The only circumstances when it is likely to remain is if it forms a hard non-toxic tarmacadam. Even in these conditions, the tar will eventually be eroded away. The mass mortality of the grazing molluscs is likely to have a significant effect on the ecology of polluted shores. This is because limpets form an important function in keeping seaweed growth in check by cropping the growths of algae. Unchecked, vast areas of green seaweeds are likely to become established in a few weeks, followed by the fucoid wracks which may become the dominant fauna on all but the most exposed shores.
Limpets reproduce by discharging sperm and eggs into the sea, followed by a planktonic larval stage.
The young limpet then settles on the shore and in two years will be 5 cm diameter and graze an area of about 150 sq. In areas where periwinkle over-collection has caused the same seaweed explosion, the shore shows very little evidence of returning to normal even after 10 years. It seems probable that the limpet kills will not be high enough to cause any faunal alterations that are greater than natural fluctuations on most of the oiled shores. Periwinkles also reproduce by sexual discharge into the oceans. Other Rocky Shore Animals Acorn barnacles are a fouling organism on piers and boats, and ever since people found that they had a planktonic stage have been trying to find a safe method to discourage them from settling on suitable surfaces.