Ecological network analysis of traits reveals variable response capacity to stress

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Response diversity increases the potential ‘options’ for ecological communities to respond to stress. An indicator of community response diversity is the diversity of different traits associated with their capacity to be resistant to stress, to recover, and to regulate ecosystem functions.

We conducted a network analysis of traits using benthic macroinvertebrate community data from a large-scale field experiment to explore the loss of response diversity along environmental gradients. We elevated sediment nutrient concentrations at 24 sites (in 15 estuaries) with varying environmental conditions. Macroinvertebrate community response capacity to nutrient stress was dependent on the baseline trait network complexity in the ambient community (i.e., non-enriched sediments). The greater the complexity of the baseline network, the less variable the network response to nutrient stress was; in contrast, more variable responses to nutrient stress occurred with simpler networks. Empirical studies that explore the mechanisms responsible for loss of resilience are essential to inform our ability to predict changes in ecological states.