The Orinoco River Delta, Venezuela
67
During many decades the absence of roadways has protected the Orinoco Delta from destructive human activities, apart from illegal wildlife extraction and unauthorized logging. Environmental impacts, however, have
increasingly been felt over the last decades and are likely to augment in
coming years. For example, a gold rush has attracted some 40,000 Garimpeiro miners to the Middle Orinoco River basin; the sediments and mercury
contamination from mining activities will find their way into the waterways
and the biota of the delta. Furthermore, the Orinoco River and the Rio Grande channel in the delta are among the most important fluvial waterways in
the world and are the main shipping route (21 x 10 6 tons year- 1 )for minerals
(i.e., bauxite, iron, aluminum) to the Atlantic Ocean. Continuous dredging
activities in the channel are likely to modify physico-chemical and biological characteristics in the delta and nearshore waters.
In 1965, the construction of a cofferdam, aiming at land reclamation at
the Manamo channel, turned vast areas into barren land (cat clays) unsuitable for agricultural use. Additionally, the obstruction of waterways
modified the hydrological regime (Colonnello 1996), and the advance of
saltwater into the oligohaline Manamo channel led to the expansion of
mangroves at rates six times faster ( 6-7 ha year- 1 ) than before ( Colonnello
and Medina 1998 ). In the near future, however, oil prospecting and drilling
might be the major threat to the delta. Although concessions for oil extraction in the delta were granted as early as 1928, owing to the inherent difficulties of working in swamps and channels and high operating costs,
activities soon ceased. New exploration rights have been awarded over the
last decade and at present production is approximately 100,000 barrels per
day. During the following years, oil extraction in an area of 213,000 ha
could produce up to 160,000 barrels per day.
The exploitation (silviculture) of mangrove timber in the northern Orinoco Delta during the 1970s has resulted in ecological consequences that
still need to be assessed and, although exploitation was abandoned, the
community is far from having recovered (Ernesto Medina, pers. comm.).
The semi-industrial extraction of palm hearts (Euterpe spp.) has been
steadily expanding (239,841 kg year- 1 ) in past years. The alternative extraction of palm heart from plantations of Bactris gasipaes might eventually
attenuate the large-scale exploitation of Euterpe oleracea. Apart from palm
hearts, the pulp of Euterpe oleracea fruits is used for juice, ice cream and
liquor.
More than 60 species of fishes are commercially exploited in the Orinoco River and the delta. Fisheries are largely artisanal, using small wooden canoes (curiaras) carved from tree trunks. Since catches are landed
at different ports in the delta and the lower Orinoco River, fisheries statistics for the delta are not precise. About 45% of the total catch is com-
67
During many decades the absence of roadways has protected the Orinoco Delta from destructive human activities, apart from illegal wildlife extraction and unauthorized logging. Environmental impacts, however, have
increasingly been felt over the last decades and are likely to augment in
coming years. For example, a gold rush has attracted some 40,000 Garimpeiro miners to the Middle Orinoco River basin; the sediments and mercury
contamination from mining activities will find their way into the waterways
and the biota of the delta. Furthermore, the Orinoco River and the Rio Grande channel in the delta are among the most important fluvial waterways in
the world and are the main shipping route (21 x 10 6 tons year- 1 )for minerals
(i.e., bauxite, iron, aluminum) to the Atlantic Ocean. Continuous dredging
activities in the channel are likely to modify physico-chemical and biological characteristics in the delta and nearshore waters.
In 1965, the construction of a cofferdam, aiming at land reclamation at
the Manamo channel, turned vast areas into barren land (cat clays) unsuitable for agricultural use. Additionally, the obstruction of waterways
modified the hydrological regime (Colonnello 1996), and the advance of
saltwater into the oligohaline Manamo channel led to the expansion of
mangroves at rates six times faster ( 6-7 ha year- 1 ) than before ( Colonnello
and Medina 1998 ). In the near future, however, oil prospecting and drilling
might be the major threat to the delta. Although concessions for oil extraction in the delta were granted as early as 1928, owing to the inherent difficulties of working in swamps and channels and high operating costs,
activities soon ceased. New exploration rights have been awarded over the
last decade and at present production is approximately 100,000 barrels per
day. During the following years, oil extraction in an area of 213,000 ha
could produce up to 160,000 barrels per day.
The exploitation (silviculture) of mangrove timber in the northern Orinoco Delta during the 1970s has resulted in ecological consequences that
still need to be assessed and, although exploitation was abandoned, the
community is far from having recovered (Ernesto Medina, pers. comm.).
The semi-industrial extraction of palm hearts (Euterpe spp.) has been
steadily expanding (239,841 kg year- 1 ) in past years. The alternative extraction of palm heart from plantations of Bactris gasipaes might eventually
attenuate the large-scale exploitation of Euterpe oleracea. Apart from palm
hearts, the pulp of Euterpe oleracea fruits is used for juice, ice cream and
liquor.
More than 60 species of fishes are commercially exploited in the Orinoco River and the delta. Fisheries are largely artisanal, using small wooden canoes (curiaras) carved from tree trunks. Since catches are landed
at different ports in the delta and the lower Orinoco River, fisheries statistics for the delta are not precise. About 45% of the total catch is com-