Deterioration of Sediment Quality in Seagrass Mead

Authors: Marianne Holmer Núria Marbà Morgane Lamote Carlos M Duarte

Publish Date: 2009/02/04

Volume: 32, Issue: 3, Pages: 456-466

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Abstract

Species of the macroalgae Caulerpa sp are increasingly being observed in meadows of the endemic Mediterranean seagrass Posidonia oceanica and in particular Caulerpa taxifolia has been considered as an invasive species leading to seagrass decline Studies have so far failed to reveal the underlying mechanisms of the success of the macroalgae and here we examine how biogeochemical changes of the environment associated to indigenous Caulerpa prolifera and nonindigenous Caulerpa racemosa and C taxifolia species affect the habitat of P oceanica Two of the species C prolifera and C racemosa affect the sediment biogeochemical conditions by increasing organic matter pools microbial activity and sulfide pools of the sediments and limited effects were found for C taxifolia Biomass of the macroalgae contributed to the extent of impacts and high sulfide invasion into the seagrasses and regression of the meadow were pronounced at the location with the highest Caulerpa biomass This suggests that Caulerpa invasion contributes to seagrass decline probably because Caulerpa thrives better than the seagrasses in the modified environmentThis research is a contribution to the MarBEF Network of Excellence the project “Invasoras” funded by the Spanish Ministry of Education and the project “Praderas” funded by the BBVA Foundation MH was supported by Danish Research Council grant no 212050408 and Thresholds EU contract no 003933

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