Pantanal

 The Pantanal is one of the best examples of natural heritage in Brazil. It is the biggest continental wetland in the world – covering approximately 210.000 km2, of which 140.000 km2 lies in Brazil, in parts of the states of Mato Grosso and Mato Grosso do Sul. The Pantanal is noteworthy for the richness of its fauna, including 263 species of fish, 122 species of mammal. 93 species of reptile, 1.132 species of butterfly and 656 species of bird. Heavy rain is a characteristic of this biome. The land; almost always flat, is flooded periodically by innumerable creeks and ebb tides that run between ox-bow lakes and marshes. During the flood season these waters flow into and blend with the waters of the Rio Paraguay, renewing and fertilizing the region.

The balance of these ecosystems depends, basically, on the flood cycle which is directly connected to regional rainfall levels.Generally speaking, the rains occur with greater frequency at the source of rivers which then spill out over the flood plain.

Jaguar

Generally speaking, the rains occur with greater frequency at the source of rivers which then spill out over the flood plain. With the beginning of the wet season in the uplands (from November), the water level in the rivers rises, leading to flooding.
The same occurs in parallel in the Rio Paraguay, because there is nowhere for the water to run to. The floodwater bursts its banks and covers vast areas as it flows in search of somewhere to run to, which lies hundreds of kilometres away at the confluence with the Rio Paraná, which in turn flows into the Rio da Prata and this, into the Atlantic Ocean and away from Brazil. The floodwaters cover up to 2/3 of the Pantanal.

Giant Otter

From May the floodwaters start to recede and the water level lowers
steadily. When the surface dries out there lies under it a fine mixture of sand, the remains of animals and plants, seeds and humus, which boost the fertility of the soil.
This flooding spectacle is naturally – occurring on an annual basis, enabling a renewal of local Pantanal flora and fauna. The enormous volume of water, which practically covers the Pantanal region, forms a true freshwater sea where thousands of fish proliferate. Small fish feed bigger ones or birds and other animals.
When the floodwaters begin to subside, a large quantity of fish remain caught in the ox-bow lakes and bays, unable to return to the rivers. For months, birds and carnivorous animals (caiman, otters and others) therefore have a veritable banquet available to them.

Birds at dawn

The waters continue dropping more and more and in the lakes, which are now very shallow, fish such as dorado, pacu and traíra can be caught by hand. Birds both large and small fly over the water, forming a spectacle of natural beauty.
Source: wwf.org