Roadless wilderness area determines forest elephant movements in the Congo Basin

A dramatic expansion of road building is underway in the Congo Basin fuelled by private enterprise, international aid, and government aspirations. Among the great wilderness areas on earth, the Congo Basin is outstanding for its high biodiversity, particularly mobile megafauna including forest elephants (Loxodonta africana cyclotis). The abundance of many mammal species in the Basin increases with distance from roads due to hunting pressure, but the impacts of road proliferation on the movements of individuals are unknown. We investigated the ranging behaviour of forest elephants in relation to roads and roadless wilderness by fitting GPS telemetry collars onto a sample of 28 forest elephants living in six priority conservation areas. We show that the size of roadless wilderness is a strong determinant of home range size in this species. Though our study sites included the largest wilderness areas in central African forests, none of 4 home range metrics we calculated, including core area, tended toward an asymptote with increasing wilderness size, suggesting that uninhibited ranging in forest elephants no longer exists. Furthermore we show that roads outside protected areas which are not protected from hunting are a formidable barrier to movement while roads inside protected areas are not. Only 1 elephant from our sample crossed an unprotected road. During crossings her mean speed increased 14-fold compared to normal movements. Forest elephants are increasingly confined and constrained by roads across the Congo Basin which is reducing effective habitat availability and isolating populations, significantly threatening long term conservation efforts. If the current road development trajectory continues, forest wildernesses and the forest elephants they contain will collapse

Congo Basin peatlands: threats and conservation priorities

The recent publication of the first spatially explicit map of peatlands in the Cuvette Centrale, central Congo Basin, reveals it to be the most extensive tropical peatland complex, at ca. 145,500 km2. With an estimated 30.6 Pg of carbon stored in these peatlands, there are now questions about whether these carbon stocks are under threat and, if so, what can be done to protect them. Here, we analyse the potential threats to Congo Basin peat carbon stocks and identify knowledge gaps in relation to these threats, and to how the peatland systems might respond. Climate change emerges as a particularly pressing concern, given its potential to destabilise carbon stocks across the whole area. Socio-economic developments are increasing across central Africa and, whilst much of the peatland area is protected on paper by some form of conservation designation, the potential exists for hydrocarbon exploration, logging, plantations and other forms of disturbance to significantly damage the peatland ecosystems. The low level of human intervention at present suggests that the opportunity still exists to protect the peatlands in a largely intact state, possibly drawing on climate change mitigation funding, which can be used not only to protect the peat carbon pool but also to improve the livelihoods of people living in and around these peatlands

Averting biodiversity collapse in tropical forest protected areas

The rapid disruption of tropical forests probably imperils global biodiversity more than any other contemporary phenomenon¹⁻³. With deforestation advancing quickly, protected areas are increasingly becoming final refuges for threatened species and natural ecosystem processes. However, many protected areas in the tropics are themselves vulnerable to human encroachment and other environmental stresses⁴⁻⁹. As pressures mount, it is vital to know whether existing reserves can sustain their biodiversity. A critical constraint in addressing this question has been that data describing a broad array of biodiversity groups have been unavailable for a sufficiently large and representative sample of reserves. Here we present a uniquely comprehensive data set on changes over the past 20 to 30 years in 31 functional groups of species and 21 potential drivers of environmental change, for 60 protected areas stratified across the world’s major tropical regions. Our analysis reveals great variation in reserve ‘health’: about half of all reserves have been effective or performed passably, but the rest are experiencing an erosion of biodiversity that is often alarmingly widespread taxonomically and functionally. Habitat disruption, hunting and forest-product exploitation were the strongest predictors of declining reserve health. Crucially, environmental changes immediately outside reserves seemed nearly as important as those inside in determining their ecological fate, with changes inside reserves strongly mirroring those occurring around them. These findings suggest that tropical protected areas are often intimately linked ecologically to their surrounding habitats, and that a failure to stem broad-scale loss and degradation of such habitats could sharply increase the likelihood of serious biodiversity declines.Keywords: Ecology, Environmental scienc

Fishes of Lake Tumba (Democratic Republic of Congo): Evaluation of present status and comparisons with previous studies

Background. Lake Tumba with a surface area of 830 km2 is very humic (pH = 3.6–4.6). The fishery is important for the riparian population but there are concerns about overfishing. The objective of this study was to assess changes in the fish species composition by comparing the presently reported survey (2005–2010) with earlier studies carried out in 1938–1939, 1955–1956, and 1959 Our hypothesis was that Lake Tumba had been overfished. Materials and methods. Fishing was done in the pelagial with gillnet (25 and 30 mm) and line with hooks at three sites within 166 days in 2005–2006 and 2009–2010. Results. A total of 40 species were identified. Five species were caught all years and at all sites, namely Chrysichthys cranchii (Leach, 1818), Chrysichthys ornatus Boulenger, 1902, Chrysichthys punctatus Boulenger, 1899, Mormyrops anguilloides (Linnaeus, 1758), and Tylochromis lateralis (Boulenger, 1898). Twelve species were only caught once. Weight Per Unit Effort (WPUE) differed with site and season: ranging from 0 to 4200 g · day–1 and the Number of fish Per Unit Effort (NPUE) varied from 0 to 27 fishes · day–1. Conclusion. Out of 49 pelagic species caught by Matthes in 1959, we considered five as diminished in numbers or even missing. This may be attributed to high fishing pressure. The protected site Mabali hosted the majority of previously reported species of which two were noted in Matthes’s list but not caught by him. Many parameters demonstrated a “positive” difference between Mabali (which is protected from fishing) and the other sites. This site should be a reference area for future monitoring if its status can be maintained. A trend in the fishery based on interviews with fishers indicated a change from larger species to smaller. This was deemed a result of fishing pressure and nine species were identified as diminishing. The presently reported survey introduced quantitative aspects while earlier studies were qualitative. This impairs the ability to draw strong conclusions about overfishing and other anthropogenic activities. The threat of overfishing calls for the need for consistent quantitative monitoring of the fish population, including monitoring of waters in the drainage area, to enable assessment of impact of anthropogenic pressure

Fishes of Lake Tumba (Democratic Republic of Congo): Evaluation of present status and comparisons with previous studies

Background. Lake Tumba with a surface area of 830 km2 is very humic (pH = 3.6–4.6). The fishery is important for the riparian population but there are concerns about overfishing. The objective of this study was to assess changes in the fish species composition by comparing the presently reported survey (2005–2010) with earlier studies carried out in 1938–1939, 1955–1956, and 1959 Our hypothesis was that Lake Tumba had been overfished. Materials and methods. Fishing was done in the pelagial with gillnet (25 and 30 mm) and line with hooks at three sites within 166 days in 2005–2006 and 2009–2010. Results. A total of 40 species were identified. Five species were caught all years and at all sites, namely Chrysichthys cranchii (Leach, 1818), Chrysichthys ornatus Boulenger, 1902, Chrysichthys punctatus Boulenger, 1899, Mormyrops anguilloides (Linnaeus, 1758), and Tylochromis lateralis (Boulenger, 1898). Twelve species were only caught once. Weight Per Unit Effort (WPUE) differed with site and season: ranging from 0 to 4200 g · day–1 and the Number of fish Per Unit Effort (NPUE) varied from 0 to 27 fishes · day–1. Conclusion. Out of 49 pelagic species caught by Matthes in 1959, we considered five as diminished in numbers or even missing. This may be attributed to high fishing pressure. The protected site Mabali hosted the majority of previously reported species of which two were noted in Matthes’s list but not caught by him. Many parameters demonstrated a “positive” difference between Mabali (which is protected from fishing) and the other sites. This site should be a reference area for future monitoring if its status can be maintained. A trend in the fishery based on interviews with fishers indicated a change from larger species to smaller. This was deemed a result of fishing pressure and nine species were identified as diminishing. The presently reported survey introduced quantitative aspects while earlier studies were qualitative. This impairs the ability to draw strong conclusions about overfishing and other anthropogenic activities. The threat of overfishing calls for the need for consistent quantitative monitoring of the fish population, including monitoring of waters in the drainage area, to enable assessment of impact of anthropogenic pressure

Eastern Chimpanzees, but not Bonobons, represent a simian immunodeficiency virus reservoir

Chimpanzees in west central Africa (Pan troglodytes troglodytes) are endemically infected with simian immunodeficiency viruses(SIVcpzPtt) that have crossed the species barrier to humans and gorillas on at least five occasions, generating pandemic and nonpandemic forms of human immunodeficiency virus type 1 (HIV-1) as well as gorilla SIV (SIVgor). Chimpanzees in east Africa (Pan troglodytes schweinfurthii) are also infected with SIVcpz; however, their viruses (SIVcpzPts) have never been found in humans. To examine whether this is due to a paucity of natural infections, we used noninvasive methods to screen wild-living eastern chimpanzees in the Democratic Republic of the Congo (DRC), Uganda, and Rwanda. We also screened bonobos (Pan paniscus) in the DRC, a species not previously tested for SIV in the wild. Fecal samples (n!3,108) were collected at 50 field sites, tested for species and subspecies origin, and screened for SIVcpz antibodies and nucleic acids. Of 2,565 samples from eastern chimpanzees, 323 were antibody positive and 92 contained viral RNA. The antibody-positive samples represented 76 individuals from 19 field sites, all sampled north of the Congo River in an area spanning 250,000 km2. In this region, SIVcpzPts was common and widespread, with seven field sites exhibiting infection rates of 30% or greater. The overall prevalence of SIVcpzPts infection was 13.4% (95% confidence interval, 10.7% to 16.5%). In contrast, none of the 543 bonobo samples from six sites was antibody positive. All newly identified SIVcpzPts strains clustered in strict accordance to their subspecies origin; however, they exhibited considerable genetic diversity, especially in protein domains known to be under strong host selection pressure. Thus, the absence of SIVcpzPts zoonoses cannot be explained by an insufficient primate reservoir. Instead, greater adaptive hurdles may have prevented the successful colonization of humans by P. t. schweinfurthii viruses

Population status of Pan troglodytes verus in Lagoas de Cufada Natural Park, Guinea-Bissau

The western chimpanzee, Pan troglodytes verus, has been classified as Endangered on the IUCN Red List since 1988. Intensive agriculture, commercial plantations, logging, and mining have eliminated or degraded the habitats suitable for P. t. verus over a large part of its range. In this study we assessed the effect of land-use change on the population size and density of chimpanzees at Lagoas de Cufada Natural Park (LCNP), Guinea-Bissau. We further explored chimpanzee distribution in relation to landscape-level proxies of human disturbance. Nest count and distance-sampling methods were employed along 11 systematically placed linear transects in 2010 and 2011. Estimated nest decay rate was 293.9 days (%CV = 58.8). Based on this estimate of decay time and using the Standing-Crop Nest Count Method, we obtained a habitat-weighted average chimpanzee density estimate for 2011 of 0.22 nest building chimpanzees/km2 (95% CI 0.08–0.62), corresponding to 137 (95% CI 51.0–390.0) chimpanzees for LCNP. Human disturbance had a negative influence on chimpanzee distribution as nests were built farther away from human settlements, roads, and rivers than if they were randomly distributed, coinciding with the distribution of the remaining patches of dense canopy forest. We conclude that the continuous disappearance of suitable habitat (e.g. the replacement of LCNP's dense forests by monocultures of cashew plantations) may be compromising the future of one of the most threatened Guinean coastal chimpanzee populations. We discuss strategies to ensure long-term conservation in this important refuge for this chimpanzee subspecies at its westernmost margin of geographic distribution.Publisher PDFPeer reviewe