top of page
Malta Rocky Beaches
Littoral Zones
1/1
 |  |  |
|---|---|---|
 |  |  |
Coastal area is divided into zones depending on environmental condition such as light, salinity, wetness etc.
The terrestrial part is called the adlittoral region. This is followed by four other zones: supralittoral, mediolittoral, infralittoral, circalittoral.
The supralittoral zone, also known as the ‘splash zone’ is the area which is never completely submerged in water, but which is regularly splashed especially when the tide is high or in Malta, when a storm takes place.
Organisms living in this area should be adapted to deal with periods of exposure and immersion, and other abiotic factors such as heat. They must also cope with predation by both aquatic and terrestrial organisms.
The Supralittoral Zone
The Mediolittoral Zone
|  |  |
|---|---|---|
 |
This zone is characterised by frequent immersion but not continuous submersion in seawater. It may extent from 10 to 150cm, sometimes but very rarely up to 200cm. Vertical zonation can be observed in this zone as organisms colonize distinct horizontal bands, allowing further distinction between upper, middle and lower mediolittoral.
Upper Mediolittoral Zone Organisms:
These organisms must have a greater tolerance to desiccation as this area is exposed for a longer duration than the other zones of the mediolittoral. In this area, organisms are continuously facing a different environment, from marine to terrestrial, and vice versa.
As a result organisms have to deal with heat stress, desiccation and change in oxygen levels. These organisms therefore become adapted to these changing environments due to fluctuations in water level.
Examples:
-
Mobile organisms move to deeper water when sea level is low to avoid desiccation or heat stress
-
Some sessile animals become active only when covered with water
-
Structural adaptations, such as limpet shell shape to protect the organism from wave shock
This area is characterized by barnacles, such as the Star Barnacle, microscopic blue-green algae, limpets and chitons.
Mid-Mediolittoral Zone Organisms:
Macroalgae are noted in the mid-mediolittoral zone, examples of which include Palisada tenerrima and Polysiphonia sertularoides(refer to Catalogue of algae for a comprehensive list).
Lower Mediolittoral Zone Organisms:
The lower mediolittoral is generally rich in snail species such as Dendropoma petreaum and Vermetus triqueter. With regards to alga, Ulva sp. dominate polluted waters.
The border between the lower mediolittoral and infralittoral is usually characterised by a band of Cystoseira species.
The Infralittoral Zone
|  |  |
|---|---|---|
 |
This area is very rarely completely exposed. This area is inhabited by species of the genera Cystoseira and Dictyopteris. These algal beds, provide a variety of microhabitats supporting many fish amongst other fauna. Refer to catalogue ‘Fish’ for overview of species present in this area.
The Circalittoral Zone
This zone reaches from the end of the infralittoral zone down to the zone where photosynthesis can take place. Species present in this zone include encrusting algae, tubeworms, sponges and corals.
Summary
bottom of page