Length–biomass equations to allow rapid assessment of semi-aquatic bug biomass in tropical streams


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Abstract

Length–biomass equations are relatively easy and cost‐effective for deriving insect biomass. However, the exact relationship can vary between taxa and geographical regions. Semi‐aquatic bugs are abundant and are indicators of freshwater quality, but there are no studies investigating the effect of habitat disturbance on their biomass, although it is useful in assessing ecological processes. We identified the best‐fit length–biomass models to predict the biomass of semi‐aquatic bugs (Hemiptera, Gerromorpha) collected from streams in Sabah, Malaysia. We used 259 juvenile and adult semi‐aquatic bugs to compare a range of plausible length–biomass functions, and to assess whether relationships differed across the following families and body forms: (1) Cylindrostethinae, Gerrinae, and Ptilomerinae, which are subfamilies within Gerridae consisting of small‐to‐large bugs that have long and slender bodies, (2) Halobatinae, a subfamily within Gerridae, consisting of small‐to‐medium bugs with wide heads and thoraxes as well as short abdomens, and (3) Veliidae, which are small bugs with stout bodies. Estimation used five fitting functions – linear regression, polynomial regression order 2, 3, and 4, and power regression – on the following groupings: three body forms combined; each body form with life stages (juvenile and adult) combined; and each body form with life stages separated. Power regressions were the best fit in predicting the biomass of semi‐aquatic bugs across life stages and body forms, and the predictive power of models was higher when the biomass of different body forms was calculated separately (specifically for Halobatinae and Veliidae). Splitting by life stages did not always result in additional improvement. The equations from this study expand the scope of possible future ecological research on semi‐aquatic bugs, particularly in Southeast Asia, by allowing more studies to consider biomass‐related questions.

Description

Funder: Cambridge Trust; Id: http://dx.doi.org/10.13039/501100003343


Funder: Cambridge University Commonwealth Fund


Funder: Hanne and Torkel Weis‐Fogh Fund


Funder: Jardine Foundation


Funder: Panton Trust


Funder: Proforest


Funder: S.T. Lee Fund


Funder: Tim Whitmore Fund


Funder: Varley Gradwell Travelling Fellowship

Keywords
bioindicator, body forms, Gerromorpha, habitat disturbance, Hemiptera, indicator species, length-biomass relationships, life stages, power regression, Sabah, semi-aquatic bugs, water quality
Journal Title
Entomologia Experimentalis et Applicata
Conference Name
Journal ISSN
0013-8703
1570-7458
Volume Title
Publisher
Wiley
Sponsorship
NERC (1122589)
Jardine Foundation, the Cambridge Trust, Proforest, the Varley Gradwell Travelling Fellowship, the Tim Whitmore Fund, the Panton Trust, the Cambridge University Commonwealth Fund, the Hanne and Torkel Weis-Fogh Fund, the S.T. Lee Fund
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