Avoidance, biomass and survival response of soil dwelling (endogeic) earthworms to OECD artificial soil: potential implications for earthworm ecotoxicology

C Brami,A R Glover,C N Lowe,K R Butt

doi:10.1007/s10646-017-1788-1

C Brami, A R Glover + Show 2 more

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https://doi.org/10.1007/s10646-017-1788-1

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Abstract

Soil dwelling earthworms are now adopted more widely in ecotoxicology, so it is vital to establish if standardised test parameters remain applicable. The main aim of this study was to determine the influence of OECD artificial soil on selected soil-dwelling, endogeic earthworm species. In an initial experiment, biomass change in mature Allolobophora chlorotica was recorded in Standard OECD Artificial Soil (AS) and also in Kettering Loam (KL). In a second experiment, avoidance behaviour was recorded in a linear gradient with varying proportions of AS and KL (100% AS, 75% AS + 25% KL, 50% KS + 50% KL, 25% AS + 75% KL, 100% KL) with either A. chlorotica or Octolasion cyaneum. Results showed a significant decrease in A. chlorotica biomass in AS relative to KL, and in the linear gradient, both earthworm species preferentially occupied sections containing higher proportions of KL over AS. Soil texture and specifically % composition and particle size of sand are proposed as key factors that influenced observed results. This research suggests that more suitable substrates are required for ecotoxicology tests with soil dwelling earthworms.

Highlights

The potential for earthworms as bio-indicators of environmental quality is widely recognised
Litter dwelling earthworms have been widely adopted for use in both acute and chronic ecotoxicological studies, with Eisenia fetida proposed in a number of standardised tests (OECD Acute Toxicity Test (OECD 1984), USEPA OCSPP 850.3100 Earthworm Subchronic toxicity test (USEPA 2012), ISO 11268-1:2012 acute toxicity test (ISO 2015) and ISO 17512-1:2008 avoidance test (ISO 2012)
Artificial soils are often preferred to natural soils in standardised toxicity tests as they allow conformity in, and comparability of results, are available throughout the year and do not contain organisms or pollutants that can influence the test

Summary

Introduction

The potential for earthworms as bio-indicators of environmental quality is widely recognised (reviewed by Fründ et al 2011). Litter dwelling (compost) earthworms have been widely adopted for use in both acute and chronic ecotoxicological studies, with Eisenia fetida proposed in a number of standardised tests (OECD Acute Toxicity Test (OECD 1984), USEPA OCSPP 850.3100 Earthworm Subchronic toxicity test (USEPA 2012), ISO 11268-1:2012 acute toxicity test (ISO 2015) and ISO 17512-1:2008 avoidance test (ISO 2012). This is due to a short life cycle, high fecundity, relative ease of cultivation and commercial availability. Hofman et al (2009) refer to several specific issues including: (1) validity of test result extrapolation to field conditions, as the properties of OECD AS are substantially different to natural soils; (2) variation in toxicity results between laboratories employing OECD

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