Cordell Bank National Marine Sanctuary
Encyclopedia
Cordell Bank National Marine Sanctuary is a marine sanctuary located of the coast of California
, at 38.0665921°N 123.3677881°W. It protects an area of 339 sqnmi of marine wildlife. The administrative center of the sanctuary is on an offshore granite outcrop 4.5 sq mi (12 km²) by 9.5 sq mi (25 km²), located on the continental shelf
off of California. The outcrop is, at its closest (Reye's Point), 6 mi (10 km) from the sanctuary itself.
Cordell Bank is one of the United States' 13 National Marine Sanctuaries that protect and preserve ocean ecosystems in the U.S. Cordell Bank is a seamount
approximately 50 miles (80.5 km) northwest of San Francisco where the ocean bottom rises to within 120 feet (37 meters) of the surface. The seamount was discovered in 1853 by the U.S. Coast Survey, and named for Edward Cordell, who surveyed the area more thoroughly in 1869. It was extensively explored and described during 1978-86 by Robert Schmieder, who published a monograph about it [Schmieder, 1991]. It has been protected as a sanctuary since 1989. The protected area encompasses 526 square miles (1347 km²) of ocean.
The unique blend of ocean conditions and undersea topography
creates a rich and diverse underwater ecosystem. A subsurface island rises from soft sediments covering the continental shelf. The upper pinnacles reach to within 115 ft (35 m) of the surface, and the average depth is 400 ft (122 m). The sanctuary serves as a breeding ground for migratory marine mammals, birds, and fish. The prevailing Californian current flows southward along to coast, causing an upwelling of nutrient-rich water that provided the foundation for the area's marine ecosystem.
Sanctuary regulations prohibit extraction of hydrocarbons (oil, natural gas), the removal of benthic (bottom-dwelling) organisms, discharge of wastes, and removal of cultural resources. Recreational scuba diving
is not recommended in the sanctuary due to depth and currents.
Cordell Bank was originally created 93 million years ago, as a member of the Sierra Nevada mountains. The grinding of the plates at the San Andreas Fault
, with the Pacific Plate
moving north and the North American Plate
moving south, parts of the Sierra Mountains were sheared off and carried northwards, including Cordell Bank. Eventually this grinding carried Cordell Bank to its present location opposite Reyes Point. Cordell Bank is still moving, by an average of 3 cm (1 in) per year.
Between 20,000 and 15,000 years ago the sea level
in the area was 360 ft (110 m) below the current level, leaving most of Cordell Bank exposed and making it a true island. Today the bank rises out of soft sediment, deposited on the bank more recently by coastal erosion
. Within just 7 miles (11,265 m) of Cordell Bank, the continental shelf drops to over 1 mi (2 km) deep. The seamount is largely composed of granite
.
Coastal California has a rich history of marine utilization by Native American
s and early settler
s. Cordell Bank was a mystery prior to the 19th century because neither the Miwok
natives nor the settlers had any incentive to venture far out from shore, when food resources were available close to shore. Many European mariners sailed right over Cordell Bank without even knowing it was there.
In the later half of the 1800s there was a strong incentive to survey the coast of California so as to promote maritine safety. Cordell Bank was discovered in 1853 by George Davidson
of the US Coast Survey during a mapping expedition on California's north coast.
In 1869 Edward Cordell (the reserve's namesake) was sent to collect additional information on a "shoal west of Point Reyes". He found the area by following the numerous birds and maritime mammals. To measure the depth, Cordell lowered a lead weight into the water until it hit the bottom and then measured the length of the line on its return to the surface. The area was considered a productive fishing area, but not much was discovered about its marine life until an expedition in 1977.
The expedition was led by a non-profit research group, Cordell Expeditions. Over the next 10 years, scores of underwater dives documented the organism and wildlife living in, on, and around the bank. The efforts gave rise to an understanding of the diversity in the back, and the efforts were instrumental in the decision to make it a sanctuary.
s, dolphin
s, seal
s, and sea lion
s, are known to frequent the waters of the sanctuary. In addition, Cordell Bank is one of the most important feeding grounds in the world for the endangered blue
and humpback
whales; these species travel all the way from their breeding grounds in coastal Mexico and Central America to feed on the krill
that aggregate near the bank. Another unique species is the Pacific white-sided dolphin
(Lagenorhynchus obliquidens), which can be seen in large numbers. Other visitors include California sea lion
s (Zalophus californianus), Northern elephant seal
s (Mirounga angustirostris), Northern fur seal
s (Callorhinus ursinus), and steller sea lions (Eumetopias jubatus), all of which are attracted to the abundance in krill
, squid
, and juvenile fish. Leatherback Sea Turtle
s also inhabit sanctuary waters.
Cordell Bank is also a major foraging ground for passing seabirds. Known as the "Albatross capital of the world," 5 of the 14 major species of albatross
have been documented there. The two most common are the Black-footed albatross
(Phoebastria nigripes) and Sooty shearwater
(Puffinus griseus). It is also one of the few places to see a Short-tailed albatross
(Phoebastria albatrus), which is extremely rare; the species was thought to have gone extinct after World War II
. Currently the world population hovers at around 1000 individuals.
Cordell Bank is also known for its abundance of fish. Flatfish
, most notably sanddabs, make their home on the mud of the seafloor in the sanctuary. Both solitary and schooling fish find refuge for predators among the bank's rocky pinnacles. Cordell Bank supports more than 246 species of fish, including 44 species of rockfish
, ranging in size from the 8-inch Pygmy rockfish
to the 3 foot (0.9144 m) Yelloweye rockfish
.
Although far from shore, sport fishers prize Cordell Bank as a fishing spot, and regularly venture out from shore to catch albacore
and salmon
.
This unusual granite mountain is surrounded on three sides by deep waters, which allows the flow of deep nutrient-rich waters over relatively shallow waters with sufficient light to support photosynthesis
.
The ecological cycle at Cordell Bank can be divided into three oceanographic seasons. During the spring, strong northwestern winds push the water southward along the California coast. Gale wind
s and the Earth's rotation drive surface water away from the shore, only to be replaced by an upwelling of colorer, deeper, and more nutrient-rich waters from offshore. this contributes to the growth in numbers of phytoplankton
, which are the foundation of the marine food web
, in turn leading to a rise in food, and thus numbers, of the organism higher on the chain.
During the late summer and fall seasons, the coastal winds that stirred up the deeper waters die down, and the northward-flowing Davidson Current
prevails, bringing warm but nutrient-poor water from the south.
During the winter storm months, the sea is dominated by rough weather, which mixes the deeper water with that above. The temperature on top of the continental shelf mixes, and the temperature, salinity
, and concentration of water and the nutrients in them assimilate.
Future:
A bill (H.R. 5352) was recently proposed to Congress by local Representative Lynn Woolsey
to expand the size of the Cordell Bank National Marine Sanctuary and the neighboring Gulf of the Farallones National Marine Sanctuary
by 1094 square miles (2,833.4 km²).
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, at 38.0665921°N 123.3677881°W. It protects an area of 339 sqnmi of marine wildlife. The administrative center of the sanctuary is on an offshore granite outcrop 4.5 sq mi (12 km²) by 9.5 sq mi (25 km²), located on the continental shelf
Continental shelf
The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...
off of California. The outcrop is, at its closest (Reye's Point), 6 mi (10 km) from the sanctuary itself.
Cordell Bank is one of the United States' 13 National Marine Sanctuaries that protect and preserve ocean ecosystems in the U.S. Cordell Bank is a seamount
Seamount
A seamount is a mountain rising from the ocean seafloor that does not reach to the water's surface , and thus is not an island. These are typically formed from extinct volcanoes, that rise abruptly and are usually found rising from a seafloor of depth. They are defined by oceanographers as...
approximately 50 miles (80.5 km) northwest of San Francisco where the ocean bottom rises to within 120 feet (37 meters) of the surface. The seamount was discovered in 1853 by the U.S. Coast Survey, and named for Edward Cordell, who surveyed the area more thoroughly in 1869. It was extensively explored and described during 1978-86 by Robert Schmieder, who published a monograph about it [Schmieder, 1991]. It has been protected as a sanctuary since 1989. The protected area encompasses 526 square miles (1347 km²) of ocean.
The unique blend of ocean conditions and undersea topography
Topography
Topography is the study of Earth's surface shape and features or those ofplanets, moons, and asteroids...
creates a rich and diverse underwater ecosystem. A subsurface island rises from soft sediments covering the continental shelf. The upper pinnacles reach to within 115 ft (35 m) of the surface, and the average depth is 400 ft (122 m). The sanctuary serves as a breeding ground for migratory marine mammals, birds, and fish. The prevailing Californian current flows southward along to coast, causing an upwelling of nutrient-rich water that provided the foundation for the area's marine ecosystem.
Sanctuary regulations prohibit extraction of hydrocarbons (oil, natural gas), the removal of benthic (bottom-dwelling) organisms, discharge of wastes, and removal of cultural resources. Recreational scuba diving
Scuba diving
Scuba diving is a form of underwater diving in which a diver uses a scuba set to breathe underwater....
is not recommended in the sanctuary due to depth and currents.
Geological setting
San Andreas Fault
The San Andreas Fault is a continental strike-slip fault that runs a length of roughly through California in the United States. The fault's motion is right-lateral strike-slip...
, with the Pacific Plate
Pacific Plate
The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At 103 million square kilometres, it is the largest tectonic plate....
moving north and 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...
moving south, parts of the Sierra Mountains were sheared off and carried northwards, including Cordell Bank. Eventually this grinding carried Cordell Bank to its present location opposite Reyes Point. Cordell Bank is still moving, by an average of 3 cm (1 in) per year.
Between 20,000 and 15,000 years ago the sea level
Sea level
Mean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...
in the area was 360 ft (110 m) below the current level, leaving most of Cordell Bank exposed and making it a true island. Today the bank rises out of soft sediment, deposited on the bank more recently by coastal erosion
Coastal erosion
Coastal erosion is the wearing away of land and the removal of beach or dune sediments by wave action, tidal currents, wave currents, or drainage...
. Within just 7 miles (11,265 m) of Cordell Bank, the continental shelf drops to over 1 mi (2 km) deep. The seamount is largely composed of granite
Granite
Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...
.
History
Indigenous peoples of the Americas
The indigenous peoples of the Americas are the pre-Columbian inhabitants of North and South America, their descendants and other ethnic groups who are identified with those peoples. Indigenous peoples are known in Canada as Aboriginal peoples, and in the United States as Native Americans...
s and early settler
Settler
A settler is a person who has migrated to an area and established permanent residence there, often to colonize the area. Settlers are generally people who take up residence on land and cultivate it, as opposed to nomads...
s. Cordell Bank was a mystery prior to the 19th century because neither the Miwok
Miwok
Miwok can refer to any one of four linguistically related groups of Native Americans, native to Northern California, who spoke one of the Miwokan languages in the Utian family...
natives nor the settlers had any incentive to venture far out from shore, when food resources were available close to shore. Many European mariners sailed right over Cordell Bank without even knowing it was there.
In the later half of the 1800s there was a strong incentive to survey the coast of California so as to promote maritine safety. Cordell Bank was discovered in 1853 by George Davidson
George Davidson (geographer)
George Davidson was an geodesist, astronomer, geographer, surveyor and engineer in the United States.-Biography:Born May 9, 1825 in England, he came to the U.S. in 1832 with his parents, who settled in Pennsylvania...
of the US Coast Survey during a mapping expedition on California's north coast.
In 1869 Edward Cordell (the reserve's namesake) was sent to collect additional information on a "shoal west of Point Reyes". He found the area by following the numerous birds and maritime mammals. To measure the depth, Cordell lowered a lead weight into the water until it hit the bottom and then measured the length of the line on its return to the surface. The area was considered a productive fishing area, but not much was discovered about its marine life until an expedition in 1977.
The expedition was led by a non-profit research group, Cordell Expeditions. Over the next 10 years, scores of underwater dives documented the organism and wildlife living in, on, and around the bank. The efforts gave rise to an understanding of the diversity in the back, and the efforts were instrumental in the decision to make it a sanctuary.
Biology
26 species of marine mammals, including whaleWhale
Whale is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to suborder Odontoceti . This suborder also includes the sperm whale, killer whale, pilot whale, and beluga...
s, dolphin
Dolphin
Dolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in 17 genera. They vary in size from and , up to and . They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating...
s, seal
Pinniped
Pinnipeds or fin-footed mammals are a widely distributed and diverse group of semiaquatic marine mammals comprising the families Odobenidae , Otariidae , and Phocidae .-Overview: Pinnipeds are typically sleek-bodied and barrel-shaped...
s, and sea lion
Sea Lion
Sea lions are pinnipeds characterized by external ear-flaps, long fore-flippers, the ability to walk on all fours, and short thick hair. Together with the fur seal, they comprise the family Otariidae, or eared seals. There are six extant and one extinct species in five genera...
s, are known to frequent the waters of the sanctuary. In addition, Cordell Bank is one of the most important feeding grounds in the world for the endangered blue
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....
and humpback
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...
whales; these species travel all the way from their breeding grounds in coastal Mexico and Central America to feed on the krill
Krill
Krill is the common name given to the order Euphausiacea of shrimp-like marine crustaceans. Also known as euphausiids, these small invertebrates are found in all oceans of the world...
that aggregate near the bank. Another unique species is the Pacific white-sided dolphin
Pacific White-sided Dolphin
The Pacific White-sided Dolphin is a very active dolphin found in the cool to temperate waters of the North Pacific Ocean.-Taxonomy:...
(Lagenorhynchus obliquidens), which can be seen in large numbers. Other visitors include California sea lion
California Sea Lion
The California sea lion is a coastal sea lion of western North America. Their numbers are abundant , and the population continues to expand about 5% annually. They are quite intelligent and can adapt to man-made environments...
s (Zalophus californianus), Northern elephant seal
Northern Elephant Seal
The northern elephant seal is one of two species of elephant seal . It is a member of the family Phocidae . Elephant seals derive their name from their great size and from the male's large proboscis, which is used in making extraordinarily loud roaring noises, especially during the mating...
s (Mirounga angustirostris), Northern fur seal
Northern Fur Seal
The Northern fur seal is an eared seal found along the north Pacific Ocean, the Bering Sea and the Sea of Okhotsk. It is the largest member of the fur seal subfamily and the only species in the genus Callorhinus.-Physical description:Northern fur seals have extreme sexual dimorphism, with males...
s (Callorhinus ursinus), and steller sea lions (Eumetopias jubatus), all of which are attracted to the abundance in krill
Krill
Krill is the common name given to the order Euphausiacea of shrimp-like marine crustaceans. Also known as euphausiids, these small invertebrates are found in all oceans of the world...
, squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
, and juvenile fish. 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...
s also inhabit sanctuary waters.
Cordell Bank is also a major foraging ground for passing seabirds. Known as the "Albatross capital of the world," 5 of the 14 major species of albatross
Albatross
Albatrosses, of the biological family Diomedeidae, are large seabirds allied to the procellariids, storm-petrels and diving-petrels in the order Procellariiformes . They range widely in the Southern Ocean and the North Pacific...
have been documented there. The two most common are the Black-footed albatross
Black-footed Albatross
The Black-footed Albatross, Phoebastria nigripes, is a large seabird from the North Pacific of the albatross family Diomedeidae. It is one of three species of albatross that range in the northern hemisphere, nesting on isolated tropical islands...
(Phoebastria nigripes) and Sooty shearwater
Sooty Shearwater
The Sooty Shearwater is a medium-large shearwater in the seabird family Procellariidae. In New Zealand it is also known by its Māori name tītī and as "muttonbird", like its relatives the Wedge-tailed Shearwater and the Australian Short-tailed Shearwater The Sooty Shearwater (Puffinus griseus) is...
(Puffinus griseus). It is also one of the few places to see a Short-tailed albatross
Short-tailed Albatross
The Short-tailed Albatross or Steller's Albatross, Phoebastria albatrus, is a large rare seabird from the North Pacific. Although related to the other North Pacific albatrosses, it also exhibits behavioural and morphological links to the albatrosses of the Southern Ocean...
(Phoebastria albatrus), which is extremely rare; the species was thought to have gone extinct after World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. Currently the world population hovers at around 1000 individuals.
Cordell Bank is also known for its abundance of fish. Flatfish
Flatfish
The flatfish are an order of ray-finned fish, also called the Heterosomata, sometimes classified as a suborder of Perciformes. In many species, both eyes lie on one side of the head, one or the other migrating through and around the head during development...
, most notably sanddabs, make their home on the mud of the seafloor in the sanctuary. Both solitary and schooling fish find refuge for predators among the bank's rocky pinnacles. Cordell Bank supports more than 246 species of fish, including 44 species of rockfish
Rockfish
Rockfish may refer to one of the following fishes:* One of several species in the Sebastes genus of the Sebastidae family, including the Shortraker rockfish, Rougheye rockfish, Blue rockfish, Yellow tail rockfish and many others....
, ranging in size from the 8-inch Pygmy rockfish
Pygmy rockfish
The Pygmy rockfish is a rockfish of the genus Sebastes. It is one of the smallest fish of its species. It is reported to grow to a maximum of and can live up to 26 years. The rockfish lives between and of depth, and its range is in the East Pacific, for the Gulf of Alaska to Baja California,...
to the 3 foot (0.9144 m) Yelloweye rockfish
Yelloweye rockfish
The Yelloweye rockfish is a rockfish of the genus Sebastes, and one of the biggest members of the genus. Its name derives from its coloration. It is also known as the "red snapper." The Yelloweye is one of the world's longest-lived fish species, and is cited to live to a maximum of 114 to 120...
.
Although far from shore, sport fishers prize Cordell Bank as a fishing spot, and regularly venture out from shore to catch albacore
Albacore
The albacore, Thunnus alalunga, is a type of tuna in the family Scombridae. This species is also called albacore fish, albacore tuna, albicore, longfin, albies, pigfish, tombo ahi, binnaga, Pacific albacore, German bonito , longfin tuna, longfin tunny, or even just tuna...
and salmon
Salmon
Salmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true...
.
Ecologic cycle
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
.
The ecological cycle at Cordell Bank can be divided into three oceanographic seasons. During the spring, strong northwestern winds push the water southward along the California coast. Gale wind
Gale
A gale is a very strong wind. There are conflicting definitions of how strong a wind must be to be considered a gale. The U.S. government's National Weather Service defines a gale as 34–47 knots of sustained surface winds. Forecasters typically issue gale warnings when winds of this strength are...
s and the Earth's rotation drive surface water away from the shore, only to be replaced by an upwelling of colorer, deeper, and more nutrient-rich waters from offshore. this contributes to the growth in numbers of phytoplankton
Phytoplankton
Phytoplankton are the autotrophic component of the plankton community. The name comes from the Greek words φυτόν , meaning "plant", and πλαγκτός , meaning "wanderer" or "drifter". Most phytoplankton are too small to be individually seen with the unaided eye...
, which are the foundation of the marine food web
Food web
A food web depicts feeding connections in an ecological community. Ecologists can broadly lump all life forms into one of two categories called trophic levels: 1) the autotrophs, and 2) the heterotrophs...
, in turn leading to a rise in food, and thus numbers, of the organism higher on the chain.
During the late summer and fall seasons, the coastal winds that stirred up the deeper waters die down, and the northward-flowing Davidson Current
Davidson Current
In oceanography, the Davidson Current is a coastal countercurrent of the Pacific Ocean running north along the western coast of the United States from Baja California Mexico to northern California to at least latitude 40°N. It prevails during the winter months, generally from September through...
prevails, bringing warm but nutrient-poor water from the south.
During the winter storm months, the sea is dominated by rough weather, which mixes the deeper water with that above. The temperature on top of the continental shelf mixes, and the temperature, 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...
, and concentration of water and the nutrients in them assimilate.
Future:
A bill (H.R. 5352) was recently proposed to Congress by local Representative Lynn Woolsey
Lynn Woolsey
Lynn C. Woolsey is the U.S. Representative for , serving since 1993. She is a member of the Democratic Party. The district includes all of Marin County and most of Sonoma County. She is a member of the Congressional Progressive Caucus, and its co-chair...
to expand the size of the Cordell Bank National Marine Sanctuary and the neighboring Gulf of the Farallones National Marine Sanctuary
Gulf of the Farallones National Marine Sanctuary
The Gulf of the Farallones National Marine Sanctuary is one of 13 marine sanctuaries in the U.S., found outside San Francisco's Golden Gate surrounding the Gulf of the Farallones-History:...
by 1094 square miles (2,833.4 km²).