Fish assemblages structure and function along environmental gradients in rivers of Gabon (Africa)

Abstract

We examined patterns in fish species assemblages structure and function along environmental gradients in rivers of Gabon. Species presence-absence data from 52 sites were first analysed by canonical correspondence analysis. Results showed that the position of sites along the upstream-downstream gradient, together with elevation and water conductance were the most important predictors of local fish assemblage composition. Assemblage richness and trophic structure were further investigated using regression tree analysis. Results revealed a general increase in species richness from upstream to downstream areas and a transition from insectivorous to omnivorous, herbivorous and piscivorous species along this longitudinal gradient. There were several similarities between these previous patterns and those observed in other temperate streams suggesting a potential convergence in fish assemblage along environmental gradients in tropical and temperate riverine systems. From a conservation standpoint, these results highlight the need to evaluate all habitat types along rivers longitudinal gradient to integrate the full spectrum of species assemblages within conservation plans.

Distribution patterns of fish communities with respect to environmental gradients in Korean streams

“…Whereas BOD was correlated with axis 2 and the distribution of P. parva, C. auratus, and C. carpio, most physical variables (altitude, stream order, stream width, and water temperature), were more appropriately matched with fish distribution. As physical variables of streams are well correlated with fish distribution (Ibanez et al, 2007); they can be used to predict the composition of local fish assemblages in Korea. Kuehne (1962) studied the relationship between fish distribution and stream order; this correlation that has been frequently used when analyzing the longitudinal distribution of fish.…”

Seasonal flooding, instream habitat structure and fish assemblages in the Mulgrave River, north-east Queensland: towards a new conceptual framework for understanding fish-habitat dynamics in small tropical rivers

“…These are: the distance of a study site from the river mouth (Lyons and Schneider 1990;Winemiller and Leslie 1992;Pusey and Kennard 1996;Hoeinghaus et al 2003;Ibanez et al 2007); the biological characteristics of the individual species present, including their feeding morphology and dietary composition, life-history requirements and water quality tolerances (notably salinity and pH); the duration and intensity of wet season flooding (Pearsons and Li 1992;Agostinho and Zalewski 1995;Hoeinghaus et al 2003); and the complexity and diversity of micro-and mesohabitat features (Gorman and Karr 1978;Pearsons and Li 1992). In general, authors report distinct longitudinal changes in fish assemblage structure from upstream to downstream (owing to addition or replacement of species according to their salinity tolerance; Winemiller and Leslie 1992;Pusey et al 1995a), with a relatively stochastic redistribution of fish within the catchment following wet season flooding (Rodriguez and Lewis 1994;Rodriguez and Lewis 1997).…”

Fish assemblage structure in the Chishui River, a protected tributary of the Yangtze River

“…Godinho et al, 2000) and Africa (e.g. Ibanez et al, 2007), but are still lacking for Asia (Shahnawaz et al, 2010), and especially for China rivers. With at least 286 fish species and subspecies distributing in the main channel and its affiliated tributaries, the upper Yangtze River is considered as a biodiversity hot spot for fish conservation (He et al, 2011).…”