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science, health & technology
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Using freshwater invertebrates to measure
the health of a river or stream If one accepts the general premise that pollution is on the whole harmful for living things, then it would make intuitive sense that one good measure of how clean or polluted a body of water might be would be by reference to its abundance of life or lack thereof. However, life tends to not be so simple --- after all, E coli bacteria, algae and carp are living things, too, so one might get a lot of living things in a sample taken from a grossly polluted river. You would not, however, be likely to get the same rich diversity of life found in a healthy river. But what should one expect in the first place, in order to have a baseline against which to measure? These are the questions that James Harrington has been sorting out with the California Department of Fish and Game’s Water Pollution Lab for many years. He’s still working for the organization that The Terminator heads, but his wife has retired, and the couple has bought a house in Bocas. En route to this retirement in Panama, he and a number of his colleagues with the State of California have made a habit of coming to Panama and doing some of the same sorts of measurements in our rivers and streams as are done in California. (Please don’t terminate them, Arnold --- they’re doing it on their own time, with their own money, and publishing the results on a website that could let you claim credit for this California foreign policy triumph, were you so disposed.) California is a relatively wealthy state, with relatively advanced environmental laws and a good scientific and technological infrastructure. The state actually has the chemistry and toxicology means to measure pollution by methods arguably more “exact” and “objective” that life surveys. So when Harrington started out working for the state, “they didn’t want to use biological measures” because there was already strong chemical monitoring in place. But California is also the place that decades ago passed Proposition 13, wherein voters expressed a desire for more economical government. There are various forms of biological monitoring that can differentiate healthy from unhealthy rivers, and some, like studying bird life, are relatively expensive while others, like looking at the insects, are fairly cheap --- cheaper, in fact, than chemical monitoring. However, Harrington noted, “the biggest problem was convincing the toxicologists and chemists.” But how to do this? The presence of a lot of mutant frogs in a stream is a cliché about water pollution, and in fact can be a very good warning sign. Frogs, however, are vulnerable to all manner of threats other than pollution, as the ongoing fungus pandemic that threatens our golden frogs with extinction indicates. Harrington offers his condolences to those who have been trying to monitor water quality by using frogs. He concentrates on benthic macroinvertebrates, that is, spineless organisms that are big enough to see and live underwater. As in, for example, the larvae and nymphs of mayflies, caddis flies and snowflies. “We never rely on an indicator organism,” Harrington explained. “We want a community.” The signals are better, he said, if you look at 50 or 60s species at a time. What sort of signals, for what purposes? It turns out that a lot of the work that the lab where Harrington works is used for law enforcement purposes. And which laws? It turns out that a fair amount of the litigation in which he’s called upon to provide evidence is fought under the California Commercial Code, as it’s a most unfair and illegal business practice to flout environmental laws while the competition goes to the expense of compliance. Some of the worst offenses are not the dumping of chemical wastes in waterways at all, but sloppy construction or logging techniques that leave the bottoms of rivers and streams silted. Chemicals tend to wash away, but mud on the bottom of a stream where once there was gravel destroys habitat for a long time. It’s possible to look at the insect larvae abundance and diversity above the point where the silting takes place and at a number of points below it, and show to a jury’s satisfaction that the developer who should have built a retention pond but skipped that expense has damaged the environment in a measurable way. The science that Harrington does gets ever more sophisticated. For rapid biological assessments, it’s wise to eliminate rare species from the count and to avoid using those organisms whose presence in the environment is typically too variable. To get a good baseline of what should be expected where, it’s necessary to have a good base of data on which organisms tend to inhabit which parts of rivers and streams, and measure for those which the database tells you to expect. In general, Harrington noted, things that filter their food out of the water tend to be good indicators of the effect of a dam. The number of beetle larvae present is a good indicator of the overall health of a stream. But to get more precise, ever more complicated models are needed. The state of the science these days, developed in the UK, is the River Invertebrate Predictive and Classification System (RIVPACS). That takes into account “where certain species belong” in terms of elevation, geology, latitude and longitude, temperature, precipitation, watershed area and so on. On those bases the probability of the capture of each organism is predicted, and the better the match between the prediction and what is found, the better the water quality. But of course, collecting all the background data over an entire watershed can be a problem. Many parts of many streams can only be reached by crossing private property, whose owners may not be amenable to letting government researchers onto their land. What’s needed now, Harrington said, is to standardize protocols for such analysis. And getting back to old rivalries, he argued for new cooperation. Biological measurements can show that there is or probably is a problem, but then chemical or toxicological tests are often best when it comes to specifically identifying the cause of distress in a river system. Beyond that, Harrington noted, it’s not a good idea to impose a single standard of aquatic health. Comparing Panama City’s Matasnillo River, essentially an open sewer, to the Chiriqui River that’s so popular with rafters and trout fishers, is a fairly pointless exercise in his eyes. The problem in the United States, he believes, is that most environmental enforcement resources go to the bad streams that will never run clean again, while more attention needs to be paid to saving the good ones. As a state employee he has interactions with citizen groups, which has its good and bad points. “There’s too much emotion,” he said, but if citizen activists can be taught to use the proper methods, their “scientifically sound environmental activism” can complement the work that the government does. “Instead of just crying and moaning, just get the data,” he advised. Harrington concluded with some remarks about his work in Panama. He helped to do a bio-survey for the Panama Canal’s expansion plan, looking at insects and fish in both rainy and dry seasons. He and a number of his colleagues have been coming down here for several years, and have collected data on 23 rivers and streams. A lot of the work is found in the “Panama Digital Reference Collection” part of the California Aquatic Bioassessment Laboratory website, at http://ospr.dfg.ca.gov. He said that the tolerance values used are based on North America, but local figures would be better. When the taxonomy work at the reference sites is done, he said he’d like to transfer the database to the University of Panama. Eventually, he hopes, there will be a Panama Water Quality Management Program.
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