Comparison of fish assemblages in two littoral habitats in a Neotropical morichal stream in Venezuela

Abstract

Morichales are lowland streams in South American savannas with riparian forest dominated by the moriche palm (Mauritia flexuosa). We sampled littoral habitats from ten flooded vegetated patches (dominated by Mauritiella aculeate) and six sand banks in two months of the dry season (Feb-Mar 2005) in a stream in the savannas of Apure State, Venezuela. We collected samples that compromised 12,407 individual fishes of 107 species. Small-bodied fishes (< 100 mm), representing diverse trophic and life history strategies, were abundant. The most abundant species were in the families Characidae and Cichlidae. Fish assemblages from flooded vegetated patches differed significantly from those on adjacent sand banks. High structural complexity along vegetated shoreline habitats of morichal streams likely contributes to species richness and affects assemblage composition.Morichales ou buritizais são tipos de habitats de planícies de savana da América do Sul com vegetação ripária dominada por buritis (Mauritia flexuosa). Nós amostramos habitats litorâneos de dez fragmentos de buritis e seis bancos de areia durante dois meses de estação seca (Fev-Mar de 2005) em um curso de água de savana no Estado de Apure, Venezuela. Foram coletados 12.407 peixes pertencentes a 107 espécies. Espécies de pequeno porte (< 100 mm), representando diversas estratégias de vida e categorias tróficas foram abundantes. As espécies mais abundantes pertenceram às famílias Characidae e Cichlidae. As assembléias de peixes dos fragmentos de vegetação inundada (buritis) diferiram significantemente daquelas dos bancos de areia adjacentes. A elevada complexidade estrutural ao longo dos habitats marginais dos riachos que corriam pelos buritizais provavelmente contribuiu para a riqueza de espécies e influenciou a composição das assembléias nesses sistemas.

Habitat characteristics and environmental parameters influencing fish assemblages of karstic pools in southern Mexico

“…Higher and significant values of this ecological parameter were recorded at habitat B, where 23% and 92% of the total pools presented aquatic vegetation and arboreal cover. Similar results were found by Montaña et al (2008) and Silva et al (2010) in lowlands streams from Venezuela and the Amazonas, respectively. A high degree of structural complexity in the karstic pools increased the number of ecological niches, supporting rare and endemic species.…”

<b>Co-occurrence patterns of fish communities in littorals of three floodplain lakes of the Orinoco River, Venezuela</b>

“…An interesting pattern was showed by the Hemigrammus species in Aricagua and Mamo, all of which tended to be aggregated. These were mostly small-sized species that have an opportunistic life strategy and feed upon small invertebrates and seeds and also shared a habitat affinity (Montaña et al 2008). This pattern could be a result of the natural disturbance, allowing ecologically similar species to coexist by keeping potential better competitors at lower densities and by propitiating frequent dispersal processes among patches (Townsend 1989).…”

Mauritia flexuosa palm swamp communities: natural or human-made? A palynological study of the Gran Sabana region (northern South America) within a neotropical context

“…The M. flexuosa swamp communities owe their structure and functional features to this dominant palm, which provides the structural complexity and the habitat diversity for the occurrence of a characteristic and unique terrestrial and aquatic flora and fauna that, otherwise, would not occur (e.g. Marrero et al, 1976;González, 1987;Huber & Febres, 2000;Montaña et al, 2008;Tubelis, 2009). This contributes to enhance neotropical forest, savanna and wetland diversity not only from a taxonomic ( -diversity) but also from a landscape ( -diversity) perspective.…”

“…Montaña et al (2008) reported 107 fish species in a Venezuelan M. flexuosa swamp, corresponding to small-bodied cichlids, characins, lebiasinids, and silurids. Fish diversity was significantly higher in the palm swamp than in nearby river banks devoid of this vegetation type, likely due to the enhanced micro-habitat diversity created by the submerged aquatic and semi-aquatic vegetation (Montaña et al, 2008). On the same note, Antonio & Lasso (2001) reported the highest fish diversities of the Orinoco basin in the river Morichal Largo, whose gallery forest is a huge M. flexuosa swamp, with 109 species belonging to 9 orders.…”