| Summary: | On the coast of Labrador in sheltered locations, broad intertidal flats have developed despite isostatic rebound of about 0.3 metres per hundred years. The action of sea Ice Is a major process controlling the distribution of boulders on the surface, which in turn determines the nature of the substratum and the biota which inhabits it. The stability of the surface, the abundance of boulders and the number and diversity of plants and animals increases from a barren zone near shore to luxuriant growths of algae (especially Fucus sp.), barnacles and molluscs (dominated by Mytilus edulls) at the boulder barricade and associated tide pools near the outer edge. A number of the burrowing molluscs (especially Macoma balthica) and polychaetes (including Arenicola marina) prefer the finer, softer sediments of the inner and middle intertidal flats. The subtidal environment on exposed coasts and channels consists of a lag of gravel, cobbles and boulders. Encrusting, calcified algae cover the surfaces along with green and brown algae. In protected areas where sand and mud have accumulated, polychaetes dominate to about 15 to 20 m depth on sand, and molluscs and echinoderms are found on the finer sediments below. On exposed, moderately and steeply sloping bedrock shores above high water, a prominent barren zone occurs. Elsewhere the sand ridges and coastal sand dunes associated with beaches are thickly colonized by grasses, especially Elymus mollis. Blowouts are common behind these areas. Salt marshes occur on shores of low slope. These are small compared to marshes to the south and are made up of turf of grasses dominated by Puccinellla phryganodes which terminates on the barren surface of the intertidal flats. RÉSUMÉ En dépit d'un relèvement isostatique d'environ 0.3 mètres par siécle, de vastes zones d'estran se sont formées dans les secteurs abrités de la côte du Labrador. L'action des glaces marines constitue l’élément ...
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