break) on the return hike home. Fixable, but definitely not great for avoiding leaks.
On 27 June, we had at least one instance of chambers leaking (solved by placing more clamps on, or positioning the clamps more strategically), and more battery issues. The battery problem was exacerbated by the fact that the chargers I bought in the US, which worked when I tested them before getting to camp, do not work. On the 28
th I discovered spare chargers in camp and managed to partly charge a couple of my batteries for the final day of productivity measures. This was a nice boon, since the final chamber joined his brethren in the broken department on the hike out of the stream. Again, they can all be glued back together, but it definitely doesn’t help their structural integrity.
On 29 June, at least one of the probes turned itself off. This issue has been plaguing us all week. The battery indicator said that the batts still had life in them (at least half full), but I’ve learned that for some reason, these probes don’t like anything less than about ¾ battery capacity. So now I’ve got plenty of C batteries on hand to keep them happy and running.
Which brings us to today—and our imminent departure for Danum Valley where I’ll get to run these measures on three new streams, as well as on the remaining streams here at SAFE when I’m back in a few weeks. The take home message from all of this? Don’t try out a new experimental procedure without having run through the entire thing with an expert first!
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