RESPONSE OF COMMUNITY AND TRAIT PATTERNS TO SIMULATED SPECIES LOSS IN COASTAL LAGOONS

Species loss is usually considered to have negative impacts on ecosystem integrity and stability, but the details of the relationship between biodiversity and ecosystem functioning are still far from being thoroughly understood. In this study we computationally simulate species loss in six Mediterranean coastal lagoons and investigate how the species distribution patterns and the associated biological traits patterns change under scenarios of increasing species loss, using polychaetes as a model taxon. Species were progressively removed from the original dataset and the similarity between the full assemblage and the reduced datasets of both species and associated biological trait patterns was calculated. The results indicate the extent of changes that could follow species loss in the real world, and allow insights into the potential resistance of these lagoons to loss of species, both in terms of community pattern and functional capacity. The results indicate that while the change of species and trait patterns was strongly correlated in most lagoons, each lagoon showed an individual reaction: In several lagoons, the dominance of one or few species was the major driver for the observed patterns and extreme and unpredictable changes followed the loss of these species, whereas other lagoons showed indications for niche partitioning and seemed to have a higher resistance towards species loss. Species richness appeared to be less important for the ability of the lagoons to buffer changes, instead the initial composition of the assemblage and the identity of the lost species determined the observed patterns in each lagoon.