Belize -- We spent Thursday traveling through the Belizean countryside, sampling streams and utilizing the information and methods we had learned in our tropical stream ecology course over the last few days.
Mark (Eastern U.) sampling macroinvertibrates in the Mopan River
We turned off the road onto a steep dirt track that led to our second stream site of the day. Caves Branch is a beautiful stream that flows out of the Maya Mountains and down through the karst valleys until it reaches the Sibun River and finally the Caribbean. As the van approached an opening in the shrubs and trees that form the riparian zone, some small children scattered, leaving their mud pies in the trail. They splashed into the river and joined their mother who was busy washing clothing on the concrete at the base of the bridge, a fairly typical sight in the streams and rivers throughout Belize.
Rachael (Calvin C.) and Neil (Eastern U.) testing water chemistry
After finishing their pack lunches, the students piled out of the van and started scanning the area. By this time in their stream ecology course they had begun to recognize the indicators of stream health using a visual assessment. What is the composition of the stream bottom - sand, gravel, boulders, limestone, silt? How is the stream bank cover? What seem to be the uses of the watershed of this area? What are the anthropogenic uses of the stream?
Students preparing to measure discharge rates
Having completed the visual assessment, we began to form certain hypotheses regarding the health of this stream. The next step was to test it. During the week the students had learned how to use tests to collect data on dissolved oxygen, pH, alkalinity, stream discharge and E. coli, as well as methods for biomonitering using macroinvertibrates, which serve as indicators of stream health. The students got to work.
Performing measurements at Caves Branch
At this particular river they were measuring discharge, E. coli, and macroinvertibrate diversity. A measuring tape was swum up the river to prepare for measuring discharge. "Kick nets" were pulled out and students waded out into the riffle of the stream to begin agitating the gravel and collecting the larvae of dobsonflys, dragonflies, damselflies and mayflies along with their many friends. Sterile E. coli plates, prepared earlier that morning, were filled with water from the stream and put in the shade to set.
The lady washing her clothing looked on with some interest as the data were collected with much laughter. When all the tasks were complete, Dr. Bill Deutsch, who had been teaching the class, gathered the group together and pointed out some distinct characteristics of this stream and the life that was present here. He was interrupted briefly by the spotting of a King Vulture, a huge and beautiful bird usually only seen in these mountain areas.
Collecting macroinvertibrates at Caves Branch
Having completed our work we filed back into the van and headed back to campus. We were happy to find two days later that in Caves Branch E.coli levels were very low, macroinvertibrate diversity was high and flow rate was adequate for a stream this size. These results suggested that this was in fact a healthy stream that provided wonderful habitat and nourishment for the creatures - both human and non-human - who made their homes in its watershed.
Olive (Calvin C.) and Michelle (Dordt C.) measuring stream width and depth
