Blogpost by Hilary Brumberg, Ríos Saludables Program Coordinator
Students in bright blue uniforms dip nets into a small stream and retrieve soggy masses of leaves, branches, rocks, and candy wrappers. They comb through the leaves with plastic spoons, and excitedly pluck small insects and crustaceans from the foliage and place them into the stream water filled ice cube tray – our fancy specimen holder.
The students rush the specimens over to our identification station, a tree stump bearing a laminated booklet with dozens of pictures of aquatic critters. They methodically scan each page of the identification guide, enthusiastically pointing at pictures that look like their specimens. When these young scientists finally decide on the identity of the critter swimming around their tray, they return their specimen to the stream and begin fishing again. Other groups of teenagers wander around the stream in pursuit of litter, tossing snack wrappers in black trash bags to help clean the streams.
These students attend Colegio Industrial Técnico Puerto Jiménez, one of two secondary schools on the Osa Peninsula and the closest one to our biological station. In the yard behind their school is Cacao Stream. Students usually eat lunch alongside the stream, and often snack wrappers mysteriously make their way into the stream.
Today, these students are surveying the stream for macroinvertebrates, mini mighty organisms that are bio-indicators for river health. Many of the students had never thought twice about Cacao Stream, let alone the crustaceans and insects that call it home.
This field activity is part of Rios Saludables’ first ever workshop with the Colegio Puerto Jiménez. Before heading to the stream to sample, I began the workshop with a presentation, assisted by one of the program’s community partners.
We discussed the importance of water and specifically rivers for nature and humans. Reasons they suggested included sources of drinking water, important ecological habitat, and nutrient transport.
One of my favorite parts of these presentations is to show a map of Osa’s expansive freshwater network. Rivers and streams expand like a spider web across the peninsula in every direction. Students always gasp when the map is projected, because they realize the extent that the peninsula’s ecosystems rely on rivers.
A trademark Rios Saludables saying is “the problem with water on the Osa is not quantity, but rather quality.” This leads nicely into an explanation of the ways we determine water quality, namely water chemistry tests and macroinvertebrate surveys. These students had recently learned about pH and alkalinity in their chemistry class, and I described what ranges indicate that a river is healthy. Then I passed around samples of macroinvertebrates I collected with community partners across the region, many from rivers close to students’ homes.
Now it is time for these newly ordained freshwater ecologists to head to Cacao Stream to practice these surveys.