Artificial structures as tools for fish habitat rehabilitation in a neotropical reservoir

Abstract

ABSTRACT1. Since most of the natural habitats critical for freshwater fish survival have been adversely affected by human disturbance, the effectiveness of artificial structures in providing new and suitable habitats for fish has been increasingly investigated.2. This paper evaluates the role of artificial structures as fish habitat in a structureless 30 km 2 Brazilian reservoir, through underwater surveys conducted monthly from April 1999 to March 2000.3. In total, 5759 fish in nine species were recorded, but only three cichlid species } one native, Geophagus brasiliensis and two non-native, Cichla kelberi and Tilapia rendalli } showed consistent association with the artificial habitats, suggesting that this family reacts to submerged structures.4. The absence of fish at control sites compared with high occurrences in sites provided with a physically complex structure suggests that artificial structures can play an important ecological role for cichlids smaller than 150 mm TL, probably related to shelter and/or feeding benefits.5. The level of structural complexity and position in the water column influenced fish use of artificial structures. C. kelberi was associated with highly complex structures, whereas moderately complex bottom structures were more effective in harbouring G. brasiliensis. Bottom structures are apparently more important than midwater structures in harbouring T. rendalli, but structural complexity seemed to play a secondary role.6. This study is the first in demonstrating that adding complex artificial structures can expand habitats for small fish (5150 mm TL), especially cichlids, in a neotropical impoundment. It seems reasonable to expect that deploying physically complex structures in other oligotrophic, structureless and cichlid-dominated impoundments in Brazil will lead to similar results to those found in this work.

Experimental assessment of the effects of a Neotropical nocturnal piscivore on juvenile native and invasive fishes

“…This nocturnal feeding activity probably explains why prey selection and consumption by P. corruscans were less dependent of habitat complexity. However, further studies addressing the activity patterns of both predator and prey at dark conditions and testing other kind of shelters, different from the ribbon-like structures used here, are essential to fully understand the role of habitat complexity in P. corruscans piscivory, since the use of submersed structures by fish often changes over the 24-hour period (Reebs, 2002;Pelicice et al, 2005) and with habitat shape, complexity and position in the water column (Santos et al, 2008(Santos et al, , 2011b.…”

“…obs. ), probably because of the intensive bi-parental care provided to small juveniles and the additional shelter offered by submerged structures (Santos et al, 2008). However, these life-history strategies seem to be ineffective against a nocturnal piscivore, such as P. corruscans, in which prey consumption was unaffected by habitat complexity and because cichlid parental care is expected to be weak or null at night (LoweMcConnell, 1991, Reebs, 2002.…”

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“…As channelization of a river has many habitat implications such as decrease in food productivity, limiting pool areas, increase in water velocity RESEARCH PAPER Turkish Journal of Fisheries and Aquatic Sciences www.trjfas.org ISSN 1303-2712DOI: 10.4194/1303-2712 and elimination of natural covers in the river body, resulting in an overall decrease in area suitable for fish and decreases growth and survival conditions (Jacobson et al, 2015;Jowett et al, 2008;Pretty et al, 2003). Several correct habitat improvement actions may be taken (Jacobson et al, 2015;Kondratieff & Richer, 2014;Santos, Arau, & Brotto, 2008), among which include:…”

Habitat heterogeneity on feeding habit of two sympatric and congeneric characidae fishes in two tropical reservoirs

“…Feeding habits of several Astyanax species have been well studied in different Brazilian aquatic ecosystems such as in streams and rivers (Vilella et al, 2002;Loureiro-Crippa & Hahn, 2006;Borba et al, 2008;Vidotto-Magnoni & Carvalho, 2009;Manna et al, 2012;Moraes et al, 2013), floodplain (Esteves, 1996, Peretti & Andrian, 2004, 2008Crippa et al, 2009) and coastal lagoons (Hartz et al, 1996;Aguiaro & Caramaschi, 1998). Besides feeding plasticity (Santos et al, 2008), the proliferation of some species of Astyanax, especially A.bimaculatus and A. parahybae, in reservoirs has been associated with their reproductive strategy, including a long reproductive period, rapid maturation, prolific spawning, small eggs and high fecundity (Suzuki et al, 2005). Astyanax species have also a great ecological importance in the trophic web of fish community in reservoirs (Loureiro- Crippa & Hahn, 2006;Wolff et al, 2009) linking nutrients and carbon sources available in marginal areas to the limnetic food chain.…”

“…Aquatic macrophytes are important habitats for many groups of organisms as immature stages of Diptera, Ephemeroptera and Trichoptera (Carpenter & Lodge, 1986;Lalonde & Downing, 1992;Dibble et al, 1996;Agostinho et al, 2003;Casatti et al, 2003) and many fish species are found in these habitats, benefiting from a diversity of food items as well as refuge from predation (Pelicice & Agostinho, 2006). Macrophytes have also been considered key components in aquatic environments, enhancing the spatial heterogeneity and increasing the number of niches (Margalef, 1983;TrivinhoStrixino & Strixino, 1993;Santos et al, 2008).…”