They are everywhere, but they are tiny. Sometimes, not so small as to be invisible, and with a little attention and patience you might even see them with the naked eye. But if you want to examine their extravagant forms very carefully you need a microscope. The photo below show some of these unique inhabitants of the alpine lakes of the Gran Paradiso National Park.

Fine weather over the last few weeks had almost made us forget that winter was imminent. It took nearly two days of incessant rain to remind us that it was time to get ready… and we, being the transhumant researchers that we are, will soon leave the lakes of the Park. This morning, all of a sudden, the Orco Valley was overwhelmed by the sound of cowbells: the cows are returning to their grazing grounds in the lowlands and we will follow them in a couple weeks. As a matter of fact, the entire valley is bustling with preparations: people gather wood, marmots get fat, birds migrate… but what happens to the alpine lakes and their inhabitants?

On the right, a young specimen of Daphnia longispina seen under a microscope

Even though seasonal temperature variations in high-altitude mountain lakes are not as large as in terrestrial environments (the minimum temperature under the ice is 3-4 °C), winter is not a favourable season for many aquatic organisms. Ice cuts off the lake from the surrounding habitats depriving the ecosystem from all the nutrients flowing in from the catchment area (just think of the quantity of bugs that fall into the water or the vegetable materials carried by the wind). Then, when snow piles up on the ice, light can no longer penetrate into the water and the lakes are plunged into darkness! In short… winter is a harsh season, even under the water. Since many aquatic organisms cannot migrate to milder climates, some of them “opt” to skip winter.

Daphnias have adopted a drastic wintering strategy: towards the end of summer – no sooner and no later – they produce extremely sturdy eggs, which are called winter eggs or “ephippia”. These eggs may survive dehydration and may be carried quite a distance by the wind to new habitats, but this is a different story… The ephippia take up the rear portion of their mother’s body and when mature break free of the maternal body. Having completed her lifecycle the mother dies, and yet the story’s ending is not sad: the ephippia drop onto the bottom of the lake and stay there until the following summer. With the arrival of the sunny season, little Daphnias are hatched. Without chasing the sun by flying across continents, Daphnias live only a summer.

In the photo: microscope image of a large Daphnia longispina female with an ephippium, flanked by copepod Arctodiaptomus alpinus.

Il 2 settembre 2014, i risultati delle azioni di eradicazione del Salmerino di fonte sono stati presentati a Perugia, dove numerosi esperti di ecologia lacustre provenienti da tutto il mondo si sono dati appuntamento in occasione del WLC (World Lake Congress ). Nel corso della presentazione sono stati spiegati i motivi del progetto di eradicazione e sono stati presentati i risultati relativi alle catture di salmerino che in breve tempo hanno portato al collasso  e forse al completo (nei laghi Djouan e Nero) azzeramento delle popolazioni di salmerino nei laghi del Parco. In particolare sono stati mostrati i primi incoraggianti segnali di recupero degli ecosistemi, che, lentamente, vengono ripopolati da organismi fino a poco tempo fa introvabili nei laghi con i pesci.

Federica Defilippi, nature guide who attended training and refresher courses on the LIFE+BIOAQUAE project, led one of the excursions to the intervention sites organised last summer and open to all visitors to the Gran Paradiso National Park who wanted to learn about these important conservation initiatives. In this article, she kindly tells us about the visit…

Hi Federica, when did you accompany the group to the Park to learn about the LIFE+BIOAQUAE project?

The first guided excursion to the LIFE+BIOAQUAE intervention sites, organised within the framework of the “Walking in the Clouds” program and called “THE WATERS OF PARADISE”, took place on Sunday July 13. The itinerary unfolded along the paths that from the Nivolet plateau reach the Rosset Lake through the mountain pastures above the Savoy Shelter.

What did you talk about during your visit to this splendid natural environment?

The main theme was the LIFE+BIOAQUAE project: so I spoke about the eradication of the brook trout and the actions undertaken to improve the quality of high-altitude aquatic environments. Special attention was devoted to the measures adopted to improve the quality of waste waters in the alpine pastures visited and the area of the lower Nivolet lake.

How many people participated in the excursion and what seemed to be most interesting to them?

We had 47 participants, aged 10 to 50. The topics that seemed most interesting to young people were those regarding the delicate equilibrium of lake ecosystems, with a special focus on the impact of the brook trout on macroinvertebrates and the common frog (Rana temporaria). Adults were particularly interested in the techniques used to eradicate the brook trout and phytodepuration methods. They asked about the types of plants used to treat the water.

A day rich with valuable information for all...

Yes, and at the end of the visit, on the banks of the Rosset Lake, while we were talking about the two main species of salmonids living in the Park, I had a chance to mention the conservation program undertaken for the protection of the marble trout along the torrents of Piantonetto, Campiglia and Forzo - the third action of the LIFE+BIOAQUAE project.

Thank you Federica, and bye bye till next time!

(In the photo: a moment in the excursion to the Nivolet plateau guided by Cinzia Garino on 17 August)