The Marajó Bay, or Marajoara gulf and Amazon gulf, is an
recessed body of water of the Brazilian coast located in the state of
Pará
Pará is a state of Brazil, located in northern Brazil and traversed by the lower Amazon River. It borders the Brazilian states of Amapá, Maranhão, Tocantins, Mato Grosso, Amazonas and Roraima. To the northwest are the borders of Guyana a ...
. It is roughly in size, and is a receptacle for the waters of the
Pará River distributary channel, the waters of the
Tocantins basin
The Tocantins basin, or Araguaia-Tocantins basin, is a Brazilian river basin, almost entirely located between the 2ºS and 18ºS parallels and the 46ºW and 56ºW meridians. The main rivers in the basin are Tocantins and Araguaia.
The basin exten ...
and the waters of the Guajará Bay, serving as the eastern aquatic border of both the
Marajó Island and the
Marajó Archipelago.
[Lima, Ricardo Fonseca de; Cardoso, Raísa Nicole Campos; Sena, Manoel José dos Santos]
Estudo do Modelo Hidrodinâmico da Baía do Guajará Calibrado para o Período de Chuva
ABES, 2013 Marajó Bay is an estuary consisting of both salt and fresh water, resulting in the classification of an estuarine system.
[Menezes, Maria Ozilea Bezerra, et al. “Estuarine Processes in Macro-Tides of Amazon Estuaries: A Study of Hydrodynamics and Hydrometeorology in the Marajó Bay (Pará-Brazil).” ''Journal of Coastal Research'', 2013, pp. 1176–1181. ''JSTOR'', www.jstor.org/stable/26490946. Accessed 1 Mar. 2021.] Marajó Bay also receives sediments from the Amazon River through the Breves Channel as well as the Pará River, causing the water to be turbid.
The
Pará River is a small fraction of the
Tocantins River
The Tocantins River ( pt, Rio Tocantins, link=no , , Parkatêjê: ''Pyti'' ɨˈti is a river in Brazil, the central fluvial artery of the country. In the Tupi language, its name means "toucan's beak" (''Tukã'' for "toucan" and ''Ti'' for "beak" ...
that is one of the providers of water for Marajó. The river is vital to the surrounding areas and makes different areas and ports very accessible for locals.
The river also eventually clashes with salt water from the Atlantic Ocean in the Marajó Bay. A circulation process of salinity, temperature, and tidal range in the two different water types occurs in the bay as they meet.
Salt water concentrations are also impacted by low water periods of the Amazon River.
Ecology


Marajó Bay's estuarine waters provide a diverse feeding and nursery area for marine species in this ecosystem, and provides overall habitat for an estimated 108 marine species.
There are many different marine species found in the Bay's waters, some examples of which are Scomberomorus brasiliensis, Cynoscion acoupa, Mugil sp. and Bagre bagre, are vital to the fishing health of locals.
On the shorelines of the bay, mangroves can be found, and the general classifications of surrounding lands in "vegetation mosaics" are floodplain forests, upland forests, mangroves, and grassland.
The bay provides a home to a unique variety of marine life, and mangroves in particular are vital to different life cycles of marine species such as fish or crustaceans.
Human use
Due mainly to its size and geographic location, Marajó Bay has long been used by humans for a variety of reasons. The bay has proven to be a rewarding spot for both local, and industrial fishermen. Additionally, it is frequented by boats as a popular spot for shipping, due to its entrance at the Atlantic, and eventual deeper penetration into the mainland.
Lastly, there have been past attempts in the area for fossil-fuel drillings, however they have proved futile.
References
{{coord, -1.03, -48.49, type:waterbody_region:BR_dim:200000, display=title
Bays of Brazil
Geography of Pará