Populations of seagrasses Zostera marina, Zostera noltii, and Cymodocea nodosa occupy predictable physicochemical regions and harbor characteristic animal communities within and among central Croatian Adriatic embayments

Although seagrass meadows are known for their value as animal habitat, little information exists on the relative habitat value of individual species. We investigated populations of cooccurring seagrasses Zostera marina, Z. noltii, and Cymodocea nodosa and their associated macro-fauna within their physical context in seven distinct embayments in the central Croatian Adriatic Sea. Total seagrass cover varied significantly among embayments, was negatively affected by slope of the sea bottom, and positively affected by marina developments. Variation in coverage of individual seagrass species within and between bays significantly correlated with depth, wave exposure, and salinity. At three meters depth, faunal abundance was higher in monocultures of C. nodosa (four times) or Z. noltii (seven times) than in beds of Z. marina (pure or invading Z. noltii). Likewise, the effective number of taxa (diversity) was higher in Z. noltii and C. nodosa than in Z. marina. Several taxa were exclusively found either in C. nodosa or Z. noltii meadows. Our results are consistent with the hypothesis that physical processes control seagrass cover and distribution, and that this species-specific cover and distribution has significant and predictable effects on the associated animal assemblage.