Preliminary results of the RAP survey are outlined below. Full reports can be viewed in the preliminary report.
The creeks of the Palumeu River have lower oxygen levels (1.72 -7.93 mg/L) than the river (5.58-7.34 mg/L) mainly due to the lack of rapids in the creeks and high input of nutrients from the forest (phosphate: max 0.13 mg/L; ammonia: 0.09 mg/L). Both creeks and river have clear water (max turbidity: 11 NTU, which was measured after rain). The water quality data indicate undisturbed conditions for all creeks and river sites. Additional analyses for metals (aluminum, iron and mercury) are still needed to confirm this. The strong meandering aspect of the upstream Palumeu River was not expected for the origin of the Palumeu River.
We collected a total of 608 plants during the RAP, including 433 fertile and 175 sterile plants. The majority, 264 plants, with more than half sterile collections, was collected in the surroundings of Kasikasima site 4. At site 1 (188 plant collections), on the Grensgebergte site 2 (69 plant collections), and at Makrutu site 3 (75 plant collections) we collected mostly flowering and fruiting plants. We also collected 9 plants in Palumeu.
We found two new tree species for Suriname so far, Solanum semotum and Hirtella duckei. This shows how unexplored the forests in South Suriname are. We also observed several rare species. We encountered three tree species on the IUCN Red List, namely Minquartia guianensis (Lower Risk (LR)/near threatened), Syagrus stratincola (Vulnerable B1+2c), and Vouacapoua americana (Critically Endangered). We also encountered one tree species, Manilkara bidentata, which is protected by Surinamese law against felling.
The preliminary results of four 0.1 ha plot inventories showed the tree alpha diversity of the forests showed relatively high values for Suriname. This suggests that the forests in the South of Suriname are quite diverse. Forest in the South of Suriname may differ in species composition from areas further north, and our findings do not support a view that forests in the central and south of Suriname are one uniform forest.
We found many rare species and unique habitats in this area especially on the rocky outcrops along the rapids and at higher elevations at the Grensgebergte and the Kasikasima Mountains. Further analyses of the results might further stress the conservation value of these areas.
In total, more than 45 genera of aquatic beetles were found. A conservative estimate for the number of species stands at 98, but this will likely grow once samples can be processed in the lab. Based on field identifications, at least 5 genera are undescribed, although all are also known from Venezuela and/or the Kwamalasumutu RAP. Similarly, field identifications suggest at least 15 undescribed species, although more are likely.
Sites 1 and 4 had somewhat similar estimated numbers of genera, with 31 and 36 respectively The increase in genera at Site 4 can be at least partly attributed to the rock seep taxa found on the rocks at Kasikasima itself. Rock seepages and related hygropetric habitats were the only aquatic habitats present at Site 2, which resulted in the much lower raw taxonomic diversity with only 9 genera.
The lowland fauna (excluding the rock outcrops), at a glance, seems similar to that found in the Kwamalasamutu region. Some taxa that were frequently found at Site 1--including the genera Megadytes and Berosus—were not found at other camps, nor collected on the Kwamalasamutu RAP. By far the most significant result of the expedition was the discovery of large Myxophagan communities at sites 2 and 4. This represents the first known collection of the families Hydroscaphidae and Torridincolidae in Suriname.
Dung beetles were sampled using baited pitfall traps and flight intercept traps in the Grensgebergte Region of southeastern Suriname. Although many of the samples still need to be processed, about 70 dung beetle species are estimated, which represents high diversity for the region. Approximately 10% (~7 species) are probably new to science, but require further study. Dung beetle diversity and biomass was highest at the Upper Palumeu site, which probably reflects the extensive intact forest and low hunting pressure with no people living nearby. Dung beetle diversity at Kasikasima was also high, but lower beetle biomass probably reflects mild to moderate hunting of large mammals and birds in the region. Nonetheless, all sites studied were characterized by relatively high dung beetle diversity, biomass, and endemism, including several rare species, demonstrating the high biodiversity value of the region.
The dung beetle fauna of the Grensgebergte region is relatively similar to the Kwamalasamutu region, and richer than most other lowland forests of Suriname and the Guianas, containing a mix of range restricted endemics, Guiana Shield endemics, and Amazonian species. The high abundance of several large-bodied dung beetle species in the region is indicative of the intact wilderness that remains. These species support healthy ecosystems through seed dispersal, parasite regulation and other processes. Maintaining continuous primary forest and regulating hunting (such as through hunting-restricted reserves) in the region will be essential for conserving dung beetle communities and the ecological processes they sustain.
Preliminary observations on the ant fauna indicate a diverse fauna typical of lowland humid rainforest of the Guiana Shield, with at least 100 species likely to be identified in the samples, which have yet to be examined in detail. Genera typical of the region including many large ants that were commonly seen in the forest, including the arboreal species Daceton armigerum, Cephalotes spp., and Camponotus spp., the large-eyed terrestrial Gigantiops destructor, and several species of army ants. Many species within the ant tribe Dacetini were collected in leaf litter, indicating good primary forest. Species of the genera Pheidole, Pachycondyla and Odontomachus were commonly observed.
The abundance of katydids encountered during this survey was low compared to that typically encountered in lowland Neotropical forests. This may be related to the fact that the two main sampling sites (Juuru Camp and Kasikasima Camp) were located in seasonally inundated forest, thus limiting the number of species associated with the forest floor and the lower layers of the forest’s understory. It is likely that most of katydid diversity at these sites is concentrated in the forest canopy, a habitat difficult to sample without either direct access to it or the canopy fogging.
At least 50 morphospecies of katydids were recorded during the survey. This number, however, is very preliminary and based entirely on field identifications. Once the specimens are physically examined, it is likely that more species will be found in the samples. Of the four sampling sites, the Kasikasima Camp had the highest number of species (33) followed by the Juuru Camp (29 species); additionally, 5 species were recorded in the Palumeu Village, and 4 species were collected on the Grensgebergte. In addition to physically collected specimens, sound recordings of a yet unknown number of katydids were also made.
Preliminary results revealed 86 fish species in the Palumeu River at the three collection sites, 59 species at the Upper Palumeu River site, 14 species at the Makrutu Island site, and 35 species at the Kasikasima site. The relatively low number of species collected can probably be attributed to the high water level in the main stem of the river that prevented sampling the rapids at the Makrutu Island and Kasikasima sites. Catfishes (e.g. Loricariidae, Doradidae, Corydoras spp.) are thus conspicuously underrepresented or even absent in the species list. The electric eel, known to occur in the Palumeu River, was also not collected or observed.
We collected many large-sized specimens of large-sized species, attesting to the healthy fish populations in the Palumeu River. Some of the species we collected at the Upper Palumeu and Kasikasima sites may be new to science, e.g. Hypessobrycon sp. blackline, Hyphessobrycon sp. half-black-line-black caudal spot, Bryconops sp. red-fins and Ituglanis sp. Fish species collected during this expedition that are known to be endemic for the Marowijne River are: Cyphocharax biocellatus, Semaprochilodus varii, Jupiaba maroniensis, Tometes lebaili, Bunocephalus aloikae, Aequidens Palumeuensis and Kryptolebias sepia.
The fish populations of the Palumeu River seem to be in good condition as attested by the large number of large-sized fishes that was collected during the present study, including top-level piscivores. Many of the fishes of the Palumeu River may be of interest to the aquarium hobby. We recommend that an aquarium in be set up in Palumeu village with fishes of the Palumeu River, for the viewing of both visiting ecotourists and the people of Palumeu and neighboring villages (Apetina, Tepu). This will increase understanding of the fish fauna of Palumeu River and thus presumably promote conservation of the aquatic habitat and the fish fauna.
Reptiles and Amphibians
The RAP team recorded an estimated 40+ species of amphibians and 40+ species of reptiles. None of the specimens collected appeared vastly different morphologically, and thus obviously novel species, but two frogs stand out as requiring further morphological investigation (e.g. Anomaloglossus sp. and Hysiboas sp.). Furthermore, the snail-eating snake (Dipsas copei) is potentially a new record for Suriname, and an amphisbaenian (Amphisbaena sleveni) is recorded for just the second time. The total number of amphibians encountered is comparable to previous RAP surveys in Suriname, although many more reptiles were encountered than during the most recent (2010) RAP survey of Kwamalasamutu. Encountering more than 80 total species (including >20 snakes) is evidence for a healthy, diverse and seemingly pristine forest ecosystem.
Birds were surveyed using line transect counts and casual observation in lowland forest around the Juuru and Kasikasima camps. A limited survey using mist nets was undertaken in high-elevation (800 m) savanna forest and scrub in the Grensgebergte. The list of 313 species includes all birds seen or heard at the two RAP camps, the high-elevation satellite camp, the village of Palumeu, and during excursions along the Palumeu River. Records of several species represent range extensions within Suriname and the Guiana Shield. Whereas the lowland forest avifauna was broadly similar at the different localities, the high-elevation savanna forest harbored several species not known to occur in the adjacent lowlands, and therefore had the most unique species assemblage of any site. RAP results indicate that the lowland forest of SE Suriname probably contains the vast majority of bird species known to occur in the country’s interior, including many species of high conservation value. We recommend further surveys of high-elevation sites in the Grensgebergte and other mountain ranges in southern Suriname, to better determine the range limits of species restricted to high-elevation forests.
In total, preliminary field identifications documented 40 species of small mammals represented by 366 individual captures. More specifically, 28 species of bats were represented by 345 individuals, 9 species of rats and mice were represented by 18 individuals, and 3 species of opossums were represented by 3 individuals. In addition, a gray four-eyed opossum (Philander opossum) was seen climbing up a tree in a swampy area on the trail to Kasikasima Mountain. The commonest species of bat (larger fruit-eating bat, Artibeus planirostris) represented over 1/3 of the total captures in mist nets. It was more than twice as frequently caught as the next most abundant species (moustached bat, Pteronotus parnellii) and were documented at all three sites as were two other species (Seba’s short-tailed fruit bat, Carollia perspicillata, and round-eared bat, Lophostoma silvicolum).
The Upper Palumeu site was the most diverse for bats but the Kasikasima site had a higher abundance of bats. In contrast, the Grensgebergte site had the highest species diversity and relative abundance for rats. Each of the three sites documented only one species of opossum represented by one individual. There were three individuals of a rat collected at Grensgebergte that were not readily identifiable based on the available keys for mammals of the Guianas. Until further study of the morphology and molecular variation can be done to positively identify this species, it appears to represent at least a new country record for Suriname.
Large and Medium Sized Mammals
We surveyed medium- and large-bodied mammals by means of three main methods: camera trapping, searching for scat and animal tracks, and making visual and aural observations. During the RAP we recorded 18 species of medium- and large-bodied mammals. Primates are not included in this number. We recorded 11 mammal species at the Grensgebergte site and 15 species at the Kasikasima site.
The large caviomorph rodents were the most frequently photographed by the camera traps; this group appears to be the most common group of medium- and large-bodied nonvolant mammals in the area. The rodent species most frequently photographed by the camera traps were Paca (Cuniculis paca), Red-rumped Agouti (Dasyprocta leporina) and Red-acouchy (Myoprocta acouchy). Two species of peccary and two species of armadillo were also recorded.
Of the six species of cats known to occur on the Guiana Shield, the Jaguar (Panthera onca), Puma (Puma concolor), Ocelot (Leopardus pardalis) and Margay (Leopardus wiedii) were found during the survey. Ocelot was the most frequently recorded cat species during this survey and is common in the area. Tracks and scratch marks of Jaguar were found at the Grensgebergte site.
Six of the eight Suriname monkey species were recorded during the RAP survey: the Black Spider Monkey, Red Howling Monkey, Brown Capuchin, Squirrel Monkey, Golden Handed Tamarin, and Bearded Saki. The White Faced Saki and the Wedge Capped Capuchin were not spotted at either site.
Preliminary results indicate that the large bodied species (Black Spider Monkey, Red Howling Monkey) are present in relative abundance. They were either spotted or heard on a regular basis at both sites. Since these two species are the most hunted by local communities (pers. comm.), this indicates sustainable hunting practices by these communities. The absence of the Bearded Saki, White Faced Saki, and Wedge Capped Capuchin at the Grensgebergte site does not necessarily mean that they are not present. These three species are quite difficult to spot due to rarity and elusiveness. The Bearded Saki however, was spotted once at the Kasikasima site. More data need to be collected regarding these “missing” species. From a conservation perspective both sites can be considered to have healthy populations of monkey species.