Site length for biological assessment of boatable rivers

Abstract

There is increasing international interest by water resource management agencies worldwide in developing the capacity for quantitative bioassessments of boatable rivers. This interest stems from legal mandates requiring assessments, plus growing recognition of the threats to such systems from multiple and co-varying stressors (e.g. chemical pollutants, physical habitat alterations, altered flow regimes, channel modifications and alien species). The elevated cost and inefficiencies of jurisdictionally-and taxonomicallysegregated assessments is widely recognized, as is the desire to obtain comparable data that can be easily shared among political jurisdictions and ecological regions. The objectives, sampling methods, indicators, site-scale sampling designs and geographic extent of the resources being sampled differ among programmes, thereby limiting such data exchanges. Our objective in this paper is to review major biological assessment design alternatives for boatable rivers, with special attention given to the sample site length from which data are collected. We suggest that sufficient site length determinations should be based on the survey objectives, the relative heterogeneity of the habitat template, and the quality of data necessary for meeting programmatic data quality objectives. Future sampling effort studies should be designed to allow separate samples of several short sub-sites at many diverse sites to generate multiple data points for each site. Data from those multiple sub-sites should be analysed using randomization-based data evaluation methods. We hope that our recommendations will be useful to the maximum number of institutions, including those with limited funds and a purely local focus, as well as those responsible for sampling at continental geographic extents.

Estimating vertebrate, benthic macroinvertebrate, and diatom taxa richness in raftable Pacific Northwest rivers for bioassessment purposes

“…unpublished data). The negative correlation between taxa richness and mean thalweg and littoral depth may have been an artifact of decreased sampling effectiveness because deeper sites are more difficult to sample effectively (Flotemersch et al 2010). Increased temperature, nutrients, and anthropogenic disturbance were occasionally highly significantly correlated with increased taxa richness, particularly of vertebrates.…”

“…Such percentages also have been reported sufficient for assessing fish assemblage condition through use of multimetric indices of biological integrity at individual sites (Reynolds et al 2003;Hughes and Herlihy 2007;Maret et al 2007). Those site-scale levels of sampling effort have also been found sufficient for assessing the dissimilarity of benthic macroinvertebrate assemblages among sites (Cao et al 2002;Flotemersch et al 2010). Based on our field experience and the literature, we hypothesized that seven to ten sites would be sufficient for collecting 90-95% of the vertebrate species collected from 20 sites 75-95% of the time, but 14-19 sites would be necessary for the more speciose benthic macroinvertebrate and diatom assemblages.…”

Scaling fish metacommunities in stream networks: synthesis and future research avenues

“…Difficulties in estimating community parameters, however, can change with network position. Sampling becomes more difficult with increasing stream size, and requires multiple collecting devices (Flotemersch et al 2011, Loisl et al 2014, Erős et al2016b). Overall, much higher sampling effort is needed for the same level of sample representativeness in the downstream sections of rivers, than in upstream areas (Fig.…”

“…Overall, much higher sampling effort is needed for the same level of sample representativeness in the downstream sections of rivers, than in upstream areas (Fig. 6a,b, Cao et al 2001, Erős 2007, Flotemersch et al 2011). This calls attention to the critical importance of scaling in understanding within community (alpha) and between community (beta) diversity (Angermeier and Winston 1998, Pegg and Taylor 2007, Erős and Schmera 2010.…”

Partitioning Error Sources for Quality Control and Comparability Analysis in Biological Monitoring and Assessment

“…The actual dimensions of the sampling area ultimately depend on technical objectives and programmatic goals of the monitoring activity (Flotemersch et al, 2010). The spatial area from which the biological sample is drawn is that segment or portion of the waterbody the sample is intended to represent; for analyses and higher level interpretation, biological indicators are considered equivalent to the site.…”