The Living Surfaces project aims to develop physical structures – substrates – that will house sea urchins after settlement, the stage in their life cycle when they metamorphose and adopt a life-style on the seabed. These substrates will be placed at sea in shallow areas, as part of programmes to regenerate populations of these animals, offering protection and maximising their survival during the first weeks of their insertion into their natural habitat.
Sea urchins are key species of our coastal ecosystems and can be considered bio-engineers of intertidal and shallow habitats. They are voracious grazers responsible for transforming leafy kelp forests in rocky bottoms populated by (“only”) coralline algae and for excavating the characteristic alveoli of our coastline that are home to great biodiversity of other animals and algae. Sea urchins are also marine resources of high commercial value. Their roe is a gastronomic delicacy appreciated in many regions of the world. The common European sea urchin Paracentrotus lividus is the species with the highest commercial value and for this reason the most susceptible to overfishing, with several populations already practically decimated along the Mediterranean.
In this context, aquaculture appears as an option both to produce roe with high commercial value and juvenile sea urchins, which can be used to repopulate wild populations under intense coastal exploitation and other anthropogenic risks. One of the biggest challenges in producing juveniles for repopulation is finding a substrate that offers both shelter and food in the first weeks of life after the small and fragile sea urchins metamorphose.
The Seed Reef project seeks to develop such substrates, which mimic the rocky forms colonized by sea urchins in their natural habitat, providing food and shelter at a stage when survival rates are often low. At this stage of their life cycle, sea urchins measure around 1 mm in length and feed on microalgae and newly germinated macroalgae. The substrates to be developed must allow these algae to grow in order to provide food for the small urchins.
To be installed in the natural habitat of the intertidal zones of the Portuguese coast these substrates must resist the force of the sea for at least the necessary time for the small urchins to transit to the surrounding natural structures and must not leave any contaminating residues in the habitat where they are inserted.
These artificial structures, by having a presence in the intertidal habitat, cohabit also with people and for that reason present a great potential to be used in educational and environmental awareness programs, promoting not only the observation of the various stages of growth of these life forms but also contributing to an awareness of the importance of preserving the marine ecosystem in which they live.
External team members:
MARE Politécnico de Leiria: Sílvia Lourenço, Ana Sofia Gomes, Ana Pombo
MARE Universidade de Évora: David Jacinto