Which is the best environment for the development of the early life stages of fish during the dry season?

Abstract

Aim:The main objective of this study was to investigate the quality of habitats for early life stages of fish in the Jacaré-Guaçu River, during the dry phase; Methods: For assessing the quality of the habitats for the development of early life stages, the relative condition factor was applied to the juveniles of five species of fishes, captured in four different habitats (reservoir, floodplain lake, main river, and tributary). The juveniles were caught in macrophytes of the littoral zone by a rectangular sieve, in the dry season of 2008 and 2009; Results: The species Astyanax altiparanae thrived similarly in the four habitats, and A. fasciatus, Hyphessobrycon eques, Hoplias malabaricus and Serrapinnus notomelas, showed higher values of relative condition factors in the reservoir and in the lake. Among the species, A. fasciatus showed the highest values of the relative condition factor in these two habitats; Conclusions: It is likely that the complexity of the macrophytes' stands and the current velocity were the main factors influencing the development of juveniles. It was found that a lower current velocity can propitiated the establishment of a greater richness of macrophytes, which in turn can influence positively the development of fish juveniles. Moreover, a higher current velocity ends in a higher energy demand for swimming.Keywords: Upper Paraná River Basin, Neotropical Characiformes, fish nurseries, nutritional condition.Resumo: Objetivo: O objetivo principal deste estudo foi investigar a qualidade dos habitats para as primeiras fases de vida dos peixes no Rio Jacaré-Guaçu, durante a estação seca; Métodos: Para avaliar a qualidade dos hábitats para o desenvolvimento das primeiras fases, o fator de condição relativo foi aplicado aos juvenis de cinco espécies de peixes, capturados em quatro habitats diferentes (reservatório, lago de planície de inundação, canal principal e tributário). Os juvenis foram coletados em macrófitas litorâneas com uma peneira retangular, na estação seca de 2008 e 2009; Resultados: Somente Astyanax altiparanae se desenvolveu similarmente bem nos quatro hábitats, sendo que as outras, A. fasciatus, Hyphessobrycon eques, Hoplias malabaricus e Serrapinnus notomelas, tiveram maiores valores do fator de condição relativo no reservatório e no lago. Entre as espécies, A. fasciatus foi a que apresentou os maiores valores do fator de condição relativo nesses dois hábitats; Conclusões: É provável que a complexidade dos bancos de macrófitas e a velocidade da corrente tenham sido os fatores que mais influenciaram o desenvolvimento dos juvenis. Foi verificado que habitats de baixa correnteza podem permitir o estabelecimento de uma maior riqueza de macrófitas, o que por sua vez pode influenciar positivamente o desenvolvimento de juvenis de peixes. Além disso, hábitats com correntezas maiores provavelmente demandam um maior custo energético para a natação.Palavras-chave: Bacia do Alto Rio Paraná, Characiformes Neotropicais, criadouros de peixes, condição nutricional. Biological Limnolog...

Habitat complexity and individual variation in diet and morphology of a fish species associated with macrophytes

“…We found that Moenkhausia forestii exhibits a compressed body and low body depression. These characteristics are expected to occur in fish that occupy lentic environments and facilitate occupation and establishment in structured environments, such as macrophyte stands (Esguícero & Arcifa, 2010;Oliveira et al, 2010;Prado et al, 2016).…”

Ecomorphology and use of food resources: inter- and intraspecific relationships of fish fauna associated with macrophyte stands

“…Characiformes H. eques, M. forestii, S. calliurus and S. notomelas were characterized by compressed bodies, which are expected in fish that occupy lentic environments and enable increased efficiency in vertical movements (Gatz, 1979;Watson & Balon, 1984), because this characteristic provides less resistance to perform maneuvers such as pitch (dorso-ventral movements) or yaw (lateral movements) (Alexander, 1967). Thus, this body shape may facilitate the occupation of structured environments such as macrophyte stands in areas of low water flow (Esguícero & Arcifa, 2010). Nevertheless, they showed larger anal fins, which implies in greater maneuverability and stabilization of movement (Breda, 2005).…”

Habitat and host associations of the fish‐burrowing parasite Artystone minima (Cymothoidae: Isopoda) in eastern Amazonia

“…The primary host, N. beckfordi, mainly inhabits slower moving backwater bays (in this case ≤0.023 m/s), swimming at intermediate depths (in this case observed at estimates of about ~5–15 cm depth in the 18 cm depth recorded in November 2017 and ~5–30 cm depth in the 46 cm depth recorded in May 2018) in the water column and feeding on plant material, occasionally rising to the surface to feed on food items that fall onto the water surface (Chondoma, 1979). Species in the genera Hyphessobrycon Durbin & Eigenmann, 1908 and Moenkhausia Eigenmann, 1903 are also commonly found in these backwater bays (Barros, 2012; Esguícero & Arcifa, 2010) and in association with aquatic vegetation (Agostinho et al., 2007; Declerck et al., 2005). Both of these habitat characteristics are associated with a higher concentration of aquatic invertebrates (Thomaz et al., 2008; Vieira et al., 2007), the main dietary component of these two genera that also both feed in intermediate depths in the water column (Cunha et al., 2007; Lima et al., 2008), and places them consistently alongside the primary host N. beckfordi in these habitats (as also found here Table S2) and therefore exposed to potential settlement by cymothoid mancae .…”