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Neighbors Collaborate for Stream Health


Pilar (far right) explains and demonstrates the dissolved oxygen test.

Last week, the Osa Conservation Rios Saludables team joined four staff members from the Lapa Rios Ecolodge for their second monthly chemical and biological assessment of Rio Carbonero’s stream health. Pilar Bernal (Education Outreach Coordinator) led the chemical portion of the monitoring, walking us through testing water temperature, pH, dissolved oxygen, turbidity, conductivity, alkalinity, and nitrates. Julieta Chan, the Lapa Rios Ecolodge Experience Manager, took detailed notes and filmed most of the workshop. Jim Palmer, Science Education Director and photographer, also did not let any of these details escape. We love seeing their dedication to accurate aquatic testing! Accuracy in experimental nuances, such as adding reagent drops into a water sample or waiting for an alkalinity test strip reading, can directly affect the end results. Avoiding even the smallest mistakes ensures that our citizen-scientists are collecting trustworthy data to fill a baseline water quality database of streams in the Osa Peninsula.


Nelson and Tabea read the pH measurement in order to determine the acidity of the stream.

Tabea Zimmermann (Research Field Assistant) led the crew through the biological assessment portion of stream monitoring. She explained how macro-invertebrates serve as bioindicators of stream health. Certain species are more sensitive to pollution than others, so a strong presence of sensitive species in a stream indicates clean water and an adequate macro-invertebrate habitat. Armed with scoop nets and forceps, each participant explored riffles, pools, and leaf packs in the bubbling stream in search of mayflies, caddisflies, stoneflies, dragonfly larvae, beetles, snails, and shrimp. After some time, a staff member exclaimed that he discovered a hellgrammite! Hellgrammites, commonly nicknamed “perros del agua” in Costa Rica, are top predators in stream ecosystems. Due to their avid hunting skills and carnivorous diet, their presence indicates that a stream contains sufficient prey for them to survive – in other words, there is a thriving food web that is able to sustain its top species! Everyone huddled around the container to witness the food web live at work: the hellgrammite was enjoying some easy snacking among the tiny shrimp and larvae we had collected. Good news for Rio Carbonera!


The team looks for macro-invertebrates and stores them into ice cube trays for identification.


No one hesitated to get wet and muddy while searching for macro-invertebrates along the stream bank









Julieta and her staff appreciated the second training and we are all excited to continue strengthening the Rios Saludables – Lapa Rios Ecolodge partnership. Moving forward, we hope to forge a future collaboration with the Rio Carbonera primary school so that Lapa Rios staff and local students can learn about and monitor the stream together in their shared backyard. Possibilities abound and the Rios Saludables crew look forward to engaging our local community towards appreciating and protecting the Osa’s vital aquatic resources and ecosystems.


This group is ready to lead other Lapa Rios staff members through visual, chemical, and biological monitoring protocols. Let’s spread the skills and excitement for protecting a local stream!

InternUser Osa Conservation
[email protected]
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