As the fast-flowing river meets a lake or reaches the relatively calm sea waters, the river flow is abruptly reduced. As such, the mud and silty materials transported by the river are deposited at the river mouth in the shape of a fan. Τhis formation is known as the river delta which was named after the Greek capital letter "Δ".

The delta area is very fertile and offers protection to innumerable plant and animal species. The main river has many and important tributaries.

The Nestos delta and the coast of the Thrace Sea were created from the continual interaction of three factors: the river waters, the sea currents and the regional winds. The many and diverse habitats which characterize the region give it its ecological importance. These habitats provide ideal living conditions for many plant and animal species. Through his activities man added farmlands, created tree farms and drainage channels.

The Nestos delta contibutes a valuable link to a series of wetlands from the Axios river to the Evros river. It is one of the country's most important wetlands because of the large area it encompasses and because of its diverse habitats. It belongs to the Specially Protected Areas of Wild Birds of the Εurοpean Union and to the Ramsar Convention οn Wetlands of International Importance. Let us discover the habitats in the delta region:

SMALL FRESHWATER LAKES

Near Hrissoupoli, one comes across small freshwater lakes, unique to the greater delta region. Μany plant species can be found, such as the white water-lily (Nymphaea alba), species of reed (Phragmites sp.), reedmace (Typha sp.), the small fioating fern (SαΙνίηία natans), and the waterchestnut (Trapa natans). These lakes provide refuge to rare animal species such as the otter, the purple heron (Ardea purpurea), the pygmy cormorant (Phalacrocorax pygmaeus), the ferruginous duck (Aythya nyroca) and the marsh harrier (Circus aerugίnosus).

ΤΗΕ REEDS

Areas of vegetation with reeds (Phragmίtes phragmites) and reedmace (Typha latifolίa) grow around the freshwater lakes, in marshy regions, οn the river and channel banks and in parts of Ιagoons where freshwater penetrates. Reed stands pΙay an important ecological role; they not onΙy act as living filters which clean the waters, but they also provide shelter in which many rare bird species nest. They provide refuge to over 90 species of bird! Birds which prefer the reed stands include the purple heron, the night heron(Nycticorax nycticorax), the little bittern (Ixobrychus minutus), the marsh harrier, the spoonbill (Platalea leucorodia), and the glossy ibis (Plegadis falcinellus).

ΤΗΕ RIVERINE FOREST

Οn the banks of the Nestos, from Toxotes to the Thrace Sea, grows one of the most beautiful riverine forests of all Europe. The forest is 27 km long and 3-7 km wide, covering an area of about 7,200 hectares, making it the largest forest of its kind in the southern ΒaΙkans. It is a gigantic, impenetrable wall of trees! Its name "Grand Forest" is justified! Over the past decades, careless human activity began to reduce this beautiful forest-covered expanse.

What is a riverine forest?

Woody plant species which have adapted either to saturated and/or insufficiently oxygenated soils can be found in riverine forests. There are two types of riverine forests:1) those which have adapted to very moist soils in regions which are frequently flooded; and 2) those which have adapted to somewhat drier conditions in regions which rarely flood. Both their ecological and economic roles are significant. Today, however, most riverine forests are increasingly under threat as a result of man' s activities in these wetland areas.

Today, as a result of land reclamation and logging, only small sections remain. However, it still is one of the country's largest riverine forests. Ιn the parts of the forest where flooding occurs, the predominant trees are: two species of poplar (Ροpulus alba, Ροpulus nigra), three species of willow (Salix alba, Salix purpurea, Salix triandra), and oriental planes. These are the trees that made up the forest prior to man's intervention. Countless climbing vines entwine themselves around the tree trunks. Up until now, twelve different species of these plants have been identified! Those which are greatest in number are the hop (Numulus lupulus), the common vine (Vitis vinifera), the hooked smilax (Smilaχ excelsa), brambles (Rubus sp.) and the black byrony (Tamus communis). Ιn areas with less water, those plants which can afford drier conditions flourish, such as the elm tree (Ulmus minor), the ash tree species (Fiaxinus paruiflora) and a rare species of European oak tree (Quercus penduculiflora). The elm and the ash were in demand for their wood, useful in making furniture. The ancient Greeks used to make spears and javelins from the ash wood. Myth has it that Nemessis, goddess of Justice, held in her hand a branch from an ash tree, which symbolized her firmness and calmness. Around these trees, the climbing vines are even more dense! Here one can find the ivy (Hedera helix).

Ιn the protective areas of dense forest, birds such as the lesser spotted eagle (Aquila pomarina), the goshawk (Accipiter gentilis), and the buzzard (Buteo buteo) find shelter and a place to nest. This is the οnΙy area in Greece which has a not bred wild pheasant pοpulation (Phasianus colchicus).

As the river nears the delta, willows, elms and climbing vines become less prevalent with tamarisk shrubs taking their place.

CULTIVATION OF POPLAR TREES

Poplar trees are cultivated in tributary regions where the soil is saturated with water. The purpose of the cultivation, which began in 1952-53 and is part of a project of the Kavala Forestry Department, is to use the wood for local industries. In contrast with the natural forest, the cultivated poplar tree forests cannot recreate appropriate conditions capable of supporting many species of plant and animal life.

TAMARISK SHRUBS

Around the marsh and along the banks of the river and its tributaries, where the soil is saturated with water, tamarisk shrubs (Tamarίx sp.) grow.

Thousands of white and pink flowers bloom in the spring, giving exceptional beauty to the plants. This is why even in ancient times the plant symbolized beauty and youth, and was dedicated to goddess Aphrodite.

Various plants, shorter in height but just as resistant to the environmental conditions, accompany the tamarisk, such as the sharp rush (Juncus acutus).

ΤΗΕ SALT MARSHES

As we move away from the tamarisk shrubs, we come to the salty meadows which precede the salt marshes.

This continues to be an area of shrubs and rushes. Here, we encounter bird species such as the crested lark (Galerida cristata), the collared pratincole (Glareola pratincola), shanks and sandpipers (Tringa sp.), godwits (Limosa sp.), the stone curlew (Burhinus oedicnemus). Plants which are salt-tolerant, predominate here. During the autumn, the salt marshes take οn a purplish-red hue; this is the time when the annual glassworts (Salicornia sp.) bloom. Ιn these marshes, the blackwinged stilt (Nίmantopus himantopus) and other aquatic birds make their nests.

THE LAGOONS

Along the length of delta shores, the lagoons extend their silver-grey waters. From them, the seven largest cover an area of 1750 hectares.

Where the Nestos meets the sea, the water flow is abruptly slowed and the river sand and silt carried by the river settle and accumulate forming oblong ridges called sand spits. These spits act as natural dams, separating the waters, over time forming the lagoons. Usually the lagoons are connected to the sea by a channel. The majority of the lagoons in the region are shallow, with a depth of barely one meter. Tides, sea currents and winds determine not οnly the water level in the lagoons, but also their shape and structure. ΑΙΙ of these continuous changes, along with the variations in salinity levels, create the particular environmental conditions of the lagoons which are so important to wildlife.

Ιn the shallow waters live a host of microscopic plant organisms -phytoplankton-, which are at the bottom of the lagoon food chain. Ιn the water, there are shoals of fish, such as mullet (Mugil cephalus), sea-bream (Dicenthrarchus labrax), and sole (Solea sp.).

Οn the sea bed, many sea snails (Cerithium νυlgarum, Nassa nerites, Αlexia myosotis, etc.) and a variety of sea worms (Marphysa bellii; Eunice sp. Pherusa sp., etc.) live.
The shores of the lagoons host many bird species which reproduce or remain only during the migratory period. This is where the shag (Phalacrocorax aristotelis), the little tern (Sterna albifions), the common tern (Sterna hirundo), the little grebe (Podiceps ruficollίs) and many sea gulls fish. However, there are many species that winter here. Amongst the winter visitors are the great crested grebe (Podiceps crίstatus), the red-throated diver (Gavia stellata), the black-throated diver (Gaνίa arctίca), the coot (Fulica atra) and many ducks.

ΤΗΕ COAST

Sea currents and winds continually push sand towards the land, creating a series of sand dunes. Backing about 50 km of coastline, these dunes spread out taking up almost all of the land beginning at α distance of 10 m from the waterline and in certain areas reaching 1,5 km! Different types of vegetation are zoned, depending οn their distance from the sea. Closer to the sea, there are plants which have adapted to the sandy bed and to the coastal conditions, such as the beautiful sea daffodil (Paneratium maritimum), the sea holly (Eηngium maritimum) and the annuaΙ seablite (Suaeda maritima). At a greater distance from the sea we find the marram grass (Ammophila arenaria) and the sedge (Cyperus capitatus), while in pebbly areas, we find the impressive yelIow-horned poppy (Glaucium flavum).

Αll along the coastline aquatic birds find food. This is where the kentish plover (Charadrius alexandrinus), the oystercatcher (Naematopus ostralegus) and the little tern nest.

HABITATS CREATED ΒΥ ΜΑΝ

Μan's activities have often lead to the creation of various unusual habitats οn agricultural land, in pens and in inhabited areas.

Ιn the drainage channels we find the pondweeds (Potamogeton sp.) along with frogs (Ηaηa sp.), terrapins (Emys orbicularis, Mauremys caspica) and water snakes (Natrix sp.). Quite often the little bittern and the squacco heron (Ardeola ralloides) can been seen here.

Coppices and hedges rows between farmlands make up natural vegetation zones which link the various habitats.

Ιn inhabited areas we can see the white storks (Ciconia ciconia) in their nests either οn the top of posts or in specially designed man-made nests. The scops οwl (Otus scops), the little οwl (Athene noctua) and the barn οwl (Tyto alba) make their nests in abandoned buildings.
Stone fences are rocky areas that make ideal homes for lizards such as the green lizard (Lacerta υiridis). The hoopoe (Upupa epops) likes to wander here.