Abstract
This study focused on life strategies of species from functional feeding groups (FFGs) found in a tropical stream of the Sirumalai hills, South India. We examined the life cycle and secondary production of species of shredders (Lepidostoma nuburagangai), scrapers (Baetissp.), collectors (Choroterpes alagarensis), and predators (Neoperla biseriata). In addition, we studied the assemblage structure of functional feeding groups. We found the collectors occupied the highest percentage, followed in turn by scrapers, predators, and shredders. The diversity of FFGs was higher at riffle areas and assemblage with stream substrates differing in each functional group. An asynchronous life cycle was observed forBaetis,C. alagarensis, andN. biseriata, whileL. nuburagangaiwas found in four to five generations per year. We acquired data on secondary production of scraper species ofBaetis, which reached the highest values among all investigated species. This observation stresses the importance of scrapers as playing a key role in converting coarse particulate organic matter to fine particulate organic matter with low or high abundances of shredder population and maintaining the food chain in tropical streams.
Highlights
Tropical forests cover 15–20% of the earth’s land surface and about half of this is being converted to agricultural land and for other human purposes
19 species belonging to 15 families and 8 orders of aquatic insects were collected from both riffle and pool areas of the stream
Third order stream of the present study area had the highest percentage of collectors. This may be due to the enormous FPOM concentration available in the study sites
Summary
Tropical forests cover 15–20% of the earth’s land surface and about half of this is being converted to agricultural land and for other human purposes. The allochthonous organic substrate provides protection and habitat space and it has fundamental importance as a food source for aquatic macroinvertebrates [2]. Aquatic macroinvertebrates are classified into four major functional feeding groups (FFGs) based on the morphobehavioural mechanisms of food acquisition rather than taxonomic groups as follows: shredders, scrapers, collectors, and predators [3]. The major food sources utilized by macroinvertebrates are the epilithic layer that grows on the surfaces of substrates (consumed by scrapers), the coarse detritus of leaves falling from riparian vegetation (consumed by shredders), the fine detritus either deposited on the substrate or suspended in the water column (consumed by collector/filter-feeders), and live animals (consumed by predators) [3,4,5]
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