Hydropeaking impact assessment for Iberian cyprinids and leuciscids: An adaptation of the hydropeaking tool method

Abstract

Hydropeaking negatively affects fish assemblages, but knowledge gaps still constrain our ability to rank and mitigate the impacts of different hydropower operation regimes at particular power plants. This is especially relevant for species and rivers for which the effects of hydropeaking are less investigated, such as the Iberian Cypriniformes and Mediterranean rivers. Recognizing the potential of the hydropeaking tool method (HT) developed for salmonids to systematically assess hydropeaking impacts, we adapted it for Iberian Cypriniformes. The general tool framework developed for the salmonids was kept for the Cypriniformes, with the combined use of factors describing the hydromorphological effects and factors related with fish vulnerability to assess hydropeaking impact. Effect and vulnerability factors were developed for Iberian cyprinids and leuciscids establishing preliminary thresholds for each indicator with three different levels of hydropeaking impact on the targeted taxa. The proposed factors and thresholds were critically reviewed and ranked by experts on Iberian Cypriniformes ecology and Mediterranean rivers functioning. Overall, the timing and distribution of peaking events were ranked higher by the experts in the effect factors, whereas the population size of barbel and smaller native Cypriniformes, as well as the degree of limitations in recruitment, were ranked higher in the vulnerability factors. Although there was some divergence in the expert opinions, a final set of effect and vulnerability factors was established, that retained most of the ones proposed for the salmonids, but included new ones, particularly for vulnerability. The present study provided a comprehensive, straightforward, and systematic assessment tool for evaluating hydropeaking impacts on Iberian Cypriniformes.

Stranding of larval nase (Chondrostoma nasus L.) depending on bank slope, down-ramping rate and daytime

“…This study aimed to assess the single and combined effects of 1) varying down-ramping rates, ranging from 0.7 to 3.0 cm min −1 at 2) two different lateral bank slopes (2% and 5%), 3) each during day and night on stranding of 4) different larval stages of common nase. This paper, therefore, establishes a solid baseline for ecologically-based management of peak-operating hydropower plants in rivers inhabited by cyprinid fish (Moreira et al, 2019;Godinho et al, 2022).…”

“…Recent studies underline the knowledge gap regarding nonsalmonid fish species also affected by hydropeaking (Costa et al, 2018;Moreira et al, 2019); to date, however, the species-rich cyprinid fish family has hardly been considered in hydropeaking research (Moreira et al, 2019), despite such works being needed for mitigation efforts in non-salmonid rivers (Godinho et al, 2022). The common nase (Chondrostoma nasus L.), for example, is a cyprinid indicator species widespread throughout Europe and home to grayling and barbel zone of rivers (Schiemer et al, 2002).…”

Innovations in hydropeaking research

“…Bakken et al (2023) presents a novel classification to systematically assess the effects of hydropeaking in rivers on salmonid fish populations. The tool, created in Norway for Atlantic salmon, was adapted to Iberian cyprinids by (Godinho et al, 2023), allowing for hydropeaking impact assessment in Iberian peaking rivers. The tool represents a valuable support to decision‐makers.…”

“…Ten contributions provided exhaustive analysis of field data, based on either single sites (e.g., Abernethy et al, 2023;Bartoñ et al, 2023;Boavida et al, 2023;Judes et al, 2023;Pander et al, 2023), or comparisons between several sites (e.g., Halleraker et al, 2023;Tena et al, 2023;Tonolla et al, 2023) Different modelling approaches are presented in the SI: from hydraulic, temperature, and habitat modelling (e.g., Antonetti et al, 2023;Jelovica et al, 2023;Judes et al, 2023), to rule-or processbased classification tools (e.g., Bakken et al, 2023;Godinho et al, 2023;Greimel et al, 2023;Reindl et al, 2023), to individual-based models (Hajiesmaeili et al, 2023). Two contributions specifically focus on numer- single contribution examines the use of remote sensed data for the investigation of fish stranding in a large river (Glowa et al, 2023).…”

“…When focusing on the biotic compartment, fish are a primary consideration, with investigations covering different life‐history traits: from spawning (Pander et al, 2023), to juveniles (Antonetti et al, 2023; Auer et al, 2023), and adults (Bakken et al, 2023). Salmonid species, which have received long‐lasting attention probably due to their economic value, are still dominant (Antonetti et al, 2023; Auer et al, 2023; Bakken et al, 2023; Hajiesmaeili et al, 2023; Halleraker et al, 2023; Jelovica et al, 2023; Pander et al, 2023); nevertheless the attention on cyprinid species has increased (Bartoñ et al, 2023; Boavida et al, 2023; Godinho et al, 2023; Judes et al, 2023).…”