Whilst the Aegean seas may be rich in marine organisms, the maritime zone is generally poorly-developed. Essentially this is because of the weak tide in the Mediterranean, resulting in a small tidal range and little erosion. Similarly, the influence of salt spray is much reduced by comparison with more exposed coasts and halophilic plants are, therefore, confined to a narrow band above the shoreline. Thásos is no exception to this description and most of its coastline is devoid of maritime vegetation, with low sections of bare rocky cliff rising from the sea to meet with phrygana or pine woodland.
Sadly, most stretches of soft coast on the island have been affected by tourism and nearly all of the accessible sandy beaches have been modified by development or tourist pressure. So far I am aware of only two sandy localities where significant remnants of natural vegetation persist - the dunes of Skala Potamia at Golden Beach (Chrissi Ammoudi) and the long quiet stretch of sandy grassland on the south side of Cap Prinos. Paradise Beach also retain vestiges of the original flora, including sea daffodil Pancratium maritimum, on a low area of fore dune but this site appears to be developing as a tourist location and increased trampling pressure may reduce the small area of valuable habitat in the future. Similar low fore dune habitat to the east of Potos, at the mouth of the Dipotamos river, is degraded by trampling but supports characteristic vegetation such as an abundance of sea holly Eryngium maritimum.
The dunes at Skala Potamia are shrinking fast and are in urgent need of conservation. Golden Beach is one of the most popular tourist resorts on the island and beachfront cafés and bars are steadily encroaching on this small but unique area of habitat. Further development should be prohibited immediately but this seems unlikely in the face of considerable pressure to maximise financial returns. The surviving dunes are small, probably only a kilometre or so long and extending a couple of hundred metres inland at most, and low. Characteristic fore dune plants, such as sea rocket Cakile maritima, sea holly Eryngium maritimum and saltwort Salso kali, are present along the front edge but much of the system appears stable with old marram Ammophila arenaria dunes supporting pockets of scrub and dry slacks containing sharp rush Juncus acutus. Rhizomes of Cyperus capitatus reach out across patches of bare sand, whilst golden-drop Onosoma ?heterophylla and sand catchfly Silene conica are locally common.
On the southern shore of Cap Prinos there is a quiet beach which backs onto sandy grassland and dry, sparse reed beds. The construction of a new hotel (the Ilio Mare) perhaps marks the beginning of the end for this peaceful and attractive corner of Thásos. The northern half of the beach, up to the hotel, has now been levelled to make it more 'convenient' for tourists (see conservation issues) and although the southern half is still largely intact localised dumping is increasing. Here, the characteristic strandline vegetation gives way to a herb-rich grassland, between 50 and 100 metres broad, with many rosette-forming plants. Behind this is an extensive area of unimproved scrubby dry grassland with spectacular invertebrates such as the ladybird spider Eresus cinnaberinus and the thread-winged lacewing Nemoptera sinuata. This may be the last example of this type of habitat on the island, as so many other sandy beaches have been extensively developed, and it would be a great pity if tourism was allowed to claim this splendid place.
By contrast, the shingle beaches of Thásos are relatively neglected. Small examples occur at intervals around the coast, such as on the east bay of the Aliki isthmus, but one of the best is below the coast road just north of Skala Kallirachi. Here the shingle is mixed with fine sand and a rich flora of coastal shrubs is interspersed with open shore species such as yellow-horned poppy Glaucium flavum, sea holly Eryngium maritimum and rock samphire Crithmum maritimum. Late in the season the sea holly becomes swathed in dodder Cuscuta sp. Stretches like this may be presumed to be safe from damage, continuing to present a flowering spectacle and supporting a rich diversity of wildlife, but in the last couple of years access by four-wheel drive vehicles has effectively flattened the best section of this beach (see conservation issues). At present the beach should recover but if this level of disturbance continues then the quality of this site will substantially decrease: the simple act of placing a few boulders at the end of the access track would probably safeguard this rich habitat.