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 Le Tegnùe
 Le Tegnùe |
Just a few miles off the Cavallino Treporti shoreline, lies an extraordinary ecosystem distinguished by its muddy or sandy bed, quite unlike anything else in the Alto Adriatico. This is le Tegnùe, natural rocky outcrops, occurring haphazardly off the Veneto coast.
The name comes from the Venetian word Tegnùe, or kept back, as fishermen venturing out around here would either ‘mysteriously’ lose their nets or haul them up from the depths to find them badly damaged. Because of this, they avoided these parts whenever possible, allowing the ecosystem‘s gradual and undisturbed development over the centuries.
It wasn’t until the 1960’s that the true ‘nature’ of this unusual phenomenon was discovered and from then on, le Tegnùe became the subject of numerous scientific studies and research.
Today, we know that there are three rock types:
- clastic sedimentary or ‘beach rocks’, formed following ‘cementation’ of the carbonates present in the sand or marine organisms;
- organogenic rocks: produced from the deposition and subsequent stratification of vegetable and animal organisms;
- sedimentary rocks of chemical origin: formed from the reaction between the methane emerging from the sea bed and sea water, causing precipitation of the carbonates present in the water which then leads to cementation.
These areas of solid substrate change the ecosystem’s typology unexpectedly, creating an environment which is clearly different from the sandy one usually seen. Biological and ecological characteristics are changed, with an increase in the number of species present (mainly animal) and, consequently, the biodiversity.
The variety of forms of rocky substrate, with countless cavities and ravines, ensures the presence of diverse microhabitats which, in turn, enable the development of a complex biological community. This food chain is very flexible and gives rise to the growth and reproduction of numerous species of invertebrates, echinoderms, molluscs, crustaceans and fish.
Added to these particularly advantageous conditions is the fact that the le Tegnùe areas have been subject to only very limited fishing over the centuries and this has been a determining factor in their preservation.
Le Tegnùe, therefore, are today considered true submerged oases of biodiversity. To care for this natural heritage, the Municipality of Cavallino Treporti, and the Department for Tourism in particular, has set-up a project with the Veneto Region, which has made a small contribution, to protect, safeguard, and make the most of le Tegnùe’s environment together with the development of sustainable tourism.
Strange but true
Amongst the species living in le Tegnùe, there are also sponges like the ‘hermit crab sponge’ (Suberites domuncula), which develops on the shell of a gastropod, the hermit crab to be precise. The mussel or mytilus (Mytilus galloprovincialis) is also common. This is a bivalve mollusc capable of filtering up to four litres of water an hour!
Numerous species of starfish are to be found, capable of reaching up to 30 cms.; not forgetting sea urchins, used in scientific studies as bio indicators for studying water and ecosystem quality.
A typical resident of le Tegnùe: the lobster (Homarus gammarus) – Photo: Andrea Bergamasco (Scuola Subacquea Amici del Mare - http://www.amicidelmare.altervista.org
The tube anemone (Ceriantus membranaceus), capable of living up to 50 years Photo: Ferruccio Dalla Pietà (Scuola Subacquea Amici del Mare - http://www.amicidelmare.altervista.org)
The small red scorpion fish (Scorpaena notata Rafinesque), equipped with exceptional ability to camouflage itself – Photo: Andrea Bergamasco (Scuola Subacquea Amici del Mare - http://www.amicidelmare.altervista.org)
The diversity of life forms, typical of solid substrate, in le Tegnùe – Photo: Ferruccio Dalla Pietà (Scuola Subacquea Amici del Mare - http://www.amicidelmare.altervista.org)
Materiale gentilmente concesso da dott. Pra Levis e studio grafico Input di Carraro Elisa
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