Description: Background One of the most influential forms of biological invasions is that of invasive ecosystem engineers, species that affect other biota via alterations to the abiotic environment. Such species can have wide-reaching consequences because they alter ecosystems and essentially “change the rules of existence” for a broad suite of resident biota. They thus affect resources or stressors that affect other organisms.The objective of this systematic review will be to quantify the positive and negative impacts of invasive ecosystem engineers on ecosystem structure and functioning, and to identify factors that cause their effects to vary. Methods We will search a number of online databases to gather empirical evidence from the literature on the impacts of invasive ecosystem engineers on: (1) species richness and other univariate and multivariate measures of biodiversity; (2) productivity and abundance of algae, and animals; and (3) biogeochemical cycling and other flows of energy and materials, including trophic interactions. Data from relevant studies will be extracted and used in a random effects meta-analysis in order to estimate the average effect size of invasive ecosystem engineers on each response of interest.

Description: The relationship between biodiversity and stability of marine benthic assemblages was investigated through meta-analyses using existing data sets (n = 28) covering various spatial (m-km) and temporal (1973-2006; ranging from 5 to 〉250 months) scales in different benthic habitats (emergent rock, rock pools and sedimentary habitats) over different European marine systems (North Atlantic and western Mediterranean). Stability was measured by a lower variability in time, and variability was estimated as temporal variance of species richness, total abundance (density or % cover) and community structure (using Bray-Curtis dissimilarities on species composition and abundance). Stability generally decreased with species richness. Temporal variability in species richness increased with the number of species at both quadrat (〈1 m2) and site (100 m2) scales, while no relationship was observed by multivariate analyses. Positive relationships were also observed at the scale of site between temporal variability in species richness and variability in community structure with evenness estimates. This implies that the relationship between species richness or evenness and species richness variability is slightly positive and depends on the scale of observation. Thus, species richness does not stabilize temporal fluctuations in species number, rather species rich assemblages are those most likely to undergo the largest fluctuations in species numbers and abundance from time to time. Changes within community assemblages in terms of structure are, however, generally independent of biodiversity. Except for sedimentary and rock pool habitats, no relationship was observed between temporal variation of total abundances and diversity at either scale. Overall, our results emphasise that the relation between species richness and species-level measures of temporal variability depend on scale of measurements, type of habitats and the marine system (North Atlantic and Mediterranean) considered.