Laguna Madre, Gulf of Mexico
The Laguna Madre is the name of two long, shallow bays along the western coast of the Gulf of Mexico in the United States and Mexico; the two being separated by the outlet of the Rio Grande.
Meaning “mother lagoon” in Spanish, the Laguna Madre proper is 130 miles (209 km) long, the length of Padre Island. Its biological corridor, though, extends well into Mexico, to the mouth of the Río Soto la Marina in the state of Tamaulipas.
In the United States, the section visible here, Laguna Madre is separated from the Gulf of Mexico on the east by Padre Island, and bounded on the west by mainland Texas, and extends from Corpus Christi in the north to Port Isabel in the south.
In Mexico, Laguna Madre is separated from the Gulf of Mexico on the east by a number of barrier islands, including Barra Los Americanos, Barra Jesús María, and Barra Soto la Marina. It is bounded on the west by mainland Tamaulipas.
The Laguna Madre is very shallow, with an average depth of only 0.9 m. It is connected to the ocean by only two narrow inlets, so the tidal range – which is already minor in this part of the Gulf of Mexico – is negligible.
Oceanographically, the Laguna Madre is considered a hypersaline lagoon; this indicates that it is usually much saltier than the ocean, due to being nearly landlocked in a semiarid environment, and is one of only six hypersaline lagoons in the world. The Laguna Madre has been experiencing a persistent algal bloom (including drift algae) that may be partially caused by its hypersaline conditions, which favor algal growth.
Atmospheric effects are much more important than tides in its circulation; its weak currents generally follow the prevailing winds, and these winds can influence the water level by as much as a meter. Some such currents are visible to the South, their movements made visible by green algae.