stranded green seaweeds overgrowth on brittany coast

aground alga algae armoricana beach brittany coast covered density dry drying edible finistere france green hydrogen image invasive july landscape lettuce low methane much natural nature nitrates north ocean overgrowth photography picking pollution problem proliferation putrefaction rocks sand season seaweed seaweeds spring stranded sulphide summer tide too toxic tregor ulva waves wild