Biodiversity of the Gamba Complex
Vegetation | Arthropods | Fish | Amphibians | Reptiles | Birds | Mammals | Vembo Lab
GabonGIS
Gabon GIS is a project of the Smithsonian Institution's Monitoring and Assessment of Biodiversity Program (MAB). This site is the first step in an effort to share the results of MAB's research on the complex relationship between human settlements, oil production, and biodiversity in the Gamba Complex of protected areas on the southwest coast of Gabon. 
GabonGIS
The Gamba Complex of Protected Areas is an 11,320 km2 wildland mosaic of primary and secondary tropical rainforest set on hillock and swamp, patched with prairie and woodlot, and lined with rivers and lagoons that exit the coast through a long, deserted beach. Historically, divided into five hunting grounds and three reserves, the land was partly re-zoned in September 2002, when President El Hadj Omar Bongo established Gabon 's national park system. Two of the country's 13 parks are carved from the Complex—1,550 km2 Loango National Park, covering coast, lagoon, grassland, and sedimentary forests in the west, and 4,500 km2 Moukalaba-Doudou National Park, encompassing the low-strung Doudou Mountain range and coastal basin to the east. The middle corridor—with extensive upland forest and oil concessions—remains under a lesser degree of environmental protection.
Some 9,000 people live in the complex, with 7,000 concentrated around the oil industry in Gamba and 2,000 in villages and subsistence outposts. It is a remote existence: one sand track hooks Gamba to national roads, rendering most travel by air and supplies by water. Onshore oil fields pioneered by foreign companies are active but declining after 40 years, creating economic uncertainty at community-to-national levels. Where accessible, the land has been selectively logged since early days for okoumé plywood; overgrown timber roads cross the complex. Like so many places on Earth, it is harvested land.
Yet, in the same stands, forest elephants weave through towering tree columns, and ape nests are strewn atop paths of red river hog, sitatunga, and brush-tailed porcupine. Packs of Nile and slender-snouted crocodiles, hangs of guenon and mangabey monkeys, and roves of hornbills and parrots circulate freely. Amphibian richness—75 species—sets the complex above any place nationwide. The most productive oil field in the country, Rabi, also pumps the longest list of reptiles for any locality in Gabon: 65. Along the beach at least four species of sea turtle come to nest, including the world's largest and one of the most endangered, the leatherback. Aquatic systems—fresh, brackish, and marine—are recognized for whale and dolphin migrations, biogeographically important watersheds, and record catches. In Gamba, impressive collections of wildlife coexist with human influences, definitely touched by human presence, yet unusually preserved.
The Gamba landscapes, like many in Gabon, are writ with human history, but remain remarkably intact, wild, and free of many of the usual marks of time and development, entrusting a real opportunity and responsibility for their care to the world. Few other places on Earth have as much rawness and character to claim—or to lose. Valuing this wilderness and ensuring its longevity through local stewardship, wise management and scientific study means that conservation must be a way of life. For without these last brave tracts—places of barking gorillas and elusive terrapins, where colonies of Rosy Bee-eaters swarm en masse over the backs of elephants—goes much of our remaining natural heritage, knowledge, refuge, and assets.
Upland dry forest, lowland wet forest, secondary and primary forest, savanna, coastal scrub, mangroves: biodiversity includes the variety of habitat types across a landscape. Even seemingly solid-cover rainforest like that in the Gamba Complex has distinctions—thick and thin, slopes and valleys, wet and dry areas. The Complex's wide range of habitat types and plant communities provides a structure and food base for all levels of wildlife, from fruit-eating birds to the leopards that stalk them. Such high habitat diversity leads to a varied resource base for different animals, strongly influencing wildlife populations.
Vegetation research in the Complex centers on 75 study plots established in different habitat types. Through inventories, botanists are constructing a baseline for vegetation monitoring over time to better understand vegetative community structure and composition and to address impacts on the forest. So far, botanists have examined nearly 7,000 trees and described 11 habitats represented by 353 species.
In the Rabi region, canopy height reaches 40 meters and lianas are abundant, indicating a mature and dynamic forest in process of continual change. Forests in Loango National Park along the coast are much less diverse than inland forests, but exhibit a variety of habitats. Highlands in the Monts Doudou range are known for species unique to Gabon.
As oil fields begin to play out, there is concern that pressure for unsustainable logging will increase, along with clearing of forest for agriculture. Forest fragmentation caused by roads and other developments also pose threats to intact, mature rainforest. Minimizing the effects of such forest conversion on the structure and composition of vegetation communities will, in turn, help conserve the complex's wildlife.
Given that more than half of all species known on Earth—nearly 1 million of the 1.75 million—are insects, it is not surprising that insects comprise the bulk of species recorded at the Gamba Complex: to date, more than 1,000. From ants, grasshoppers, beetles, spiders, and scorpions to moths, wasps, bees, and many more, the Complex contains a wide variety of arthropods, and specifically insects, that act as decomposers of detritus, soil builders, pollinators, populations control agents, and prey for birds, reptiles, amphibians, fishes, mammals, and even other insects.
A study focused on insect diversity in four major habitat types around Gamba. Researchers determined differences in insect diversity in areas of human influence, created a baseline of insect data for all seasons at a variety of sites, trained insect parataxonomists, and initiated arthropod reference collections. The team examined more than 440,000 insects, many of them now professionally prepared as specimens in a reference collection to serve Gabon and the scientific community.
Local towns and villages depend on fish as an important source of protein and livelihood in Gabon, making it all the more important to complete inventories and conduct baseline studies of aquatic systems—swamps, lagoons, streams, and rivers.
The Rabi oil field lies in the headwater streambed of the Rabi River, and habitat modification—permanently inundated swamps and ditches created by the construction of roads and oil platforms—is the greatest industry effect on aquatic systems. The Rabi oil field yielded a surprising number of fish species—69 in all, compared to an expected 40 to 50 based on similar studies elsewhere. Three marine species were recorded, despite the 40-kilometer distance from saltwater environments. Seven species of electric fish of the family Mormyridae, which frequent good-quality waters and produce unique, weak electric signals to orient and communicate, were recorded at Rabi, three of them new to science. The rare carnivorous leaffish Polycentropsis abbreviate was discovered in the calm waters of a swampy forest zone where, camouflaged as a leaf, it stalks its prey.
The Gamba area, including the Ndogo Lagoon, rivulets, seasonal lagoons, and swamps, produced 84 fish species. The inner edge of the lagoon, completely freshwater, held mixed groups of fresh and saltwater fish; its mouth ran with mostly marine species. Unlike Rabi, oil production sites in the Gamba area showed signs of pollution and negatively impacted fish communities—reason to monitor water communities and their health.
Amphibian life in the Gamba Complex is richly diverse—75 species recorded to date, an impressive number when the total for the whole country was just 72 prior to the Smithsonian Institution studies. Only one other comparable region in Africa has more: Korup National Park in Cameroon, where 90 species of amphibians have been documented or are believed to occur.
Amphibians rely on often-fragile watery habitats and can be sensitive to water and air quality, thus serving as indicators of change in both aquatic and terrestrial environments. Frog populations around the world are declining, and monitoring of amphibians over time in the Gamba Complex is therefore important to help determine natural or human-caused alterations in ecosystems.
Two of the amphibians found are caecilians, legless creatures resembling worms; the rest are frogs, some of which are likely new to science with confirmative identification underway. Of special taxonomic and biogeographic significance, Moukalaba-Doudou National Park yielded the highest number of amphibians—69—for any studied area in Gabon, 21 of them unique to the park. Second highest for the country was Rabi, where 49 amphibian species were documented.
Reptiles—snakes, lizards, turtles, crocodiles—act as predators and prey both locally and across wide ranges; sea turtles for example, may migrate between hemispheres.
The Gamba Complex's mix of forest, savanna, fresh water, and marine environments encourages a diversity of reptiles: 84 species recorded to date, including 11 turtle species, 3 crocodiles, 2 amphisbaenians, 22 lizards, and 46 snakes—the longest list for any site studied in Gabon. Of the 84 species recorded in the complex, 56 species have been documented in the two national parks.
Many reptiles in Gabon, including the three African crocodile species and leatherback turtle, are at risk across all or parts of their historic global ranges. Thus it is important to learn about them and their habitats in the complex and to devise conservation strategies such as species protection laws, better control of logging and deforestation, community awareness, and additional studies on their biology and ecological requirements. Although the forest herpetofauna of Gabon is very rich, it is also one of the least known and potentially one of the most endangered over the long term.
The green-backed heron (Butorides striatus), sooty boubou (Laniarius leucorhynchus), great blue turaco (Corythaeola cristata), African fish eagle (Haliaeetus vocifer)—so begins a list of the 455 different birds recorded from the Gamba Complex, 67 percent of Gabon's known total. Birds are the most diverse and best-known group of terrestrial vertebrates and can play key ecological roles as consumers of fruits, plants, insects, amphibians, reptiles, and mammals. As frugivores, they disperse seeds; as nectivores, they pollinate; as insectivores, they control insect populations. Some birds, like the Olive Sunbird (Nectarinia olivacea), play dual roles as nectivore-insectivore. In turn, birds are prey for numerous carnivores. Because of these critical ecological roles, disappearance of certain bird species may affect the ecological health of the rest of the biological community in a given area.
Taken as a whole, bird communities in the Gamba Complex seem little affected by resource development to date. Deforestation, including logging, is the primary habitat disturbance; road building, habitat fragmentation, and hunting are secondary but important. Controlling these impacts and promoting education about birds through ecotourism and other means are positive steps for bird conservation in the Complex.
Shrews, dormice, rats, and bats are important consumers of fruits and insects, distributors of seeds, and prey for other species. A healthy number of shrew and rodent species—24 in total—was documented in the Gamba Complex, matching or exceeding the number in other habitats of northeastern Gabon and at research sites in Equatorial Guinea, Central African Republic, and Nigeria. Bats were studied only at Rabi, where 15 species were recorded.
The ten insectivore species found include the giant otter shrew (Potamogale velox), an aquatic species that inhabits forest streams, and the golden mole (Chlorotalpa leucorhina), a subterranean animal adapted for burrowing. The agile climbing African dormouse (Graphiurus murinus ) was the sole rodent species recorded that is not in the Muridae family, the largest of all rodent families worldwide. The Muridae are typically frugivorous or omnivorous (the
rat Deomys ferrugineus was the only insectivorous rodent found) and terrestrial, although the arboreal Grammomys rutilans and three species of climbing Hylomyscus were recorded. Several genera of rodents (Lophuromys, Hybomys, Deomys, and Grammomys) were found only at inland locations, while others (Stochomys and Mus) were only found in secondary growth around oil facilities and other developments at Rabi. The giant pouched rat (Cricetomys emini) was the largest rodent documented, weighing one kilogram.
Large animals such as elephants and buffalos play key roles in the structure and composition of vegetation, plant productivity, and nutrient cycling. Carnivores may regulate populations of other species. These important functions suffer when populations of large mammals decline, and many mammals found in the Gamba Complex—because they are valued for meat, skins, and ivory across their broader ranges, or more importantly because of habitat decline—are imperiled.
Forty-two different medium and large mammals have been recorded in the Gamba Complex. The list includes the western lowland gorilla (Gorilla gorilla gorilla) and chimpanzee (Pan troglodytes); the African forest elephant (Loxodonta africana cyclotis) and African forest buffalo (Syncerus caffer nana); the common hippopotamus (Hippopotamus amphibius), leopard (Panthera pardus pardus), and side-striped jackal (Canis adustus); and eight species of monkey.
Past studies in the complex focused on elephants, buffalos, and great apes. Current research strives to expand the list of mammals, determine their distribution and relative abundance, and assess the impact of roads, industry, and rural communities on mammals.
In 2001 the Vembo Laboratory was established, and it is know locally as Labo Vembo. The goal of the laboratory has been to support on-going Smithsonian activities related to research, education, outreach and upcoming monitoring activities that will promote the conservation of biodiversity in the Gamba Complex. Labo Vembo has quickly grown into a world-class laboratory housing one of the most comprehensive biodiversity reference collections in Gabon. It serves as a training center for local researchers and provides outreach and education opportunities for the Gamba community, other national and international visitors, and is the headquarters for the operation of the Smithsonian activities in the Gamba Complex. Labo Vembo has hosted many school tours, trainings, VIP stakeholders, biodiversity exhibitions and assemblies of various government and NGO bodies working together for conservation of the Complex. Labo Vembo served as a focal point for a series of baseline studies documenting species and habitat richness of mammals, birds, vegetation, amphibians, reptiles, fish and insects in protected and non-protected areas throughout the complex. This information is being used for the ongoing best practice studies on the impact of industrial activities on biodiversity under different management practices as well as in the management of national parks, the targeting of sites for sustainable development, and the national and international scientific community.
Additional products to have evolved from the lab include a number of publications and activities that have greatly benefited the communication and outreach programs of Shell and Smithsonian such as scientific publications, an acclaimed photographic documentary on the Gamba Complex, promotional marketing for Shell and Smithsonian such as calendars, posters, brochures, and websites, and the first and only faunal collection in Gabon—the start to a potential natural history museum for the country and region.
