Changes in the microbial community based on seawater pH variations

Ocean acidification is an effect of the rise in atmospheric CO2, which causes a reduction in the pH of the ocean and generates a number of changes in seawater chemistry and consequently potentially impacts seawater life. The effect of ocean acidification on metabolic processes (such as net community production and community respiration and on particulate organic carbon (POC) concentrations was investigated in summer 2012 at Cap de la Revellata in Corsica (Calvi, France). Coastal surface water was enclosed in 9 mesocosms and subjected to 6 pCO2 levels (3 replicated controls and 6 perturbations) for approximately one month. No trend was found in response to increasing pCO2 in any of the biological and particulate analyses. Community respiration was relatively stable throughout the experiment in all mesocosms, and net community production was most of the time close to zero. Similarly, POC concentrations were not affected by acidification during the whole experimental period. Such as the global ocean, the Mediterranean Sea has an oligotrophic nature. Based on present results, it seems likely that seawater acidification will not have significant effects on photosynthetic rates, microbial metabolism and carbon transport.

Portofino Seaweed Garden: a local citizen science case study on Ericaria amentacea (C.Agardh) Molinari & Guiry, 2020 restoration

Ericaria amentacea is an endemic alga of the Mediterranean Sea that lives in the littoral rocky fringe. The species is sensitive to environmental changes, so it’s used to assess the water ecological quality. Nevertheless, E. amentacea is deeply impacted by coastal development which cause rapid regression despite data on its distribution and healthy status are still limited. Moreover, it’s little known by people outside the scientific community. In this context, Portofino Seaweed Garden was born, a conservation and citizen science project aim to involve marine outdoor enthusiasts in protecting and restoring E. amentacea, creating a submerged garden. Restoration measures have been encouraged by EU regulations. Here, using citizen science, 1) I evaluated the spatial variability of E. amentacea abundance along the central-eastern Ligurian coast, to evaluate its status and choose donor and restoration sites. 2) I carried out an E. amentacea restoration (with outplanting lab-cultured embryos on 50 clay tiles). 3) I assessed the community involvement and education of volunteers. Simple protocol was created to train them on the monitoring. Unprecedented E. amentacea reproductive mismatch affected the restoration performance, probably caused by marine heat wave that hit the Mediterranean in summer 2022. After fertile apices collection in Pontetto (GE) and during laboratory phase, gametes spawned on the discs didn’t settle as expected. Only 16 tiles showed juveniles and they were outplanted at Punta Castello (C zone of Portofino MPA). Unfortunately, they didn’t survive in the field due to an interplay of physical and biological factors. From citizen science point of view, the project demonstrated positive outcomes of collaborations between people and scientists by involving more than 100 participants. Citizen scientists became specialize in the protocol providing quality data for E. amentacea conservation. Current results suggest that outplanting should be further tested.