A new fish-based index of biotic integrity for lowland rivers in Flanders (Belgium)—Corrigendum

This Corrigendum corrects an error in Table 2 that was published in Breine et al. (2021) on the pages 114–115: the line concerning the weatherfish Misgurnus fossilis (Linnaeus, 1758) on the page break was erroneously removed during publication and is added here.

A new fish-based index of biotic integrity for lowland rivers in Flanders (Belgium)

The first fish-based index to assess the ecological quality of lowland rivers in Flanders (Belgium) is based on data obtained from different fishing techniques without considering the gear specificity. As a consequence, this index could not be intercalibrated with other European indices which concentrate on one gear type only. In order to comply with the European Water Framework Directive, we developed a new fish-based index using data obtained from surveys in rivers with electric gear only. All 293 selected rivers belonged to the bream or barbel zone. An updated reference list of fish species was compiled based on previous work and recent data. Abiotic data were collected according to standard methods and habitat quality of all surveyed sites was pre-classified using pressure indicators. To develop the new index candidate metrics were selected from the literature and metric values were calculated. Linear mixed regression models selected metrics based on their response to the pre-classified habitat status. Correlation tests were performed to avoid redundancy among responsive metrics. Boundaries for metric scores were defined based on the calculated metric values. The new index of biotic integrity (IBI) was calculated by summation of the metric scores, and transformed to an ecological quality ratio (EQR), ranging between 0 and 1. Five integrity classes, ranging from bad to maximal ecological potential, were attributed and compared to the pre-classified habitat status of the site. In addition, the new index was also validated with an independent set of data. The new IBI proved to successfully assess the ecological status of the rivers.

Using the Multi-metric Index of Biotic Integrity methodological approach to determine the major river catchment that most pollutes a lake

We present the Multi-metric Index of Biotic Integrity methodological approach that allows for the ranking of major river catchments based on pollution status in the Kenyan portion of Lake Victoria, Africa. The study has a broader applicability to all of Lake Victoria, other African Great Lakes, and all lakes that have riverine discharge. The method presented utilizes water quality and environmental data, local knowledge, and pre-existing literature. The parameters considered were sampled from 2016 to 2018 during the dry season (July sampling) and the wet season (March sampling). Separation power of Mann-Whitney U test (p < 0.05) qualified 11 discriminant metrics for both macroinvertebrate and fish samples into the scoring system of 1, 3 and 5 in the formulation of final Multi-metric Index of Biotic Integrity methodological approach. Rivers in the northern section had lower Multi-metric Index of Biotic Integrity methodological approach scores, as compared to southern counterparts. The Multi-metric Index of Biotic Integrity methodological approach ranking herein was validated by community perceptions on pollution levels. River Nzoia catchment emerged as the most polluted, followed by River Yala, River Kuja, and Sondu-Miriu. Siltation, domestic washing, litter and refuse emerged as the main agents of pollution. Management authorities ought to reinforce a balanced utilization of the vital water resources to minimize future impacts, and promote catchment wide practices that ensure ecological health sustainability of the lake ecosystem.