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To the memory

To the memory of those who have passed away and who played an important role in my professional development as a teacher and researcher, and with whom I developed friendships and shared true feelings of affection.
 
 
Bernard Roché (1948-2004): An excellent scientist and an activist, committed to preserving the biodiversity of the island’s natural environments. He passed away too soon. I had the chance and the privilege to carry out scientific research with him on the fresh waters of Corsica.
 
Jean Giudicelli (1936-2021): An exceptional man, an immense researcher of extraordinary intellectual power. The body of knowledge on Mediterranean running waters owes him a great debt. I owe him my passion for aquatic environments. Like a spiritual father, he guided me along the path of ecology.
 
Arlette Cazaubon (1942-2022): The greatest specialist in Mediterranean freshwater algae, particularly from the south-east of France (Provence and Corsica). An exceptional personality. A shining example of courage and generosity. She felt more joy in giving than in receiving. She passed on to me her passion for seaweed.
 
 
 
 
 
 
I would like to thank the people who helped and supported me in writing this book:
 
My wife Sylvie (Chou)
My daughters Sophie, Alicia and Manon
My beloved grand-daughter Bianca
My sons-in-law François Tramoni and François Colonna
Nicolas Alfaro
 
A special thanks to my friend and photographer Philippe Pierangeli for 
his remarkable photographic work in this book
 
Thanks also to Jean Christophe Barbier, Martin Boone, Morgan Calu, François Colonna, Frank Fetzner, Alain Gauthier, Stéphane Muracciole (ONF), Thomas Pesquet and the European Space Agency for their contribution to the photographic illustrations

PREFACE
  
                  Antoine Orsini is a hydrobiologist. As a meteorologist I deal with meteors and water falling from the sky, his interest is in the clear water of rivers, lakes and mountain streams. We were destined to meet.
 
            Above and beyond the demanding scientist from whom I have learned so much, Antoine is also a child of water and of Corsica. In this respect, he confided to me that he studied the fauna of the rivers of the Restonica valley in his early years in a rather unusual way.
 
He is a demanding and passionate scientist. His enthusiasm runs through this meticulous work. He evokes the complex economic, ecological, cultural and spiritual relationships between mankind and water.
 
He takes us on a journey from the Amazon and the Nile to Golu and Tavignani; from Lakes Baikal and Tanganyika to Melu and Capitellu. The author presents the mineral and thermo-mineral waters of Corsica, a largely under-exploited heritage.
 
This work reveals the particularities of the aquatic fauna of Corsica: faunistic gaps and a high rate of endemism. And its curiosities: freshwater jellyfish, invulnerable tardigrades, the planaria (immortal worms), the Corsican gordian (a manipulative parasite). But this biodiversity is threatened by extreme natural events (floods and low water). And by direct anthropisation (dams, pollution, contamination) and indirect anthropisation (climate change).
 
The author shows the importance of alluvial forests, riparian forests and pozzines in the process of carbon sequestration, an issue related to resistance and resilience to the consequences of climate change. This book is also a journey through time, the evolution of pozzines over 2000 years is presented.
 
            We learn about past and future water use. It is acknowledged that water in Corsica is a resource to be preserved, as are its fauna and ecosystems. This asset is fragile, and has come under pressure from both human activity and the natural disturbances of rivers, such as floods.
. This chapter undoubtedly leads us to a growing awareness of this crucial issue, to considering our attitudes to preserving this water, which is an essential element, in both quantity and quality, for our environment…  and for life.
 
 
 Patrick REBILLOUT
Director of Météo France, Ajaccio

Table of contents
 
Introduction
I. The geographic and topographical situation of Corsica
II. The climatology of Corsica 
III. Geology : Corsica, two mountains in the sea
IV. Surface water
. Permanent environments
– Running water: rivers and streams
– Stagnant water: lakes
Natural lakes: mountain lakes
Artificial lakes: dam reservoirs
. Temporary environments; Mediterranean temporary pools
V. Groundwater: spring water, mineral water and thermos-mineral water
VI. The particularities of the aquatic fauna of Corsica
. Fauna gaps
. The high rate of endemism
VII. Biodiversity of Corsica’s fresh waters
. Fish
. Amphibians or batrachians
. Reptiles (turtles and aquatic snakes)
. Invertebrates
. Aquatic flora
VIII. Terrestrial vegetation in hydrosystems
. Alluvial forests and riparian forests
. Pozzines
IX. Biodiversity under threat
                  . Extreme natural events: floods and low water
                  . Direct anthropisation: dams, pollution and contamination
                  . Indirect anthropisation: climate change
X. Water use in Corsica
. Past use
. Current use
XI. Water and human health
XII. Climate change
 
Bibliographic references

INTRODUCTION
 
Freshwater, the future of humanity
 
Water is the predominant element on the planet Earth; oceans cover 70 % of the world’s surface. But freshwater accounts for only 2.5 % of all water. Almost 70 % of freshwater is stored in ice, so the available freshwater is less than 1 % of the Earth’s water.
 
Water is LIFE
The age of the Earth is estimated at 4.55 billion years. The appearance of life on our planet dates back 3.85 billion years. The first land animals appeared 440 million years ago (“Out of the water”). Life in water alone has therefore lasted 3.41 billion years.
 
But water is also DEATH
Today, 2.5 to 3 billion people do not have access to safe drinking water. The consumption of poor quality water leads to the deaths of one million people per year, including 360,000 children under the age of five. There are several causes, including the presence of biological agents such as bacteria, viruses or parasites, along with both natural and man-made chemical elements such as arsenic, antimony, nitrates, pesticides, etc.
 
The relationship between man and water is complex, due to the economic, ecological, cultural and spiritual relationships that exist with water. In the most ancient civilisations, water is seen as a sacred source of life. Water holds an important place in both mythology and religion. Its combined powers of life and death make it a metaphysical element.
 
Great flourishing civilisations have developed in the valleys of great rivers. Most of the great ancient civilisations are described as “water civilisations”. Their levels of development were directly linked to their degree of control of water management. Conversely, the weakening of this social mastery of water automatically led to their decline and disappearance.
 
Religions and water
In the Judeo-Christian tradition, water occupies a significant place in the Book of Genesis in the Bible: “darkness was upon the face of the deep; and the spirit of God moved over the waters”. God organised the universe out of water: “let the waters under heaven be gathered together unto one place and let the dry land appear”. The first baptisms were performed in nature – in springs and rivers. This was followed by the building of specific baptismal fonts. The word “font” comes from the Latin “fons”, which means both along with the source of the water and the god who lives there.
 
For the Hebrews, cleanliness was a moral obligation: “Cleanliness is next to godliness”. Before entering a sacred place, rabbis wash their hands and feet. Ritual baths are used for washing and purification before religious events.
 
The origins of Christian baptism have parallels in Egypt, Greece and the ancient East, including India with the bathing in the river Ganges.
 
References to water are also prominent in the Qur’an: “We made from water every living thing”. In the Qur’an, water, along with the sky and the earth, is an essential element that testifies to the existence of the Prophet. The Islamic custom of performing ablutions before entering the mosque originally came from a concern for hygiene and it gradually evolved into a prayer to Allah. In the heart of Mecca is the Zamzam spring. According to Islamic legend, Ishmael, the son of Abraham, and Hagar, his mother, while fleeing in the desert, were making a plea for water when a spring suddenly appeared. Since then, part of the pilgrimage to Mecca is to pay homage to the Zamzam spring, whose waters are drunk.
 
 
Water, the great challenge of the 21^st century
Water is an essential factor for development, particularly in islands of the Mediterranean. Water, which used to be part of the natural heritage, has become an economic element, a commodity and a source of conflict. The various antagonistic interests are social (rich / poor), economic (domestic / industrial / agricultural) and political (international conflicts).
 
An increase in greenhouse gas emissions has led to a rise in both global temperatures and sea levels. The effects of climate change must be factored into the management of water resources.
 
Extreme climatic events, such as droughts and floods, highlight the acute vulnerability of the aquatic ecosystem.
 
Human health is threatened by emerging or re-emerging infectious and vector-borne diseases, such as malaria, chikungunya, dengue, zika, and so on.
 
The consequences of climate change will have an impact on the energy sector. The low filling rate of hydroelectric dams will compromise the energy mix, leading to an increase in the share represented by thermal energy, in particularly the use of oil and coal.
 
The scarcity of water resources will lead to an increase in prices of domestic and agricultural water and consequently an increase food prices. Social inequalities will arise linked to the distribution and pricing of water.
 
In the long term, the current system for governing of water resources will be called into question. Changes in behaviour and lifestyles as well as upheavals in the agricultural sector will become inevitable.
 
 
Water in Corsica
On the island, the main users of water resources are the human population, including tourists, and farmers, particularly with irrigated agriculture. As the region is not highly industrialised, the other main activities related to aquatic environments are large-scale hydroelectricity (from which produces 25 % Corsica’s energy needs).
 
In 2019, the surface water bodies with a good or very good ecological status have an exceptional rate of 88 % (50 % for the other French basins). However, the quantitative status of some groundwater bodies on the island’s eastern coast is deteriorating. The overexploitation of resources in summer and the consequences of climate change go to explaining this degradation. Nevertheless, 98 % of surface water bodies and 100 % of groundwater bodies are in good chemical condition.
 
 
In this book, the typology chosen for freshwater is as follows: firstly groundwater, and secondly surface water. 
 
These are classified as:
1. In permanent environments: these are flowing waters (rivers) and stagnant waters, natural lakes (such as mountain lakes), and artificial lakes (such as reservoirs and dams).
2. In temporary environments: these are temporary watercourses and temporary Mediterranean pools.
 
The presentation of running water (rivers) and stagnant water (lakes and reservoirs) ecosystems begins with an overview of these hydrosystems on a global, European and national scale.
 
 
 
 

Antoine ORSINI, Hydrobiologist.
Senior Lecturer at the University of Corsica.
Director of the Hydrobiology Laboratory UMR-CNRS 6134 SPE.
Board member of the RM&C Water Agency.
Former board member of the Corsican Environment Office.
President of the Scientific and Environmental Committee of the Project for the Development of the new infrastructures for the port of Bastia.
Member of the Corsica Basin Committee.
Member of the Regional Scientific Council of the Natural Heritage of Corsica.
Member of the Scientific Council of the Regional Natural Park of Corsica.
Former President of the Scientific Councils of (1) the Corsican Regional Nature Park, (2) the Scandola Nature Reserve, (3) the UNESCO MAB Fango Nature Reserve.
 
President of the Central Corsica Community of Communes. 

I. The geographic and topographical situation of Corsica 
 
The Mediterranean is an inland sea that communicates with the Atlantic Ocean through the Straits of Gibraltar. The Italian peninsula and Sicily divide the Mediterranean into two basins of differing size. The larger, eastern basin extends to the Middle East; the western basin is smaller. In the latter, Corsica and Sardinia occupy a meridian position bordering the Tyrrhenian Sea.
Corsica lies at a latitude of between 41° and 43° north. Stretching in a north-south direction, it is about 160 km from Provence, as is at a distance of 82 km from Tuscany and only 12 km from Sardinia. With almost 1,000 km of coastline, 183 km in length and 84.5 km at its widest point, it has a surface area of 8,748 km². Corsica is the most mountainous island in the Mediterranean, although it does not have the highest peak, Monte Cintu (2,707 m), is surpassed by Mount Etna, which rises to 3,323 m in Sicily. But in Corsica, half of the territory has an altitude of over 400 metres and the island has almost 120 peaks over 2,000 metres.
 
 
Corsica photographed by Thomas Pesquet on 6 July 2021 during the Alpha space mission, with the following comment: “Corsica in majesty. It’s always surprising to realise that it’s closer to Italy than to France – looking at weather maps or geography books where it’s closer to the mainland, I grew up thinking it was 200m off Nice, and I was surprised to find that it has a close sister, Sardinia, a stone’s throw to the south. This photo is a perfect example of what astronauts like to photograph from space: landscapes that are recognisable at a glance, an almost perfect vertical, and the reflection of the sun on the sea.
 
Note that the white spots on the centre of the island are not snow but clouds.  However, they cling remarkably well to the highest relief.