Comparison of thermodynamic-oriented indicators and trait-based indices ability to track environmental changes: Response of benthic macroinvertebrates to management in a temperate estuary

Abstract Reliable ecosystem status assessment of coastal and marine environments is key due to mounting pressures from human activities. Aiming at a successful management, a plethora of evaluation tools currently exist, but there is no consensus on what index or indices should be used by environmental managers in establishing benthic quality. The main goal of this investigation was to evaluate the suitability of thermodynamic-oriented indicators (Eco-Exergy and Specific Eco-Exergy) and trait-based indices (Rao’s Quadratic Entropy, Functional Redundancy and Community-Weighted Mean trait value) as tools to capture potential ecological changes, comprehending their utility for addressing specific management objectives. In order to do so, a long-term data set (1993–2012) from a southern European estuary (Mondego estuary, Portugal) was used to assess the responsiveness of macroinvertebrates assemblages to a large-scale management intervention, and the performance of thermodynamic-oriented indicators and trait-based indices was compared. The results indicated that the undertaken management efforts were successful at improving the ecosystem state and confirmed that hydrodynamic conditions in the estuary have been the major drivers of the changes observed over the last three decades. Both Exergy-based and trait-based indices coherently reflected the ecological changes observed along the temporal disturbance-recovery gradient analysed. Indices response was congruent but of different nature and detail level. Trait-based indices provided a more detailed assessment of the benthic communities and informative picture than Exergy-based indices but the overall outcome of both types of indices was broadly convergent. Combining multiple indicators should thus be more likely to improve transparency and to provide a more robust assessment method.