White pelicans (Pelecanus erythrorhynchos) Lake Chalapa, Mexico Photograph by John Mitchell/ Earth Images foundation   Mexico: State of Michoacán Flooded Grasslands and Savannas   100 square miles (300 square kilometers) -- about twice the size of Washington DC Critical/Endangered

· High Mountain Lakes
· Special Features
· Did You Know?
· Wild Side
· Cause for Concern
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High Mountain Lakes

In the valleys of the Mexican volcanic highlands lie rush-filled lakes and swamps. The climate is temperate, with some areas getting more rain than others. Lakes and reed beds dominate the ecoregion. Several lakes, like Lake Patzcuaro, are filled with many endemic fish and aquatic plants. Xeric scrubs grow around the lake and pine-oak forests grow in the surrounding mountains.

Special Features

Lake Patzcuaro, one of the largest volcanic lakes in Mexico, contains more than 45 aquatic plants and 13 aquatic birds, 10 of which are migratory. Some of the dominant water plants are pond weeds, cattails, bullrushes, and Mexican water lilies. Many commercially important fish depend on the health of these wetlands. They not only act as nurseries for many species, but they also help filter water, recharge underground water tables, and provide habit for fish in one or more of their life stages.

	Colonies of slender-billed grackles once nested in marshes of the headwaters of the Lerma River, but these birds are now extinct.

Wild Side

Endemic fish of the Silverside and the Sardine families inhabit these lakes. Other fish include the black sea bass (which is actually found in freshwater), the endemic Patzcuaro chub, and the blanco fish. Many migratory birds rest and feed here as they fly between North and South America. Large flocks of Canada geese are a familiar sight. The endemic black-polled yellowthroat bird lives in the reeds, sedges, and cattails that surround the lakes.

Cause for Concern

While a significant portion of Lake Patzcuaro and the surrounding wetlands has been protected, a large part of the forests surrounding this and other lakes has been logged. This causes erosion, which increases sedminentation and salinity, and in turn alters nutrient exchange and plant-animal interactions. Severe water pollution is caused by human activities and the nearby leather industry. Water extraction reduces lake levels contributing to the destruction of marshes. This is one of the biggest threats to the marshes, as well as filling in these wetlands for development. Byproducts of the nearby industries also contaminate the lakes. And exotic fish, like the black lobina, have been introduced, which out-compete or eat the native fish.

For more information on this ecoregion, go to the World Wildlife Fund Scientific Report.