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{{Short description|Species of crustacean}}
{{Taxobox
{{Speciesbox
|regnum = [[Animal]]ia
| image = Crangon franciscorum.jpg
|phylum = [[Arthropod]]a
| genus = Crangon
|classis = [[Malacostraca]]
| species = franciscorum
|ordo = [[Decapoda]]
| authority = [[William Stimpson|Stimpson]], 1856
|familia = [[Crangonidae]]
|genus = ''[[Crangon]]''
|species = '''''C. franciscorum'''''
|binomial = ''Crangon franciscorum''
|binomial_authority = [[William Stimpson|Stimpson]], 1856
}}
}}
[[File:Cragon franciscorum.jpg|thumb|Cragon franciscorum]]
'''''Crangon franciscorum''''' is a species of [[shrimp]] in the [[Crangonidae]] family which is endemic to [[California]],<ref>{{cite WoRMS|author=Fransen, C.; De Grave, S.|title=''Crangon franciscorum'' Stimpson, 1856|id=241261 |year=2015|accessdate=March 12, 2015}}</ref> and found from [[Puget Sound]] in the north to [[San Diego, California]] in the south.<ref name=PSMFC/> The species is especially abundent in [[San Francisco Bay]], despite population fluctuations due to environmental stresses. Its common names include '''bay shrimp''', '''sand shrimp''', '''common shrimp''', '''grass shrimp''', '''black shrimp''', '''California shrimp''' and '''black tailed shrimp'''.<ref name=PSMFC>{{cite web | url =ftp://ftp.streamnet.org/pub/fishfacts/pdf/fish_shel.pdf| title =Shellfish of the Pacific Northwest | last = | first = | date = | website =SteamNet Project | publisher =Pacific States Marine Fisheries Commission | access-date = July 4, 2016 | quote = }}</ref>


'''''Crangon franciscorum''''' is a species of [[shrimp]] in the family [[Crangonidae]] which is endemic to the [[brackish]] [[estuaries]] of [[California]],<ref>{{cite WoRMS|author=Fransen, C.|author2=De Grave, S.|title=''Crangon franciscorum'' Stimpson, 1856|id=241261 |year=2015|accessdate=March 12, 2015}}</ref> and found from [[Puget Sound]] in the north to [[San Diego, California]] in the south.<ref name=PSMFC/> The species is especially abundant in [[San Francisco Bay]], despite population fluctuations due to environmental stresses. Its common names include '''bay shrimp''', '''sand shrimp''', '''common shrimp''', '''grass shrimp''', '''black shrimp''', '''California shrimp''' and '''black tailed shrimp'''.<ref name=PSMFC>{{cite web | url =ftp://ftp.streamnet.org/pub/fishfacts/pdf/fish_shel.pdf| title =Shellfish of the Pacific Northwest | website =SteamNet Project | publisher =Pacific States Marine Fisheries Commission }}</ref> The species has been commercially fished from 1869 to the present.

==Role in the Bay food web==
This shrimp species is "an important part of the estuarine food web" in the greater [[San Francisco Bay]].<ref name = Ecology>{{cite journal
This shrimp species is "an important part of the estuarine food web" in the greater [[San Francisco Bay]].<ref name = Ecology>{{cite journal
| last =Wahle
| last =Wahle
| first =Richard A.
| first =Richard A.
| title =The feeding ecology of ''Crangon franciscorum'' and ''Crangon nigricauda'' in San Francisco Bay, California
| author-link =
| title =The Feeding Ecology of Crangon franciscorum and Crangon nigricauda in San Francisco Bay, California
| journal =Journal of Crustacean Biology
| journal =Journal of Crustacean Biology
| volume =5
| volume =5
| issue =2
| issue =2
| pages =311-326
| pages =311–326
| publisher =Crustacean Society
| location =
| date =May 1985
| date =May 1985
| language =
| jstor =1547879
| url =http://www.jstor.org/stable/1547879
| doi =10.2307/1547879
| jstor =
| doi-access =free
}}</ref> It feeds on [[Bivalvia|bivalves]], [[Amphipoda|amphipods]] and [[Foraminifera|foraminiferins]], and is prey for various fish,<ref name=Ecology/> including [[striped bass]], [[white sturgeon]], [[Microgadus proximus|Pacific tomcod]] and shellfish such as [[Dungeness crab]].<ref name=PSMFC/> Its diet is "heavily influenced by predator size, temperature-salinity preferences, and prey availability."<ref name=Ecology/>
| issn =
| doi =
| id =
| mr =
| zbl =
| jfm =
| access-date = July 2, 2016}}</ref> It feeds on [[Bivalvia|bivalves]], [[Amphipoda|amphipods]] and [[Foraminifera|foraminiferins]], and is prey for various fish,<ref name=Ecology/> including [[striped bass]], [[white sturgeon]], [[Microgadus proximus| Pacific tomcod]] and shellfish such as [[Dungeness crab]].<ref name=PSMFC/> Its diet is "heavily influenced by predator size, temperature-salinity preferences, and prey availability."<ref name=Ecology/>


==Life cycle==
==Lifecycle==


The shrimp are short-lived, with a lifespan ranging up to 18 months for males and 30 months for females. The males spawn once while longer lived females spawn twice. There is some evidence that the species may be [[Sequential hermaphroditism|protandrous hermaphrodites]], which means that surviving males are transformed into females after one year of life. This may account for the longer lifespan of females.
The shrimp are short-lived, with a lifespan ranging up to 18 months for males and 30 months for females. The males spawn once, while longer-lived females spawn twice. Some evidence indicates the species may be [[Sequential hermaphroditism|protandrous hermaphrodites]], which means that surviving males are transformed into females after one year of life. This may account for the longer lifespan of females.


The two most important natural environmental factors affecting the health of the shrimp population are water temperature and salinity. The shrimp thrive in [[brackish water]], with a preferred salinity of 14 parts per thousand when young to 24 parts per thousand when ready to spawn.<ref name = Ellinger/> In contrast, open ocean waters have a salinity of about 35 parts per thousand. The species prefers a water temperature of about 18 degrees centigrade, or 65 degrees Fahrenheit. <ref name = Ellinger/> Because these factors vary within the bay, based on the seasons each year, and the variations in the inflow of fresh water in heavy rainfall years as opposed to drought years, the shrimp migrate around the bay, seeking optimal conditions. When heavy flows of fresh water enter the bay, mature females migrate to the saltier parts of the central bay, or out the [[Golden Gate]] to the [[Gulf of the Farallones]].<ref name = Ellinger/> There, they mate with males who prefer a slightly saltier environment. The females then incubate from 2,000 to 8,000 eggs<ref name=PSMFC/> <ref name = Ellinger/> and when hatched, the young shrimp migrate back to the shallower and less salty estuaries around the bay.<ref name = Ellinger>{{cite news | last = Ellinger| first =Micky | title =From the Bottom Up: The Tiny Bay Shrimp Makes History | newspaper =Bay Nature | location = [[Berkeley, California]]| pages = | language = | publisher = | date =January 1, 2002 | url =http://baynature.org/article/from-the-bottom-up/| accessdate = July 2, 2016}}</ref> As the newly hatched shrimp develop and mature, they gradually migrate to "deeper, cooler and more saline water". <ref name=Estuary>{{Citation
The two most important natural environmental factors affecting the health of the shrimp population are water temperature and salinity. The shrimp thrive in [[brackish water]], with a preferred salinity of 14 parts per thousand (ppt) when young to 24 ppt when ready to spawn.<ref name = Ellinger/> In contrast, open ocean waters have a salinity of about 35 ppt. The species prefers a water temperature of about 18&nbsp;°C, or 65&nbsp;°F.<ref name = Ellinger/> Because these factors vary within the bay, based on the seasons each year, and the variations in the inflow of fresh water in heavy rainfall years as opposed to drought years, the shrimp migrate around the bay, seeking optimal conditions, and their population levels fluctuate dramatically. When heavy flows of fresh water enter the bay, mature females migrate to the saltier parts of the central bay, or out the [[Golden Gate]] to the [[Gulf of the Farallones]].<ref name = Ellinger/> There, they mate with males which prefer a slightly saltier environment. The females then incubate from 2,000 to 8,000 eggs<ref name=PSMFC/><ref name = Ellinger/> and when hatched, the young shrimp migrate back to the shallower and less salty estuaries around the bay.<ref name = Ellinger>{{cite news | last = Ellinger| first =Micky | title =From the Bottom Up: The Tiny Bay Shrimp Makes History | newspaper =Bay Nature | location = [[Berkeley, California]]| date =January 1, 2002 | url =http://baynature.org/article/from-the-bottom-up/| access-date = July 2, 2016}}</ref> As the newly hatched shrimp develop and mature, they gradually migrate to "deeper, cooler and more saline water".<ref name=Estuary>{{Citation
| last =Smith
| last1 =Smith
| first =Susan E.
| first1 =Susan E.
| last2 =Kato
| last2 =Kato
| first2 =Susumu
| first2 =Susumu
Line 51: Line 39:
| year =1979
| year =1979
| chapter =The Fisheries of San Francisco Bay: Past, Present and Future
| chapter =The Fisheries of San Francisco Bay: Past, Present and Future
| pages =462–463
| pages =[https://archive.org/details/sanfranciscobayu00conorich/page/462 462–463]
| isbn =0-934394-01-6
| isbn =978-0-934394-01-7
| chapter-url-access =registration
| chapter-url =https://archive.org/details/sanfranciscobayu00conorich/page/462
}}</ref>
}}</ref>


==Environmental stresses==
==Environmental stresses==


When exposed to sewage in a laboratory, the species shows behavior described as "avoidance of the toxicant".<ref>{{cite book|url=https://books.google.com/books?id=DoE3gchMBv4C&pg=PA55&dq=Crangon+franciscorum&hl=en&sa=X&ei=EPQBVZqCAYjFggTDt4S4CQ&ved=0CDcQ6AEwBQ#v=onepage&q=Crangon%20franciscorum&f=false|title=Environmental Toxicology and Risk Assessment|publisher=[[ASTM International]]|volume=2|page=55-56|isbn=0803114850}}</ref> It is "sensitive to pollution in estuaries".<ref name=PSMFC/>
When exposed to sewage in a laboratory, the species shows behavior described as "avoidance of the toxicant".<ref>{{cite book|url=https://books.google.com/books?id=DoE3gchMBv4C&dq=Crangon+franciscorum&pg=PA55|title=Environmental Toxicology and Risk Assessment|publisher=[[ASTM International]]|volume=2|pages=55–56|isbn=978-0803114852|year=1993}}</ref> It is "sensitive to pollution in estuaries".<ref name=PSMFC/>


In the late 19th and early 20th century, San Francisco Bay became increasingly polluted. The Gold Rush, which proceeded commercial shrimp fishing, caused the first significant environmental damage to San Francisco Bay. [[Hydraulic mining]] techniques introduced tens of millions of cubic meters annually of rock and soil debris into the Sacramento and San Joaquin rivers, the main sources of fresh water input into the bay. The accumulation of sediment on the bottom of the bay reduced total water volume and changed tidal patterns. Hydraulic mining was banned by an 1884 court decision.<ref name = Modification>{{cite journal
In the late 19th and early 20th centuries, San Francisco Bay became increasingly polluted. The Gold Rush, which proceeded commercial shrimp fishing, caused the first significant environmental damage to San Francisco Bay. [[Hydraulic mining]] techniques introduced tens of millions of cubic meters annually of rock and soil debris into the Sacramento and San Joaquin Rivers, the main sources of fresh water put into the bay. The accumulation of sediment on the bottom of the bay reduced total water volume and changed tidal patterns. Hydraulic mining was banned by an 1884 court decision.<ref name = Modification>{{cite journal
| last =Nichols
| last1 =Nichols
| first =Frederic H.
| first1 =Frederic H.
| author-link =
| last2 =Cloern
| last2 =Cloern
| first2 =James E.
| first2 =James E.
| author-link2 =
| last3 =Luoma
| last3 =Luoma
| first3 =Samuel N
| first3 =Samuel N.
| author-link3 =
| last4 =Peterson
| last4 =Peterson
| first4 =David H.
| first4 =David H.
| title =The modification of an estuary
| author-link4 =
| title =The Modification of an Estuary
| journal =[[Science (journal)|Science]]
| journal =[[Science (journal)|Science]]
| volume = 231
| volume = 231
| issue =4738
| issue =4738
| pages =567-573
| pages =567–573
| publisher =[[American Association for the Advancement of Science]]
| location =
| date =February 7, 1986
| date =February 7, 1986
| language =
| url =http://science.sciencemag.org/content/231/4738/567
| jstor =
| issn = 1095-9203
| issn = 1095-9203
| doi = 10.1126/science.231.4738.567
| doi = 10.1126/science.231.4738.567
| id =
| pmid =17750968
| mr =
| s2cid =35846027
}}</ref> The size of the bay shrank as dikes were built to create farmland and salt ponds, and areas of the bay were filled to create real estate, such as San Francisco's Marina District, Treasure Island, and Foster City.<ref name = Ellinger/> The vast majority of the tidal marshes around the bay, where the shrimp thrive, were lost to development by the 1980s.<ref name = Modification/>
| zbl =
| jfm =
| access-date =July 10, 2016 }}</ref> The size of the bay shrank as dikes were built to create farmland and salt ponds, and areas of the bay were filled to create real estate, such as San Francisco's Marina District, Treasure Island and Foster City.<ref name = Ellinger/> The vast majority of the tidal marshes around the bay, where the shrimp thrive, were lost to development by the 1980s.<ref name = Modification/>


The [[Central Valley Project]], which began in 1933, and the [[California State Water Project]], which began in 1960, were efforts using dams, reservoirs and canals, to divert water from the Sacramento and San Joaquin river systems for use in agricultural irrigation and urban development. By the 1980s, the annual inflow of fresh water into the bay was reduced to about 40% of historic levels.<ref name = Modification/>
The [[Central Valley Project]], which began in 1933, and the [[California State Water Project]], which began in 1960, were efforts using dams, reservoirs, and canals, to divert water from the Sacramento and San Joaquin River systems for use in agricultural irrigation and urban development. By the 1980s, the annual inflow of fresh water into the bay was reduced to about 40% of historic levels.<ref name = Modification/>


Following prolonged droughts, the shrimp population declines, and following wet years, it rebounds. In 1996, after two wet years, the shrimp population was 20 times larger than it was in 1980, following the severe drought of the late 1970s.<ref name = Ellinger/>
Following prolonged droughts, the shrimp population declines, and following wet years, it rebounds. In 1996, after two wet years, the shrimp population was 20 times larger than it was in 1980, following the severe drought of the late 1970s.<ref name = Ellinger/>
Line 97: Line 76:
==Commercial fishing==
==Commercial fishing==


This species was by far the most common type of shrimp in [[San Francisco Bay]] in the 19th century, and was the most important species for its commercial shrimp fishery from the 1870s to the 1930s, accounting for about 90% of the shrimp catch.<ref name = Bonnot>{{cite news | last = Bonnot| first =Paul | title = The California Shrimp Industry| newspaper =Fish Bulletin No. 38 | location = Terminal Island, California| publisher =Division of Fish and Game of California | date =1932 | url =http://content.cdlib.org/view?docId=kt3f59n68z&brand=calisphere&doc.view=entire_text | accessdate = June 26, 2016}}</ref>
This species was by far the most common species of shrimp in San Francisco Bay in the 19th century, and was also the most important species for its commercial shrimp fishery from the 1870s to the 1930s, accounting for about 90% of the shrimp catch.<ref name = Bonnot>{{cite news | last = Bonnot| first =Paul | title = The California Shrimp Industry| newspaper =Fish Bulletin No. 38 | location = Terminal Island, California| publisher =Division of Fish and Game of California | date =1932 | url =http://content.cdlib.org/view?docId=kt3f59n68z&brand=calisphere&doc.view=entire_text | access-date = June 26, 2016}}</ref>


==References==
==References==
{{Reflist}}
{{Reflist}}
{{Taxonbar|from=Q4485789}}


[[Category:Caridea]]
[[Category:Crustaceans of the eastern Pacific Ocean]]
[[Category:Animals described in 1860]]
[[Category:Endemic fauna of California]]
[[Category:Endemic fauna of California]]
[[Category:Endemic crustaceans of the United States]]

[[Category:Crustaceans described in 1856]]

[[Category:Taxa named by William Stimpson]]
{{Decapoda-stub}}
[[Category:Fauna without expected TNC conservation status]]
[[Category:Crangonidae]]

Latest revision as of 15:58, 23 August 2023

Crangon franciscorum
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Malacostraca
Order: Decapoda
Suborder: Pleocyemata
Infraorder: Caridea
Family: Crangonidae
Genus: Crangon
Species:
C. franciscorum
Binomial name
Crangon franciscorum
Stimpson, 1856

Crangon franciscorum is a species of shrimp in the family Crangonidae which is endemic to the brackish estuaries of California,[1] and found from Puget Sound in the north to San Diego, California in the south.[2] The species is especially abundant in San Francisco Bay, despite population fluctuations due to environmental stresses. Its common names include bay shrimp, sand shrimp, common shrimp, grass shrimp, black shrimp, California shrimp and black tailed shrimp.[2] The species has been commercially fished from 1869 to the present.

Role in the Bay food web[edit]

This shrimp species is "an important part of the estuarine food web" in the greater San Francisco Bay.[3] It feeds on bivalves, amphipods and foraminiferins, and is prey for various fish,[3] including striped bass, white sturgeon, Pacific tomcod and shellfish such as Dungeness crab.[2] Its diet is "heavily influenced by predator size, temperature-salinity preferences, and prey availability."[3]

Lifecycle[edit]

The shrimp are short-lived, with a lifespan ranging up to 18 months for males and 30 months for females. The males spawn once, while longer-lived females spawn twice. Some evidence indicates the species may be protandrous hermaphrodites, which means that surviving males are transformed into females after one year of life. This may account for the longer lifespan of females.

The two most important natural environmental factors affecting the health of the shrimp population are water temperature and salinity. The shrimp thrive in brackish water, with a preferred salinity of 14 parts per thousand (ppt) when young to 24 ppt when ready to spawn.[4] In contrast, open ocean waters have a salinity of about 35 ppt. The species prefers a water temperature of about 18 °C, or 65 °F.[4] Because these factors vary within the bay, based on the seasons each year, and the variations in the inflow of fresh water in heavy rainfall years as opposed to drought years, the shrimp migrate around the bay, seeking optimal conditions, and their population levels fluctuate dramatically. When heavy flows of fresh water enter the bay, mature females migrate to the saltier parts of the central bay, or out the Golden Gate to the Gulf of the Farallones.[4] There, they mate with males which prefer a slightly saltier environment. The females then incubate from 2,000 to 8,000 eggs[2][4] and when hatched, the young shrimp migrate back to the shallower and less salty estuaries around the bay.[4] As the newly hatched shrimp develop and mature, they gradually migrate to "deeper, cooler and more saline water".[5]

Environmental stresses[edit]

When exposed to sewage in a laboratory, the species shows behavior described as "avoidance of the toxicant".[6] It is "sensitive to pollution in estuaries".[2]

In the late 19th and early 20th centuries, San Francisco Bay became increasingly polluted. The Gold Rush, which proceeded commercial shrimp fishing, caused the first significant environmental damage to San Francisco Bay. Hydraulic mining techniques introduced tens of millions of cubic meters annually of rock and soil debris into the Sacramento and San Joaquin Rivers, the main sources of fresh water put into the bay. The accumulation of sediment on the bottom of the bay reduced total water volume and changed tidal patterns. Hydraulic mining was banned by an 1884 court decision.[7] The size of the bay shrank as dikes were built to create farmland and salt ponds, and areas of the bay were filled to create real estate, such as San Francisco's Marina District, Treasure Island, and Foster City.[4] The vast majority of the tidal marshes around the bay, where the shrimp thrive, were lost to development by the 1980s.[7]

The Central Valley Project, which began in 1933, and the California State Water Project, which began in 1960, were efforts using dams, reservoirs, and canals, to divert water from the Sacramento and San Joaquin River systems for use in agricultural irrigation and urban development. By the 1980s, the annual inflow of fresh water into the bay was reduced to about 40% of historic levels.[7]

Following prolonged droughts, the shrimp population declines, and following wet years, it rebounds. In 1996, after two wet years, the shrimp population was 20 times larger than it was in 1980, following the severe drought of the late 1970s.[4]

Commercial fishing[edit]

This species was by far the most common species of shrimp in San Francisco Bay in the 19th century, and was also the most important species for its commercial shrimp fishery from the 1870s to the 1930s, accounting for about 90% of the shrimp catch.[8]

References[edit]

  1. ^ Fransen, C.; De Grave, S. (2015). "Crangon franciscorum Stimpson, 1856". WoRMS. World Register of Marine Species. Retrieved March 12, 2015.
  2. ^ a b c d e "Shellfish of the Pacific Northwest" (PDF). SteamNet Project. Pacific States Marine Fisheries Commission.
  3. ^ a b c Wahle, Richard A. (May 1985). "The feeding ecology of Crangon franciscorum and Crangon nigricauda in San Francisco Bay, California". Journal of Crustacean Biology. 5 (2): 311–326. doi:10.2307/1547879. JSTOR 1547879.
  4. ^ a b c d e f g Ellinger, Micky (January 1, 2002). "From the Bottom Up: The Tiny Bay Shrimp Makes History". Bay Nature. Berkeley, California. Retrieved July 2, 2016.
  5. ^ Smith, Susan E.; Kato, Susumu (1979) [1977], "The Fisheries of San Francisco Bay: Past, Present and Future", San Francisco Bay: The Urbanized Estuary, San Francisco: American Association for the Advancement of Science, Pacific Division, pp. 462–463, ISBN 978-0-934394-01-7
  6. ^ Environmental Toxicology and Risk Assessment. Vol. 2. ASTM International. 1993. pp. 55–56. ISBN 978-0803114852.
  7. ^ a b c Nichols, Frederic H.; Cloern, James E.; Luoma, Samuel N.; Peterson, David H. (February 7, 1986). "The modification of an estuary". Science. 231 (4738): 567–573. doi:10.1126/science.231.4738.567. ISSN 1095-9203. PMID 17750968. S2CID 35846027.
  8. ^ Bonnot, Paul (1932). "The California Shrimp Industry". Fish Bulletin No. 38. Terminal Island, California: Division of Fish and Game of California. Retrieved June 26, 2016.