The lemna sp, or duckweed, extends like a skein about 30 centimeters thick over Lake Maracaibo in western Venezuela. The weed covers 13 percent of the lake's 12,000 square kilometer surface. The increase this month is due to “changes in the wind, and the green patches, which reproduce rapidly, shifting away from the center of the lake,” José Rincón, a biologist with the University of Zulia's aquatic contamination lab, told Tierramérica.

When the duckweed rots, it emits a foul odor that forces local residents to seek refuge inside, and scares off people from lakeside restaurants and tourist activities. The thick patches also get in the way of fishing operations.

The government will provide 900,000 dollars for manual removal of the plant this season.