Nutrient enrichment can alter negatively benthic communities and reduce their ecological services. This study explores in two contrasting seasons (winter and summer), the effects of in situ nutrient enrichment at the community level on carbon metabolism and dissolved organic carbon (DOC) fluxes in two benthic communities dominated by the seagrass Cymodocea nodosa and by the macroalga Caulerpa prolifera. Under nutrient enrichment, C. nodosa increased total community biomass and diversity in summer, while net community production shifted from net autotrophic to net heterotrophic in winter. In contrast, C. prolifera became heterotrophic in summer, while no significant effects were found in winter. Regarding DOC fluxes, nutrient enrichment shifted C. nodosa from net DOC consumer in winter to a strong net DOC producer in summer, while C. prolifera seemed unaffected. Therefore, nutrient enrichment can promote conditional effects (positive, negative or neutral) in coastal areas depending both on macrophyte assemblages and season.

营养丰富会改变底栖生物群落并减少其生态服务。这项研究在两个相反的季节（冬季和夏季）中探索了社区水平的原位养分富集对两个海底结节藻（主要由海藻Cymodocea nodosa和Macroalga Caulerpa主导）底栖生物群落中碳代谢和溶解有机碳（DOC）通量的影响。苔。在养分富集的情况下，结节梭菌在夏季增加了总生物量和多样性，而冬季的净社区生产则从净自养变为净异养。相反，C。prolifera在夏天变成异养，而在冬天没有发现明显的影响。关于DOC的通量，养分的富集使结节梭菌从冬季的DOC净消费者转移到夏季的DOC净产生者，而C. prolifera似乎没有受到影响。因此，取决于大型植物的种类和季节，养分富集可以促进沿海地区的条件效应（正，负或中性）。