homepage   |    about mafia   |    history & culture   |    nature   |    kinasi   |    activities   |    excursions   |    doing nothing   |    logistics & services Home :: nature :: Corals and Fish   Corals and Fish Mafia Island Marine Park - Global biodiversity hotspot   At 822 km² the Mafia Island Marine Park (MIMP) is the largest marine protected area in the Indian Ocean. Encompassing the southern part of Mafia Island and an archipelago of several small islands and islets. The park is sandwiched between the Rufiji River Delta to the west and the open Indian Ocean to the east. The twin influences of river and sea have combined over thousands of years to create an undersea landscape of unique variety; underwater cliffs, tidal channels, coral reefs and sea-grass meadows. This allows an extraordinary variety of marine life to exist and is the basis of Mafia's exceptional biodiversity.   The underwater realm is the most diverse and spectacular, hosting an outstanding mosaic of tropical marine life. Outside Kinasi Pass, where Chole Bay empties into the Indian Ocean, vertical reef walls 15 metres high are patrolled by giant potato grouper. Smaller Malaba grouper race around on the bottom amidst a host of smaller emperors (changu), triggerfish, sweetlips and angelfish. On the surface above, bottlenose and spinner dolphins are often seen leaping through the waves. In Kinasi Pass itself, clouds of yellow and blue-striped Kasmiri snapper drift above dramatic undersea cliffs, whilst sting rays lurk in caves beneath. Barracuda and bluefin trevally cruise the main channel scouting for prey, occasionally shadowed by a giant eagle ray or a reef shark.   In many areas the underwater limestone landscape supports extensive and diverse coral communities. At Milimani reef, scores of soldiersfish shelter amidst giant pillars of Stylopora coral whilst brightly marked lion and scorpion fish drift in pairs near the bottom. A rich and colourful array of other invertebrates abounds on the reefs in Chole Bay; featherstars, bryozoans, cleaner shrimps and coral crabs. Cyanea and blue-ringed octopus hide in hollow dens, hunting by night for molluscs and small fish. Gigantic sea anemones harbour vivid orange and black anemonefish amongst their tentacles, the fish immune to the stings.   At the Marimbani sandbank, a community of seahorses thrives in the sandy hollows on the sea floor, each clinging by its tail to a strand of seaweed. The seahorses are sometimes accompanied by bizarre yellow frogfish whose pectoral fins have evolved into quasi-legs. Most colorful and surprising of all are the nudibranchs, or sea slugs, hundreds of species painted every bright color and pattern imaginable. On the outer reef slopes of Juani Island, Lobophyton and Sarcophyton soft corals render the reef a dazzling patchwork of purple, violet and indigo. Amidst the stacks of Porites corals, green and hawksbill turtles are common, feeding on seagrasses and sponges.   Above water the exquisite scenery is dominated by sparkling seas. At Kinasi Pass these are studded with dramatically sculpted limestone crags and islets covered in Euphorbia plants, proving excellent nesting sites for cormorants and egrets. Fish eagles and black kites glide overhead, while black and white reef herons stalk the vast inter-tidal flats around Jobondo Island, stabbing in the shallows for their food.   The islands inside the park also have their share of fascinating wildlife. On Chole Island the leaves of the coconut palms sway and clatter in the fresh monsoon winds, standing side by side with giant baobab trees. Nearby, huge fig trees provide roosting space for hundreds of large fruit bats, Comores flying foxes, a species found only in Mafia, Madagascar and the Comores. In Mrora forest, the dry coastal thicket harbours rare trees and plants and two species of toad and gecko that occur nowhere else in the world.   In fact Mafia is increasingly renowned internationally as a critical site for biodiversity. In all, the diversity of coral reef fauna is amongst the highest recorded in the western Indian Ocean. Over 460 species of fish and 52 genera of hard corals so far, and certainly more to be identified.   And Mafia's diversity is not restricted to the sea. Over 160 species of bird plus endemic amphibians and reptiles and a rare fruit bat also occur. Six species of plant are probably found only on Mafia and a further eight are restricted to very few other coastal forest sites in East Africa. Beyond this, Mafia's environment is one of the least contaminated in Tanzania. The habitats within the park, under protection since 1994, are amongst the most intact of their kind in East Africa.   But Mafia's environment is not only physical and biological, there are also important social and cultural dimensions. Several sites of historic ruins lie within the marine park, one at Ras Kisimani dating back to the 12th Century. Chole Island in the 15th - 19th Centuries was a major Arab town on the monsoon trade routes from Arabia to Sofala in Mozambique. The large number of people residing within or along the marine park boundary today (at least 15,000) distinguishes Mafia from terrestrial parks in Tanzania and from other marine protected areas in the western Indian Ocean. About half of the community resident within MIMP depend heavily on marine resources for their livelihood. Another 10-15% have traditionally relied on extraction of various resources from the Mlola Forest, also lying within the park boundary. The proximity of such a large number of people to such a complex, diverse and sensitive physical and biological environment calls for special management attention. Chole Bay - a Diving and snorkelling paradise   Probably the most outstanding part of Mafia Island Marine Park's marine environment is the wonderful Chole Bay. It is a vast circular bay over 50 sq km in size with a depth varying from 1 to 28 metres, and a tremendous variety of coral, fish and other marine species. An important feature of Chole Bay is that the water is continuously exchanged as fresh ocean water flushes in through Kinasi Pass every flood tide. This may one reason why the extensive coral reef areas in Chole Bay largely survived the calamitous coral bleaching that obliterated corals in most other parts of the Indian Ocean in 1998. This happened when sea temperatures in the Indian Ocean became unusually high as a consequence of the "Ėl Nino" in 1997-98.   As a result, Chole Bay's coral reefs remained largely intact and even the damaged areas are regenerating well. This is increasingly attracting SCUBA divers from other Indian Ocean locations, where corals have been badly affected.   Another crucial feature of Chole Bay is that it is shielded from both of the annual monsoon winds by surrounding islands. Most other diving destinations in the western Indian Ocean, including Zanzibar, Pemba and Kenya are exposed wither to the NE (Kaskazi) or the SE (Kusi) winds and diving is therefore seasonal. In Chole Bay, it is possible to dive throughout the year. The fact that the bay provides a sheltered marine environment throughout the year has been appreciated by local fishers for decades, and now increasingly also by SCUBA divers.   For these reasons Mafia Island, for so long a well-kept secret amongst international tourists, is gradually acquiring a reputation as a world class SCUBA diving destination. It is a chance to witness at first hand the full spectacle of Mafia's rare marine life.   FRONTIER'S diving guide to the multi user marine park, Mafia Island   This diving guide was compiled by Frontier, a U.K. based non-profit making organization, whose objectives are to implement practical projects contributing to the conservation of natural resources. For this reason, Frontier, in collaboration with Tanzania's University of D ar es Salaam, formulated A Management Strategy for Mafia's Multi User Marine Park. Since 1989, Frontier volunteers continue to prepare the necessary groundwork.   Mafia's Marine Environment   The spectacular reef systems around Mafia's waters have been moulded by climatic and geological events. Mafia is a recently formed group of delta islands whose separation from the Tanzanian mainland, dates no further than the Pleistocene Period. They have been overgrown by corals through geological time. This deposited limestone has since been exposed to a combination of a fall in sea level and rising of the East African continental plate, thus forming the land mass of the Mafia Island group.   The evidence of this can be seen by the outstanding dead coral rag which tower above the water line and are home only to some of the islands' bird population. These old coral rags are especially visible at the mouth of Chole Bay, protected by the outer fringing reef system which minimizes the impact of the Indian Ocean swell. The fringing reef systems are characterized by a shallow, back reef on the landward side. To the seaward side is a slow growing reef front. At Mafia most areas of the fringing reef are accessible to divers, depending on the weather. Diving is tide-dependent   Diving on Mafia is also determined by the pattern of tides. There are two high and tow low water tides during every 24.5 hour period. The mean tidal range is approximately 3.3m, with a maximum of 4.2m. There are many tidal currents in the area, which in certain narrow stretches of the coastline, are subjected to 180 degree reversals, most noticeable are Kinasi Pass and The Ferry Channel of Chole Bay. As a result of this diving operations should be planned on a day to day basis, especially during the months of the year when the monsoons dominate the climate.   The distribution of marine organisms is governed mainly by the prevailing sea currents, which recirculate supplies of nutrients, essential for growth and reproduction. This - combined with Mafia's geographical isolation - has produced the rich diversity of marine species. The tropical environment provides a good supply of sunlight and high temperatures, thus providing optimal conditions for the very slow growing reef forming corals. Light is essential for the growth of corals because the anemone like coral polyp lives together in symbiosis with microscopic algae or Dinoflageltes which need light for growth and regeneration.   There are tow types of coral i.e. hard and soft. The hard types build a calcareous skeleton around the polyps and the soft corals lay down internal skeletal fragments, giving them a soft, fleshy texture. However, there are many organisms that help to strengthen coral reef skeleton. The hard red coralline algae are of greatest importance. They effectively bind the reef skeleton together. Some green algae's, such as the Halimedas, help consolidate the reef by depositing coarse sediments. The death of molluscs, echinoderms and other animals with limestone skeletons also adds calcareous matter to this fragile framework.   Corals feed on suspended microscopic matter mainly zooplankton, carried in the water column. The coral polyps catch these small floating prey with their anemone like tentacles. These are armed with stinging cells, nematocysts which inject poison into the prey. Most corals extend their tentacles and feed at night when the density of zooplankton are at their highest. Changing the apparently lifeless corals into a waving mass of color, seen only by the night diver.   Corals and their skeletons provide a microhabitat for numerous organisms. Some seek shelter, food or living space. There are innumerable small organisms including bacteria, protozoan, copepods and flatworms, that move about on the surface of corals. Other large animals like mollusks; brittle stars and crabs hide in nooks and crannies, emerging periodically for food. Countless reef fish also seek shelter, especially among branched coral colonies and beneath coral heads. Many fish use the coral skeleton as a spawning and nursery site with the eggs being attached to a suitable surface.   In turn, the corals are fed upon by worms, crabs, starfishes, snails, nudibranchs and fishes that feed off living coral tissues. Fishes are by far the largest and most specialized group, browsing on polyps or the surface growing, epiphytic algae. Parrotfish trim the coral surface and digest the fine algal film that grows there. Their powdery excrement is thought to make a substantial contribution to the accumulation of coral sand. Butterfly fish and angelfish are prolific around hard corals, cropping the polyps with their delicate specialized mouths. The activities of these and other fishes are localized rather than extensive, and the coral quickly regenerates the lost tissue and continue growing. Sometimes white scars are seen on a coral surface where a mass of polyps has died. The culprit is usually the Crown of Thorn Starfish, Acanthaster which fees by inverting its stomach and digesting living coral polyps. On parts of the Great Barrier reef, Australia, due to mans influence there have been population explosions of these starfish resulting in vast areas of dead coral. But in the mafia ecosystem they are quite rare and are a vital component of healthy reefs.   More importantly, this fragile ecosystem can easily be disturbed. Fishing practices result in net damage to the corals. Illegal dynamiting, for a quick and abundant fish catch, causes irreversible damage and increased erosion of localized corals. The rubble left behind, under the influence of wave action, scours the surface of nearby lying corals and adds to their degeneration.    Sites of Special Interest   Tuties Reef Tutia Reef stands out alone in beauty and isolation, on the edge of the outer fringing reef, several kilometers south of Jibondo Island. After a tow hour boat journey often accompanied by dolphins, tourists will stumble across two half moon shaped sandbanks which mark the core to the gently sloping coral rich waters. The sandbanks are separated in part by reef rock covered in coralline and filamentous algae. Accessible by boat, the sands provide an interesting experience to science likewise to the tourist of feeling marooned on a desert island. Outstanding coral formations protruded from 20m revealing fields of mainly stag horn, branching, tabulate, foliose, massive and encrusting coral types. An outstanding feature here is the massive "mush shaped" coral bomie, towering about six metres above a canopy of tabulate corals on the seaward side of Tutia Reef.   Aside from the spectacular coral formations, over 244 fish species have been identified here. Groupers are common as are large schools of snappers, 17 types of butterfly fish, triggerfish, blue and brown surgeons. Damsels, sweetlips, wrasse and parrotfish are in abundance, among other reef fish i.e. Lionfish. Rays, and the odd white tipped shark frequent these waters, with direct access from the vast Indian Ocean. The full impact of the oceans' force has caused storm damage on the reef's seaward side, and El Nyino did cause some serious bleaching at Tutia in 1998. However, recolonisation by hard and soft corals, in addition to a variety of sponge types and algae's, is evident.   Nevertheless Tutia provides an excellent day excursion with picnic lunch.   Jina Wall Jina Wall is located south of Jina Island, as part of the outer fringing reef system, close to the mouth of Chole Bay. Composed of ancient reef limestone, the wall spectacularly plunges from 7-27m, encompassing overhangs, undercutting at it's base and caves which become more prominent as the wall stretches for about 200m in a northerly direction.   Although minimal amounts of coral are present along the face of the wall, it provides shelter to a whole host of marine life. The prevailing sea conditions around Chole Bay act as a flushing agent for nutrients and sediments, limiting corals to whip and encrusting types found on the reef top, however, compensated by a wide variety of algae's, soft corals, sponges, sea urchins and shrimps which collectively act as a filter, draining the nutrient rich waters.   The absence of hard corals minimizes butterfly fish present, but numerous anglefish and small reef fish feed off the soft corals and basket sponges. Giant clams are littered at all depths of the wall with the odd octopus retracted in a hole. Large groupers patrol the base of the wall, encountering moray eels and the odd turtle taking refuge in the many caves. Large schools of snappers, fusiliers, surgeons, unicorns and Moorish idols are common. Occasionally shoals of Jack and Barracuda are seen. Divers may be fortunate enough to see dolphins in the vicinity of Jina Wall itself.   Juani Slope Juani Slope lies south of Jina Wall, as part of the outer fringing reef system, plunging to depths of up to 30m in a southerly direction. Soft corals are predominantly present in the shallow and deeper parts of the slope. Some areas of deep gullies are characteristic on the top of the reef. At depths greater than 15m, the coral cover gradually decreased onto rubble and sand. There is evidence of a distinct change in coral cover along the reef. The greatest amount is found between 10 and 18m. In shallow water (four to six m), only few corals are limited to massive or branching. Encrusting and filamentous algaes are found covering dead coral colonies and rubble at all depths. Schools of Moorish idols, red toothed triggers (up to 70 individuals have been sighted here), threadfin and white-browed butterfly fish, unicorns and blue surgeons, Forskal's goatfish are common. Moontailed groupers, and the spectacular Clown Triggerfish are present. Dolphins, turtles, rays, and the Hammerhead shark frequent these waters.   Kinasi Wall Unlike the other three tourist dive sites already mentioned, that are situated on the outer fringing reefs, Kinasi Wall provides a more accessible dive site sheltered within the confines of Chole Bay and it can also be used as a snorkel site. Plunging to 22m, and open to a wide diversity of marine life, it provides yet another superb dive diversity of marine life, it provides yet another superb dive site. Kinasi Wall borders Kinasi Pass, the deepest channel located at the east of Chole Bay. The significance of this mean's it provides a pathway for outer reef fish and alike, in and out of the bay.   The most impressive section of Kinasi Wall is found at it's eastern end, towards, "Pemba" (Local Swahili word for corner), which marks the junction between Chole Wall and Kinasi Wall.   Fields of tabulate and foliate corals, with whip varieties are prominent at depth. Branching corals are in abundance where the wall levels off to shallower waters(ie. Four to six m). Due to the marked change in coral types at various depths along the face of the wall, various fish species are present. Schools of Moorish idols, unicorns (of up to 120 individual have been sighted here), parrotfish, blue surgeons, triggerfish, goatfish, and a wide variety of butterflyfish and angelfish are common. At the base of the wall itself, large groupers patrol. Reef sharks have been sighted here and turtles are common. [ Top of page ] banner fish on kinasi... [+]   barracuda kinasi pass [+]   lion fish on a night .. [+]   honeycomb moray on ch... [+]   damselfish, Kinasi wa... [+]   Where is Kinasi Gallery CONTACT US Prices and Special Offers Enquiries & bookings Useful Web Links SIte Map