Sea Lettuce

Sea lettuce driven together at the bottom of Borrevejle Vig.

Sea lettuce is a relatively large green alga, whose fronds resemble those of gutweed, but have two layers of cells. It forms lettuce-like sheets that can grow up to several metres in length and breadth in still, shallow water (its normal size is however under 50cm). It gives a reliable measure of pollution, and it is much smaller now than formerly, as well as being less common in the fjord. Its decline is caused by the reduced phosphate content of the water due to the improved treatment of domestic waste water. Sea lettuce is an important element in the diet of mute swans etc, and the formerly lavish supplies have doubtless contributed to the maintenance of the large swan population in the fjord.