Linking morpho-taxonomy to ecosystem functions: trait-based estimation of biomass and potential carbon budget in omnivore nematodes

Omnivore nematodes within the order Dorylaimida are among the largest free-living soil-dwelling nematodes, suggesting a significant role in soil biomass and carbon cycling. However, their contribution to these soil processes remains underexplored. Estimating biomass based on nematode morphological traits provides a practical and reliable approach for assessing their contribution in carbon dynamics. This study provides estimated individual biomass and the daily carbon budget of dorylaimids, utilizing a database of taxon-specific body-size measurements sourced from publicly available literature. We calculated biomass and potential carbon budgets for 618 reported populations worldwide, encompassing 464 species, 127 genera, 47 subfamilies, and 19 families. Biomass estimates, using body diameter as a single predictor, based on two recently developed formulae and two adjusted formulae developed in this study were compared against Andrássy's original formula which is using both body length and body diameter as predictors. Adjusted formulae fitted in this study provided a better fit than recently published formulae. Overall, we found an estimated average individual omnivore nematode biomass (fresh weight) of 3.33 µg for females and 3.55 µg for males, and the corresponding daily carbon budgets of 0.03903 µg and 0.04163 µg for females and males, respectively. The considerable variability in biomass data across the taxonomic ranks, highlight the need for robust taxonomic resolution for ecological studies. This study offers a comprehensive dataset and improved formulae for estimating biomass and potential carbon budget in omnivore nematodes, enhancing our understanding of their functional roles in carbon dynamics and other ecosystem processes.