Science knows a lot of different forms of symbiosis, but this the first time scientists have found: Corals call for help calves to protect them from those toxic algae.
Examples of symbiosis that is close co-existence and mutual adaptation of members of different species in nature abound. To mind immediately come microorganisms that live in the intestines of mammals, without which digestion would be virtually impossible, or, say, widespread in the tropics, ants and community trees. Typically, speaking of symbiotic mutualism mean, that is a win-win cooperative species, although there are other forms of cohabitation — for example, one kind of useful, but are indifferent to one. Or even harmful. In the latter case, to speak of parasitism, but it is, strictly speaking, is a form of symbiosis.
Be that as it may, science knows a lot of different manifestations of a symbiotic relationship. Yet now the group American researchers studying the ecology of coral reefs in the south-western Pacific Ocean off of Fiji, unexpectedly stumbled upon a completely new form of symbiosis. The results of this work are published in the journal Science.
In dlinnovetvistoy Acropora has a security service
Scientists have found that one of the native species of tropical coral — Acropora dlinnovetvistaya (Acropora nasuta) — got kind of personal protection that protects it from toxic green algae form "Hlorodesmis ponytail" (Chlorodesmis fastigiate). Perform the function of the guard immediately inhabit small fishes of the family Gobiidae. Let them not come growth (the length of their body is less than 4 inches), and the special valor not shine (more hiding in coral thickets and occasionally peeking shyly from there), but to cope with the task of her perfectly.
Project manager Mark Hay (Mark Hay), a biology professor at Georgia Tech and a fellow of the Center of Chemical Ecology of the Sea in Atlanta, describes this symbiosis as follows: "As soon as the algae get in contact with coral, he immediately calls for help guard and gives them an order deal with the aggressor, and immediately. "
Without steers Acropora would be doomed
Coral reef — a very complex ecosystem, and Professor Hay studies it is not the first year. Previous observations have shown that in the Pacific lives a lot of toxic algae that can cause significant damage to coral polyps. One of the most common and toxic species of green algae — Hlorodesmis pony tail, sometimes also called the turtle grass. This is sufficient to settle the algae is not even on the colony of coral, but only with her to cause discoloration, and then the death of polyps. "The algae release toxic chemicals and uses them against the coral — explains Professor Hay. — The action of toxins manifests quickly: within 2-3 days after the first contact with the turtle grass coral bleaching begins."
Corals are vulnerable against the poison, and in this situation they would be doomed if not for their calves bodyguards. "Coral synthesize certain chemicals — we do not yet know what it is, but do know that it is isolated coral — said Professor Hay. — This substance is a signal for breeding is advised that their call for help. And bulls do appear near algae aggressor almost instantly — at the latest, in fifteen minutes — and gnaw it. "
Pomatsentrovye retreat, defend gobies
With this form of symbiosis scientists still do not have to face: the representative of one type of signal through the material calls for help from members of another species, so they fought back to a competitor. The idea of the possibility of such a symbiosis prompted Professor Hay found it a fact that the colonies dlinnovetvistoy Acropora, populated by fish to suffer from toxic algae by 70-80 per cent less than the same colony without fish.
It remained only to find out which fish to help protect corals from turtle grass. The scientist said: "We shopped a variety of fish species and found that four of them are most commonly associated with this coral — two types of family goby (Gobiidae) and two of the family pomatsentrovyh (Pomacentridae). Pomatsentrovye live near, and gobies — inside coral colony. We conducted an extensive series of experiments and found that when exposed to the invasion of the colony of poisonous algae, the pomatsentrovye just looking for a different shelter, and gobies immediately start nibbling algae so that between it and the coral was no contact. "
With each passing day, this protective mechanism becomes more and more important for corals: not only that the resulting greenhouse effect warming of the oceans for them a lot of stress, so it is also contributes to the widening of the algae, and natural enemies of algae — fish — is becoming less of- for overfishing.
To save the reefs, to understand how they function
But hardly moves gobies generosity, they clearly have an interest. "Both protect your home — says Professor Hay — a place where they spend their whole life. This their environment, and it gives them food and protection. DEFENSE corals from algae, gobies thus defending his home."
But that's not all: as it turned out, two species of gobies bodyguards behave differently. The scientist explains: "One view is really eats algae, resulting in a special poisonous mucus released by these bulls for protection from predators, it is twice more toxic than usual. So behaving" golubopyatnisty gobiodon "(Gobiodon histrio). Second type — it is called "volosogolovy red bull" (Paragobiodon echinocephalus) — just gnaws algae, biting her, but do not swallow and spit out. Indeed he is not poisonous, and he algal toxins to anything. "
Today, environmentalists around the world pretty concerned about the fate of coral reefs. According to some estimates, by the end of this century, many of them may cease to exist. "In my lab, we are trying to understand how a coral reef, to understand the language in which it expresses itself inhabitants. Only by understanding the language of chemical signals in all its complexity, we can save the reefs. And now we have found a phenomenon of which had not even suspected. phenomenon for the conservation of coral. "