Impact of habitat diversity on the sampling effort required for the assessment of river fish communities and IBI

Abstract

The spatial variation in the fish communities of four small Belgian rivers with variable habitat diversity was investigated by electric fishing to define the minimum sampling distance required for optimal fish stock assessment and determination of the Index of Biotic Integrity. This study shows that the standardised sampling distance of 100 m was not always sufficient to collect most species present. The required minimum sampling distance seems to be correlated with habitat diversity. In homogeneous streams, a mean sample distance of 282, 452 and 572 m is necessary to capture 80, 90 and 95% of all species present, respectively. In heterogeneous streams, these sample distances decrease to 217, 380 and 503 m. Hence, at least 300 m should be sampled to catch most species present with a single-pass sampling method. However, our results show that a 100 m sampling distance as presently used in the Flemish monitoring programs is sufficient to accurately describe the ecological quality since differences in IBI evaluation between adjacent stretches could at least for some rivers be explained by differences in habitat heterogeneity

Inter-annual patterns in the stability and persistence of stream macroinvertebrate communities: relationship with water physicochemical parameters

“…Species persistence and assemblage stability might vary considerably depending on habitat diversity (Liefferinge et al 2010). In streams of the Denali National Park, Alaska, USA, community persistence showed a significant relationship with winter snowfall; stability was significantly related to the Pfankuch Index of channel stability .…”

A scientometric assessment of 30 years of the Index of Biotic Integrity in aquatic ecosystems: Applications and main flaws

“…Several approaches have been used to define reference conditions, among them the use of physical and chemical water variables (Detenbeck and Cincotta, 2008;Zhu and Chang, 2008;Casatti et al, 2009), water quality and habitat data (Astin, 2007), historical data on environmental conditions or on the aquatic fauna (Hu et al, 2007;Qadir and Malik, 2009), maximum scores of the IBI for less altered sites (Bozzetti and Schulz, 2004), gradients of human interference and occupation (Kanno et al, 2010), or protocols for environmental assessment (Oliveira et al, 2011). Some studies did not clearly state if or how reference conditions were defined (Van Liefferinge et al, 2010). The WFD associates reference conditions with stream typology; the biological attributes of the reference site should represent the range of conditions that are expected to occur naturally within each type of stream (Stoddard et al, 2006).…”

Fish catchability and comparison of four electrofishing crews in Mediterranean streams

“…Although a single pass without nets may sometimes be appropriate to estimate abundance (given the correlation with removal estimates) and richness, block nets are necessary for removal estimates (Peterson et al, 2005) and differences amongst reaches may introduce biases in abundance comparisons (Pusey et al, 1998;Rosenberger and Dunham, 2005). The use of block nets is probably not cost effective in standard surveys (Kruse et al, 1998;van Liefferingere et al, 2010) and impossible to apply in large rivers or during high flows, making it difficult to correct for capture efficiency along rivers.…”