Leaf Packs Help Measure Water Quality

ACEER scientists conduct a benthic survey to measure the health of a stream in Peru. Photo: ACEER


Photo: Leaf packs
Leaf packs. Photo: ACEER

We recently covered the expedition to Peru by the Amazon Center for Environmental Education and Research (ACEER) to measure water quality along the new Transoceanic Highway, which will cross South America from east to west when finished.

The ACEER team has been using stream surveys and leaf packs developed by the Stroud Water Research Center in Pennsylvania as relatively simple assessment tools, before the full impacts of the emerging road are in swing.

ACEER now has some more results to share (you can also view field notes on their Facebook page).

The project is being supported by National Geographic and the Blue Moon Fund. Field operations are led by Bern Sweeney of the Stroud Center. In the first phase of a two-year project, conducted in late spring, study sites were established from Cuzco to Puerto Maldonado in Peru, along the highway corridor.

ACEER team members then conducted benthic surveys by wading into a stream and collecting aquatic insects with a net. Scientists examined the catch through a microscope, and used an assessment of the populations of so-called indicator species as an estimate of the health of the ecosystem.

The team explains, “In this study, ten watersheds were assessed with 2 point sampling sites in each: one site as a pristine control point and the other as a variable in that it would be a likely impacted site.  Final reports provide to us interpretations of the patterns of distribution of invertebrates and the possible correlational or causal relationships to factors both natural and from human influence. ”

Photo: Therany Gonzalez of ACEER deploys leaf packs.
Therany Gonzalez of ACEER deploys leaf packs. Photo: ACEER


The ACEER group also deployed leaf packs, which are mesh bags filled with leaves from local trees and weighted down in the water. After six weeks the packs are examined for the aquatic insects that colonized them.

According to the team, “When correlated with our previous benthic surveys this simple leaf pack tool is a powerful way to assess ongoing aquatic biodiversity. In our study, the indicators of highest water quality are insects known as stoneflies, mayflies, and caddisflies. When we find large populations of midge larvae called chironomids it is a pretty sure sign that the stream is under stress or severely degraded.”

Scientists will conduct three rounds of leaf pack tests this year, followed by several rounds at 10 new sites next year. In 2013, the team will also train Peruvian university faculty and students in assessing water quality. “By the end of 2013 we will have an excellent picture of ecosystem health along the Transoceanic Highway,” the group points out.

At the end of the study, ACEER will also share their findings with a wide array of local people, as well as the scientific community.

Photo: ACEER stream survey in Peru
The team assesses a stream along the Transoceanic Highway corridor. Photo: ACEER


Response in the Field

Therany Gonzalez, ACEER’s director of field operations, said that while he was evaluating one site he was approached by a group of three local people. “They were very interested in what we were doing,” he said.

“They asked us to give a talk for their community and for the children. They said to me that they do not know the macroinvertebrates that are living in the streams but they want their children and all the population to be aware of the bugs in their stream. They were very interested in conserving the water quality in their town,” said Gonzalez.

Photo: ACEER team members meet locals in Peru
ACEER team members meet locals and tell them about the importance of water quality. Photo: ACEER


Brian Clark Howard is an Environment Writer and Editor at National Geographic News. He previously served as an editor for TheDailyGreen.com and E/The Environmental Magazine, and has written for TheAtlantic.com, FastCompany.com, PopularMechanics.com, Yahoo!, MSN, Miller-McCune and elsewhere. He is the co-author of six books, including Geothermal HVACGreen Lighting and Build Your Own Small Wind Power System.

Changing Planet