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)
On 20 and 21 August we had the pleasure of receiving a group of Catalan researches. The numerous group headed by Dr. Marc Ventura Oller (Centre d’Estudis Avançats de Blanes – CEAB, CSIC) visited sites (the Dres and Leynir lakes) where several BIOAQUAE project actions are underway, and experiences and views were exchanged since they are planning an alien fish eradication programme along the same lines as the one being implemented in the Gran Paradiso National Park. Starting next year, in fact, eradication initiatives will be carried out in some Pyrenees National Parks using similar methods as we are using in our Park. During the visit, arrangements were made for some extremely interesting scientific collaborations, which will help the researchers get a better understanding of the ecology of Park lakes. The presence of the families of the researchers and their children brought a joyous note to those fine days, despite an unexpected, out-of-season snowfall!
Gràcias per la seva visita!
Researchers of the Gran Paradiso National Park, in collaboration with the University of Pavia and Università Milano Bicocca, have recently published the results of genetic analyses conducted on a remarkable crustacean that lives in four alpine lakes of the Park (http://onlinelibrary.wiley.com/doi/10.1111/zoj.12151/abstract). The Trebecchi, Nivolet and Lillet lakes, in fact, host a rare melanic (i.e., dark) form of Daphnia pulicaria, which reproduces by parthenogenesis only (that is to say, no males are involved, and the population is entirely made of females that reproduce by cloning themselves). For many years, these characteristics led the scientists to refer to this crustacean with a different name, perfectly impossible to pronounce: Daphnia middendorffiana. The extension of genetic analysis to ecology made it possible to determine the evolutionary history of this crustacean, give it an appropriate scientific name (Daphnia pulicaria), and understand how it has come to live in the Gran Paradiso lakes.
The most surprising result of molecular analyses is the realisation that the melanic populations of the Daphnia pulicaria found in the Gran Paradiso belong to two groups that differ greatly in their genetic makeup. In particular, the populations inhabiting the Trebecchi and Nivolet lakes are identical to one another, while the population found in the Lillet lake is very different. Why is it so? To find an explanation we must go back to the end of the Ice Age, when the alpine lakes were being formed by occupying the depressions left in the ground by the receding glaciers, and the new aquatic environments were ready to be colonised by various animal and vegetable organisms.
The presence of two genetically different groups of Daphnia pulicaria is probably the outcome of two different colonisation events. The population of the three Valsavarenche lakes (Nivolet and Trebecchi) are very similar from the genetic standpoint to the population of the Icelandic circumpolar regions and the Svalbard Islands, whereas the population living in the Lillet lake, in the Orco Valley, belongs to a group more typical of the Alps. This alpine group probably evolved in a glacial refuge close to the alpine chain, i.e., a “warm” ice-free oasis. As the glaciers receded, these populations gradually moved to higher altitudes, searching for a suitable habitat. Conversely, the Valsavarenche populations, similar to the circum-arctic populations, were probably pushed south by the expansion of the polar cap in northern and central Europe during the glacial period. At the end of the Ice Age, some populations, such as the Lillet lake community, remained in their southern habitat (glacial relicts), while most of the population followed the withdrawal of the glaciers and returned to their areas of origin. An alternative hypothesis is that the arctic populations arrived at a later date, possibly as eggs stuck to the legs of migratory birds; it is interesting to observe that the plains surrounding the Nivolet and Trebecchi lakes provide a stopping area for the dotterel, a small migratory bird that has its nesting sites in Northern Europe and every year passes through the Gran Paradiso on its way to its wintering grounds in Africa.
The case of the Gran Paradiso Daphnia pulicaria attracted the attention of some Canadian geneticists who are currently coding its DNA in greater detail, to understand how and why these organisms “gave up” on sexual reproduction. Hence the story of the Gran Paradiso Daphnia pulicaria is not over yet.
This is the story of a journey extending over thousands of kilometres, which started thousands of years ago and resulted in the presence of extremely isolated animal populations, very different from other better known populations. The alpine lakes, in fact, may be seen as “islands of water in a sea of land,” where biodiversity may be created through genetic diversification and speciation processes. This is why every alpine lake might contain unique or extremely rare organisms, and yet another reason why the alpine lakes should be preserved.
Introducing fish species is the quickest way to destroy the biodiversity of an alpine lake and possible obliterate one-of-a-kind organisms. As a matter of fact, the Gran Paradiso Daphnia pulicaria is not present in the lakes that contain fish. The brook trout eradication activities carried out within the framework of the BIOAQUAE project may restore these aquatic environments to their original conditions, paving the way for the return of locally extinct species.
How can we assess the effects of eradication on the ecosystem? How can we determine whether nature is able to return to its original conditions and resume good health? One of the methods available consists of identifying and monitoring the community of macroinvertebrates populating a lake. Each fresh water ecosystem, in fact, is populated by a large variety of organisms that are more or less sensitive to changes in their habitat, each species having adapted to certain physical conditions (temperature, turbulence of the water, etc,), chemical conditions (dissolved oxygen, concentration of nutrients, etc.) and environmental aspects (current velocity, substrate, place in the food web). An undamaged ecosystem can host a number of species that depends on its intrinsic environmental diversity, whereas the impact of human activities often brings about variations in the abundance and composition of a community, which therefore will be impoverished to a greater or lesser degree in terms of species richness depending on the severity of the impact. In the picture above a per lodes of the Nero lake, Valsavarenche