Intertidal Object: 

recording the tension between water and land
2020, tutors Studio Ossidiana (Alessandra Covini & Giovanni Bellotti)published in the MIARD archive


An exploration of the beach as a place of impermanence, becoming a productive space to question the perceived stability of the world’s landscapes.

The research contextulizes a proposal for a mediative object constructed out of differently erodible materials, positioned in the intertidal zone, enabling alternate forms of engagement between species and making visible the movement of water. The object puts the fluidity of the ocean into the foreground. The natural forces engaged in the formation of the beach are perceived as building machines.











The object lives in the space of the intertidal zone. Every 12 hours and 25 minutes it is taken by the high tide, barely submerged by water. The top layer peeks out from the water when the dip of the wave reaches the object. As the water slowly recedes in the next 6 hours and 12.5 minutes, transitioning to the low tide the object becomes more and more terrestrial. At the low tide, the water reaches the object only by the force of a high wave. This happens twice every day of every week, of every month, of every season, of every year…

The first layer covering the elements, constructed from a mixture of sand, cement and lime, conceals the elements beneath. Slowly the first changes to the object occur. Pockets of sodium bicarbonate dissolve in water. This boosts the pH of the surrounding ecosystem lowering the acidity, facilitating better development of neurons of mollusks (Kostenko et al., 1983). After 3 months the first marks of erosion are visible in the object. The salt of the sea persistently eats away at the object. At around 6 months the first small specimens of the common blue mussel Mytilus edulis and the Ulva linza a species of green algae emerge.






The object is increasingly shifting its habitat to the marine. The second layer constructed from a composite structure made of burned terracotta ceramics facilitates the filtration of seawater through the burned clay. This enables better quality of water to attract organisms. Progressively the object attracts more species, apart from the pioneers.

The marine life is slowly taking over. Some Oyster types and variations of brown and red algae such as Liminaria digitata and Palmaria palmata are starting to appear, while the Mytilus edulis forms larger clusters. These organisms being filter feeders, aid the material structure of clay in the filtration of water. Foraging activities emerge. The first signs of erosion are slowly visible by the objects’ 8th season in the tide. During the time it is ever more colonized by the marine organisms, while also becoming a popular spot for birds to feed and seek shelter on the higher structures. The pool develops its own micro ecology, becomming a nursery for organisms such as crabs, barnacles and other molluscs. In around 20 years’ time, the second material reaches its last cycle, only single clusters and small debris of the eroded structure remaining.






In the 40th year since the placement of the object into the intertidal zone, for the first time, the rise of the sea level is evident. The object now lives in the subtidal zone, becoming fully marine, peaking out of the water only in the lowest tides. The human can now interact with the object only by immersing themselves into the marine ecosystem. More organisms habitate the area around and inside the object. As it is now fully submerged into the marine the object attracts a rich diversity of organisms, such as cephalopods, arthropods, echinoderms and a variety of fish populations feeding on those organisms.

The third layer, constructed from limestone, is the most durable of all materials used. The material serves to reduce the acidity of the sea by lowering the pH and aiding with the biomineralization processes of many algae and invertebrate shells. Furthermore, studies show that limestone CaCO3 can store CO2 (Riding and Liang, 2005).

In the 50th season of the object, the structure is fully overcome with the marine organisms, the original structure barely visible. As a consequence of the rising sea levels, it continues to become more and more marine, never emerging from the water again. The object can now be accessed by humans only by diving to the seabed and interacting with the object. All signs of this being a man-made object had disappeared. At this stage, the erosion is significantly halted, due to the organisms living on the object, strengthening the material structure beneath. The organisms turn the erosion around, the object thus becoming a center from which mussel and algae colonies spread, forming a natural reef reinforcing the seabed and thus counteracting the coastal erosion.



Stage I: 1 year Stage II: 20 years Stage III: 60 years
© Eva Garibaldi 2020