The IUCN Red List of Threatened Species™ISSN 2307-8235 (online)
IUCN 2008: T173372A7001725
Halodule wrightii, Species code: Hw
Assessment by: Short, F.T., Carruthers, T.J.R., van Tussenbroek, B. & Zieman, J.
View on www.iucnredlist.org
Citation: Short, F.T., Carruthers, T.J.R., van Tussenbroek, B. & Zieman, J. 2010. Halodule wrightii. The
IUCN Red List of Threatened Species 2010: e.T173372A7001725.
http://dx.doi.org/10.2305/IUCN.UK.2010-3.RLTS.T173372A7001725.en
IUCN Red List of Threatened Species 2010: e.T173372A7001725.
http://dx.doi.org/10.2305/IUCN.UK.2010-3.RLTS.T173372A7001725.en
Copyright: © 2015 International Union for Conservation of Nature and Natural Resources
Reproduction of this publication for educational or other non-commercial purposes is authorized without prior written permission from the copyright holder provided the source is fully acknowledged.
Reproduction of this publication for resale, reposting or other commercial purposes is prohibited without prior written permission from the copyright holder. For further details see Terms of Use.
The IUCN Red List of Threatened Species™ is produced and managed by the IUCN Global Species Programme, the IUCN Species Survival Commission (SSC) and The IUCN Red List Partnership. The IUCN Red List Partners are: BirdLife International; Botanic Gardens Conservation International; Conservation International; Microsoft; NatureServe; Royal Botanic Gardens, Kew; Sapienza University of Rome; Texas A&M University; Wildscreen; and Zoological Society of London.
If you see any errors or have any questions or suggestions on what is shown in this document, please provide us with feedback so that we can correct or extend the information provided.
Citation: Short, F.T., Carruthers, T.J.R., van Tussenbroek, B. & Zieman, J. 2010. Halodule wrightii. The
IUCN Red List of Threatened Species 2010: e.T173372A7001725.
http://dx.doi.org/10.2305/IUCN.UK.2010-3.RLTS.T173372A7001725.en
Copyright: © 2015 International Union for Conservation of Nature and Natural Resources
Reproduction of this publication for educational or other non-commercial purposes is authorized without prior written
permission from the copyright holder provided the source is fully acknowledged.
Reproduction of this publication for resale, reposting or other commercial purposes is prohibited without prior written
permission from the copyright holder. For further details see Terms of Use.
The IUCN Red List of Threatened Species™ is produced and managed by the IUCN Global Species Programme, the IUCN
Species Survival Commission (SSC) and The IUCN Red List Partnership. The IUCN Red List Partners are: BirdLife
International; Botanic Gardens Conservation International; Conservation International; Microsoft; NatureServe; Royal
Botanic Gardens, Kew; Sapienza University of Rome; Texas A&M University; Wildscreen; and Zoological Society of London.
If you see any errors or have any questions or suggestions on what is shown in this document, please provide us with
feedback so that we can correct or extend the information provided.
IUCN Red List of Threatened Species 2010: e.T173372A7001725.
http://dx.doi.org/10.2305/IUCN.UK.2010-3.RLTS.T173372A7001725.en
Copyright: © 2015 International Union for Conservation of Nature and Natural Resources
Reproduction of this publication for educational or other non-commercial purposes is authorized without prior written
permission from the copyright holder provided the source is fully acknowledged.
Reproduction of this publication for resale, reposting or other commercial purposes is prohibited without prior written
permission from the copyright holder. For further details see Terms of Use.
The IUCN Red List of Threatened Species™ is produced and managed by the IUCN Global Species Programme, the IUCN
Species Survival Commission (SSC) and The IUCN Red List Partnership. The IUCN Red List Partners are: BirdLife
International; Botanic Gardens Conservation International; Conservation International; Microsoft; NatureServe; Royal
Botanic Gardens, Kew; Sapienza University of Rome; Texas A&M University; Wildscreen; and Zoological Society of London.
If you see any errors or have any questions or suggestions on what is shown in this document, please provide us with
feedback so that we can correct or extend the information provided.
Taxonomy
Kingdom Phylum Class Order Family
Plantae Tracheophyta Liliopsida Najadales Cymodoceaceae
Kingdom Phylum Class Order Family
Plantae Tracheophyta Liliopsida Najadales Cymodoceaceae
Taxon Name: Halodule wrightii Asch.
Common Name(s):
• English: Shoalgrass, Species code: Hw
Taxonomic Notes:
Halodule wrightii is a well established species. However, the taxonomy of the other species of Halodule
in the Atlantic is less certain (Larkum et al. 2006) and there are questions about its taxonomy in the
Indo-Pacific as well (Green and Short 2003).
Halodule wrightii is a well established species. However, the taxonomy of the other species of Halodule
in the Atlantic is less certain (Larkum et al. 2006) and there are questions about its taxonomy in the
Indo-Pacific as well (Green and Short 2003).
Assessment Information
Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2010
Date Assessed: March 21, 2007
Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2010
Date Assessed: March 21, 2007
Justification:
Halodule wrightii has a disjunct global distribution. The main part of its range is in the Atlantic, although it is also found in the eastern tropical Pacific and the Indian Ocean. It is the dominant species in Brazil and West Africa. Halodule wrightii is a widespread species and is locally abundant. The overall population trend for this species is stable, and possibly increasing in some parts of its range. It is highly tolerant to a range of environmental conditions, however, it is affected locally by coastal development and destructive anthropogenic activities. This species is listed as Least Concern.
Halodule wrightii has a disjunct global distribution. The main part of its range is in the Atlantic, although it is also found in the eastern tropical Pacific and the Indian Ocean. It is the dominant species in Brazil and West Africa. Halodule wrightii is a widespread species and is locally abundant. The overall population trend for this species is stable, and possibly increasing in some parts of its range. It is highly tolerant to a range of environmental conditions, however, it is affected locally by coastal development and destructive anthropogenic activities. This species is listed as Least Concern.
Geographic Range
Range Description:Halodule wrightii has a disjunct global and predominantly tropical distribution. The main part of its range is in the Atlantic: the western tropical Atlantic from northern Florida (USA) to Venezuela including the Gulf of Mexico and the Caribbean Sea; also in Bermuda and North Carolina (USA). In the southern Atlantic, it is present on the coast of Brazil. In the eastern Atlantic, it occurs from southern Morocco on the coast of Africa and the Canary Islands, to the northern part of Angola.
Halodule wrightii is found in the eastern tropical Pacific from the Gulf of California to the Gulf of
Panama. In the Indian Ocean it is found from the northern extent of the Bay of Bengal to along the
Coromandel Coast as well as Oman. Also from southern Somalia to the north part of South Africa
including the Mozambique Channel, Mauritius and Madagascar.
Panama. In the Indian Ocean it is found from the northern extent of the Bay of Bengal to along the
Coromandel Coast as well as Oman. Also from southern Somalia to the north part of South Africa
including the Mozambique Channel, Mauritius and Madagascar.
Country Occurrence:
Native: Angola (Angola); Antigua and Barbuda; Aruba; Bahamas; Barbados; Belize; Bermuda; Bonaire, Sint Eustatius and Saba (Saba, Sint Eustatius); Brazil; Cayman Islands; Colombia; Costa Rica; Cuba; Curaçao; Dominica; Dominican Republic; Grenada; Guadeloupe; Guatemala; Guinea-Bissau; Haiti; Honduras; India; Jamaica; Kenya; Madagascar; Mauritania; Mexico; Montserrat; Mozambique; Nicaragua; Panama; Puerto Rico; Saint Kitts and Nevis; Saint Lucia; Saint Martin (French part); Saint Vincent and the Grenadines; Sao Tomé and Principe; Sint Maarten (Dutch part); Tanzania, United Republic of; Trinidad and Tobago; Turks and Caicos Islands; United States; Venezuela, Bolivarian Republic of; Virgin Islands, British; Virgin Islands, U.S.
FAO Marine Fishing Areas:Native: Atlantic - eastern central, Atlantic - northwest, Atlantic - southeast, Atlantic - southwest, Atlantic- western central, Indian Ocean - eastern, Indian Ocean - western, Pacific - eastern central
Population
Halodule wrightii is a widespread species which is locally abundant. It is the dominant species in Brazil and West Africa. In other areas it may be found in mixed beds with other seagrass species. Its presence on the western side of Central America appears to be a migration through the Panama Canal and therefore its range appears to be expanding and there is potential for future range extension if it is
introduced into other areas.
Halodule wrightii is a widespread species which is locally abundant. It is the dominant species in Brazil and West Africa. In other areas it may be found in mixed beds with other seagrass species. Its presence on the western side of Central America appears to be a migration through the Panama Canal and therefore its range appears to be expanding and there is potential for future range extension if it is
introduced into other areas.
According to the Global Seagrass Trajectories Database, (Carruthers pers. comm. 2007) there are 64 published studies that monitored this species over time and of these 40 had no change, 15 decreased in coverage, and nine increased in coverage (all aerial extent, density, biomass, or cover). The overall
population trend for this species is increasing (2% increase). Data from 2000 shows a 28% occurrence when sampling 188 stations at Big Bend, Florida. This is a 23% increase from the data reported by Iverson and Bittaker (1986). Despite the increase in occurrence, maximum depth range decreased from 10.6-8.3 m (Hale et al. 2004). Research by Hall et al. (1999) show a significant widespread decrease in the Florida Bay with a bay wide short shoot density off about 267.5 shoots/m² in 1984 to about 22.5 shoots/m² in 1994. Decrease in abundance was most likely cause by increased light attenuation due to primary die-off off Thalassia testudinum. Reduction can also be linked to a decrease in phosphorus availability caused by reduction in freshwater input (Hall et al. 1999). Global average maximum biomass is estimated to be 253.5 g dw/m² above ground (from 19 observations) and 193.3 g dw/m² below ground (from 12 observations) (Duarte and Chiscano 1999).
Current Population Trend: Increasing
Habitat and Ecology (see Appendix for additional information)
Halodule wrightii is typically found on sandy to muddy bottoms and can be found in mixed seagrass species beds. It is highly tolerant to a range of environmental conditions including wide ranging salinity (hypersaline), high temperatures, turbidity, and eutrophication (Zieman 1982, UNESCO 1998, Hemminga and Duarte 2000, Green and Short 2003, Larkum et al. 2006). Optimum temperatures for H. wrightii range between 20-30°C (Phillips 1960).
Halodule wrightii is typically found on sandy to muddy bottoms and can be found in mixed seagrass species beds. It is highly tolerant to a range of environmental conditions including wide ranging salinity (hypersaline), high temperatures, turbidity, and eutrophication (Zieman 1982, UNESCO 1998, Hemminga and Duarte 2000, Green and Short 2003, Larkum et al. 2006). Optimum temperatures for H. wrightii range between 20-30°C (Phillips 1960).
This species is ephemeral with rapid turn-over and high seed set and forming effective seedbanks, well adapted to high levels of disturbance. It is a pioneer species in Mozambique in exposed sandy areas close to the coastline. It is the dominant species in Texas (USA). It is established along both the eastern and western margins of the lagoon in Tamaulipas (Mexico). In Veracruz (Mexico), it is found in the shallower areas where it tolerates changes in temperature and salinity. In the Caribbean, it is found growing on sand and mud from the intertidal zone to five m. It is the most widely distributed seagrass in Brazil. In South America, it is associated with shallow habitats without much freshwater input, such as reefs, algal beds, coastal lagoons, rocky shores, sand beaches, and unvegetated soft-bottom areas and nearby mangroves (Green and Short 2003).
After a complete destruction of seabeds, a rapid recovery was observed with early recovery characterized by small patches suggesting recovery through fragments. Studies show that fragments stay viable for up to four weeks in the spring months and up to two weeks during the autumn months.
High viability of fragments suggests a high dispersal distance (Hall et al. 2006).
This is usually an early colonizing species yet studies in Florida Bay shows that with increased nutrient levels, Halodule wrightii becomes the dominant species as it is able to out-compete Thalassia
testudinum for light resources, suggesting that areas in Florida Bay with high nutrient availability will be dominated by Halodule wrightii while areas with low nutrients will be dominated by T. testudinum
(Fourqurean et al. 1995).
testudinum for light resources, suggesting that areas in Florida Bay with high nutrient availability will be dominated by Halodule wrightii while areas with low nutrients will be dominated by T. testudinum
(Fourqurean et al. 1995).
Halodule wrightii can rapidly and densely recolonize denuded areas in warm months. Most bed maintenance and new shoot production probably occurs through rhizome elongation (Phillips 1960).
Systems: Marine
Threats (see Appendix for additional information)
Halodule wrightii is a tolerant species to most disturbances. It replaces less tolerant species under conditions of habitat deterioration, eutrophication, and increased turbidity, and therefore general threats are not considerable except in localized situations. Localized threats include trawling activities, coastal development, habitat destruction and mechanical damage from anchoring and recreational and commercial boating.
Halodule wrightii is a tolerant species to most disturbances. It replaces less tolerant species under conditions of habitat deterioration, eutrophication, and increased turbidity, and therefore general threats are not considerable except in localized situations. Localized threats include trawling activities, coastal development, habitat destruction and mechanical damage from anchoring and recreational and commercial boating.
Conservation Actions (see Appendix for additional information)Halodule wrightii is protected in numerous marine protected areas throughout its range.
Credits
Assessor(s): Short, F.T., Carruthers, T.J.R., van Tussenbroek, B. & Zieman, J.
Reviewer(s): Livingstone, S., Harwell, H. & Carpenter, K.E.
Assessor(s): Short, F.T., Carruthers, T.J.R., van Tussenbroek, B. & Zieman, J.
Reviewer(s): Livingstone, S., Harwell, H. & Carpenter, K.E.
