About UNEP UNEP Offices News Centre Publications Events Awards Milestones UNEP Store
GEO Year Book 2004/5  
UNEP Website GEO Home Page

Progress has been made in biodiversity conservation, but the strain on natural resources is still high. Fragmentation of habitat in particular demands new approaches for conservation from a bioregional perspective, and on a continental scale compatible with new economic strategies.

Countries are trying to strengthen their economies by increasing bilateral trade agreements and promoting sub-regional market blocks. This will affect the pace and patterns of natural resources consumption. However, these same efforts of collaboration can help to develop and implement environmental policies and initiatives that cross over national boundaries, such as watershed management and adaptation to climate change impacts.

Our Changing Environment
Lake Maracaibo, Venezuela: Invasive species

Lake Maracaibo in northwestern Venezuela is the largest natural lake in South America at 13 330 km2. At its widest point, it is more than 125 km wide. It has been suffering from a serious problem of invasive duckweed, a tiny aquatic plant that grows in freshwater. The first image (right), from the Aqua MODIS satellite on 17 December 2003, shows the lake during the winter months, when duckweed is absent from the lake’s waters, and the silvery sunglint is absent.

In summer the weed blooms. The true-colour image from 26 June 2004 (bottom left) shows strands of duckweed curling through the lake, floating at the surface or slightly submerged in the brackish water. The lake itself lies in the Maracaibo basin, which is semi-arid in the north, but averages over 1 200 mm of annual rainfall in the south.

A closer look in August 2004 (bottom right) reveals the stranglehold the duckweed has on port areas, especially along the important oil shipping routes in the neck of Lake Maracaibo. Fish and the fishing industry suffer: thick green mats block photosynthesis and alter fish habitats. The weed also adheres to boats, affects cooling systems and obstructs travel.

In September 2004 Venezuela’s Ministry of Environment and Natural Resources reported that it had reduced the duckweed area by 75 per cent, using duckweed harvesting machines from the United States. The ministry is investigating using the harvested weed as fodder.

Source: Jeff Schmaltz MODIS Land Rapid Response Team, NASA GSFC
http://modis. gsfc.nasa.gov/gallery/individual. php?db_date=2004-07-09# September update:
http://www.vheadline. com/ readnews.asp?id=22759

Sources: CCRS/NRC 2004, UNEP/GRID – Sioux Falls

Earthprint.com Order the Book