Using long-term data to predict fish abundance: the case of Prochilodus lineatus (Characiformes, Prochilodontidae) in the intensely regulated upper Paraná River

Abstract

Populations show spatial-temporal fluctuations in abundance, partly due to random processes and partly due to self-regulatory processes. We evaluated the effects of various external factors on the population numerical abundance of curimba Prochilodus lineatus in the upper Paraná River floodplain, Brazil, over a 19-year period. Panel data analysis was applied to examine the structure of temporal and spatial abundance while controlling auto-regressive processes and spatial non-homogeneity variances that often obscure relationships. As sources of population variation, we considered predation, competition, selected abiotic variables, construction of a dam upstream of the study area, water level and flood intensity during the spawning period. We found that biological interactions (predation and competition) were not significantly related to variations in curimba abundance; specific conductance was a space indicator of abundance, apparently linked to the biology of the species; intensity of floods determined inter-annual variation in abundances; Porto Primavera Dam negatively impacted the abundances at sites in the floodplain directly affected by discharges from the dam. Panel data analysis was a powerful tool that identified the need for intense flooding to maintain high abundances of curimba in the upper Paraná River. We believe our results apply to other species with similar life strategy.Keywords: Abiotic conditions, Biological interactions, Dam, Floodplain, Flood pulse.As populações apresentam flutuações espaço-temporais em abundância devido a processos aleatórios e auto-regulatórios. Nesse trabalho avaliamos efeitos de vários fatores sobre a abundância da curimba, Prochilodus lineatus, em cinco ambientes da planície de inundação do alto rio Paraná, Brasil, durante 19 anos. A análise de dados em painel foi utilizada por examinar variações espaço-temporais na abundância considerando processos auto-regressivos e variâncias espacialmente heterogêneas, que por vezes dificultam a identificação das relações. Como fontes de variação na abundância da curimba foram consideradas: predação, competição, variáveis abióticas selecionadas, construção da barragem de Porto Primavera, nível da água do rio Paraná e intensidade de cheia no período reprodutivo. Foi identificado que predação e competição não foram significativamente associadas às abundâncias da curimba; condutividade específica foi indicadora espacial da abundância; intensidade das cheias foi determinante de variações interanuais na abundância; barragem de Porto Primavera influenciou, negativamente, a abundância em corpos d'água diretamente afetados. A análise de dados em painel mostrou ser uma poderosa ferramenta preditiva, que possibilitou identificar a necessidade de cheias intensas para manutenção de elevadas abundâncias de curimba no alto rio Paraná. Acreditamos que o mesmo seja válido espécies de peixes que apresentam estratégia de vida similar.

Drivers and spatial patterns of population synchrony of fish species in a floodplain

“…However, among the floodplain systems, the Paraná River is the most impacted by hydrological regulation from several upstream dams (Agostinho, Gomes, et al., 2004). In fact, fish populations in these sites have been directly impacted by daily fluctuations in water level (e.g., Poff & Schmitz, 2016) and native species population declines have been associated to oligotrophication caused by sediment retention in the upstream reservoirs (Granzotti et al., 2018) and hydrological regulation (Agostinho, Gomes, et al., 2004; Piana et al., 2017). Overall, these impacts are less pronounced (although not entirely absent) in the other river systems, especially in the Ivinhema River.…”

“…Predation has been indicated as a possible driver of spatial synchrony (Ims & Andreassen, 2000). The detritivore Prochilodus lineatus is an important prey species in the Upper Paraná River floodplain, being highly predated upon by several species (Almeida et al., 1997; Luz‐Agostinho et al., 2008; Piana et al., 2017). The dynamics of this species was also highly synchronous (see results).…”

“…The dynamics of this species was also highly synchronous (see results). Therefore, we tested the relationships between population synchrony of P. lineatus and population synchrony of different piscivorous species that are reported to prey on their juveniles (Piana et al., 2017), including Acestrorhynchus lacustris , Astronotus crassipinnis , Cichla kelberi , Hoplias mbigua , Hoplias sp.2, Pseudoplatystoma corruscans , Rhaphiodon vulpinus , and Serrasalmus marginatus . Moreover, we explored additional relationships between population synchrony of A. lacustris and other species (prey species and possible competitors).…”

Temporal effects and changes in the parasitic community ofProchilodus lineatus(Valenciennes, 1837) (Characiformes: Prochilodontidae) in a floodplain

“…Their diet consists of inorganic detritus and particles of organic matter that comprise the bottom body of aquatic environments, in addition to algae and benthic macroinvertebrates that are found in this environment (Fugi et al, 1996;Lopes et al, 2007). Considered medium-sized, their migratory habits are dependent on the flood pulses of floodplains because they migrate upstream during floods to spawn in tributaries (Lizama et al, 2005;Oyakawa et al, 2009;Piana et al, 2017). After hatching, the larvae drift downstream, reaching floodplain lakes where they develop into the juvenile and adult stages, grow and mature until the flood pulses again when they are apt to reproduce.…”

EFFECTIVENESS OF BENZOCAINE AS ANESTHETIC AT DIFFERENT WATER TEMPERATURES FOR EARLY JUVENILE CURIMBA (<i>Prochilodus lineatus</i> Valenciennes, 1836), A NEOTROPICAL FISH SPECIES

“…Many studies related to P. lineatus have been undertaken with the purpose of maximizing the potential of the species in terms of productivity. This species plays an important role in the ecosystem, but its populations have been declining in some regions (Taylor et al, 2006;Piana et al, 2017) such as in the Rio Doce river basin, after the Mariana disaster in Minas Gerais, Brazil. The genus Prochilodus includes many endangered species, and P. lineatus is classified in the vulnerable category (IBAMA, 2015).…”