Predictive factors of species composition of follower fishes in nuclear-follower feeding associations: a snapshot study

Abstract

We tested whether habitat, identity, size of nuclear fishes, and intensity of bottom disturbance caused by their foraging can predict the composition of fish followers in nuclear-follower feeding associations. The study was carried out in a stream of the Serra da Bodoquena, Mato Grosso do Sul State, Southwestern Brazil. We performed underwater observational sessions (total 12 h) of such interspecific interactions to obtain data about the identity and abundance of the followers in the association, as well as the identity and size of the nuclear fish. We also evaluated whether different intensities of bottom disturbance due to the nuclear fish foraging and type of habitat may influence interactions. We recorded 38 episodes involving nuclear and follower species. Using a multivariate analysis with distance matrices, we noted that the intensity of bottom disturbance caused by nuclear fishes was the main predictor of the composition of the follower species (r = 0.55, p < 0.01), as well as the identity of the nuclear species, although this latter relation was weak (r = 0.09, p = 0.05). Such results indicate that followers react readily to sediment suspension, which reflects the trophic plasticity and opportunistic foraging characteristic of most tropical freshwater fishes.Neste estudo testamos se o hábitat, a identidade e o tamanho da espécie nuclear, bem como a intensidade do distúrbio causado pela atividade do nuclear podem predizer a composição de seguidores na associação alimentar do tipo nuclear-seguidor. O estudo foi conduzido em um riacho da Serra da Bodoquena, estado do Mato Grosso do Sul, bacia do alto Rio Paraguai. Foram realizadas sessões de observação subaquática (totalizando 12 h), visando a obter informações sobre identidade e abundância dos seguidores, assim como identidade e tamanho da espécie nuclear, hábitat e intensidade do distúrbio causado pela atividade de forrageamento da espécie nuclear. Foram registradas 38 associações envolvendo cinco espécies nucleares e nove espécies seguidoras. A análise multivariada com matrizes de distância demonstrou que a intensidade do distúrbio causado pelos nucleares foi o principal preditor da composição de seguidores (r = 0,55, p < 0,01), assim como a identidade da espécie nuclear, embora essa relação tenha sido fraca (r = 0,09, p = 0,05). Esses resultados indicam que os seguidores respondem prontamente à suspensão de sedimento, refletindo a plasticidade trófica e o oportunismo de forrageio característico da maioria dos peixes tropicais de água doce.

Positive co‐occurrence between feeding‐associative savannah fishes depends on species and habitat

“…The probability of occurrence in a reach by the follower L. octomaculatus increased significantly in the presence of the nuclear species L. friderici ; this represents evidence that small‐scale positive biotic interactions among fishes can have observable effects at larger spatial scales in freshwater systems (in this case, the reach scale). By contrast, and contrary to expectations based on the literature (Sabino et al., ; Teresa et al., ), model evidence supported the hypothesis that occurrence of the follower L. striatus was independent of the nuclear L. friderici . Feeding‐associative behaviour of L. octomaculatus with L. striatus is probably facultative and may only be advantageous in certain contexts (e.g.…”

“…Based on field observations, we expected habitat use by L. striatus to be conditional to the presence of L. friderici , as L. striatus seemed to take advantage of the presence of L. friderici to forage. This is a common behaviour in mixed schools with anostomids in clear water streams and small rivers of Central Brazil (Sabino et al., ; Teresa et al., ). Our results suggest that co‐occurrence between L. striatus and L. friderici is more opportunistic and probably has little effect on habitat use or occurrence of L. striatus .…”

“…Leporinus striatus (Kner, 1858) measures up to 25 cm, has a diet based primarily on Chironomidae larvae and filamentous algae (Balassa, Fugi, Hahn, & Galina, 2004;Froese & Pauly, 2015). Leporinus striatus can function both as a nuclear species (Sabino et al, 2016;Teresa et al, 2014), but also as a follower of the larger Leporellus vittatus and Leporellus macrocephalus (Sabino et al, 2016). With a maximum total length of 13 cm, Leporinus octomaculatus is the smallest of the three species and is a feeding associate of L. friderici and/or L. striatus (Britski & Caravello, 1993;Froese & Pauly, 2015).…”

“…We expected the relative importance of this interaction to depend on both biotic and abiotic context. For biotic context, we expected the role of feeding association to differ based on individual size; larger nuclear species generally create more disturbance and may attract more followers, and smaller species may be more prone to following behavior (Krajewski, ; Matsumoto & Kohda, ; Teresa, Sazima, Sazima, & Floeter, ). For abiotic context, we expected the relationship to vary along gradients of abiotic variables that affect food availability, such as substrate composition (Teresa et al., ), or the intensity of anthropogenic disturbance (Teresa et al., ).…”

Juvenile silver grunter Mesopristes argenteus shift benthic objects to access food

“…There are also a number of fishes (and other fauna) in both marine and freshwater systems that are known to disrupt the benthos during feeding and are followed by fish that stand to gain from prey being flushed from hiding (Baker & Foster, ; Sazima et al, ; Teresa et al, ). In the past decade, there has been a steady increase in scientific interest in this form of behavioural interaction within freshwater ecosystems and notably in a tropical South American context (Azevedo et al, ; Costa‐Pereira, ; Garrone Neto & Carvalho, ; Sabino et al, ; Teresa et al, , ). This literature primarily addresses how disrupting soft benthos has the capacity to alter stream fish assemblages by exposing benthic prey for both nuclear and follower fishes, with ramifications for fish assemblage composition specifically as a function of conditions favouring particular nuclear and follower species (Baker & Foster, ; Sabino et al, ; Teresa et al, , ).…”