A quick method of determining rock surface area for quantification of the invertebrate community

Stone and rock substrates provide important habitat for many types of stream-dwelling invertebrates. Measures of the invertebrate communities inhabiting rock substrates are often an important component of ecological, monitoring and disturbance studies in streams. A major obstacle to researchers examining rock-inhabiting invertebrates is the time and effort expended on currently used methods of determining rock surface area to derive invertebrate densities on these substrates. In an attempt to more efficiently determine invertebrate densities from rock substrates in streams, we tested a direct method of calculating rock surface area from rock weight or displacement volume. This method allows very quick determinations of rock surface area in the field. Surface area estimates made using this technique were highly correlated to those from a widely used and more time-consuming method. Measurements made using this new method should theoretically give better surface area estimates than any other commonly used technique.