Trade in wildlife, including reptiles, represents an important component of the livelihoods of many indigenous people globally. Characterizing the extent of this trade and its relationship to livelihoods is necessary to understand its sustainability. We report on the trade of reptiles for food, traditional medicine, and crafts in Yaounde, the capital of Cameroon, for which data has been lacking compared to elsewhere in the country. We interviewed 28 people, including 13 from craft stalls, five traditional healers, seven from restaurants, and three wildmeat traders on the origin, acquisition and use of reptiles. We documented 16 species, including nine CITES listed species, of which 69% were used for meat, 38% in traditional medicine, and 69% for leather products. The most harvested species for meat included the Gaboon Viper (Bitis gabonica), Nile Monitor (Varanus niloticus), Dwarf Crocodile (Osteolaemus tetraspis), Rock Python (Python sebae), and forest tortoises (Kinixys sp.). Species sold for traditional medicines included the Rock Python and two chameleon species. There was at least one incidence of a critically endangered African Slender Snouted Crocodile (Mecistops cataphractus) being traded for its meat and skin. Crocodiles, pythons, vipers, cobras, and monitor lizards were predominately utilized for clothing products. The demand for reptiles in these multiple uses requires further documentation, with only anecdotal reports from traders of reductions in availability of certain species traded; notably vipers and crocodylians. We discuss possible measures to improve monitoring of this trade network to determine its sustainability and requirements for sustainable management.
Official protection of an exploited species sometimes precedes any quantitative understanding of its use, including any dependence of local residents on it for food and livelihood. Conservation initiatives could suffer without this information. The Goliath frog Conraua goliath is iconic globally because of its large size, and is categorized as Endangered on the IUCN Red List. The main threat to this species in Cameroon is overexploitation, but any associated socio-economic aspects of this have not been quantified. We provide insights into local perceptions of the Goliath frog and its consumption through structured interviews with 223 people living alongside this species. The Goliath frog is well known and hunted both for home consumption and the wild meat trade. We trailed seven collaborative Cameroonian Goliath frog hunters over two seasons to determine offtake. A total of 192 Goliath frogs were collected by these hunters, peaking in March. The hunters used nets, shotguns and spears. Their catch was eaten at home or sold fresh within the community or to travellers for XAF 1,500–5,000 (USD 3–10) each. We also studied the Goliath frog trade by examining the databases of the Cameroonian Ministry of Forestry and Wildlife, and CITES. CITES and hunters reported large exports of Goliath frogs but no trade was documented by the Ministry of Forestry and Wildlife. To support conservation planning, this study provides preliminary quantitative information on the extent of the threat of hunting to this Endangered frog.
Sub-Saharan Africa is under-represented in global biodiversity datasets, particularly regarding the impact of land use on species’ population abundances. Drawing on recent advances in expert elicitation to ensure data consistency, 200 experts were convened using a modified-Delphi process to estimate ‘intactness scores’: the remaining proportion of an ‘intact’ reference population of a species group in a particular land use, on a scale from 0 (no remaining individuals) to 1 (same abundance as the reference) and, in rare cases, to 2 (populations that thrive in human-modified landscapes). The resulting bii4africa dataset contains intactness scores representing terrestrial vertebrates (tetrapods: ±5,400 amphibians, reptiles, birds, mammals) and vascular plants (±45,000 forbs, graminoids, trees, shrubs) in sub-Saharan Africa across the region’s major land uses (urban, cropland, rangeland, plantation, protected, etc.) and intensities (e.g., large-scale vs smallholder cropland). This dataset was co-produced as part of the Biodiversity Intactness Index for Africa Project. Additional uses include assessing ecosystem condition; rectifying geographic/taxonomic biases in global biodiversity indicators and maps; and informing the Red List of Ecosystems.
Amphibians are challenging to mark for recapture due to their small size and permeable, sensitive, and often frequently shed skins. Photographic identification and pattern matching techniques are increasingly used as a non-invasive method to identify individual amphibians for the purposes of monitoring individuals over time. The Critically Endangered Lake Oku Clawed Frog (Xenopus longipes) has distinctively patterned ventral patterns as adults. We used Wild-ID to explore the use of photographic identification for the longitudinal identification of both adult and juvenile X. longipes. We photographed juvenile frogs twice over a 180-d period and adult frogs seven times over 624 d. Juvenile belly patterns underwent marked ontogenetic shifts over the 180-d period and Wild-ID was not able to match photographs of the same individuals over the study period. Markings were more stable in adult frogs and Wild-ID was successful in matching photographs of individual adult frogs over 180 d but became less effective at distinguishing between individuals at 624 d (i.e., Wild-ID similarity scores halved and false rejection rates increased substantially). We detected no false acceptances. Our results provide evidence to guide management of this species in captivity and in the field and demonstrate the importance of considering life-stage linked ontogenetic changes when validating a photographic identification method for amphibians.
We present a checklist of amphibian and reptile species that occur in the Ntem Iron ore mining concession in southern Cameroon. As part of a broader biodiversity impact survey, a two week survey of herpetofauna was conducted. Visual and acoustic encounter surveys were carried out during day and night, covering the entire area of mining exploration. We document the presence of 38 amphibian and 28 reptile species. A notable observation was a large, southward range extension of the Dwarf Toad Didynamipus sjostedti Andersson 1903 (IUCN: VU). Other species of conservation concern include the Goliath Frog Conraua goliath, (Boulenger 1906) (EN), the egg frogs Leptodactylodon albiventris (Boulenger 1905) (EN), and L. ventrimarmoratus, (Boulenger 1904) (VU). Records of threatened reptiles include the Dwarf Crocodile Osteolaemus tetraspis, (Cope 1861) (VU; CITES I), the Forest Monitor Lizard Varanus ornatus (Daudin 1803) (NE; CITES II) and the Forest Tortoise Kinixys erosa (Schweigger 1812) (DD; CITES II). These and numerous other forest dwelling species indicate the intact nature of herpetofauna forest assemblages within the study sites. Efforts to conserve the herpetofauna at these sites should focus on protecting and monitoring the intact forest corridors linking the concession to a neighbouring forest reserve, as well as plans for restoration once extraction is completed. Keywords. Herpetofauna, Species richness, conservation, habitat, fragmentation, biodiversity
Phylogenetic relationships of sub-Saharan African natricine snakes are understudied and poorly understood, which in turn has precluded analyses of the historical biogeography of the Seychelles endemic Lycognathophis seychellensis. We inferred the phylogenetic relationships of Seychelles and mainland sub-Saharan natricines by analysing a multilocus DNA sequence dataset for three mitochondrial (mt) and four nuclear (nu) genes. The mainland sub-Saharan natricines and L. seychellensis comprise a well-supported clade. Two maximally supported sets of relationships within this clade are (Limnophis,Natriciteres) and (Afronatrix,(Hydraethiops,Helophis)). The relationships of L. seychellensis with respect to these two lineages are not clearly resolved by analysing concatenated mt and nu data. Analysed separately, nu data best support a sister relationship of L. seychellensis with (Afronatrix,(Hydraethiops,Helophis)) and mt data best support a sister relationship with all mainland sub-Saharan natricines. Methods designed to cope with incomplete lineage sorting strongly favour the former hypothesis. Genetic variation among up to 33 L. seychellensis from five Seychelles islands is low. Fossil calibrated divergence time estimates support an overseas dispersal of the L. seychellensis lineage to the Seychelles from mainland Africa ca. 43-25 million years before present (Ma), rather than this taxon being a Gondwanan relic.
The amphibian chytrid fungus Batrachochytrium dendrobatidis ( Bd ), responsible for numerous amphibian declines and extinctions, was previously thought to originate from the African continent. This was based on infected museum specimens from early 20th century South Africa, Cameroon and Uganda. Further research on archived specimens from other continents eventually revealed early 20th century records also in Brazil and Japan. Recent robust analysis of genomic diversity and phylogeny of Bd has shown origin from Asia to be more plausible. This raises the issue that the threat of Bd for African amphibians as a novel pathogen has been underestimated. There are now cases where dramatic amphibian declines in disparate mountains on the continent could be attributed to Bd , and this necessitates an urgent realigning of hypotheses and the research agenda for amphibian conservation on the continent. Notably, hotspots of amphibian host naivety include West Africa where this pathogen has so far not been detected. We discuss research gaps that amphibian conservationists might focus on, notably more genomic sequencing of the Bd CAPE (the less virulent) lineage to determine its date of emergence, and assessing the susceptibility of different amphibian species to infection, disease and decline to better prioritize conservation actions.
Amphibians on African mountains are threatened by habitat loss and fragmentation, pollution, disease and climate change. In particular, there have been recent reports of declines of montane endemic frogs in Cameroon. Mount Bamboutos, although home to numerous species of endemic amphibians, has no official protection and its amphibian populations have so far not been studied quantitatively. We surveyed frog assemblages on this mountain along a gradient of forest modification over a 2-year period. Through visual encounter surveys stratified across forest and farmland, we found that threatened montane amphibian species are closely associated with forested areas, particularly the Critically Endangered Leptodactylodon axillaris and Endangered Leptodactylodon perreti, Astylosternus ranoides and Cardioglossa oreas. Using the updated inventory of amphibians, which includes species with broader ranges across Africa, we found 69% of amphibian species on Mount Bamboutos to be threatened. We did not record several species present in historical records, which suggests they may have disappeared from this mountain, including Cardioglossa pulchra, Phrynobatrachus steindachneri, Phrynobatrachus werneri, Sclerophrys villiersi, Werneria bambutensis and Wolterstorffina mirei. The pattern of change detected in the amphibian community is consistent with declines on other mountains in the country, with a loss of Phrynobatrachus, Werneria and Cardioglossa spp., but persistence of Astylosternus, Arthroleptis and Leptodacty-lodon. The observed relationships of land-use patterns and amphibian diversity suggest that ongoing land-use changes could extirpate the remaining montane endemic frog species, particularly L. axillaris and L. perreti. Preserving a network of connected forest patches is therefore critical to save the endemic amphibians of Mount Bamboutos.
Changes to species composition, such as biological invasions and extinctions, have the potential to alter ecosystems. Invaders often replace taxonomically similar species, resulting in potentially redundant impacts. For example, freshwater decapod crustaceans are pervasive invasive alien species but they often extirpate native decapods. This study addresses whether or not these compositional shifts lead to impacts on the structure of the macroinvertebrate community, key ecosystem functions such as decomposition rates and primary productivity, and freshwater properties such as turbidity. In a controlled outdoor mesocosm experiment that ran for 33 days, impacts on biodiversity, ecosystem functioning and properties were compared between a native, endangered crayfish (Austropotamobius pallipes) and two invasive alien decapods: the crayfish Pacifastacus leniusculus and crab Eriocheir sinensis. Equal densities of these decapod species were compared between mesocosms, with a replicated array of decapod free controls. Measurements included macroinvertebrate densities, decomposition of leaf litter, production of biofilms, plankton, macrophytes, gross primary productivity, turbidity, and dissolved nutrients. While taxonomic richness of non-decapod macroinvertebrates was marginally higher in the invasive alien treatments, differences in Shannon diversity were negligible, and beta-diversity was higher for the invasive alien crab. Gastropod density was reduced in the benthos of invasive alien treatments. This was associated with increased primary productivity of periphyton, particularly in the presence of P. leniusculus. Increased turbidity was, however, inversely correlated with periphyton primary productivity in the E. sinensis treatment. Nitrate concentration was significantly lower in invasive compared to native crayfish mesocosms, but similar to decapod free controls. This reflects the potential for the invasive crayfish to act as a nitrogen sink, mediated through both enhanced periphyton and reduced nitrogen recycling. Other processes, such as decomposition rates, sediment respiration, community respiration, and gross primary productivity, did not differ between treatments. This study demonstrates impacts of both native and invasive alien decapod species on certain aspects of benthic biodiversity and ecosystem processes, but with many of these parameters unaffected. This assumes equal densities of each species in its environment. The enhanced gastropod predation and associated trophic cascade by invasive decapods are likely explained through higher consumption rates, metabolism and activity. These per-capita impacts are likely to be exacerbated further in-situ due to typically higher densities of invasive compared to native crayfish.
Habitat loss and degradation are the primary threats to biodiversity, especially for amphibians. In the Highlands of Cameroon, knowledge on the impacts of different forms of habitat loss, such as livestock management, is restricted to anecdotal reports. This study investigated the impact of forest fragmentation, driven primarily by livestock grazing, on the amphibian assemblage on Mount Mbam, West Region, Cameroon. Stratified, multi-season surveys over two years recorded the abundance and community composition of anuran species. Based on the revised inventory of amphibians the proportion of threatened species on Mount Mbam was calculated at 23.52%. A small population of Phrynobatrachus steindachneri was found to occur despite having completely disappeared on other mountains in its distribution range. One species known to the mountain, Cardioglossa schioetzi, was not found during the surveys. The remaining forest patches were found to be significant habitat for several species endemic to the mountains of Cameroon-Nigeria. The savanna, likely expanded by livestock grazing, held numerous reed frog species that likely benefit from forest loss, especially in low- to mid-range elevations. The observed relationship between land-use and amphibians on this mountain indicates that the ongoing conversion of forest to pasture threatens remaining montane endemic anuran species, with conservation planning and action now necessary.
AbstractBiological invasions have the potential to alter ecosystem processes profoundly, but invaders are rarely found alone. Interactions between different invasive alien species, and their cumulative impact on ecosystem functioning, have led to hypotheses of invasion meltdown whereby effects become additive leading to further ecosystem stress. Invasive riparian plants (e.g., Rhododendron ponticum) deposit leaf litter in freshwaters, which may be unconsumed by indigenous species, potentially affecting habitat heterogeneity and flow of energy to the food web. However, invasive alien decapod crustaceans are effective consumers of leaf litter, and it was hypothesized that they would also consume inputs of invasive riparian leaf litter. This study shows that invasive alien signal crayfish (Pacifastacus leniusculus) and Chinese mitten crab (Eriocheir sinensis) effectively break down different types of leaf litter, including invasive alien R. ponticum, at higher rates than indigenous white‐clawed crayfish. Secondary products were more varied, with more fine particulate organic matter generated for the less palatable alien leaf litter species. Leaf species caused different changes in body mass of decapods but effects were heterogeneous by leaf and decapod: P. leniusculus showed lower mass loss when consuming R. ponticum while E. sinensis lost mass when consuming A. pseudoplatanus. Impacts of riparian invasions on detritus accumulation in freshwaters are thus potentially buffered by invasive alien decapods, illustrating a need for a more detailed consideration of both positive and negative interspecific feedbacks during biological invasions.
Invasive alien species have the potential to alter biodiversity and ecosystem processes. In freshwaters, detritus decomposition is a major ecosystem service but it remains uncertain whether invasive alien decapods process detritus differently to natives. This study examined leaf litter processing, and cascading effects on biofilms, by the European native white clawed crayfish (Austropotamobius pallipes) compared to two invasive alien decapod species: the American signal crayfish (Pacifastacus leniusculus) and the Chinese mitten crab (Eriocheir sinensis). Invasive alien decapods were responsible for higher leaf litter decomposition than the native. In comparison with native crayfish, invasive alien crab and crayfish showed higher rates of litter consumption, increased production of smaller leaf fragments, fine particulate organic matter (FPOM) and dissolved organic carbon. Nutrients (ammonia and soluble reactive phosphorous) derived from excretion (measured separately in the absence of biofilms) varied among decapod species, being lower for P. leniusculus. However, nutrient concentrations did not vary among species in the detritivory experiments with biofilm, implying nutrients were utilised for biofilm production and respiration as no differences in biomass were evident among decapod treatments. These results show invasive alien decapods have the potential to increase the magnitude of detrital processing to FPOM in rivers, but indirect impacts on primary producers due to nutrient release are uncertain based on this experimental context.
Parasitic chytrid fungi have emerged as a significant threat to amphibian species worldwide, necessitating the development of techniques to isolate these pathogens into culture for research purposes. However, early methods of isolating chytrids from their hosts relied on killing amphibians. We modified a pre-existing protocol for isolating chytrids from infected animals to use toe clips and biopsies from toe webbing rather than euthanizing hosts, and distributed the protocol to researchers as part of the BiodivERsA project RACE; here called the RML protocol. In tandem, we developed a lethal procedure for isolating chytrids from tadpole mouthparts. Reviewing a database of use a decade after their inception, we find that these methods have been applied across 5 continents, 23 countries and in 62 amphibian species. Isolation of chytrids by the non-lethal RML protocol occured in 18% of attempts with 207 fungal isolates and three species of chytrid being recovered. Isolation of chytrids from tadpoles occured in 43% of attempts with 334 fungal isolates of one species (Batrachochytrium dendrobatidis) being recovered. Together, these methods have resulted in a significant reduction and refinement of our use of threatened amphibian species and have improved our ability to work with this group of emerging pathogens.
Amphibians are a disproportionately threatened group of vertebrates, the status of which in Sub-Saharan Africa is still uncertain, with heterogeneous fauna punctuated by mountains. Mount Oku, Cameroon is one such mountain, which holds many endemic and restricted-range species. The history of amphibian research on Mt Oku, current knowledge on biogeography and conservation biology is reviewed, including recent findings. This updated inventory adds 25 further species, with 50 species of amphibian so far recorded to the Oku Massif (c. 900 to 3,011 m). This includes 5 endemic to Mt Oku, 7 endemic to the Bamenda Highlands, 18 restricted to the highlands of Cameroon and Nigeria, and 20 with broader ranges across Africa. This includes a new mountain locality for the Critically Endangered Leptodactylodon axillaris. Among others, the first record of Phrynobatrachus schioetzi and Ptychadena taenioscelis from Cameroon are presented. The uncertainty of habitat affinities and elevational ranges are discussed. The proportion of threatened species on Mt Oku is 44.2%, but projected to increase to 47.9% due to new species descriptions and recent dramatic declines. The natural habitats of Mt Oku are irreplaceable refuges for its endemic and restricted-range amphibian populations under severe pressure elsewhere in their range. Threats to this important amphibian fauna are increasing, including agricultural encroachment, expanding aquaculture, livestock grazing, pollution, invasive species, forest loss and degradation. Past, present and desired conservation interventions to address these threats are discussed.
Monopterus luticolus, new species, is described from Cameroon. Most of the seven known individuals were discovered in inundated soil while digging for caecilian amphibians. Monopterus luticolus differs from the two other nominal African synbranchid species in the number of vertebrae and details of its osteology. The spatial dissociation of ceratobranchial 1 from hypobranchial 1 and its close association with hypobranchial 2 and ceratobranchial 2 demonstrate that M. luticolus is a member of the 'Amphipnous group'.
Amphibian populations are vanishing worldwide. Declines and extinctions of many populations have been attributed to chytridiomycosis, a disease induced by the pathogenic fungus Batrachochytrium dendrobatidis (Bd). In Africa, however, changes in amphibian assemblages were typically attributed to habitat change. We conducted a retrospective study utilizing field surveys from 2004-2012 of the anuran faunas on two mountains in western Cameroon, a hotspot of African amphibian diversity. The number of species detected was negatively influenced by year, habitat degradation, and elevation, and we detected a decline of certain species. Because another study in this region revealed an emergence of Bd in 2008, we screened additional recent field-collected samples and also pre-decline preserved museum specimens for the presence of Bd supporting emergence before 2008. When comparing the years before and after Bd detection, we found significantly diminished frog species richness and abundance on both mountains after Bd emergence. Our analyses suggest that this may be the first disease-driven community-level decline in anuran biodiversity in Central Africa. The disappearance of several species known to tolerate habitat degradation, and a trend of stronger declines at higher elevations, are consistent with Bd-induced declines in other regions. Not all species decreased; populations of some species remained constant, and others increased after the emergence of Bd. This variation might be explained by species-specific differences in infection probability. Increased habitat protection and Bd-mitigation strategies are needed for sustaining diverse amphibian communities such as those on Mt. Manengouba, which contains nearly half of Cameroon's frog diversity.
The Lake Oku Clawed Frog Xenopus longipes is a Critically Endangered, dodecaploid anuran endemic to Lake Oku in Cameroon. An ex situ population of this species was established at Zoological Society of London (ZSL), London Zoo in 2008, as well as at several other institutions, with the intention of providing data on the biology and husbandry of this species. We report the first captive breeding of the species. Adult frogs maintained under environmental conditions designed to mimic field data produced clutches of 7-300 eggs; eggs measured 1.23 mm in diameter, and were laid singly after a period of 6.5 hours in axial amplexus. Spawning took place only during the day. Tadpoles hatched in 2-3 days and development was very long compared to congeners, lasting 193-240+ days until metamorphosis. Tadpoles grew very large (maximum 79 mm total length), particularly compared with the relatively small adult size (maximum 36 mm Snout to Vent Length [SVL]). Tadpoles proved to be highly sensitive to total dissolved solids (TDS) in the water and only thrived when low levels (20 mg/L) were used. Metamorphosis concluded with an SVL of 19-25 mm and F1 animals began first sexual activity at 5-6 months post metamorphosis. These data will inform future husbandry in captivity as well as illuminating facets of biology previously unknown and difficult to determine in the field.
We describe the tadpoles of four Cameroonian Phrynobatrachus species, P. auritus, P. chukuchuku, P. jimzimkusi, and P. manengoubensis. While P. auritus is a widespread frog of Central African rainforests, the other three species are endemic to parts of the Cameroonian Volcanic Line. All tadpoles have the short and rotund body shape that is typical of Phrynobatrachus, with comparatively short tails and delicate jaw sheaths. We describe morphological characters suited to differentiate between these species, in particular labial tooth row formulae and the presence or absence of particular papillae, and summarize corresponding data for other described tadpoles of the genus. As far as is currently known, different reproductive modes, as well as morphology and biology of Phrynobatrachus tadpoles is not mirrored in the phylogenetic relationships of the respective species. We further point out profound morphological differences between P. jimzimkusi tadpoles from the type locality, Mt. Bamboutos, and Mt. Manengouba, and argue that the taxonomic status of the latter population should be verified.
The decline of amphibian populations, particularly frogs, is often cited as an example in support of the claim that Earth is undergoing its sixth mass extinction event. Amphibians seem to be particularly sensitive to emerging diseases (e.g., fungal and viral pathogens), yet the diversity and geographic distribution of infectious agents are only starting to be investigated. Recent work has linked a previously undescribed protist with mass-mortality events in the United States, in which infected frog tadpoles have an abnormally enlarged yellowish liver filled with protist cells of a presumed parasite. Phylogenetic analyses revealed that this infectious agent was affiliated with the Perkinsea: a parasitic group within the alveolates exemplified by Perkinsus sp., a "marine" protist responsible for mass-mortality events in commercial shellfish populations. Using small subunit (SSU) ribosomal DNA (rDNA) sequencing, we developed a targeted PCR protocol for preferentially sampling a clade of the Perkinsea. We tested this protocol on freshwater environmental DNA, revealing a wide diversity of Perkinsea lineages in these environments. Then, we used the same protocol to test for Perkinsea-like lineages in livers of 182 tadpoles from multiple families of frogs. We identified a distinct Perkinsea clade, encompassing a low level of SSU rDNA variation different from the lineage previously associated with tadpole mass-mortality events. Members of this clade were present in 38 tadpoles sampled from 14 distinct genera/phylogroups, from five countries across three continents. These data provide, to our knowledge, the first evidence that Perkinsea-like protists infect tadpoles across a wide taxonomic range of frogs in tropical and temperate environments, including oceanic islands.