How resilient are coastal marine soft-bottom communities with high diversity?

Based on the large amount of data accumulated over 50 years on soft-bottom communities mainly from the English Channel and the Mediterranean Sea, this study analyses the relationship between diversity (Taxonomic Richness TR, Shannon diversity H', and Pielou evenness J') and abundance of taxa on diverse shallow benthic habitats ranging from muddy sand to gravel. Only samples with H' > 4.0 are selected for this analysis, making up a total of 379 data points. Communities with HDLA (High Diversity and Low Abundance) are common, while some samples show HDHA (High Diversity and High Abundance). Well-known significant correlations are found between H', J', TR and abundance. Moreover, temporal and spatial monitoring of oil spills, urban and industrial outfalls, harbour sediment dumping and salmon aquaculture tend to illustrate the high resilience of soft-bottom benthic communities after the cessation of a disturbance or with increasing distance from the source. Conversely, low resistance of benthic communities after an oil spill is linked to the abundance of sensitive species to hydrocarbons before the sediment pollution.