ulva make air bubble, littoral zone underwater snorkel, green algae thicket grow on coquina stone, oxygen rich low salinity

ulva rigida enteromorpha cladophora albida intestinalis aquatic biological black sea bottom coast shallow depth diving ecology environment flora grow landscape marine nature pattern rock salt ocean seascape seaweed submerged sunny travel water wildlife swim exploration space shell gravel torn muddy sand still mussel mollusc vegetation wave surface macrophyte algosociety photosynthesis oxygen synthesis selfpurification eutrophication