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Abiotic factors in reef growth

location factors
Abiotic factors limiting coral reefs in certain regions of our Earth because they limit reef growth. These factors include the temperature, lighting conditions and the salinity of the sea.

temperature
show the growth of coral reefs sites relatively consistent conditions which take place mostly in the 20 ° isotherm. Ideal growing conditions can find coral reefs in average water temperatures of 25 to 26 ° Celsius. Temperatures drop below 20 ° Celsius sinks so initially the growth rate of reef-building corals. Temperatures are dropping, but further, the corals die. At a water temperature of 15 ° C this is done after 24 hours and all the corals are dead
comes at increasing temperatures over 29 ° Celsius, the stress factor by which the corals are exposed by the so-called coral bleaching. The algae that live in the coral produces false metabolites and is repelled by her hosts. These obligate endosymbiosis between coral and its zooxanthellae is vital for the survival of the reef. Hand, the symbiont within half a year back to his hosts, the coral polyps die.

lighting
light is the limiting factor in the spread of the reef into deeper water. At depths of 70 to 90m corals can hardly grow. The light intensity is here below 10% compared to the surface. The dependence of the coral growth due to the light of the symbiotic relationship between coral and algae ago. The autotrophic zooxanthellae require sunlight for photosynthesis to win with the help of light from water and carbon dioxide, glucose and oxygen. The sugar feeds both the algae and the coral polyps.
But the light gradient in the reef is changing not only from top to bottom, but also occur within the reef due to the different growth of the corals themselves a variety of light and shadow areas. To accommodate for this light, the corals grow in different areas differently. This differentiated the reef in ecologically different areas and there are different ecological niches.
addition to the physical space, which occupies an organism, describes the ecological niche and the specific field of action of a kind, created by a system of interaction between the organism and its environment.

salinity
Ideal growing conditions are the reef-building organisms from where the average salinity in the summer of 36 per thousand in the late summer and 28-32 per thousand. In this case, higher salinities up to 45 per thousand more easily accepted as too low. This presents a problem in the rainy season and by possible discharges of fresh water by a growing number of hotels along the coastline. Although corals tolerate a short time a lower salt content up to 75% below normal, they die off after a short exposure time. Therefore, many coral reefs in no sphere of influence of fresh water such as in estuaries. prove

as limiting reef growth mainly PO4-P and NH4, which is in the oligotrophic reef even higher than in the water flowing around the reef. The concentration of PO4-P in the reef is usually only slightly higher than in the surrounding ocean. It is however close to the limiting factor for phytoplankton growth.
The NH4 concentration is usually higher than in the surrounding Ocean and the limiting of the phytoplankton concentration.
For this reason, the reefs also show very nutritious and phytoplanktonarm. The autotrophic phytoplankton as primary producers, however necessary for the food chain in any ecological system, to feed the following chain members. Energy is lost in the food pyramid, including through the metabolic reactions of living organisms. For this reason, the close endosymbiosis between coral and algae is essential for the survival of corals. The amount of the autotrophic primary production is not completely from the supply of inorganic nutrients from the coral garden, as the system is also connected to the sea water flowing around.