Seagrass meadows as ocean acidification refugia for sea urchin larvae


  • Sea urchin larvae were grown at ambient or low pH in tanks with or without plants.
  • Plant photosynthesis increased pH and altered seawater chemistry at both pH levels.
  • Positive effects of plant metabolism on larval development and growth at low pH
  • Seagrass meadows as a tool against climate-driven loss of calcifying species


Foundation species have been widely documented to provide suitable habitats for other species by ameliorating stressful environmental conditions. Nonetheless, their role in rescuing stress-sensitive species from adverse conditions due to climate change remains often unexplored. Here, we performed a mesocosm experiment to assess whether the seagrassPosidonia oceanica, through its photosynthetic activity, could mitigate the negative effects of ocean acidification on larval development and growth of the calcifying sea urchinParacentrotus lividus. Sea urchin larvae at early and late developmental stages that are generally associated to benthic habitats, were grown in aquaria with or without P. oceanica plants, under ambient or low pH conditions predicted by the end of the century under the worst climate scenario (RCP8.5). The percentage of abnormal larvae and their total body length under different experimental conditions were assessed on early- (i.e., pluteus; 72 h post-fertilization) and final-developmental stages (i.e., echinopluteus; 30 days post-fertilization), respectively. The presence of P. oceanica increased mean daily pH values of ∼0.1 and ∼0.15 units at ambient and low pH conditions, respectively, compared with tanks without plants. When grown at low pH in association with P. oceanica, plutei showed a ∼23 % reduction of malformations and echinoplutei a ∼34 % increase in total body length, respectively, compared with larvae developing in tanks without plants. Our results suggest that P. oceanica, by increasing pH and altering seawater carbonate chemistry through its metabolic activity, could buffer the negative effects of ocean acidification on calcifying organisms and could, thus, represent a tool against climate-driven loss of biodiversity.

Ravaglioli C., De Marchi L., Giannessi J., Pretti C. & Bulleri F., 2024. Seagrass meadows as ocean acidification refugia for sea urchin larvae. Science of the Total Environment 906: 167465. doi: 10.1016/j.scitotenv.2023.167465. Article.

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