Assessing ecological functions through polychaete traits in estuarine sediments

Even though functional traits have been used to make inferences about ecosystem functioning, few studies have effectively measured the direct relationship between functional traits and functioning in marine environments. This study investigated and quantified how polychaete traits influence organic matter decomposition and bioturbation functions. Seven polychaete species were collected from the Jaguaripe estuary in Brazil, and two laboratory experiments were conducted to estimate the consumption rate, volume and depth of sediment bioturbated by different species. Computer tomography techniques were employed to measure bioturbated sediment volume and depth. Traits such as body weight, feeding mode, and movement type were analyzed to assess their relationship with organic matter decomposition and bioturbation. Results showed that body weight alone was the best predictor of organic matter consumption, with a positive relationship between weight and consumption. Furthermore, movement type was the main predictor of bioturbation. Burrowing polychaetes bioturbated an average sediment volume of 4.5 cm³ (2.15-9.61 cm³), which is five times greater than that of surface modifiers and three times greater than that of tubiculous polychaetes. Tubiculous species reached greater depths, constructing tubes up to 20 cm into the sediment. The study highlights the importance of species traits in predicting ecological functions, suggesting that a trait-based approach is effective when compared with traditional taxonomic classifications. These findings enhance our understanding of the functional roles of benthic macrofauna and underscore the need for experimental data on trait-based approaches.