Lokrum is directly exposed to sea currents from the south and the Strait of Otranto, which influences the distribution of benthos organisms and planktons. A glimpse of this sea life can be seen in PORTOČ BAY.
The organisms living on cliff shores exposed to sea water spray must contend with constant changes in salt concentration and temperature and with the force of waves. Only rare organisms have adapted to such extreme conditions and vegetation is also very sparse.
Plants adapted to waters of high salinity are called halophytes: for example, Limonium anfractum, an endemic species which grows only in the south-east of the eastern Adriatic littoral, capers (Capparis spinosa), spiny rush (Juncus acutus), seaside rush (J. maritimus) and sea fennel (Chritmum maritimum).
In the intertidal zone, due to more favorable conditions, the biodiversity is higher than in the area exposed to sea water splash. These two areas are easily differentiated by color: cliffs in the intertidal zone are overgrown with various species of microscopic algae, which gives them a darker color than the rocks exposed to heavy wave action. Animals which live here have adapted to the changes in the conditions of the habitat.
The small periwinkles (Littorina neritoides) live in groups on rocky shores where they feed on algae. They are resistant to desiccation and can live several days out of the sea.
The chequered top shell (Monodonta turbinata) is a species of a sea snail which is not very resistant to desiccation and retreats to shade during high sun. It lives alone or in groups, and feeds on algae.
Sea slaters (Ligia italica) are very mobile small crustaceans which inhabit the narrow coastal area in large quantities.
Barnacles (Chthamalus spp.) are very resistant to desiccation and high temperatures. They live in cone-like houses secured to the rock’s surface, made of calcium-hard plates which form an opening they can close. As the tide comes in, a muscle opens up these plates, and the feathery legs of the barnacle sift the water for food.
The common European limpet (Patella sp.), beadlet anemone (Actinia equina) and mussels (Mytilus galloprovincialis) also live by the shoreline.
Organisms living in the benthic zone, the ecological region at the lowest level of a body of water, are called benthos. Benthos species are all species which almost never leave the seabed bed, and crawl, walk or swim very close to the seabed.
Some of the most famous sea organisms such as the rock sea urchin (Paracentrotus lividus) or the Mediterranean red sea star (Echinaster sepositus) can already be found in shallow waters.
The mermaid’s wine glass (Acetabularia acetabulum) is green algae similar to mushrooms which with time absorbs enough calcium carbonate to turn completely white.
The Neptune grass (Posidonia oceanica) inhabits the sandy and muddy sediment and is one of the three species of flowering plants that have colonized the sea. In dense, up to 80 cm high, meadows lives a multitude of diverse organisms: numerous plants and animals find shelter and food here.
The damselfish (Chromis chromis) is a common fish in the sea around Lokrumm which swims in shoals in open waters and above the very sea bed, and feeds on zooplankton and benthic organisms. In the summer months and during the reproduction cycle, the males select and prepare the space where the female will lay the eggs, which the males will then guard. In the later summer months, one can spot small fluorescent blue damselfish near the seabed.
Besides fish, perhaps a gleam of pearls could be spied…
TALE OF IMPERIAL PEARLS
After Maximilian, the island was visited by other Habsburgs. A woman with large black eyes and gorgeous long hair, the Bavarian duchess and Austrian empress Elisabeth came to the island once. She wandered under the Lokrum pines, listened to the murmur of oaks, cast her wondering gaze over the crystal clear sea and attributed something special and unusual to the islet’s beauty.
Her pearls were plagued by age. Pearls, the children of sea, were bound, she thought, to rejuvenate in their ancestral home. The Empress lowered them into a shoe and left for her travels with the intention to come back when the sea returns her pearls their youth. But a dagger stopped her journey. The pearls remained in the shoe, watched over by the island. It hides the shoe with the sun’s brilliance and the forest’s shade, and in the night covers it with darkness to protect it from the silver moonlight. When the uninvited approach, even without any intentions, the shoe, the sea becomes uneasy and its foam protects the pearls.