“If we want to promote the refuge of cod juveniles, For example, we will apply a certain reef model, but if what we want is the grip of plants like Posidonia, we will use something very different,” he tells Public the architect and diver Marc García-Durán. It refers to the structures that your company, Underwater Gardens Internationalinstalled in different marine settings to restore lost biodiversity.
They are doing it in the Port Olimpic of Barcelona, where they have already installed 50 intelligent artificial reefs, which are called that because they have a built-in artificial intelligence system –baptized as reefhopper–, along with sensors (temperature, pH, oxygen, etc.) to measure the conditions of the place and, from there, assess what some species or others need to thrive, as well as the challenges they face.
The objective is regenerate aquatic ecosystems damaged by human activity. “We promote the creation of underwater gardens that function as refuges and homes for marine life, in a natural way,” he says.
A suitable home for each case
But not just any structure is enough for life to settle. As a good architect, García-Durán pays special attention to what conditions each context needsdepending on the settlers you want to attract: roughness, shape, orientation with respect to light or sea currents, proximity to populations that may approach the place…
The first step to achieve this is to make a diagnosis of the situation, which identifies the reasons why biodiversity is reduced or eliminated and allows a recovery plan to be drawn up. This is where “smart substrates or reefs come into play, where specific species are planted that activate the wheel of colonizationattracting fish, crabs and other marine organisms,” says García-Durán.
The idea is that, over time, said space will gain life and the ecosystem will recover. The benefits of achieving this are many. Not only for the species, the artificial reef also serves as a natural barrier against erosion and storms… and the life it supports becomes a convenient way to sequester carbon from the atmosphere.
Carbon sequestrants
In this sense, García-Durán confides to us that “you always have to bet on the slow, the structural, the complex”. Thus, a eucalyptus forest has low biodiversity associated with it, compared to a chestnut or cork oak forest, which take much longer to grow but have many more associated species, such as birds, squirrels, weasels…
“The sea is the same,” he tells us. “By planting corals, gorgonians or slow-growing sponges, you ensure that marine forests are much more biodiverse. In addition, there is a very important detail: ephemeral species, such as fleshy algae, accumulate more carbon at the beginning, but their short cycles they will make it return to the atmosphere very quickly. longer-lived structures, carbon will be retained for decades, centuries or millennia.
Living purifiers
Another of its “side effects” has to do with the water quality. For example, in ports with great activity, such as the Olimpic in Barcelona, ”the waters are not exactly healthier for the fauna and flora,” this architect acknowledges.
To alleviate this problem, it is committed to promoting the growth of benthic suspension-eating organisms -which is how different species of sponges, bivalves, polychaetes, bryozoans, etc. are known- that filter the water, feeding on the organic matter that floats suspended around them. In the port of Barcelona they have developed a first phase that, “despite being small in proportion to the port and its activity, already presents notable results.”
Can the damaged biodiversity that existed before the place was invaded, for example, by pleasure yachts or oil tankers, always be reproduced? “You never have the pristine habitat you had again before a source of disturbance. The transformation has been so profound during the last centuries and decades that returning to what existed before is impossible,” he admits.
However, there is always room for improvement. “It is important that the new species that will colonize the area belong to that habitat that you want to cultivate,” he explained to us in the presentation of the project during the Sages&Scientists Zoetry Congress that took place last October, in Mallorca. In this sense, these marine gardeners pay close attention to invasive species do not proliferate.
Profitable gardens
As if that were not enough, their work, in addition to being beneficial for the environment, is also profitable. “Economic literature has established that only the installation of artificial reefs, with the consequent increase in sports, tourism and fishing activities, tends to have an impact of increasing tax collection for the territory of about five or seven euros for every euro invested,” García-Durán tells us.
Perhaps that is why more and more coastal towns are betting on their systems, such as the regenerative park of underwater gardens that will occupy 10.6 hectares in the municipality of Guia de Isora, in Tenerifeor as the Sant Sebastiá beachin Barcelona, which aims to become a center of attraction for diving.
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