Feeding ecology of Eigenmannia desantanai (Gymnotiformes: Sternopygidae) in southern Pantanal, Brazil

Gouveia, Élida Jerônimo; Rondon, Patrícia Luna; Súarez, Yzél Rondon

doi:10.1590/s2179-975x9820

Cited by 3 publications

(3 citation statements)

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“…Nevertheless, the surface fish Eigenmannia trilineata and other species of Eigenmannia have been observed to be nocturnal (Tan et al, 2005). Eigenmannia hide in roots, rocks, and leaf litter during the day and actively forage at night (Hopkins, 1974;Hopkins, 1981;Deng and Tseng, 2000;Tan et al, 2005;Stamper et al, 2010;Fortune et al, 2020;Gouveia et al, 2022) We traveled to the São Vicente II cave and measured the electrosensory and locomotor behavior of both surface Eigenmannia trilineata and cave Eigenmannia vicentespelaea (Fortune et al, 2020). We used a custom array of amplified electrodes, 50cm spacing, that both captured the electric behavior of nearby fish, and allowed us to calculate the positions of these fish (Madhav et al, 2018).…”

Section: Weakly Electric Cavefishmentioning

confidence: 99%

“…The amplitudes of electric fields increase with the size of fish (Hopkins et al, 1990;Curtis and Stoddard, 2003;Gavassa et al, 2012) and can be used as a nonvisual proxy to estimate body size. However, Gavassa et al (2013) have shown that social interactions can drive significant changes in the amplitude of electric fields. Further, hormones can increase the amplitudes of electric fields (Markham et al, 2009a;Migliaro and Silva, 2016).…”

Section: Amplitudes Of Electric Fieldsmentioning

confidence: 99%

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Adaptive shift of active electroreception in weakly electric fish for troglobitic life

Soares,

Gallman,

Bichuette

et al. 2023

Front. Ecol. Evol.

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The adaptive-shift hypothesis for the evolution of cave-dwelling species posits that ancestor species in surface habitats had exaptations for subterranean life that were exploited when individuals invaded caves. Weakly electric Gymnotiform fishes, nocturnal South American teleost fishes, have features that appear to be likely exaptations for troglobitic life. These fishes have active electrosensory systems in which fish generate weak electric fields that are detected by specialized electroreceptors. Gymnotiform fishes use their electric fields for navigation, prey capture (scene analysis), and social communication. Although active electrosensory systems appear to be exaptations for troglobitic life, as fish use these systems to “see in the dark”, producing electric fields is energetically costly. Cave habitats, which often are low in resources, may not be able to support such high energetic demands. Eigenmannia vicentespelaea, a species of weakly electric fish that is endemic to the São Vicente II cave in central Brazil, surprisingly generates stronger electric fields than their surface relatives. The increase in strength of electric fields may result simply from differences in size between cave and surface populations, but may also be due to lack of predation pressure in the cave or increases in “sensory volumes” and acuity that improve prey localization and capture. Eigenmannia vicentespelaea exhibits the classical phenotypes of any troglobitic fish: these fish have small to nonexistent eyes and loss of pigmentation. The closest living surface relative, Eigenmannia trilineata, inhabits streams nearby and has eyes and pigmentation. The electrosensory and locomotor behavior of both species of fish were measured in their natural habitats using a grid recording system. Surface Eigenmannia exhibited dramatic circadian changes in social behavior, such as hiding under rocks during the day and foraging in groups at night, while cave Eigenmannia displayed territorial behavior with no apparent circadian modulations. The territorial behavior involved electrical and movement-based interactions that may be a form of boundary patrolling. Electrosocial behavior and scene analysis are mechanistically interlinked because both stem from active sensing tactics.

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Section: Weakly Electric Cavefishmentioning

confidence: 99%

Section: Amplitudes Of Electric Fieldsmentioning

confidence: 99%

Adaptive shift of active electroreception in weakly electric fish for troglobitic life

Soares,

Gallman,

Bichuette

et al. 2023

Front. Ecol. Evol.

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“…In dynamic and productive environments, such as those found in tropical regions, hydrological variations driven by the seasonality of floods and the resultant connectivity of environments can change the availability and variety of food items (Lowe-McConnell, 1999;Scanferla & Súarez, 2016;Gouveia et al, 2022). During floods, river flow increases, connecting aquatic and terrestrial habitats.…”

Section: Introductionmentioning

confidence: 99%

Spatial variation, more than ontogenetic, explains the diet of Bryconamericus exodon in two Pantanal rivers

Sena,

Súarez

2024

Acta Limnol. Bras.

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Aim Studies of natural variations in fish diet allow, in turn, a better understanding of environmental changes along the hydrological cycle that can affect resources and, hence, biodiversity conservation. With this in mind, the present study aimed to understand how spatial and ontogenetic aspects (using Standard Length as proxy) define dietary composition, trophic position and trophic niche breadth for a small characid (Bryconamericus exodon) in streams located in two rivers of the Brazilian Pantanal. We also assessed whether spatial differences influence the structuring of trophic networks. Methods Fish were sampled monthly in the rainy season (October/2017 to March/2018) in four tributaries of the Negro and Apa Rivers, using different sampling methods. In the laboratory, fish were measured and weighed, followed by excision of stomach for posterior analysis. Results We analyzed 211 individuals, 126 from the Apa River (Standard lengthmin= 11.28mm; Standard lengthmax= 43.53mm) and 85 from the Negro River (Standard lengthmin= 13.26mm; Standard lengthmax= 40.05mm), that consumed mainly aquatic insects (Alimentary indexTotal= 87.97%), followed by terrestrial insects (Alimentary indexTotal= 9.02%). Dietary composition was mainly influenced by spatial variation (Pseudo-F1,194=12.21; p<0.001), followed by ontogenetic variation (Pseudo-F1,190=7.23; p<0.001), however, for trophic niche breadth, we did detect a higher importance of spatial variation (t=4.71; p<0.001) and an absence of ontogenetic variation (t=1.24; p=0.213). No spatial variation was detected for complementary specialization (p=0.998); only connectance showed a significant variation (p=0.047) with higher mean values in the Negro River (C= 0.27 ± 0.016) when compared to those of populations in the Apa River (C=0.22 ± 0.019). In addition, trophic position was not influenced by spatial (t= -1.77; p=0.077) or ontogenetic (t=0.69; p=0.494) variations. Conclusions B. exodon is considered an insectivorous species whose dietary composition can be explained more by spatial than ontogenetic variation.

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Adaptations to Subterranean Environments

Lunghi,

Niemiller,

Bilandzija

2024

Frontiers Research Topics

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Feeding ecology of Eigenmannia desantanai (Gymnotiformes: Sternopygidae) in southern Pantanal, Brazil

Cited by 3 publications

References 38 publications

Adaptive shift of active electroreception in weakly electric fish for troglobitic life

Adaptive shift of active electroreception in weakly electric fish for troglobitic life

Spatial variation, more than ontogenetic, explains the diet of Bryconamericus exodon in two Pantanal rivers

Adaptations to Subterranean Environments

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