Fish ecology in tropical streams

Abstract

This chapter emphasizes the ecological responses of fishes to spatial and temporal variation in tropical stream habitats. At the global scale, the Neotropics has the highest fish fauna richness, with estimates ranging as high as 8000 species. Larger drainage basins tend to be associated with greater local and regional species richness. Within longitudinal stream gradients, the number of species increases with declining elevation. Tropical stream fishes encompass highly diverse reproductive strategies ranging from egg scattering to mouth brooding and livebearing, with reproductive seasons ranging from a few days to the entire year. Relationships between life-history strategies and population dynamics in different environmental settings are reviewed briefly. -

Fishes in tropical streams exhibit diverse feeding behaviors, including specialized niches, such as fin and scale feeding, not normally observed in temperate stream fishes. Many tropical stream fishes have greater diet breadth while exploiting abundant resources during the wet season, and lower diet breadth during the dry season as a consequence of specialized feeding on a subset of resources. Niche complementarity with high overlap in habitat use is usually accompanied by low dietary overlap. Ecological specializations and strong associations between form and function in tropical stream fishes provide clear examples of evolutionary convergence. -

Several studies have revealed the major influence of fishes on benthic ecosystem dynamics in tropical streams including effects on primary production and nutrient cycling. Tropical stream fishes are important food resources for humans in many countries, and significant conservation challenges include drainage-basin degradation, pollution, dams, overfishing, and introductions of exotic species.