Phillip J. Haubrock1,2,3,‡, Ismael Soto1, Irmak Kurtul 4,5, Antonín Kouba1
1University of South Bohemia in České Budějovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Zátiší 728/II, 389 25 Vodňany, Czech Republic 2CAMB, Center for Applied Mathematics and Bioinformatics, Gulf University for Science and Technology, Hawally, Kuwait 3Senckenberg Research Institute and Natural History Museum Frankfurt, Department of River Ecology and Conservation, Gelnhausen, Germany. 4Marine and Inland Waters Sciences and Technology Department, Faculty of Fisheries, Ege University, 35100, Bornova, İzmir, Türkiye 5Department of Life and Environmental Sciences, Bournemouth University, Poole, Dorset, The United Kingdom
‡ Corresponding author: phillip.haubrock@senckenberg.de
Background: Long-term biomonitoring of macroinvertebrates is a popular and valuable approach for assessing the status of freshwater ecosystems, identifying the impact of stressors, and evaluating ecosystem health. Although macroinvertebrate-based biomonitoring can be effective in detecting changes in distribution patterns and community trends over time, crayfish often remain undetected or unreported by biomonitoring efforts despite their importance in maintaining the functioning of aquatic ecosystems. Results: By analysinganalyzing a comprehensive database of long-term macroinvertebrate time series, we found that most sampling methods and assessment schemes listed can detect both native and non-native crayfish in running waters if sites are continuously sampled for at least two years at least. However, Nnative crayfish were however detected to a lesser extent and by fewer methods. Kick-net sampling and assessment techniques prevailed as the most efficient methods for capturing crayfish, outperforming alternative approaches. However, the substantial number of time series lacking crayfish data calls into question whether these methods are sufficiently comprehensive to encapsulate crayfish populations accurately. The use of other targeted methods like baited traps or more ideally less time and equipment-demanding hand catching, which can may provide a more reliable estimate of their presence. Conclusions: Given the detrimental impacts of non-native crayfish and the decline in native crayfish populations, we strongly recommend that stakeholders and managers incorporate a combination of these approaches into their monitoring efforts. MoreoverManagers also, the The use of of different taxonomic levels (family vs genus vs species level) in when in estimating biological indices and biomonitoring tools which can cause delays in identifying new non-native specie’s occurrences, hindering effective water quality assessment and ecosystem management by governments and stakeholders. Therefore, whenever possible, we call for standardisedstandardized taxonomic levels at for biomonitoring studies and management strategies to accurately address these issues and make recommendations going forward.