Comparison of visual census and underwater video for fish sampling in Neotropical reservoirs
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Comparison of visual census and underwater video for fish sampling in Neotropical reservoirs Fabrício de Andrade Frehse & Olaf Lawrence Friedrich Weyl & Jean Ricardo Simões Vitule
Received: 29 December 2019 / Accepted: 6 September 2020 # Springer Nature B.V. 2020
Abstract Different techniques have been employed for fish surveys in freshwater impoundments, however, despite the increasing applicability of underwater video systems for fish sampling in different aquatic ecosystems, such technology has not been tested in reservoirs. This study compares estimates of fish species richness, community composition, and size structure derived from visual census (VC) and underwater video (UWV) in two Neotropical reservoirs. The total number of species recorded by both sampling methods was similar, even though UWV recorded higher mean number of species than VC, in both reservoirs. In general, VC was more efficient in recording cryptic and resident species, while UWV, was better for highly mobile species. Considering size classes, VC was more efficient than UWV in detecting smaller individuals (i.e., 31–
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10641-020-01021-3) contains supplementary material, which is available to authorized users. F. Frehse : J. R. S. Vitule Laboratório de Ecologia e Conservação, Departamento de Engenharia Ambiental, Setor de Tecnologia, Universidade Federal do Paraná, Curitiba, Paraná, Brazil F. Frehse (*) : J. R. S. Vitule Programa de Pós-Graduação em Ecologia e Conservação, Universidade Federal do Paraná, Curitiba, Paraná, Brazil e-mail: [email protected] O. L. Weyl DSI/NRF South African Research Chair in Inland Fisheries and Freshwater Ecology, South African Institute for Aquatic Biodiversity (SAIAB), Makhanda, South Africa
79 mm total length). Although observational sampling methods depend on water transparency, UWV can be considered a complementary and promising technique for fish surveys in shallow areas of clear reservoirs. Keywords Fish assemblage . Freshwater ecosystems . Non-destructive sampling methods . Impoundments
Introduction Impoundments or reservoirs are human modified environments (Agostinho et al. 2007) that provide important ecosystem services (Postel and Carpenter 1997; Dudgeon et al. 2006). On the other hand, damming a river causes drastic abiotic and biotic alterations in the aquatic ecosystem (Rosenberg et al. 2000), resulting in changes in the fish community structure and abundance (Agostinho et al. 2004; Daga et al. 2015; Carvalho and Araujo 2020) and the invasion and establishment of non-native species (Johnson et al. 2008; Vitule et al. 2012; Brito et al. 2020). Fish and the fisheries that reservoirs support are particularly important (Holmlund and Hammer 1999) and have been the focus of many studies (e.g., Fernando and Holcik 1991; Agostinho et al. 2008, 2016; Pelicice et al. 2016). Studies typically employ a variety of capture techniques to evaluate fish assemblages in reservoirs, including: gill, seine and fyke nets (
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