Invasive ecosystem engineers and biotic indices: Giving a wrong impression of water quality improvement?

Abstract

Abstract:Benthic component of an ecosystem is considered in ecological status assessment of the key European Directives. Most of the metrics proposed for the benthic quality assessment are biodiversity based. Their robustness and applicability are widely discussed in many recent studies. However an impact of invasive alien species on biotic indices and environmental quality assessments has been largely overlooked by researchers so far. In the current study we assessed Benthic Quality Index (BQI) in a coastal ecosystem, highly affected by the invasive zebra mussel Dreissena polymorpha. Zebra mussel is able of modifying benthic habitats and enhancing local biodiversity. In the analyzed ecosystem it affected benthic species richness, abundance and community structure. As a result the calculated BQI values were significantly higher in the presence of zebra mussel with evident outliers in samples with particularly high zebra mussel abundances. Therefore we found that BQI determined in our study was artificially elevated providing false signal of the ecological status improvement. Based on the results presented, we suggested data correction framework that has been tested on the current dataset and proved to be effective minimizing zebra mussel impact on BQI assessment. Our experience could be applied for other coastal ecosystems invaded by the zebra mussel or any other aquatic invasive species with resembling biological traits and bioinvasion impacts. Highlights: We test the effect of an invasive alien species on ecological quality assessment  We calculate Benthic Quality Index for the coastal lagoon affected by zebra mussel  Zebra mussel may modify benthic habitats enhancing local biodiversity  This might bias BQI by showing false improvement of ecological status  We suggest a framework how the this bias could be minimized

Invasive alien plant species: Their impact on environment, ecosystem services and human health

“…Certain aquatic invasive alien species were observed to adversely impact the Benthic Quality Index (BQI) in marine ecosystems (Zaiko and Daunys, 2015). Thus, these coastal invaders can act as ecological indicators of the marine ecosystem health.…”

Spatial Effects of Different Zebra Mussel Farming Strategies in an Eutrophic Baltic Lagoon

“…The main aim of the developed model was to raise the awareness and demonstrate potentials of mussel farms (Figure 1). Due to the missing experience, several risks were omitted such as the interaction with other benthic species (Zaiko and Daunys, 2015) and potential species composition changes (Wolnomiejski and Witek, 2013). Applying more detailed growth models, e.g., the Dynamic Energy Budget (Saraiva et al, 2011;Thomas et al, 2011;Maar et al, 2015) may give more sophisticated results, but a broad calibration data set is then needed, which was not available for our case study.…”

The European Water Framework Directive facing current challenges: recommendations for a more efficient biological assessment of inland surface waters

“…The increasing number and expansion of IAS in freshwater ecosystems has replaced native biota in recent years, dramatically changing aquatic biodiversity and ecosystem structure and functioning (Cardoso and Free 2008) and degrading aquatic services (Mota et al 2014). Invasive species may alter the water quality (McCormick et al 2010), as in the case of the zebra mussel (Dreissena polymorpha), with consequent impacts on water supply facilities and biotic indices (Minchin et al 2002, Zaiko andDaunys 2015). Moreover, surface waters can be vectors for the spread of diseases, such as sudden oak death (Grünwald et al 2012), incurring major economic and ecological costs for the control of invasive species.…”