engleski

The effects of soil composition on behavioural endpoints and energy budget of Eisenia fetida

Earthworms play an important role in the regulation of soil physicochemical processes and ecosystem services. The burrowing activity of organisms influences physical characteristics, chemical composition, and nutrient cycling and thus affects species composition and population dynamics of other species within ecosystems. This study investigated the effects of soil composition on behavioural characteristics and energy reserves of Eisenia fetida. The test soils were prepared using different dry weight ratios of sphagnum peat (SP), kaolin clay (KC), and quartz sand (QS). By combining the ratios of the components specified in the OECD 207/222 standards (10% : 20% : 70%), a total of 6 test soils were obtained. Earthworm behaviour was monitored during 24 hours in 2D terraria filled with test soils (water holding capacity adjusted to 50%) and quantified using a system based on deep learning. The behavioural endpoints investigated were total burrow length, burrow system complexity, and burrow reuse. To test the effects of soil composition on energy reserves, the earthworms were exposed to the test soils for 7 days. The weight of the organisms was recorded at the beginning of the experiment and after 7 days. Lipid, protein, and glycogen contents were determined after the exposure, by spectrophotometric methods. Preliminary results suggest a correlation between soil composition and behavioural endpoints, as well as the quantities of macromolecules measured. Total length and burrow system complexity was the largest in soils containing 70% of QS and KC, while the most intensive burrow reuse was observed in soils containing 70% of SP. The mass gain was largest in soils containing 70% of SP, and a similar pattern was observed in energy reserve indicators, as well. The results of this research can be explained by avoidance mechanisms due to mechanical irritation or reduction of energy expenditure on movement due to food availability. Both of these effects should be considered in ecological and ecotoxicological studies, and their quantification and extrapolation could help understand the processes occurring in nature.

2D terrarium ; burrow ; deep learning ; energy reserves

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