Methods for sampling benthic macroinvertebrates in tropical lentic systems

Abstract

Reliable quantitative methods for sampling invertebrate communities are critical for effective freshwater biomonitoring. We tested a range of devices and protocols for sampling benthic macroinvertebrates in shallow tropical lakes; this is the first time this has been attempted in Southeast Asia. First, a pilot study to identify a suitable artificial substrate and colonisation period was conducted. Coconut brushes combined with split palm fronds attracted the greatest macroinvertebrate abundance and richness. A colonisation period of 4 wk was sufficient to capture the key macroinvertebrate families and orders. Second, the sampling efficiencies of 7 artificial substrate sampler designs and 2 hydraulic suction devices were compared in rocky and soft-sediment littoral habitats of a reservoir in Singapore. Among the 9 different sampling techniques tested, the samplers containing coconut brushes and split palm fronds again were the most effective at capturing the greatest total abundance and family richness of benthic macroinvertebrates. Variation in community structure among sampler types was largely explained by the abundance of Chironomidae and Polymitarcyidae (Ephemeroptera). Results were similar between sites dominated by 'rocky' and 'vegetated' littoral habitats. This project identified a sampling device suitable for biomonitoring Singapore's lentic environment, with protocols likely to apply to shallow tropical lentic systems elsewhere.

Bottom‐up influences on tropical freshwater food web structure support the “environmental filtering” hypothesis

“…Findings reported in our study are consistent (at least superficially) with the highly influential, albeit controversial hypothesis (Polis 1991) which posits that food web structures are relatively constant (Martinez 1992). In these earlier studies, connectance values were shown to be scaleinvariant, ranging from 0.05 to 0.30 (Dunne et al 2002a), and converging at a mean of 0.14 (Martinez 1992).…”

“…Primary producers were sampled via leaf clipping of numerically dominant taxa (i.e., for riparian plants and grasses), horizontal trawls with nets of mesh size 80 μ m (i.e., for phytoplankton via seston samples), and scraping of submerged rocky surfaces (i.e., for periphyton). Invertebrate specimens were collected with submerged colonizers deployed at a fixed depth of 1 m over a 1‐month period (i.e., for benthic invertebrates; Loke et al ) and by conducting horizontal trawls with nets of 80 μ m mesh sizes (i.e., for planktonic invertebrates). We collected fishes using a combination of cast netting, trapping, and electrofishing.…”

Towards holomorphology in entomology: rapid and cost‐effective adult–larva matching using NGS barcodes

“…Adult specimens for some species were also serendipitously obtained from Malaise traps (Singapore). Some larvae were collected with kick‐nets, sieves and coconut brush samplers (Loke et al ., ). Many of the samples were collected for biomonitoring purposes by the Tropical Marine Science Institute (TMSI).…”

Creating complex habitats for restoration and reconciliation

“…Artificial substrates have been shown to be effective in enhancing structural complexity in ecological engineering (Bulleri and Chapman, 2010;Chapman and Blockley, 2009) and restoration projects (Larkin et al, 2006). They are also widely used in experimental studies testing the effects of habitat complexity on species diversity and community structure (Larkin et al, 2006;Loke et al, 2010;Matias et al, 2013). At the point of construction, artificial substrates are clearly not dynamic; hence only informational complexity can be incorporated into them (usually into their topography or matrix).…”