Biological Society of Washington - Department of Botany ...

More documents

Recommendations

Info

NUMBER 17 3 and are so unusual that they inspired a fictional scientific expedition referred to one as ‘‘The Lost World’’ (Doyle 1912), a term sometimes applied to all tepuis. Notable waterfalls of the region include Angel Falls (979 m) on Auyán-tepui in Venezuela and Kaieteur Falls (226 m), which flows year around, on the eastern-most edge of the Roraima formation known as the Potaro Plateau in Guyana. Granitic dome mountains occur on the Shield in the southern part of the three Guianas (Guyana, Suriname, French Guiana), where they are known as ‘‘inselbergs,’’ as well as in the western extreme of the Shield in the Puerto Ayacucho region in Venezuela where they are called ‘‘lajas.’’ Deposits of low-nutrient white sands occur inland of the coastal plain, in belts across the Shield, and in isolated pockets. Large areas of savanna are found in the region, particularly the complex of savannas that includes the Rupununi Savanna in southwestern Guyana, the Gran Sabana in eastern Venezuela, and the savannas of northern Roraima, Brazil. In some of these areas the sands overlay a clay hardpan that is resistant to penetration by tree roots and that floods during the heavy rainy season, resulting in limited forest growth. Tertiary and Quaternary sediments separate the southern edge of the Guiana Shield from the Amazon River and the eastern edge from the Atlantic Ocean. Climate As a whole, the Guiana Shield region has a tropical climate characterized by a relatively high mean annual temperature exceeding 25uC at sea level, an annual monthly maximum temperature range of less than 5uC, and an average daily temperature range of approximately 6uC (Snow 1976). Because of the Guiana Shield’s location just north of the equator, its climate varies primarily according to elevation and effects of the trade winds that combine to affect rainfall patterns. The trade winds blow consistently from the east and northeast, off of the Atlantic Ocean onto northeastern South America, with wind speeds averaging from 3–4 m per second. Due to orographic effects, the easternmost escarpments of the mountains of the Guiana Shield are generally localities of increased precipitation where these moisture-laden winds meet the slopes (Clarke et al. 2001). Seasonal oscillations of the Intertropical Convergence Zone (ITCZ) also bring variations in rainfall as the locations of low pressure zones near the equator change (Snow 1976). Varying primarily by latitude, one or two rainy seasons result from shifts in the ITCZ. The heaviest rains usually occur between May and August, whereas the rainy season running from December to January is shorter and less intense, with rains that do not penetrate as far inland. Even during most dry seasons, frequent storms provide adequate moisture to allow evergreen tropical moist forests to persist in most low elevation parts of the region. Biological Diversity The variety of landscapes of the Guiana Shield includes sandstone tepuis, granite inselbergs, white sands, seasonally flooded tropical savannas, lowlands with numerous rivers, isolated mountain ranges, and coastal swamps, each supporting a characteristic vegetation (Huber 1995b, Huber et al. 1995). This variety accounts for a great deal of the high diversity and endemicity of the Shield’s biota. The highlands of the Shield have a flora and fauna with numerous endemic species. Some tepui endemic species occur as low as 300 m in elevation, with increasing numbers by 1500 to 1800 m, and fully developed communities occurring by 2000 m. Few if any plant or animal specimens have been collected from most medium to high elevation areas of the Guiana Shield. Many parts of the Shield are poorly explored, including parts of Brazil north of the Amazon River, much of eastern Colombia, and the southern parts of Venezuela, Guyana, Suriname, and French Guiana. Conservation With the exceptions of the populated localities such as Puerto Ayacucho, Ciudad Guayana, Ciudad Bolívar, Boa Vista, Georgetown, Paramaribo, Cayenne, the agricultural coastal areas, and open areas like the Rupununi Savanna, the environment of the Guiana Shield has benefited from limited access and low population densities, although this same isolation has hindered biodiversity research. Estimates vary, but much of the vegetation is still relatively undisturbed by human activities. Recently, however, the pace of disturbance has greatly increased. Current threats to the environment include large-scale logging by Asian and local companies, large- and small-scale gold and diamond mining, oil prospecting, bauxite mining, hydroelectric dams, wildlife trade, and populationrelated pressures such as burning, grazing, agriculture, and the expansion of towns and villages. Taken together, these impacts have begun to take their toll, with vast areas vulnerable to increasing disturbance a fact easily observed by using Google Earth and ‘‘flying’’ over the area. The status of conservation efforts varies by country. Throughout the Guiana Shield, many areas that are designated as protected or otherwise restricted are often only ‘‘paper’’ parks because of a lack of infrastructure, funds, and will to actually protect the areas. Over the last four decades, Venezuela has established seven national parks, 29 natural monuments, and two biosphere reserves covering about 142,280 km 2 , more than 30% of its share of the
4 BULLETIN OF THE BIOLOGICAL SOCIETY OF WASHINGTON Guiana Shield (Funk & Berry 2005). In Guyana, the progress of conservation efforts has been slower, with the only substantial protected area being Kaieteur National Park, its 627 km 2 comprising about 3% of the country’s area (Kelloff 2003, Kelloff & Funk 2004), with additional reserves under consideration. Guyana’s 3710 km 2 Iwokrama forest (Clarke et al. 2001) has parts listed as reserves, but overall it is dedicated to sustainable use; unfortunately, logging has begun, and the section of the road from Boa Vista, Brazil, to Georgetown, Guyana, that runs through Iwokrama is about to be paved. Suriname’s protected areas system includes one national park and a network of 11 reserves, totaling almost 20,000 km 2 , over 12% of its total area. This includes the recently created 16,000 km 2 Central Suriname Nature Reserve, a UNESCO World Heritage Site that joined and expanded three existing reserves (see http://www. stinasu.com). French Guiana has no officially designated protected areas, but 18 proposed sites total 6710 km 2 , about 7.5% of its area (Lindeman & Mori 1989). The natural areas of Venezuela and Guyana are currently under the most anthropogenic pressure, while those of French Guiana are probably less threatened. The Shield encompasses part or all of six countries with six different governments, five official languages and many more indigenous languages. Cooperation is sometimes hampered by border disputes, illegal crossborder activities involving gold and wildlife, and a lack of interest by governments that are located far away. The implementation of conservation practices is further complicated by many issues concerning the indigenous peoples of the region. All of these challenges will have to be overcome on the way to designing and maintaining a viable reserve system for the Guiana Shield. However, it is critical that we gain an understanding of the flora and fauna of the Shield area so that decisions can be made on critical areas that have high priority for conservation and so data can be collected from areas that might ultimately be destroyed. Because it is an ancient, fairly isolated geological area, it is rich in endemic plant and animal taxa, with many more likely to be discovered with additional exploration. In addition, because this area has been long neglected by biologists, it is often an area of ‘‘inadequate information’’ for many biodiversity analyses. This volume contains the fishes from the Guiana Shield, when paired with the previously published Checklist of the Terrestrial Vertebrates of the Guiana Shield (Hollowell & Reynolds 2005), we can examine the size and scope of Vertebrates, an important monophyletic group, known to inhabit the Guiana Shield. Table 2 lists the vertebrate groups and their sizes. The two checklists include a total of 53 orders, 189 families, 1190 genera, and 301 species. A large Table 2.—Number of vertebrate taxa at different ranks. Orders Families Genera Species Amphibians 2 13 59 269 Reptiles 3 22 119 295 Mammals 11 35 143 282 Birds 22 70 493 1004 Fishes 15 49 376 1168 Total 53 189 1190 3018 percentage of the species (38%) are contributed by the fishes listed in this volume. Figure 2 compares the vertebrate diversity across the major political areas of the Guiana Shield and shows the species turnover between different areas. The mammals and reptiles have the most similar fauna across the Shield with a 58% and 53% overlap, respectively, between French Guiana (the extreme east) and Venezuela-Amazonas (the extreme west). Fish and birds have the least (24% and 10%, respectively). With fishes this can probably be explained by the fact that the headwaters of the rivers in the east are widely separated from those of the west. The rivers of the Shield in the west (Venezuela) have their source in the Venezuelan Guayana and the Andes, in the central portion (Guyana) the Essequibo drains mainly from the Acari Mountains which lie on the border with Brazil as does the Corantijn River (border between Guyana and Suriname). To the east, rivers such as the Maroni and Oyapock drain from the Tumuk-Humak Mountains. The bird diversity percentage of ‘turn over’ was surprisingly small until one realizes that there are very different flyways that go across the eastern and western parts of the Shield. When the three major avenues of vertebrate mobility are examined (land, air, water), it seems that the land provides the most stable species make up and the air and water provide the least. Could this have anything to do with the resulting high species diversity of the birds and fishes? In the wider scope of biological understanding, the goal of checklists of this type is to understand diversity in terms of the spatial, evolutionary, and ecological settings of physical environments, rather than simply by political boundaries. The assembly of these lists is a step toward considering the fauna in terms of the geological entity of the Guiana Shield. Future studies will include the analyses of animal community composition on finer landscape scales, using developing abilities to produce customized checklists for research and conservation with Geographic Information System (GIS) technologies drawing upon comprehensive databases that include georeferenced museum specimen records. Biological Diversity of the Guiana Shield (BDG) The ‘‘Biological Diversity of the Guiana Shield Program’’ (BDG) is a field-oriented program of the
Page 1 and 2: BULLETIN of the Biological Society
Page 3 and 4: CHECKLIST OF THE FRESHWATER FISHES
Page 5 and 6: CONTENTS CONTRIBUTORS. . . ........
Page 7 and 8: Paulo H. F. Lucinda, Laboratório d
Page 10 and 11: In the face of the growing biodiver
Page 14 and 15: NUMBER 17 5 Figure 2. A comparison
Page 17 and 18: History A vast complex of wetlands,
Page 19 and 20: NUMBER 17 11 did so summarized belo
Page 21 and 22: NUMBER 17 13 composition of ichthyo
Page 23 and 24: NUMBER 17 15 groups of vertebrates
Page 25 and 26: NUMBER 17 17 Guayana), Venezuela.
Page 28 and 29: The cornerstone of this project was
Page 30 and 31: NUMBER 17 23 Sarmento-Soares, L. M.
Page 32 and 33: 26 BULLETIN OF THE BIOLOGICAL SOCIE
Page 59 and 60: PHOTOGRAPHIC ATLAS OF FISHES OF THE
Page 61 and 62: NUMBER 17 55 Figure 4. Author photo
Page 63 and 64:
NUMBER 17 57 white and vice versa).
Page 65 and 66:
NUMBER 17 59 (Serrasalminae), dans
Page 67 and 68:
62 BULLETIN OF THE BIOLOGICAL SOCIE
Page 69 and 70:
Page 71 and 72:
Page 73 and 74:
Page 75 and 76:
Page 77 and 78:
Page 79 and 80:
Page 81 and 82:
Page 83 and 84:
Page 85 and 86:
Page 87 and 88:
Page 89 and 90:
Page 91 and 92:
Page 93 and 94:
Page 95 and 96:
Page 97 and 98:
Page 99 and 100:
INDEX TO ORDERS, FAMILIES, AND SUBF
Page 101:
BULLETIN OF THE BIOLOGICAL SOCIETY
show all

Biological Society of Washington - Department of Botany ...

Create successful ePaper yourself

Delete template?

Save as template?