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Halophila hawaiiana

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Taxonomy [top]

Kingdom Phylum Class Order Family
PLANTAE TRACHEOPHYTA LILIOPSIDA HYDROCHARITALES HYDROCHARITACEAE

Scientific Name: Halophila hawaiiana
Species Authority: Doty & B.C.Stone
Common Name(s):
English Species code: Hh
Taxonomic Notes: Halophila hawaiiana is a member of the Halophila ovalis complex, and is under taxonomic review.

Assessment Information [top]

Red List Category & Criteria: Vulnerable A2ce ver 3.1
Year Published: 2010
Date Assessed: 2008-03-17
Assessor(s): Short, F.T., Coles, R., Waycott, M., Bujang, J.S., Fortes, M., Prathep, A., Kamal, A.H.M., Jagtap, T.G., Bandeira, S., Freeman, A., Erftemeijer, P., La Nafie, Y.A., Vergara, S., Calumpong, H.P. & Makm, I.
Reviewer(s): Livingstone, S., Harwell, H. & Carpenter, K.E.
Justification:
Halophila hawaiiana is endemic to the Hawaiian Islands. It is locally common, however the overall population trend is declining. The species has a restricted distribution and a narrow depth range. In some areas this species has been replaced by invasive algal species and it is also highly threatened by shoreline development and beach replenishment. It estimated that there has been a greater than 30% decline in population over the past 10 years and therefore reaches the threshold under A criterion. It is listed as Vulnerable.

Geographic Range [top]

Range Description: Halophila hawaiiana is endemic to the Hawaiian Islands, USA. It is not found on the island of Hawaii. Given its very shallow depth range and patchy occurrence, it has an area of occupancy estimated to be less than 2000 km2.
Countries:
Native:
United States (Hawaiian Is.)
FAO Marine Fishing Areas:
Native:
Pacific – eastern central
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: The overall population trend for Halophila hawaiiana is declining due to competition with algal species, shoreline development and beach replenishment. There has been an estimated decline of at least 30% over at least the past 10 years (M. Waycott pers. comm. 2008). Halophila hawaiiana can be locally common, and can occur in dense meadows.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: Halophila hawaiiana is found in the shallow subtidal zone in sandy protected areas. This species flowers relatively quickly. More information is needed on recruitment rate. This species has a high turnover rate, and is fast growing. The average leaf density of this species is 30,650 leaves/m². Its turnover rate is 14.7 days with a productivity of 7.11 g dw/m²/d (Herbert 1986).
Systems: Marine

Threats [top]

Major Threat(s): Halophila hawaiiana has a restricted distribution and is endemic to the Hawaiian Islands, thus making it of a higher extinction risk. It also has a narrow depth range.  The habitat of this species has been taken over by invasive algal species in some parts of its range, resulting in declines. It is also highly threatened by shoreline development and beach replenishment.

Conservation Actions [top]

Conservation Actions: Halophila hawaiiana is present in the Northwestern Hawaiian Islands World Heritage Site.

More information is needed on recruitment rates and taxonomy of H. hawaiiana.

Citation: Short, F.T., Coles, R., Waycott, M., Bujang, J.S., Fortes, M., Prathep, A., Kamal, A.H.M., Jagtap, T.G., Bandeira, S., Freeman, A., Erftemeijer, P., La Nafie, Y.A., Vergara, S., Calumpong, H.P. & Makm, I. 2010. Halophila hawaiiana. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 22 September 2014.
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