Palaeolimnological validation of estimated reference values for a lake profundal macroinvertebrate metric (Benthic Quality Index)

An extended Benthic Quality Index for assessment of lake profundal macroinvertebrates: addition of indicator taxa by multivariate ordination and weighted averaging

“…We also correlated (Pearson product-moment correlation) the index values with site-specific DCA S axis 1 scores to assess the relationship of indices with general community turnover of the profundal macroinvertebrate assemblages. We developed multiple linear regression (MLR) models (see Jyväsjärvi et al 2010) based on CAL data to estimate site-specific reference values for each index on the basis of environmental variables insensitive to human activity (Table 1). We also included water color among the candidate predictors because it is used as a proxy for geology in Finnish lake typology, but we acknowledge that the natural color value expected in the absence of human disturbance should be used.…”

“…BQI also has been used provisionally as a metric in Swedish ( Johnson and Goedkoop 2007) and Finnish (Rask et al 2011, Jyväsjärvi et al 2012) bioassessments of lakes mandated by the Water Framework Directive of the European Union (European Commission 2000). The BQI is well suited for such assessment because it can be interpreted as measuring the community characteristics, 'ratio of disturbancesensitive taxa to insensitive taxa' and 'taxonomic composition,' included in the normative definitions of ecological status by the WFD (Jyväsjärvi et al 2010). The strong response of BQI to increasing and decreasing human disturbance has been well documented in contemporary (Rask et al 2011, Jyväsjärvi et al 2012) and palaeolimnological (Ilyashuk et al 2003, Meriläinen et al 2003, Hynynen et al 2004, Verbruggen et al 2011) studies.…”

“…The strong response of BQI to increasing and decreasing human disturbance has been well documented in contemporary (Rask et al 2011, Jyväsjärvi et al 2012) and palaeolimnological (Ilyashuk et al 2003, Meriläinen et al 2003, Hynynen et al 2004, Verbruggen et al 2011) studies. Another advantage of BQI for modern reference-condition-based assessments (Bailey et al 2004, Stoddard et al 2006) is that its sitespecific reference value can be predicted reliably from environmental variables (Jyväsjärvi et al 2010). In contrast, previous studies suggest that more conventional assessment metrics, such as taxonomic completeness widely used, e.g., for river invertebrates (Hawkins 2006), cannot be applied to profundal invertebrates of boreal lakes.…”

“…Wiederholm (1980) suggested that a lack of these taxa indicates the most deteriorated status, but this interpretation can be incorrect because the few indicator species can be missing for natural reasons or simply be undetected. In fact, these taxa are often missing from samples from nearly pristine lakes (Jyväsjärvi et al 2010) because of their low abundance. This situation creates great uncertainty in BQI estimates (Veijola et al 1996).…”

The importance of sedimenting organic matter, relative to oxygen and temperature, in structuring lake profundal macroinvertebrate assemblages

“…Number of BQI indicator larvae per site varied between 0 and 39. Four sites with no indicator taxa present (Muu1, Muu2, Iso4 and Iso5) were excluded from the statistical analyses of BQI data (see Jyväsjärvi et al, 2010).…”