Home Archived February 2, 2018

A Study in Stream Ecology



In this episode we explore how scientists for the USGS National Water Quality Assessment Program investigate the ecological health of rivers and streams across the United States. Focusing on a recent sampling effort along the Minam River in northeast Oregon, this video highlights USGS sampling methods for fish, macroinvertebrates (bugs), algae, and habitat. Join us, as we show biometric data can be used to assess the health of streams, only in this episode of the USGS CoreCast.


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[Intro Music begins]


[Steven Sobieszczyk] Each year USGS scientists systematically assess the ecological health and water-quality conditions in streams and rivers across the United States. This research plays a vital role in land management and natural resource decisions around the country. Contrary to popular belief, these extensive data collection efforts completed by researchers in the USGS National Water-Quality Assessment Program involve much more than just water quality.


[Kurt Carpenter] Back when the NAWQA program first started, the National Water-Quality Assessment Program, they recognized the need to incorporate biology into the sampling. We look at the algae that’s in the different streams and rivers and the bugs that eat the algae and then also the fish that rely upon the bugs as a food source. We also look at the habitat and the water quality to see how all these different groups of organisms respond to things like nutrients, pesticides, temperature, and other stressors.


[Ian Waite] What we’ve done is we’ve developed these methods that seem to work well across the nation. We have standard methods and standard protocols and so that way when we do the sampling here…and the same methods are used back in the east coast or the Midwest or whatever, that we’ve sampled everything in the same way. So we can compare and combine the data sets and actually assess things nationally or regionally.


[Kurt Carpenter] The program, in general, is looking at watersheds across the nation in pretty large river basins. And that has provided hundreds and hundreds of sampling locations in areas of urbanization, agricultural land uses, but also in settings like this…forested ecosystems that haven’t been as impacted by anthropogenic activities.


[Ian Waite] One of the things that’s really important in what we call “biologic assessments” of streams, so how do we…can we understand the conditions of streams and make a comparison between one stream and the next is…you have to know what is your reference, or minimally impacted condition.  If you don’t know what your benchmark is, you can’t then say when are things impacted or impaired or how or when are things changing. With climate change? Or with land use changes? You need to know your benchmark.


[Ian Waite] All the different ecological data, the algae, the macroinvertebrates, the fish, they give us different indications of what’s happening. One of the things we’re realizing is that it’s important to study more than one type of biological organism in the stream. Because each one can give you a slightly different signal. The other thing that it really gives us an indication of…is land use affects. Or when we look at the affects of agricultural land use on streams that we see that the biological is a really good response indicator of impacts due to water quality, or habitat changes, or sedimentation, or things like that.


[Kurt Carpenter] When we start to see impacts from things like water pollution on the biota, we see that in a variety of indicator species, a lot of the time we’ll see the diversity decline. Instead of having a food web where nutrients and light energy combine to produce a real productive stream that we tend to see as having a healthy trout population, or at least in these mountainous streams in the west. What you find is that you don’t see very many trout and the benthic vertebrate population is greatly simplified, you don’t see a lot of mayflies and stoneflies or other types of food for the fish. That can ultimately be traced back to water pollution.


[Ian Waite] Water quality is important to sample but one of the problems is it is expensive and it is only a one-time sample. It only grabs the water and gives you an assessment of what is happening at that one time. Where the biology, they live there all year long. So what you find when you’re sampling is they’ve been living and have been exposed to all the conditions that have happened all year long. And that’s why biology is a really good indicator of the whole system.


[Kurt Carpenter] A lot of the management and policy decisions that are set are driven by bio-criteria. And so we look at the health of biologic communities, really the full assemblage of fish, bugs, and the algae to get a full assessment of what the biota look like. But then we also collect samples and analyze water samples for nutrients and pesticides. Through the monitoring that we do and these interdisciplinary studies, and multidisciplinary approaches, we use all kinds of different modeling, and multivariate statistics and tease all this stuff apart, but ultimately we hope that the information we generate can be used by management agencies that dictate things like nutrient levels that are permitted in streams and controlling runoff and erosion and all those sort of processes. And really, without this kind of information where do you really begin.


[Steven Sobieszczyk] To find out more about NAWQA sampling efforts in your area or to learn more about how the USGS monitors the ecological health of rivers in the United States, please visit the USGS online. Historical data from Oregon, as well as the rest of the country can be found at our National Water Information System or at our biodata websites.  


This has been a video production of the Oregon Science Podcast, U.S. Geological Survey, Department of the Interior.


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