Why do coral reefs affect habitats


Coral reefs: 500 million years successful,

critically endangered today!



Fascinating home builders

Hard corals form a massive limestone skeleton and are therefore excellent underwater house and town builders in the animal kingdom. Other organisms support the corals in underwater urban development and in building maintenance: Red calcareous algae are responsible for the lime plaster, microbes cement inaccessible wall gaps with rock-hard cement. The coral buildings have many floors and are inhabited by an enormous number of animals and plants, such as fish, mussels, snails, sea urchins, soft corals, sea anemones and algae.


Fascinating and, for us, super-modern is how this city is effectively self-sufficient and keeping itself alive. Many professions are necessary for this: Algae, which live in community with the corals, form solar power plants and provide the necessary energy for the corals to grow. The waste materials from the corals, but also from other reef inhabitants, are immediately recycled by the algae. Soft algae particularly like to grow on the reef buildings, but have to be mowed regularly by grazing reef fish, snails and sea urchins so that they do not overgrow everything else. The water is constantly filtered by sponges and thus kept clean. Hermit crabs and sea cucumbers are part of the garbage disposal brigade.


There is even a dentist in the reef: cleaner fish and cleaner shrimp have opened their practice at certain points in the reef. Large reef fish come there to have parasites and food debris removed from their teeth. But there are also some black sheep in the dental profession: some slimy fish look like cleaner fish and are therefore also sought out by dental patients. Slime fish then bite wounds in the glued patient at lightning speed and disappear again as quickly as possible.


All reef fish are so enthusiastic about the reef habitat that they have to share apartments and work in shifts. During the day, nocturnal fish sleep in the thousands of small and large reef caves, at night they pursue their food acquisition and leave their little rooms to the diurnal shift to rest. The surrounding area also benefits from the underwater city of reef: predatory fish such as sharks and barracudas come from the open sea and the lagoons to feed on the reef.


A fascinating underwater world that many city planners can learn from! By the way, there were also real Swabian underwater house builders: 150 million years ago stone sponges, hard corals and microbes formed reefs that are now on dry land and leave behind impressive rock formations in the Swabian Alb, such as in the upper Danube valley. There are also many other fossil reefs in Germany, Austria and Switzerland.



Coral reefs are extremely important to humanity

It is estimated that coral reefs are home to up to a million animal and plant species. Together with the tropical rainforests, they form the most biodiverse ecosystems on earth. Humans benefit from these reefs in incredibly diverse ways, without most of us being aware of it:

  • Reefs represent an immensely important coastal protection, without which many tropical islands and coasts would be quickly eroded.

  • The proverbial abundance of fish in the reefs is the livelihood of millions of people, especially in developing countries.

  • Millions of people also live from tourism in tropical and subtropical countries. If the reefs break down, many palm-tree beaches and with them the tourists will disappear, a catastrophic development for many developing countries. But also in Germany tour operators and sports equipment suppliers earn millions with tourism to tropical and subtropical regions.

  • Like rainforests, reef organisms have an immense, still largely unexplored potential for the discovery and extraction of medicinal substances. Valuable antibiotics, cardiovascular substances, but also active ingredients for the treatment of cancer and AIDS have already been found. In addition, coral skeletons are increasingly being used as compatible bone substitutes.

  • Reefs record the climate history of our earth, which can be deciphered with the help of the chemistry of the coral skeleton up to years. This makes them an important climate monitor that helps us to better predict our future climate. In addition, because of their chemical balancing effect, reefs are an important link in our earth's climate processes.



The endangerment of the reefs by humans: Nobody sees it under water!


The immense importance of the reefs for humans would be reason enough to handle our reefs with care. Although coral reefs have been around for 500 million years (and simpler types of reefs for 3 billion years!), Reefs are seriously threatened. The beautiful coral reef calendar pictures or illustrated books hide the threatening condition of our reefs. According to serious estimates, 10% of all reefs have already been irredeemably lost, and another 30-60% of all reefs will not survive for the next 20 years if nothing fundamental changes in the man-made environmental destruction.


The main dangers to our reefs lie here:

Coastal colonization and so-called cultivation lead to enormous input of mud and silt particles into the oceans and endanger the reefs that cannot tolerate this. Not all of this even has to happen directly on the coast. Rainforest deforestation leads to increased washing of the soil. The soil material then reaches the reef regions in rivers. Wastewater leads to overfertilization of the reefs. Soft algae then overgrow everything and the reefs die off. In many countries reefs are being used as quarries and are being completely dismantled.

Harmful fishing methods such as dynamite and hydrogen cyanide fishing, but also general overfishing, destroy the reefs. If the fish are missing, an important part of the lawnmower workers will also be missing and soft algae will in turn overgrow the reefs.

Non-environmentally friendly tourism also poses a great danger: feeding fish upset the delicate equilibrium in the reef, throwing anchors destroys large reef areas, touching and breaking off corals under water is damaging, buying souvenirs promotes the exploitation of reef organisms, hotel complexes can also be damaged by sewage and brine discharge from desalination plants Kill large areas of reefs. Perhaps the greatest danger, however, arises from the man-made greenhouse effect, which causes the corals to undergo temperature stress and ultimately to die.


Ways out of the dilemma

The establishment of reef parks and environmentally friendly tourism represent an opportunity not only for the reefs, but also for the reef neighbors who are depriving themselves of their livelihood through overfishing and the extraction of reef souvenirs. Coastal development and cultivation can also be carried out in an environmentally friendly manner. Environmental organizations, politicians, and especially alternative local projects with the involvement of the local population are called for here. But everyone can also contribute a lot to reef protection:

When vacationing in reef regions (e.g. Red Sea, Caribbean, Maldives, South Pacific) you should avoid excessive water and energy consumption, do not buy any marine animals as souvenirs, only go on well-guided diving and snorkeling trips, where only anchor buoys are used and no harmful motor water sports Companies. You can also get hotel managers and tour operators to take protective measures by making it clear that damaged reefs are of no interest to you.

At home, for the sake of the reefs, you should reduce your energy consumption and the amount of waste you produce (waste from industrialized countries is sometimes transported to reef regions; energy consumption increases the reef-damaging greenhouse effect). You can also support alternative food producers with organic cultivation and breeding methods.

It also depends on you whether the reefs continue to stand a chance. If we let the reefs live, mankind also has a greater chance of survival!

Prof. Dr. R. Leinfelder

(Text created on the occasion of a lecture for the Friends of Nature Leonberg-Eltingen).

please note our copyright explanations

The International Year of the Reef (IYOR) 1997 is a worldwide initiative of reef scientists supported by UNESCO and the WorldWideFund for Nature (wwf) and aims in particular to make the importance and endangerment of coral reefs clear to a broader public.

The International Year of the Reef is supported by a large number of institutions (universities, schools, museums, zoological gardens, diving organizations, environmental associations, media) and financially supported by many organizations and companies.

Further information on reefs and the year of the reef: The website for the year of the reef:


(with IYOR information and activity calendar for all of Germany)

or at

IYOR Germany c / o Prof. Leinfelder

formerly Stuttgart, since October 1998:
University Institute and State Collection for Paleontology and Historical Geology, Richard-Wagner-Str. 10, 80333 Munich

e-mail: [email protected] Fax: 0711-1211341


IYOR Committee Germany:

Coordination group:

  • Prof. Dr. Reinhold Leinfelder, formerly Institute for Geology and Paleontology, University of Stuttgart, now Munich (see above)
  • PD Dr. Franz Brümmer, Institute for Biology, University of Stuttgart
  • Dipl.-Biol. Moshira Hassan, GEOMAR Kiel
  • Dipl.-Geol. Gert Wörheide, Institute and Museum for Geology and Paleontology, University of Göttingen

Board of Trustees:

  • Prof. Dr. Erik Flügel, Institute for Paleontology, University of Erlangen-Nuremberg
  • Prof. Dr. Helmut Schuhmacher, Institute for Ecology, University of GH Essen
  • Director Prof. Dr. Fritz Steininger, Research Institute and Nature Museum Senckenberg, Frankfurt / M.
  • Dr. Friedrich Naglschmid, President of the Association of German Sports Divers e.V.