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BIOLOGY

Cleaning up the bottom of the sea

Team from Unicamp reveals the way of life of the cleaner-fish

RODRIGO MOURAA moment of truce: Batistes vetula abdicates its predator role while the French angelfish (Pomacanthus paru) cleans itRODRIGO MOURA

With the brightness of its contrasting colors – usually, combinations of black and yellow or blue and white -, the cleaner-fish parade through the coral reefs where they live, exposing themselves to bigger fish, their customers, and cleaning up their bodies. The job includes the removal of parasite crustaceans, and of tissue with necrosis, disease or mucus, a secretion that is present all over the surface of a fish. While the work is being carried out, slight touches of the fins of the cleaner give the customer a tactile stimulus, which remains in an unusual position, as if in a trance. A golden rule: nobody is attacked in the clean-up region. Outside this scenario, though, the customer can transform itself into a predator.

Little is known about this symbiotic cleaning in the reefs off the Brazilian coast, but a wide ranging and organized view of this phenomenon is arriving, in a work coordinated by Ivan Sazima, of the State University of Campinas (Unicamp). Made up of Rodrigo Moura, Cristina Sazima, Ronaldo Francini-Filho and João Gasparini, his team studied the theme in loco, all the way from the Maranhão state coast to the state of Santa Catarina, with the purpose of assessing the importance of the cleaners for the health of the reefs and of suggesting some regulation of the fishing of ornamental fish – since the cleaner-fish are frequently seen in shops selling aquarium fish, as is the case of the barber goby (Elacatinus figaro). “The absence of cleaners leaves the reefs poorer and increases the population of sick fish”, Sazima explains.

Old acquaintances
The cleaners attend to reef fish of various sizes, from the butterfly fish (of the Chaetodon genus), 7 to 13 centimeters long when adult, up to the manta ray (Manta), with its wingspan of between 1 and 7 meters. This is one of the basic interactions of the communities that live in the reefs, where the more specialized cleaners set up cleaning stations at specific places, and the customers even open their gills and mouth for the job to be done well. There are indications that the customers learn the way to the station and commit it to memory, no matter how much they move around in the environment. “It is believed that the cleaner and its customers even recognize each other individually”, says Cristina, Ivan Sazimas daughter.

The cleaning ceremony has its rituals: big fish stop, often lie on their sides, or remain slanted, with the head pointing up or down. They may even change color to attract the cleaners. The sessions last from a few seconds to 15 minutes, as in the case of the cleaning of a grouper. The daily movement of customers at the stations varies according to the region: each cleaner attends to about one hundred customers a day on the southeastern coast, close to 500 in the sea off  Bahia, and up to a thousand in Fernando de Noronha. The same customer may resort to the cleaning station more than once a day.

The smaller cleaners do not occupy more than 1 square meter in the space of their community, and they sleep in the cracks in the rocks and reefs. The larger ones cover no more than 5 square meters. Leaving the place is dangerous. “They keep themselves protected by virtue of the cleaning, as the station is identified by the predators”, says Cristina. “Moving away from the station, the cleaner of a grouper may be eaten by it, since it no longer respects it or identifies it in its function”.

Small and colorful
The cleaners are between 2 and 12 centimeters longs and have contrasting colors, which serves as a sign for the customers. “The strong visual effect, against the background of coral or rock, works for the cleaner to stand out in its environment, because fish are able to see colors”, Ivan Sazima explains. “Their diet is based on mucus and tiny ectoparasite crustaceans”.

There are more than a hundred species of cleaner fish, habitual or occasional, in other seas: 30 species in the Pacific, 12 in the Mediterranean, and 20 from Central America and the Caribbean. With time, the studies reached the seas of Australia and Hawaii. Today, Labroides dimidiatus, a wrasse from the Indo-Pacific ocean, is the most studied cleaner, and has given rise to the major part of knowledge on the theme.

Sazima hoped to find from ten to 12 species off the Brazilian coast, but his forecast was exceeded: he recorded 25 species of cleaners, eight of which have their yellow and black colors in common. “They are about 10% of known reef fish, of which some 250 to 300 species are known”, says Sazima. “It is a surprising proportion”. The team from Unicamp described two new species, the barber goby, Elacatinus figaro, and the Brazilian basslet or Brazilian Gramma, Gramma brasiliensis. The unexpected diversity restricted the study, which only went into depth into four species: the French angelfish (Pomacanthus paru), the Noronha wrasse (Thalassoma noronhanum, the barber goby (Elacatinus figaro) and the goby (Elacatinus randalli).

The smallest of the cleaners off our coast is the barber goby, some 4 centimeters in length, which carries out its job for the whole of its life. Then the French angelfish (Pomacanthus paru) – which lives off the most part of the coastline, the continental islands and some oceanic islands, measures between 20 and 60 millimeters – is only a cleaner when young. Afterwards, it abandons the cleaning business and feeds off sponges and algae. After the studies carried out by the group, its cleaning business was valued. “The French angelfish can be compared with the barber goby, one of the most specialized cleaners”, says Ivan Sazima.

The cleaning activities of the Brazilian wrasse, found both off the coast and in spots in the ocean, is to be found in the middle: it is a cleaner in its young and adult phases, when it measures from 20 to 50 millimeters in length. What really distinguishes this species from the other cleaners is its workplace: the wrasse sets up cleaning stations in the water column – so above the marine substrate of rocks and colonies of coral where the others operate – and forms large circular groupings that can have as many as 450 individuals.

To observe all this, the researchers worked on the basis of free diving, with a cylinder of compressed air. Over five years, made hundreds of dives to a depth of between 3 and 18 meters, lasting an average of an hour and a half. That was how they covered the reef environments of Parcel Manoel Luís (MA) and of the Fernando de Noronha (PE) Archipelago, the coastal reefs of Tamandaré (PE), the Abrolhos (BA) Archipelago, Escalvada Island and the Três Ilhas (ES) Archipelago, Papagaio Island and other offshore islands in Cabo Frio (RJ), Anchieta Island, Vitória Island and Laje de Santos (SP) and Arvoredo (SC) Island.

Ivan Sazima intends to continue to study the symbiosis of cleaning, which is practically limited to the oceans – in fresh water, the phenomenon is little known, although it is known that, in Africa, there are fish that clean hippopotamuses. The next focus for the group will be opportunistic fish that follow rays and other carnivorous fish that stir up the bottom of the sea. Sazima knows that his work is urgent: the trade in the colorful ornamental marine fish and shrimps – in the seas, shrimps are also cleaners of fish – is seriously altering the equilibrium of the Brazilian reefs.

The Project
Cleaner Fish of the Western South Atlantic: Natural History, Distribution and Systems
Modality
Regular research project – benefit line
Coordinator
Ivan Sazima – Unicamp
Investment
R$ 74.824,85

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