Seagrasses provide numerous environmental goods and services through coastal areas of the globe. However, a large number of man-induced impacts threats nowadays seagrass health, e.g. through alterations to coastal habitats, invasion by non-native species, enhanced sedimentation, pollution, eutrophication, etc. Some of these impacts facilitate the growth, and therefore competition, of seaweeds, also contributing to accelerate the degradation of seagrasses. We have reviewed experimental evidence on the way seaweeds interact with seagrasses, aiming at identifying attributes of both seaweeds and seagrasses (e.g. abundances, sizes, morphology, taxonomy, attachment and origin) that affect the magnitude of these impacts. This work has been excellently leaded by kiwi-Danish Mads Thomsen. The reference is: Thomsen, M.S., Wernberg, T., Engelen, A.H., Tuya, F., Vanderklift, M.A. et al. 2012. A Meta-Analysis of Seaweed Impacts on Seagrasses: Generalities and Knowledge Gaps. PLoS ONE 7(1): e28595. doi:10.1371/journal.pone.0028595.
