The IUCN Red List of Threatened Species™
ISSN 2307-8235 (online)
IUCN 2008: T63585A12684515
Desmarestia tropica, Tropical Acidweed
Assessment by: Miller, K.A., Garske, L. & Edgar, G.
View on www.iucnredlist.org
Citation: Miller, K.A., Garske, L. & Edgar, G. 2007. Desmarestia tropica. The IUCN Red List of
Threatened Species 2007: e.T63585A12684515.
http://dx.doi.org/10.2305/IUCN.UK.2007.RLTS.T63585A12684515.en
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THE IUCN RED LIST OF THREATENED SPECIES™
Taxonomy
Kingdom
Phylum
Class
Order
Family
Chromista
Ochrophyta
Phaeophyceae
Desmarestiales
Desmarestiaceae
Taxon Name: Desmarestia tropica W.R.Taylor
Common Name(s):
• English:
Tropical Acidweed
Assessment Information
Red List Category & Criteria:
Critically Endangered (Possibly Extinct) A2a ver 3.1
Year Published:
2007
Date Assessed:
March 1, 2007
Justification:
This is a conspicuous species that has not been observed since 1972, despite directed surveys in the
type locality and other deep, cool locations around the archipelago. It inhabits cool water and has likely
been affected by El Niño events in the last three decades, particularly the 1982-83 event, which greatly
reduced macro-algal coverage across the archipelago. Since this species was found at two locations
historically, and has not been found in recent decades, a 100% reduction in known populations is
evident. A cryptic gametophyte stage may exist in deeper waters, but there is no evidence that it has
been reproducing to produce the more conspicuous sporophyte stage. The species is Possibly Extinct.
Date last seen: 1972
Geographic Range
Range Description:
Desmarestia tropica is endemic to the Galápagos Islands, only known from two locations: Floreana: Post
Office Bay (Taylor 1945: type locality). Second locality: Collected in 1972, Caleta Tagus, Isabela.
Acleto (1973) reported this species from Peru; however, this report is considered an error. [A. Peters
annotated a specimen and indicated that the identification was incorrect, K.A. Miller pers. comm.]
Country Occurrence:
Possibly extinct: Ecuador (Galápagos)
FAO Marine Fishing Areas:
Possibly extinct: Pacific - southeast
© The IUCN Red List of Threatened Species: Desmarestia tropica – published in 2007.
http://dx.doi.org/10.2305/IUCN.UK.2007.RLTS.T63585A12684515.en
1
Distribution Map
© The IUCN Red List of Threatened Species: Desmarestia tropica – published in 2007.
http://dx.doi.org/10.2305/IUCN.UK.2007.RLTS.T63585A12684515.en
2
Population
Unknown. No abundance estimates from type description. This is a conspicuous species that has not
been observed since 1972, despite directed surveys in the type locality and other deep, cool locations
around the archipelago. It inhabits cool water and has likely been affected by El Niño events in the last
three decades, particularly the 1982-83 event, which greatly reduced macro-algal coverage across the
archipelago. Since this species was found at two locations historically, and has not been found in recent
decades, a 100% reduction in known populations is evident. A cryptic gametophyte stage may exist in
deeper waters, but there is no evidence that it has been reproducing to produce the more conspicuous
sporophyte stage.
Current Population Trend: Decreasing
Habitat and Ecology (see Appendix for additional information)
Collected by dredge from 14 to 60 m depth. Belongs to a cold water order of algae that is rare in the
tropics (K.A. Miller pers. comm.). The cryptic gametophyte stage of this species may exist in cooler,
deeper waters; however, no recent evidence indicates reproduction to produce the more conspicuous
sporophyte stage, which may be seasonal (K.A. Miller pers. comm.).
Systems: Marine
Threats (see Appendix for additional information)
El Niño warming events; the elevated (i.e., up to 5°C above long-term average) and persistent (i.e., >12
months) temperatures that characterize El Niño events are likely to negatively affect this cold water
species (Edgar and Garske 2004).
Conservation Actions (see Appendix for additional information)
Historic records currently within the Galápagos Marine Reserve (IUCN category VI); Galápagos
Archipelago Particularly Sensitive Sea Area (PSSA); Galápagos Island World Heritage Site (UNESCO N
(i)(ii)(iii)(iv)), and Galápagos Island Man and Biosphere Reserve (UNESCO).
Credits
Assessor(s):
Miller, K.A., Garske, L. & Edgar, G.
Reviewer(s):
Stuart, S.N. & Carpenter, K.E. (Global Marine Species Assessment Coordinating
Team)
© The IUCN Red List of Threatened Species: Desmarestia tropica – published in 2007.
http://dx.doi.org/10.2305/IUCN.UK.2007.RLTS.T63585A12684515.en
3
Bibliography
Acleto, C.O. 1973. Las algas marinas del Perú. Boletin de la Sociedad Peruana de Botánica 6: 1-164.
Edgar, G. and Garske, L. 2004. Conservation Outcomes Indicators for the Galápagos Marine Reserve.
Conservation International. 54 pp.
IUCN. 2007. 2007 IUCN Red List of Threatened Species. Available at: www.iucnredlist.org. (Accessed:
12th September 2007).
Taylor, W.R. 1945. Pacific marine algae of the Allan Hancock Expeditions to the Galápagos Islands. Allan
Hancock Pacific Expeditions 12 12(iv): 528 pp.
Citation
Miller, K.A., Garske, L. & Edgar, G. 2007. Desmarestia tropica. The IUCN Red List of Threatened Species
2007: e.T63585A12684515. http://dx.doi.org/10.2305/IUCN.UK.2007.RLTS.T63585A12684515.en
Disclaimer
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External Resources
For Images and External Links to Additional Information, please see the Red List website.
© The IUCN Red List of Threatened Species: Desmarestia tropica – published in 2007.
http://dx.doi.org/10.2305/IUCN.UK.2007.RLTS.T63585A12684515.en
4
Appendix
Habitats
(http://www.iucnredlist.org/technical-documents/classification-schemes)
Habitat
Season
Suitability
Major
Importance?
9. Marine Neritic -> 9.7. Marine Neritic - Macroalgal/Kelp
-
Suitable
-
Threats
(http://www.iucnredlist.org/technical-documents/classification-schemes)
Threat
Timing
Scope
Severity
Impact Score
11. Climate change & severe weather -> 11.3.
Temperature extremes
Ongoing
-
-
-
Stresses:
2. Species Stresses -> 2.1. Species mortality
Ongoing
-
Stresses:
1. Ecosystem stresses -> 1.2. Ecosystem degradation
2. Species Stresses -> 2.1. Species mortality
11. Climate change & severe weather -> 11.5. Other
impacts
-
-
Conservation Actions in Place
(http://www.iucnredlist.org/technical-documents/classification-schemes)
Conservation Actions in Place
In-Place Land/Water Protection and Management
Conservation sites identified: Yes, over entire range
Conservation Actions Needed
(http://www.iucnredlist.org/technical-documents/classification-schemes)
Conservation Actions Needed
1. Land/water protection -> 1.1. Site/area protection
2. Land/water management -> 2.1. Site/area management
Research Needed
(http://www.iucnredlist.org/technical-documents/classification-schemes)
Research Needed
0. Root -> 100.1. OLD 1.1.1-Policy-base actions->Management plans->Development
© The IUCN Red List of Threatened Species: Desmarestia tropica – published in 2007.
http://dx.doi.org/10.2305/IUCN.UK.2007.RLTS.T63585A12684515.en
5
Research Needed
1. Research -> 1.1. Taxonomy
1. Research -> 1.2. Population size, distribution & trends
1. Research -> 1.3. Life history & ecology
1. Research -> 1.5. Threats
1. Research -> 1.6. Actions
3. Monitoring -> 3.1. Population trends
© The IUCN Red List of Threatened Species: Desmarestia tropica – published in 2007.
http://dx.doi.org/10.2305/IUCN.UK.2007.RLTS.T63585A12684515.en
6
The IUCN Red List Partnership
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.
THE IUCN RED LIST OF THREATENED SPECIES™