Many people don’t like the look of dried up seaweed / seagrass, known locally as Posidonia, which is often found on the Virgin beaches and sometimes it has an unpleasant odour. This is a natural occurrence and helps to protect coastal erosion. During the winter months the beaches are all left to nature and before the season the larger Resort beaches are cleaned ready for the tourists.
If you visit a Virgin beach and it has a covering of Posidonia here is a short explanation that will help to understand the importance of it and why it isn’t removed:

Menorca is recognised for its crystal clear waters and beautiful beaches. However, over the years the combination of excess fishing, anchorages in important areas of our marine ecosystems, mass tourism, amount of waste ending up in the ocean, etc. have damaged Menorca’s natural marine environment, with a recent study showing a population decline of up to 80% in a number of fish species. In addition, excess anchoring on Posidonia sea-beds has also damaged the natural ecosystems supported by these plants.
The Posidonia meadows play a major role in sedimentary dynamics, they are important oxygen production and carbon sink areas, and they are where many species reproduce and seek refuge. They also act as large filters which help clean and maintain the transparency of the seawater.
For more information about Menorca and the environment visit: www.biosferamenorca.org