Gulf of California

Gulf of California

Overview
The Gulf of California (also known as the Sea of Cortez or Sea of Cortés or Vermilion Sea;
locally known in the Spanish language
Spanish language
Spanish , also known as Castilian , is a Romance language in the Ibero-Romance group that evolved from several languages and dialects in central-northern Iberia around the 9th century and gradually spread with the expansion of the Kingdom of Castile into central and southern Iberia during the...

 as Mar de Cortés or Mar Bermejo or Golfo de California) is a body of water that separates the Baja California Peninsula
Baja California Peninsula
The Baja California peninsula , is a peninsula in northwestern Mexico. Its land mass separates the Pacific Ocean from the Gulf of California. The Peninsula extends from Mexicali, Baja California in the north to Cabo San Lucas, Baja California Sur in the south.The total area of the Baja California...

 from the Mexican
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 mainland. It is bordered by the states
States of Mexico
The United Mexican States is a federal republic formed by 32 federal entities .According to the Constitution of 1917, the states of the federation are free and sovereign. Each state has their own congress and constitution, while the Federal District has only limited autonomy with a local Congress...

 of Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...

, Baja California Sur
Baja California Sur
Baja California Sur , is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. Before becoming a state on October 8, 1974, the area was known as the South Territory of Baja California. It has an area of , or 3.57% of the land mass of Mexico and comprises...

, Sonora
Sonora
Sonora officially Estado Libre y Soberano de Sonora is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided into 72 municipalities; the capital city is Hermosillo....

, and Sinaloa
Sinaloa
Sinaloa officially Estado Libre y Soberano de Sinaloa is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 18 municipalities and its capital city is Culiacán Rosales....

 with a coastline of approximately 2500 mi (4,023.4 km). Rivers which flow into the Gulf of California include the Colorado
Colorado River
The Colorado River , is a river in the Southwestern United States and northwestern Mexico, approximately long, draining a part of the arid regions on the western slope of the Rocky Mountains. The watershed of the Colorado River covers in parts of seven U.S. states and two Mexican states...

, Fuerte
Fuerte River
The Fuerte River is a river in the northwestern Mexican state of Sinaloa. It begins at the junction of the Verde and Urique rivers, on the Sierra Madre Occidental mountain range. It flows generally southwest for a distance of 290 km, emptying into the Gulf of California at Lechuguilla Island,...

, Mayo
Mayo River, Mexico
The Mayo River is located in the Mexican state of Sonora. There is an important dam, named Adolfo Ruiz Cortines after one of the Presidents of Mexico, located up river, for the purpose of generating electricity, as well as irrigation for agriculture in the Mayo Valley. It is located 30 km...

, Sinaloa
Sinaloa River
-References:*Atlas of Mexico, 1975 .*The Prentice Hall American World Atlas, 1984.*Rand McNally, The New International Atlas, 1993....

, Sonora
Sonora River
Río Sonora is a 402-kilometer-long river of Mexico. It lies on the Pacific slope of the Mexican state of Sonora and it runs into the Gulf of California.-Watershed:...

, and the Yaqui
Yaqui River
The Yaqui River is a river in the state of Sonora in northwestern Mexico. Being the largest river system in the state of Sonora, the Yaqui river is used for irrigation....

.
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Encyclopedia
The Gulf of California (also known as the Sea of Cortez or Sea of Cortés or Vermilion Sea;
locally known in the Spanish language
Spanish language
Spanish , also known as Castilian , is a Romance language in the Ibero-Romance group that evolved from several languages and dialects in central-northern Iberia around the 9th century and gradually spread with the expansion of the Kingdom of Castile into central and southern Iberia during the...

 as Mar de Cortés or Mar Bermejo or Golfo de California) is a body of water that separates the Baja California Peninsula
Baja California Peninsula
The Baja California peninsula , is a peninsula in northwestern Mexico. Its land mass separates the Pacific Ocean from the Gulf of California. The Peninsula extends from Mexicali, Baja California in the north to Cabo San Lucas, Baja California Sur in the south.The total area of the Baja California...

 from the Mexican
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 mainland. It is bordered by the states
States of Mexico
The United Mexican States is a federal republic formed by 32 federal entities .According to the Constitution of 1917, the states of the federation are free and sovereign. Each state has their own congress and constitution, while the Federal District has only limited autonomy with a local Congress...

 of Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...

, Baja California Sur
Baja California Sur
Baja California Sur , is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. Before becoming a state on October 8, 1974, the area was known as the South Territory of Baja California. It has an area of , or 3.57% of the land mass of Mexico and comprises...

, Sonora
Sonora
Sonora officially Estado Libre y Soberano de Sonora is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided into 72 municipalities; the capital city is Hermosillo....

, and Sinaloa
Sinaloa
Sinaloa officially Estado Libre y Soberano de Sinaloa is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 18 municipalities and its capital city is Culiacán Rosales....

 with a coastline of approximately 2500 mi (4,023.4 km). Rivers which flow into the Gulf of California include the Colorado
Colorado River
The Colorado River , is a river in the Southwestern United States and northwestern Mexico, approximately long, draining a part of the arid regions on the western slope of the Rocky Mountains. The watershed of the Colorado River covers in parts of seven U.S. states and two Mexican states...

, Fuerte
Fuerte River
The Fuerte River is a river in the northwestern Mexican state of Sinaloa. It begins at the junction of the Verde and Urique rivers, on the Sierra Madre Occidental mountain range. It flows generally southwest for a distance of 290 km, emptying into the Gulf of California at Lechuguilla Island,...

, Mayo
Mayo River, Mexico
The Mayo River is located in the Mexican state of Sonora. There is an important dam, named Adolfo Ruiz Cortines after one of the Presidents of Mexico, located up river, for the purpose of generating electricity, as well as irrigation for agriculture in the Mayo Valley. It is located 30 km...

, Sinaloa
Sinaloa River
-References:*Atlas of Mexico, 1975 .*The Prentice Hall American World Atlas, 1984.*Rand McNally, The New International Atlas, 1993....

, Sonora
Sonora River
Río Sonora is a 402-kilometer-long river of Mexico. It lies on the Pacific slope of the Mexican state of Sonora and it runs into the Gulf of California.-Watershed:...

, and the Yaqui
Yaqui River
The Yaqui River is a river in the state of Sonora in northwestern Mexico. Being the largest river system in the state of Sonora, the Yaqui river is used for irrigation....

. The gulf's surface area is about 62000 sq mi (160,579.3 km²). The name "Gulf of California" predominates on most maps in English today. The name "Sea of Cortés" or Mar de Cortés is the one preferred by most local residents.

The Gulf is thought to be one of the most diverse seas on the planet, and is home to more than 5,000 species of macro-invertebrates. Baja California itself is actually one of the longest, most isolated peninsulas in the world, second only to the Malay Peninsula
Malay Peninsula
The Malay Peninsula or Thai-Malay Peninsula is a peninsula in Southeast Asia. The land mass runs approximately north-south and, at its terminus, is the southern-most point of the Asian mainland...

 in Southeast Asia. The Gulf of California is a UNESCO World Heritage Site.

Geography


The International Hydrographic Organization
International Hydrographic Organization
The International Hydrographic Organization is the inter-governmental organisation representing the hydrographic community. It enjoys observer status at the UN and is the recognised competent authority on hydrographic surveying and nautical charting...

 defines the southern limit of the Gulf of California as: "A line joining Piastla Point (23°38'N) in Mexico, and the Southern extreme of Lower California
Baja California Peninsula
The Baja California peninsula , is a peninsula in northwestern Mexico. Its land mass separates the Pacific Ocean from the Gulf of California. The Peninsula extends from Mexicali, Baja California in the north to Cabo San Lucas, Baja California Sur in the south.The total area of the Baja California...

".

The Gulf of California is 1126 kilometres (699.7 mi) long and 48 kilometre wide, with an area of 177000 square kilometres (68,340.1 sq mi), a mean depth of 818.08 metres (2,684 ft), and a volume of 145,000 cubic kilometers (34,985 cubic miles).

The Gulf of California includes three faunal regions:
  1. the Northern Gulf of California
  2. the Central Gulf of California
  3. the Southern Gulf of California


One recognized transition zone is termed the Southwestern Baja California peninsula. Transition zones exist between faunal regions, and they usually vary for each individual species. (Faunal regions are distinguishable based on the specific types of animals that are found there.)

Geology


Geologic evidence is widely interpreted by geologists as indicating that the Gulf of California came into being around 5.3 million years ago as tectonic forces
Plate tectonics
Plate tectonics is a scientific theory that describes the large scale motions of Earth's lithosphere...

 rifted the Baja California Peninsula
Baja California Peninsula
The Baja California peninsula , is a peninsula in northwestern Mexico. Its land mass separates the Pacific Ocean from the Gulf of California. The Peninsula extends from Mexicali, Baja California in the north to Cabo San Lucas, Baja California Sur in the south.The total area of the Baja California...

 off the North American Plate
North American Plate
The North American Plate is a tectonic plate covering most of North America, Greenland, Cuba, Bahamas, and parts of Siberia, Japan and Iceland. It extends eastward to the Mid-Atlantic Ridge and westward to the Chersky Range in eastern Siberia. The plate includes both continental and oceanic crust...

. As part of this process, the East Pacific Rise
East Pacific Rise
The East Pacific Rise is a mid-oceanic ridge, a divergent tectonic plate boundary located along the floor of the Pacific Ocean. It separates the Pacific Plate to the west from the North American Plate, the Rivera Plate, the Cocos Plate, the Nazca Plate, and the Antarctic Plate...

 propagated up the middle of the Gulf along the seabed. This extension of the East Pacific Rise is often referred to as the Gulf of California Rift Zone
Gulf of California Rift Zone
The Gulf of California Rift Zone is the northernmost extension of the East Pacific Rise which extends some 1300 km from the mouth of the Gulf of California to the southern terminus of the San Andreas Fault at the Salton Sink....

. The Gulf would extend as far as Indio, California
Indio, California
Indio is a city in Riverside County, California, United States, located in the Coachella Valley of Southern California's Colorado Desert region. It lies east of Palm Springs, east of Riverside, and east of Los Angeles. It is about north of Mexicali, Baja California on the U.S.-Mexican border...

, except for the tremendous delta
River delta
A delta is a landform that is formed at the mouth of a river where that river flows into an ocean, sea, estuary, lake, reservoir, flat arid area, or another river. Deltas are formed from the deposition of the sediment carried by the river as the flow leaves the mouth of the river...

 created by the Colorado River
Colorado River
The Colorado River , is a river in the Southwestern United States and northwestern Mexico, approximately long, draining a part of the arid regions on the western slope of the Rocky Mountains. The watershed of the Colorado River covers in parts of seven U.S. states and two Mexican states...

. This delta blocks the sea from flooding the Mexicali
Mexicali
Mexicali is the capital of the State of Baja California, seat of the Municipality of Mexicali, and 2nd largest city in Baja California. The City of Mexicali has a population of 689,775, according to the 2010 census, while the population of the entire metropolitan area reaches 936,826.The city...

 and Imperial Valleys. Volcanism dominates the East Pacific Rise
East Pacific Rise
The East Pacific Rise is a mid-oceanic ridge, a divergent tectonic plate boundary located along the floor of the Pacific Ocean. It separates the Pacific Plate to the west from the North American Plate, the Rivera Plate, the Cocos Plate, the Nazca Plate, and the Antarctic Plate...

. The island of Isla Tortuga
Isla Tortuga
Isla Tortuga is an island in the Gulf of California, created relatively recently in geologic terms by the volcanism associated with the East Pacific Rise. It lies east-northeast of the city of Santa Rosalía, in Mulegé Municipality. It has a surface area of 11.374 km² .-References:*...

 is one example of this ongoing volcanic activity.

Weather


The average temperature of the Pacific coast of Baja California is 16–24 °C (60.8–75.2 F).
Even though the shores of the Gulf of California are generally sheltered from the continuous wave shock that is experienced by most other North American shores, storms known as a “chubasco
Chubasco
A chubasco is a violent squall with thunder and lightning, encountered during the rainy season along the Pacific coast of Mexico, Central America, South America and the American Southwest. It is also widely used when rain is accompanied by strong winds in other Spanish-speaking countries.The word...

” can cause significant damage to shorelines, despite their brevity.
Occasionally, the Northern Gulf of California will go through significantly cold winters. The water in the Northern Gulf can sometimes drop below 8 °C, which can lead to a large die-off of marine organisms. The animals that are most susceptible to the large decrease in water temperature include macroscopic algae and plankton.

Fishery



The narrow sea is home to a unique and rich ecosystem. In addition to a wide range of endemic
Endemic (ecology)
Endemism is the ecological state of being unique to a defined geographic location, such as an island, nation or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, all species of lemur are endemic to the...

 creatures, like the critically endangered Vaquita
Vaquita
The vaquita is a rare species of porpoise. It is endemic to the northern part of the Gulf of California. Estimates of the number of individuals alive range from 100 to 300. The word "vaquita" is Spanish for little cow...

 Marina, it hosts many migratory species, such as the Humpback Whale
Humpback Whale
The humpback whale is a species of baleen whale. One of the larger rorqual species, adults range in length from and weigh approximately . The humpback has a distinctive body shape, with unusually long pectoral fins and a knobbly head. It is an acrobatic animal, often breaching and slapping the...

, California Gray Whale
Gray Whale
The gray whale, Eschrichtius robustus, is a baleen whale that migrates between feeding and breeding grounds yearly. It reaches a length of about , a weight of , and lives 50–70 years. The common name of the whale comes from the gray patches and white mottling on its dark skin. Gray whales were...

, Killer Whale, Manta Ray
Manta ray
The manta ray is the largest species of the rays. The largest known specimen was more than across, with a weight of about . It ranges throughout waters of the world, typically around coral reefs...

 and Leatherback Sea Turtle
Leatherback Sea Turtle
The leatherback sea turtle is the largest of all living sea turtles and the fourth largest modern reptile behind three crocodilians. It is the only living species in the genus Dermochelys. It can easily be differentiated from other modern sea turtles by its lack of a bony shell. Instead, its...

, and the world's largest animal, the Blue Whale
Blue Whale
The blue whale is a marine mammal belonging to the suborder of baleen whales . At in length and or more in weight, it is the largest known animal to have ever existed....

. There are unusual resident populations of Fin Whale
Fin Whale
The fin whale , also called the finback whale, razorback, or common rorqual, is a marine mammal belonging to the suborder of baleen whales. It is the second longest whale and the sixth largest living animal after the blue whale, bowhead whale, and right whales, growing to nearly 27 metres long...

s and Sperm Whale
Sperm Whale
The sperm whale, Physeter macrocephalus, is a marine mammal species, order Cetacea, a toothed whale having the largest brain of any animal. The name comes from the milky-white waxy substance, spermaceti, found in the animal's head. The sperm whale is the only living member of genus Physeter...

s that do not migrate annually. This region has historically been a magnet for world class sport fishing
Fishing
Fishing is the activity of trying to catch wild fish. Fish are normally caught in the wild. Techniques for catching fish include hand gathering, spearing, netting, angling and trapping....

 activities, with a rich history of sporting world records.

The region also has a rich history as a commercial fishery
Fishery
Generally, a fishery is an entity engaged in raising or harvesting fish which is determined by some authority to be a fishery. According to the FAO, a fishery is typically defined in terms of the "people involved, species or type of fish, area of water or seabed, method of fishing, class of boats,...

. However, the data varies wildly according to the species being studied, and the Gulf's ability to recuperate after years of over fishing remains uncertain. Moreover, changes in terrestrial ecology, such as the vast reduction in flow from the Colorado River into the Gulf, have negatively affected fisheries, particularly in the northern region.

The Gulf of California sustains a large number of marine mammals, many of which are rare, and endangered. Its more than 900 islands are important nesting sites for thousands of seabirds and its waters are a primary breeding, feeding, and nursing grounds for myriad migratory and resident fish species. For decades, the gulf has been a primary source of two of Mexico's leading marine resources, sardines and anchovies. Water pollution is a problem in the Gulf of California, but the more immediate concerns are overfishing and bottom trawling, which destroys eelgrass beds and shellfish.

Efforts by the Mexican government to create conservation
Conservation ethic
Conservation is an ethic of resource use, allocation, and protection. Its primary focus is upon maintaining the health of the natural world: its, fisheries, habitats, and biological diversity. Secondary focus is on materials conservation and energy conservation, which are seen as important to...

 zones and Nature reserves have been hampered by lack of enforcement resources as well as a lack of a political consensus on this issue of conservation of the Gulf. This even though significant areas are a UNESCO World Heritage Site. The thousands of miles of coastline are remote and difficult to police, and the politically powerful commercial fishing industry has been slow to embrace even economically viable conservation measures, much less strict measures of conservation. Conservation of the Gulf's fisheries and coastlines is also complicated by a long history of over-capitalization in the sector, and the direct, often negative impacts that conservation measures have on the livelihoods of Mexico's coastal inhabitants. At present, the Mexican government and business interests have promoted a macro-level, tourist development vision for the Gulf, whose impacts on local ecology and society are uncertain.

Coastal communities that are highly reliant on both commercial and sport fishing include San Felipe
San Felipe, Baja California
San Felipe is a town on the Gulf of California in the Mexican state of Baja California, 190 km south of the United States border and within the municipality of Mexicali. It also serves as a borough seat of its surrouding area....

, San Carlos, Sonora, Cabo San Lucas
Cabo San Lucas
Cabo San Lucas , commonly called Cabo, is a city at the southern tip of the Baja California peninsula, in the municipality of Los Cabos in the Mexican state of Baja California Sur. As of the 2010 census, the population was 68,463 people...

, La Paz
La Paz, Baja California Sur
La Paz is the capital city of the Mexican state of Baja California Sur and an important regional commercial center. The city had a 2010 census population of 215,178 persons, but its metropolitan population is somewhat larger because of surrounding towns like el Centenario, el Zacatal and San Pedro...

, Loreto
Loreto, Baja California Sur
Loreto was the first Spanish settlement on the Baja California Peninsula. It served as the capital of Las Californias from 1697 to 1777, and is the current seat of the municipality of Loreto in the Mexican state of Baja California Sur...

, Guaymas
Guaymas
Guaymas is a city and municipality located in the southwest part of the state of Sonora in northwestern Mexico. The city is located 117 km south of the state capital of Hermosillo, and 242 miles from the U.S. border, and is the principal port for the state. The municipality is located in the...

, Bahia de Kino, Puerto Penasco
Puerto Peñasco
Puerto Peñasco is a city and municipality located in the northwest of the state of Sonora about 100 km from the Arizona border. It is located on the small strip of land that joins the peninsula of Baja California with the rest of Mexico. The area is part of the Altar Desert, one of the driest...

, Topolobampo
Topolobampo
Topolobampo is a port on the Gulf of California in northwestern Sinaloa, Mexico. It is the fourth-largest town in the municipality of Ahome , reporting a 2005 census population of 6,032 inhabitants....

 and Mulegé
Mulegé
Mulegé is an oasis town in the Mexican state of Baja California Sur, situated at the mouth of the Río de Santa Rosalía. It is the fourth-largest community in Mulegé Municipality...

. The well-developed shrimp and sardine fleets of Mazatlán
Mazatlán
Mazatlán is a city in the Mexican state of Sinaloa; the surrounding municipio for which the city serves as the municipal seat is Mazatlán Municipality. It is located at on the Pacific coast, across from the southernmost tip of the Baja California peninsula.Mazatlán is a Nahuatl word meaning...

, on the Mexican mainland's Pacific coast, heavily exploit the commercial fisheries of the southern Gulf.

Many marine organisms can only survive within a particular salinity
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...

 range, which makes salinity a notable factor in determining the types of potentially-commercial organisms found in the Gulf of California. The mean annual ranges of salinity of the Sea of Cortez are between 35 to 35.8 ‰ at the surface. Furthermore, the salinity of the water of the Northern Gulf of California is generally higher than the Central and Southern faunal regions due to the increased amount of evaporation that occurs in that region.

Shores and tides


Three general types of shores found in the Gulf of California include rocky shore
Rocky shore
A rocky shore is an intertidal area of seacoasts where solid rock predominates. Rocky shores are biologically rich environments, and make the ideal natural laboratory for studying intertidal ecology and other biological processes...

, sandy beach, and tidal flat. Some of the rich biodiversity and high endemism that characterizes the Gulf of California and makes it such a hotspot for fishing can be attributed to seemingly insignificant factors, such as the types of rocks that make up a shore. Beaches with softer, more porous rocks (such as Coquina limestone, rhyolites, granite, or diorite) generally have a higher species richness than those with harder, smoother rocks (such as basalt or diabase). Porous rocks will naturally have more cracks and crevices in them, making them ideal living spaces for many animals. The rocks themselves, however, generally need to be stable on the shore in order for a habitat to be stable. Additionally, the color of the rocks can affect the organisms living on a shore. For example, darker rocks will be significantly warmer than lighter ones, and can deter animals that do not have a high tolerance for heat.
The northern Gulf of California experiences tidal ranges of up to 5 metres (16.4 ft). Mixed semidiurnal tides are the norm throughout most of the Gulf.

Estuaries


An estuary
Estuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....

 is an inlet
Inlet
An inlet is a narrow body of water between islands or leading inland from a larger body of water, often leading to an enclosed body of water, such as a sound, bay, lagoon or marsh. In sea coasts an inlet usually refers to the actual connection between a bay and the ocean and is often called an...

, or bay
Bay
A bay is an area of water mostly surrounded by land. Bays generally have calmer waters than the surrounding sea, due to the surrounding land blocking some waves and often reducing winds. Bays also exist as an inlet in a lake or pond. A large bay may be called a gulf, a sea, a sound, or a bight...

 at the mouth of a river
River
A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

 or stream
Stream
A stream is a body of water with a current, confined within a bed and stream banks. Depending on its locale or certain characteristics, a stream may be referred to as a branch, brook, beck, burn, creek, "crick", gill , kill, lick, rill, river, syke, bayou, rivulet, streamage, wash, run or...

, where the salt water from the ocean mixes with fresh water. A positive estuary is one in which the seawater
Seawater
Seawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% . This means that every kilogram of seawater has approximately of dissolved salts . The average density of seawater at the ocean surface is 1.025 g/ml...

 component is diluted
Concentration
In chemistry, concentration is defined as the abundance of a constituent divided by the total volume of a mixture. Four types can be distinguished: mass concentration, molar concentration, number concentration, and volume concentration...

; therefore, the water is brackish
Brackish water
Brackish water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak," meaning "salty"...

, with salinity less than that of the ocean. In contrast, a negative estuary is an estuary in which the evaporation
Evaporation
Evaporation is a type of vaporization of a liquid that occurs only on the surface of a liquid. The other type of vaporization is boiling, which, instead, occurs on the entire mass of the liquid....

 of seawater is relatively greater than that of the fresh water input. The salinities of these inlets are higher than that of the ocean. The temperatures, poikilothermal, of these negative estuaries also are higher than the general temperature of the Gulf. In the Gulf of California, there are a number of negative estuaries, which possibly were previously positive. However, due to human modification of the land use around the Gulf of California and water diversion for municipal and agricultural use, there are no longer many rivers that freely empty into the Gulf of California. The upper Colorado River Delta
Colorado River Delta
The Colorado River Delta is the region where the Colorado River flows into the Gulf of California . The delta is part of a larger geologic region called the Salton Trough. Historically, the interaction of the river’s flow and the ocean’s tide created a dynamic environment, supporting freshwater,...

 is one example of a historically major estuary and wetlands ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....

, that since the 20th century construction of upriver dams and diversion aqueducts on the Colorado River
Colorado River
The Colorado River , is a river in the Southwestern United States and northwestern Mexico, approximately long, draining a part of the arid regions on the western slope of the Rocky Mountains. The watershed of the Colorado River covers in parts of seven U.S. states and two Mexican states...

, is now a small ephemeral
Ephemeral
Ephemeral things are transitory, existing only briefly. Typically the term is used to describe objects found in nature, although it can describe a wide range of things....

 remnant estuary. It is included in the UNESCO World Heritage Site. The remaining Gulf inlets still are important to several species of fishes, crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s, and shellfish
Shellfish
Shellfish is a culinary and fisheries term for exoskeleton-bearing aquatic invertebrates used as food, including various species of molluscs, crustaceans, and echinoderms. Although most kinds of shellfish are harvested from saltwater environments, some kinds are found only in freshwater...

 that are commercially harvested.

Islands


The Gulf of California contains 37 islands – the two largest being Isla Ángel de la Guarda
Isla Ángel de la Guarda
Isla Ángel de la Guarda, also called Archangel Island, and called Xazl Iimt east of Bahía de los Ángeles, and separated from the Baja California Peninsula by the Canal de Ballenas . It is the second largest of the eleven Midriff Islands or Islas Grandes. It is part of the state of Baja California,...

 and Tiburón Island
Tiburón Island
Tiburón Island is both the largest island in the Gulf of California and the largest island in Mexico, with an area of . It was made a nature reserve in 1963 by President Adolfo López Mateos. Tiburón is Spanish for shark. The etymology of the Seri name is unknown...

. Most of the islands are found on the peninsular side of the gulf. In fact, many of the islands of the Sea of Cortez are the result of volcanic explosions that occurred during the early history of Baja California. The islands of Islas Marías
Islas Marías
The Islas Marías are an archipelago of four islands that belong to Mexico. They are located in the Pacific Ocean, some off the coast of the state of Nayarit. They are part of the municipality of San Blas, Nayarit...

, Islas San Francisco, and Isla Partida
Isla Partida
Isla Partida is connected to Isla Espíritu Santo by a narrow isthmus. These two islands, in the Gulf of California, are protected by UNESCO as biospheres. They are located a short boat ride from La Paz, which lies on the Baja California Peninsula in Mexico...

 are thought to be the result of such explosions. The formations of the islands, however, are not dependent on each other. They were each formed as a result of an individual structural occurrence. Several islands, including Isla Coronado, are home to volcanoes.

Bathymetry


Depth soundings in the gulf have ranged from fording depth at the estuary near Yuma, Arizona
Yuma, Arizona
Yuma is a city in and the county seat of Yuma County, Arizona, United States. It is located in the southwestern corner of the state, and the population of the city was 77,515 at the 2000 census, with a 2008 Census Bureau estimated population of 90,041....

to in excess of 3000 metres (9,842.5 ft) in the deepest parts. The depth of the water helps to determine its temperature. For example, shallow depths are directly influenced by the local temperature of the air, while deeper waters are less susceptible to changes in air temperature.

Further reading

  • Richard C. Brusca, ed. The Gulf of California: Biodiversity and Conservation (University of Arizona Press; 2010) 354 pages; studies by researchers on both sides of the border on the threats to the diversity of species in the gulf's waters.

External links