Marajó is a large delta island in the state of Pará, Brazil. It is the main and largest of the islands in the Marajó Archipelago. The island is bordered by the mouth of the Amazon River to the west and northwest, the Atlantic Ocean to the northeast and by the Pará River, a distributary of the Amazon to the east. From approximately 400 BC to 1600 AD, Marajó was the site of an advanced Pre-Columbian society called the Marajoara culture, which may have numbered more than 100,000 people at its peak. Today, the island is known for its large water buffalo population, as well as the pororocatidal bore periodically exhibited by high tides overcoming the usual complex hydrodynamic interactions in the surrounding reaches of Amazon delta. It is the second-largest island in South America, and the 35th largest island in the world. With a land area of Marajó is comparable in size to Switzerland. Its maximum span is long and in perpendicular width.
Geography
The northeastern coastline of Marajó faces the Atlantic Ocean. The outflow from the Amazon between January and July is so great that the sea at the mouth is made up of freshwater for some distance from shore. The city ofBelém lies to the south across the southern fork of the river's mouth. The island sits almost directly on the equator. Together with smaller neighboring islands that are separated from Marajó by rivers, they form the Marajó Archipelago, with an aggregate area of. The archipelago is contained in the Marajó Archipelago Environmental Protection Area, a sustainable-use conservation unit established in 1989 to protect the environment of the delta region. Large parts of the islands are flooded during the rainy season because of higher water levels of the Amazon River along the coast and heavy rainfall in the interior. Marajó is almost entirely flat. During the rainy season, much of the island becomes flooded as a large lake. There are 20 large rivers on the island. Because of the changing water levels and regular seasonal flooding, many settlements are built on stilts. The island is known for the pororoca, a tidal bore phenomenon in the river that creates large waves reaching in height. It is a tourist destination, especially for surfing of the bore.
Ecology
The eastern side of the island is dominated by savanna vegetation. There are large fazendas with animal husbandry. This is also the location of Lake Arari, which has an area of, but shrinks by 80% during the dry season. There are large herds of domesticated water buffalo, which are technically invasive to the island; they now number about 450,000, higher than the island's human population. The western side of the island is characterized by Várzea forests and small farms. Lumber and açaí are produced there. The island is in the Marajó várzea ecoregion, an area of seasonally and tidally flooded várzea forest. To the north of the large savanna area are palm swamps, mainly with Buriti Palm and Euterpe oleracea. During the rainy season, the swamps are flooded one meter high. Little is known about the ecology of these swamps.
Municipalities
The most important towns are in the southeastern portion of the island: Soure, Salvaterra, and the largest city, Breves. They feature a basic touristic infrastructure and are popular because of the generous, lightly populated beaches. The city of Soure, on the island's Atlantic coast, serves as an entry point to the island via its ferry link to Belém. The island is shared by 16 municipalities of three microregions:
The island was the site of an advanced pre-Columbian society, the Marajoara culture, which existed from approximately 400 BC to 1600 AD. The island has been a center of archaeological exploration and scholarship since the nineteenth century. Scholars from the 1980s forward have divided the pre-Columbian period into the Ananatuba phase, the Mangueiras phase, the Formiga phase, the Marajoará phase, and the Aruã phase. Since the 1990s, there has been debate over the origins and sophistication of Marajó's pre-Columbian society. Based on fieldwork in the 1940s and 1950s, the archaeologist Betty Meggers initially argued that the Marajoara culture had been founded by emigrants from the Andes and that the society steadily declined until its final collapse at approximately 1400 AD, due to the Marajó's poor soil fertility and other environmental factors. Megger's hypotheses subsequently became associated with environmental determinism. Her theory has since been rejected, however, by the archaeologist Anna Curtenius Roosevelt, who re-excavated Marajó in the 1980s. According to Roosevelt, the Marajoara culture developed independently within the Amazon and featured both intensive subsistence agriculture and major public works. Roosevelt estimated that Marajó may have had a population of more than 100,000 people at its peak. The population lived in homes with tamped earth floors, organized themselves into matrilineal clans, and divided tasks by sex, age, and skill level. The arrival of Europeans in the sixteenth century was catastrophic to the indigenous population of the island; 90% died due to high mortality from Eurasian infectious diseases; they lacked immunity against these diseases that had become endemic in European and Asian cities. In contrast, however, during the 1918–1919 pandemic worldwide of the Spanish influenza, Marajó was the only major populated area not to have any documented cases of the illness. The island is also the location of the Roman Catholic Territorial Prelature of Marajó.
