Tuesday, October 26, 2010
Athos 4: The Wine-Dark Sea
Oinops pontos - the wine-dark sea - is a favourite epithet of Homer's.
It surely applies to the seas around the Athos peninsula - a crisp blue in sunshine, from a boat or shore, darkening to indigo from higher angles, in certain lighting conditions.
This happens because the water is very clear; it has little particulate material in suspension to scatter light passing through. In harbours the sea bed is easily visible to considerable depths - I would guess at least 20 feet.
This lack of suspended particles may be attributed in part to relative stillness of the sea. There are no strong tidal flows around Athos; diurnal ebbs and flows are minor, with a tidal rise of maybe one foot - scarcely noticed by visitors. So there are no strong currents or eddies to stir up sediment.
But another factor is infertility of the sea: there is little or no growth of plankton to cloud surface waters, nor of algae and seaweeds near shores. Algae and plankton are the base of the food chain, consequently there is not the abundance of barnacles, limpets, and other molluscs which is familiar on British shores.
Blue waters, bare rocks, low biological productivity.
Here is a picture of rocks near Grigoriou monastery: the absence of attached algae and molluscs is striking.
Fish also seem to be relatively few around Athos. I saw few sea birds - occasional cormorants and gulls. I saw no seals, and no dolphins [OK - human predation may have exterminated seals, and dolphins come and go]. Shoals of small fish are seen in harbours.
But the general infertility of the seas at Athos contrasts with the abundant life in comparable British waters.
Why should this be? I suspect deficiency of essential nutrients, especially iron. This is an oligotrophic environment.
The rocks of Athos are limestones, and generally white or grey. Calcium is in abundance, which may exacerbate the effects of iron deficiency. The north-eastern slopes are covered with sweet chestnut forest - and the chestnut grows well on the white chalk downs of England, another calcium-rich, iron-poor environment.
This picture shows blue sea and white rocks near the southern tip of the peninsula. The erosion at the base of the rocks illustrates the low tidal rise and fall.
Oinops pontos - the wine-dark sea; wine-dark because it is a hungry, infertile sea. Its blue waters and white beaches attract tourists, but disappoint the naturalist.
Finally, this is Cape Pennes, the southern tip of the peninsula.