Meiofauna is an important, yet often overlooked, component of biodiversity in the ecosystem formed by Posidonia oceanica

Abstract

The ecosystem formed by the marine flowering plant Posidonia oceanicais a biodiversity reservoir and provides many ecosystem services in coastal Mediterraneanregions. Marine meiofauna is also a major component of that biodiversity, and itsstudy can be useful in addressing both theoretical and applied questions in ecology, evolution, and conservation. We review the meiofaunal diversity in the meadow ecosystem of P. oceanica by combining a literature review and a case study. First, wegathered records of 672 species from 71 published studies, as well as unpublishedsources, highlighting 4 species exclusive to this ecosystem. Eighteen of those studiesquantified the spatial and temporal changes in species composition, highlightinghabitat-specific assemblages that fluctuate following the annual changes experiencedby these meadows. Hydrodynamics, habitat complexity, and food availability, all threeinherently linked to the seagrass phenology, are recognized in the literature as themain factors shaping the complex distribution patterns of meiofauna in the meadows.These drivers have been identified mainly in studies of Copepoda and Nematoda,and their effect may depend ultimately on species-specific preferences. Second, wetested the generality of these observations using marine mites as a model group,showing that similar ecological preferences might be found in other less abundant meiofaunal groups. Overall, our study highlights the high diversity of meiofauna inmeadows ofP. oceanicacompared with algae and sessile macrofauna associated withthis seagrass and shows the complexity of the interactions and habitat use bymeiofauna associated with the seagrass.