Development of a standardized large river bioassessment protocol (LR‐BP) for macroinvertebrate assemblages

Abstract

Efforts to develop benthic macroinvertebrate sampling protocols for the bioassessment of lotic ecosystems have been focused largely on wadeable systems. As these methods became increasingly refined and accepted, a growing number of monitoring agencies expanded their work and are now developing sampling protocols for non-wadeable large rivers. Large rivers can differ from wadeable streams in many ways that preclude the use of some wadeable stream sampling protocols. Hence, resource managers need clear and consistent large river bioassessment protocols for measuring ecological integrity that are cost effective, logistically feasible, and meet or are adaptable to the multi-purpose sampling needs of researchers and managers. We conducted a study using an experimental macroinvertebrate sampling method that was designed to overcome limitations of several methods currently in use. Our objectives were to: (1) determine the appropriate number of sampling points needed; (2) determine an appropriate laboratory subsample size to use and (3) examine how varying reach length affects assemblage characteristics. For six reaches in each of two large rivers, we sampled the macroinvertebrates of both banks at 12 transects separated by increasingly larger distances using a multi-habitat, semi-quantitative technique. Interpretation of results relied on the values attained for nine benthic macroinvertebrate assemblage metrics. Results from Monte Carlo methods indicated that, using the sampling methods described herein, a representative sample of the assemblage was collected by sampling both banks on 6 transects. Across all sites, we did not observe a consistent relationship between transect spacing (i.e. total reach length) and metric values, indicating that our sampling protocol was relatively robust with respect to variation in reach length. Therefore, flexibility exists that permits the study reach length to be dictated by the spatial scale (e.g. repeating geomorphic units) in question. For those preferring to use a fixed reach length, we recommend that transects be spaced at a minimum of 100 m intervals over a 500 m distance. We recommend that the field method be coupled with a fixed laboratory subsample size of 300 organisms for bioassessment purposes, with the recognition that a subsample size of 500 organisms may be needed to meet the objectives of more rigorous studies. It is likely this approach will over-sample sites of uniform composition, but the goal was to develop a robust sampling protocol that would perform well across sites of differing habitat composition. Possible modifications to the method to streamline its future application in the field are provided. Published in

Field and laboratory performance characteristics of a new protocol for sampling riverine macroinvertebrate assemblages

“…This indicated that each method was likely capturing different components of the macroinvertebrate assemblage. This conclusion provided the impetus for developing a new macroinvertebrate sampling approach specifically for non-wadeable streams and rivers which combined features of multiple field methods (Flotemersch et al, 2004(Flotemersch et al, , 2006a.…”

“…The new macroinvertebrate large river bioassessment protocol (mLR-BP) includes both field and laboratory components (Flotemersch et al, 2004(Flotemersch et al, , 2006a. The field method is based on a defined sampling zone, the systematic approach of kick net sampling at fixed transects, and a multiple habitat sampling approach that incorporates all observed habitats in a fixed sampling area.…”

Spatial patterns in the composition of shallow‐water macroinvertebrate communities of a large New Zealand river

“…Flotemersch et al (2006) found that sampling both banks at six transects provided representative estimates of macroinvertebrate community composition on major tributaries of the Ohio River. Although this approach would not provide an accurate representation of invertebrate community structure across the entire channel, it does enable comparisons of data along sections of river, especially if multiple littoral samples are integrated over the site of interest as suggested by Flotemersch et al (2006). Compositing multiple samples will also assist with acquiring sufficient invertebrate numbers to fulfil the requirements of any fixed-count procedures that may be used to process samples, as densities can be low in some habitats (Reece & Richardson 2000; this study).…”

“…Thus sampling shallow-water habitats in the photic zone at river edges might be expected to access the main sites of invertebrate species aggregation, although deep mid-river and shallow littoral faunas may be different (Neale et al 2006). In recognition of the apparent productivity of littoral areas of large rivers, macroinvertebrate sampling of shallow, near-shore habitats similar to most of those investigated in the present study has now been integrated into large river bioassessment practices in the United States (Flotemersch et al 2006).…”

Drivers of Abundance and Community Composition of Benthic Macroinvertebrates in Ottawa River Sediment near Chalk River Laboratories

“…The Canadian metal mining and pulp and paper EEM guidelines [18,19] recommend five replicate core samples per site to obtain an accurate estimate and minimize sample error. However, these guidelines were likely developed with consideration to aquatic systems that are considerably more productive and easier to sample than the Ottawa River (e.g., wadeable streams, small rivers, littoral areas of lakes) [65].…”