The fauna of the Sanagra stream and its rivulets.
The Sanagra stream is a rich and vital ecosystem, fed by organic matter such as leaves, branches and small animals that fall into it from outside. When unpolluted, as in much of its course, it is home to an incredible variety of aquatic invertebrates, called macrobenthos, essential to the life of the creek. These small animals form the base of the food chain for fish, amphibians, reptiles and birds.
During field research (Canepa Vismara, 1992), the following were identified. dozens of wildlife groups, including. Plecoptera, Trichoptera, Ephemeroptera, beetles e shellfish. Just lift a few stones in the locality Sass Corbee to discover a hidden world: nymphs of three-tailed ephemeroptera, larvae of trichoptera in their stone cases (the "stone carriers"), and two-tailed plecoptera. Also non-parasitic leeches, as Herpobdella, they anchor themselves to rocks with suction cups to resist the current.
The macrobenthos developed extraordinary adaptations: flat and hydrodynamic bodies, hooks, suction cups and heavy cases to withstand the force of water.
The rivulets and the crayfish
From the countries of Naggio e Velzo two streams flow down, joining just below the Rogolone, forming the Shrimp Valley, named for the presence of the rare Crayfish (Austropotamobius pallipes). Active at night, this crustacean is now threatened by pollution and the introduction of more hardy exotic species.
It was once harvested for its delicious meat, as recalled by the tales of village elders, who used to catch it with nets and carbide.
Life between water and land
The banks of the creek are home to a riparian microfauna, made up of insects and spiders adapted to life between water and land. To observe them, simply provoke a small "flood" by pouring water over a section of the shoreline: they will emerge carabids, as Nebria psammodes By the characteristic red "neck." metallic beetles of the kind Bembidion, and predators such as the Cincidela hybrida. Also the spiders of the genus Pirate Can be spotted running on water.
Amphibians, fish and reptiles
The symbol of the Sanagra amphibians is the Spotted salamander, which lays eggs in mountainous stretches; the larvae, however, prey on the trout and of the Collared Natrix, an aquatic snake that is harmless but greedy for amphibians. Fortunately, the adult salamander is protected by toxic secretions That make it inappetable.
In the creek live the Brown trout, with typical red dots, and the Rainbow trout, an American species introduced for sport fishing, recognizable by its silver livery. The latter, unfortunately, can alter the balance of the ecosystem.
Birds of the creek
The Dipper is a spectacular bird that dives into streams to hunt underwater: it has unique adaptations such as nostrils that close, short, powerful wings, and a special gland that waterproofs its feathers. In the lower reaches of the Sanagra, the Kingfisher, while the thickets host Robins, Little Luì, Wren and, in migration, also the Woodcock. Sometimes theGrey heron, passing along the waterway.
Hidden mammals
Among the small mammals living around the creek, the most interesting is the Alpine shrew, a tiny insectivore weighing a few grams, rarely observed but well adapted to these wet environments.
A protected ecosystem
La high water quality of the Sanagra, thanks to little urbanization, fosters a rich ecosystem that is also appreciated by fishermen. Some stretches of the stream, such as the one in the municipality of Menaggio, are protected by special regulations thanks to the Province of Como. Other areas, such as the area between the "Buca del Cion" and the "Old Chioderia," are managed by theA.P.S.- F.I.P.S.A.S., which is responsible for the conservation and enhancement of the waterway.
There is also an active Tourist Fishing Reserve, where you can fish for trout released periodically, through day pass available at the Old Chioderia Farmhouse.
The presence of Pollution-sensitive macroinvertebrates. is the clearest evidence of the good environmental health of the Sanagra, a stream that is still authentic and full of life.
Learn more about the fishing in the Sanagra stream.
