Characterization of Chironomidae (Diptera) surface-floating pupal exuviae sample sort time from coastal tropical aquatic systems

Abstract

Many studies either ignore chironomids or only identify specimens to subfamily or tribe due to the associated difficulty and high cost with processing and identifying larvae. An efficient form of sampling chironomids involves collections of surface-floating pupal exuviae (SFPE). SFPE sample sorting has been shown to be more time efficient than traditional dip-net methods in temperate urban and peri-urban streams. However, no published studies have tested the time efficiency of SFPE sample sorting from coastal tropical aquatic systems. We calculated sort times for SFPE samples collected from a coastal tropical stream and an estuary and used multiple linear regression analysis to quantify the relationship between sample sort time and number of specimens, average body length of specimens, and dry weight of sample residue. The average amount of time required to sort very small samples was 69.3 min, while moderate samples averaged 85.6 min and large samples averaged 153.5 min. However, on average, small samples were nine times more time consuming per specimen than large samples. Additionally, dry weight of small-sized residue and the number of specimens contributed significantly to sort time. Therefore, we recommend collecting larger samples, which can be achieved by sampling for 20 min over 200-m reaches for stream sites and 500- to 1,000-m reaches for riverine and estuarine sites. Also, we suggest collecting during periods of low wave action and disturbance by boat wake to reduce the amount of sample residue. This research will enhance project planning and budgeting of future studies using the SFPE method to monitor coastal tropical aquatic systems.

Trace DNA from insect skins: a comparison of five extraction protocols and direct PCR on chironomid pupal exuviae

“…Chironomid pupal exuviae are among the most useful and cost‐efficient life stages to include in aquatic biodiversity studies (Raunio et al . ; Ferrington & Coffman ; Kranzfelder & Ferrington ), but morphological species identification is challenging due to lack of species associations and comprehensive taxonomic keys. The association of chironomid pupal exuviae with adult counterparts using DNA barcodes can further increase the usefulness of this life stage in freshwater science.…”

“…This collection method has several advantages over traditional benthic larvae sampling techniques: (i) applicability in nearly all types and conditions of aquatic environments, including deep, muddy rivers, canals and lakes, and riffles in shallow rivers; (ii) accumulated pupal exuviae represent taxa that have originated from a wide range of microhabitats; and (iii) sampling and sample sorting are easy and rapid (Wilson & Ruse ; Kranzfelder et al . ).…”

High-throughput mass spectrometry analysis revealed a role for glucosamine in potentiating recovery following desiccation stress in Chironomus

“…Among aquatic ectotherms, chironomid midges form an abundant group of insects that play a key role in the maintenance of balanced ecosystems 11, 12 and are capable of thriving under extreme environmental conditions 13, 14 . We have previously reported the impressive resilience of the larvae of a tropical midge species, Chironomus ramosus 15, 16 that are prone to daily fluctuations between wet and dry in their natural habitats (18.5551° N, 73.8618° E and 18.4818° N, 73.8296° E).…”

Aquatic silk proteins in Chironomus: A review

“…Chironomid midges are dipteran insects (family Chironomidae; genus Chironomus) that inhabit freshwater bodies, temporary rock pools, wetlands and terrestrial Antarctic biomes (Kranzfelder and Ferrington, 2015). The life cycle of Chironomus comprises the egg, larva, pupa (aquatic stages) and adults (terrestrial) (Armitage et al, 1995;Nath et al, 2009).…”