Trophic organization and fish assemblage structure as disturbance indicators in headwater streams of lower Sorocaba River basin, Sao Paulo, Brazil

Abstract

Studies that investigate the relationship patterns between environmental structure complexity and fish fauna provide crucial information to stream restoration efforts. In order to test the hypothesis that streams with more complex environmental structure sustain more diverse and functionally more complex fish communities we sampled fish fauna from Sorocaba River headwater stream reaches (SE -Brazil). Reaches represented two distinct treatments: (1) a simplified reach, characterized by unstable fine substrate, clay, deeper channel and higher water velocity and (2) structurally complex reaches, characterized by coarse substrate, with gravel, pebble, rock, stems and branches and leaves inside the channel, producing a diverse pattern of microhabitat, associated with sequences of pools, runs, and riffles. Both trophic structure and taxonomic composition varied significantly between treatments. Invertivorous trophic group exclusively occurred in structurally complex reaches, which also presented greater diversity and species richness. We suggest enhancing in-stream environmental structure that suffered simplification processes due to human impacts in order to reestablish fish communities and ecossistemic functioning.Estudos que buscam investigar os padrões de relação entre a complexidade da estrutura ambiental e a fauna de peixes fornecem informações cruciais para os esforços de restauração de riachos. Para testar a hipótese de que riachos com estrutura ambiental mais complexa sustentam comunidades ícticas mais diversas do ponto de vista taxonômico e funcional, a ictiofauna de trechos de riachos de cabeceira do rio Sorocaba (SE -Brasil) foi amostrada, representando dois tratamentos distintos: (1) um trecho de riacho simplificado, caracterizado por substrato fino e inconsolidado, composto por areia e silte, curso d'água mais profundo, com maior velocidade e poucos elementos diversificadores da estrutura de habitat e (2) trechos de riacho estruturalmente complexos, com substrato de fundo composto por elementos irregulares como cascalho, rochas, seixos, troncos, galhos e restos de madeira, produzindo um padrão diverso de microhabitats, associados à sequências de poços, corredeiras e trechos rápidos. Tanto a estrutura trófica quanto a composição taxonômica foram distintas em relação aos dois tipos de riachos. O grupo trófico dos invertívoros ocorreu somente nos trechos estruturalmente mais complexos, que apresentaram também maior diversidade e riqueza de espécies. Sugere-se incrementar a estrutura ambiental de riachos que sofreram simplificação ambiental, devido à ação humana, a fim de promover a reestruturação da comunidade íctica e o funcionamento ecossistêmico.

Colorful invasion in permissive Neotropical ecosystems: establishment of ornamental non-native poeciliids of the genera Poecilia/Xiphophorus (Cyprinodontiformes: Poeciliidae) and management alternatives

“…Inter-specific competition for shelter, food and parturition sites could arise between non-native poeciliids and the livebearer endemic genus Phalloceros Eigenmann 1907 (Menezes et al, 2007) (Magalhães, Jacobi, 2013a), could be adversely affected. Species loss due to the influence of non-native poeciliids could be devastating because, according to Cruz et al (2013), in systems with few native fish species such as headwater creeks, the loss of a single species might represent the deletion of an entire component of the food chain, compromising ecosystem functioning.…”

Trophic structure of fish fauna along the longitudinal gradient of a first-order rural stream

“…Except for the detritivorous guild, regardless of the stretch occupied in the stream, the fish assemblage tended to be dominated by generalist guilds, that is, with no significant trophic specialization (Esteves & Aranha, 1999;Abelha et al, 2001). This pattern has been recurrent in several plain streams (Casatti, 2002) and headwater streams (Wolff et al, 2013;Cruz et al, 2013), most probably due to the variation in the physical structure of these systems and consequently on the availability of food resources, selecting, ultimately, flexible feeding habits (Abelha et al, 2001). Moreover, the presence of piscivorous (e.g.…”

“…Additionally, despite evidence of higher autochthonous primary productivity in tropical streams (Davies et al, 2008), it is generally agreed that allochthonous resources are essential for fish of neotropical streams (Lowe-McConnell, 1999;Esteves & Aranha, 1999;Cruz et al, 2013). In this sense, the structure and complexity of the vegetation surrounding the Itiz stream probably was so important in structuring the abundance and biomass of guilds, as the longitudinal changes predicted by the availability of food resources.…”

Ecologia Trófica De Peixes De Riacho: Uma Releitura 20 Anos Depois

“…Na escala de paisagem, enquanto alguns estudos como os de Vieira et al (2014) e Gonçalves et al (2018) procuraram verificar os fatores que determinam a estrutura trófica em riachos de áreas naturais, a maioria dos trabalhos abordou a questão da influência antrópica sobre a estrutura trófica de peixes de riacho (Cruz & Cetra 2013, Manoel & Uieda 2018, Barbosa et al 2020.…”