(Brummett et al. in press) and the upper Cross River watersheds (Mdaihli et al. 2003). To the extent that 

 these estimates are reliable, the vast majority of the biomass in these systems seems to be accumulated 

 downstream in larger order rivers. 



The Campo-Ma'an Area of Southern Cameroon: The Lower Guinea Rainforest extends over 500 000 km^ along 

 the Gulf of Guinea from the Cross River nearly to the Congo; including some 50 major and minor rivers (Mahé & Olivry 

 1999). The Campo-Ma'an area of South-Central Cameroon (Figure 2) is typical of the Lower Guinea rainforest 

 ecosystem. The Campo-Ma'an National Park and its buffer zone occupy an area of 7,762 kml. Within the buffer zone are 

 two active logging concessions and two agro-industrial estates (hévea and oil palm). Most of the zone is secondary 

 rainforest having once been logged. New economic developments include two new deepwater ports and an iron mine 

 planned in the area west of the Lobé (WWF, Personal Communication, May 2008). In the park and buffer zone are found 

 at least 1,500 plant species, 390 species of macro-invertebraes (excluding the Arthropoda which have not been 

 enumerated), 249 fish species (in three river basins), 302 species of bird, 122 species of reptile and 80 large and medium- 

 sized mammals, including endangered forest elephant (Loxodonta africana cyclotis), forest buffalo (Synerus caffer 

 nanus), lowland gorilla (Gorilla gorilla), chimpanzee (Pan troglodytes), mandrill (Mandrillus sphinx), leopard (Panthera 

 pardus) and giant Pangolin (Manis gigantea) (MINFOF 2002). Endemism in the area is high. Also in the area are some 

 60,000 people living in 120 villages and 22 pygmy camps. The average population density in the area is 7.3 persons/km\ 

 but over a third of the people (24,000) live and work in the two agro-industrial estates, leaving large parts of the area 

 completely uninhabited. 



Figure 2. South-Central Cameroon including the Campo-Ma'an National Park and its buffer zone. Main areas 



of project activity are circled (MINFOF 2005). 



Topographie du Parc et de sa zone périphérique 



National Park 

 Park Buffer Zone 



Major Road 



River 



sum 'i^HiB «laic iiaaj: ^eiixj ^-lau 



As with fish biomass, fish species diversity and richness tend to increase as one moves downstream from a 

 swamp, to first-order forest streams and to medium-sized tributaries to the main channel. This is due primarily to 

 the addition of species rather than through replacement (Géry 1965, Welcomme & de Merona 1988, Kamdem- 

 Toham & Teugels 1998). Reflecting this trend, catch rates at Nkoelon (downstream) averaged 42 g/linear m (29 

 species) of stream, as compared to 1 9 g upstream. 



The basket-trap fishery is dominated by the freshwater decapod crustaceans Macrobrachium spp. and Atya spp., 

 locally referred to as "crevettes". Although less important in headwater areas, "crevettes" are of major economic 

 interest in the lower reaches, near the towns of Campo and Kribi. At between $2.00 and $6.00 per kg, they are 2-6 



Nature & Faune Vol. 23, Issue 1 



41 



