Zostera capensis 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Plantae Tracheophyta Liliopsida Najadales Zosteraceae

Scientific Name: Zostera capensis Setch.
Common Name(s):
English Species code: Zp
Taxonomic Notes: Zostera capensis has been reclassified as Nanozostera (Tomlinson and Posluzny 2001), although here it is retained in the genus Zostera until genetic information is obtained.

Assessment Information [top]

Red List Category & Criteria: Vulnerable B2ab(ii,iii) ver 3.1
Year Published: 2010
Date Assessed: 2007-03-17
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.
Zostera capensis is present in the east coast of Africa and is a more temperate species that extends into a tropical zone. The population is severely fragmented and there is also a continuing decline in habitat quality. Major threats are coastal development, flooding, sedimentation and pollution as well as destructive shellfish harvesting for bivalves. There have been declines in the population, serious ones in Mozambique. Although it is fast growing, it does not colonize quickly. This species has a fluctuating population. The area of occupancy is less than 2,000 km² and therefore meets the threshold for criterion B2 and is listed as Vulnerable.

Geographic Range [top]

Range Description:Zostera capensis occurs in the Indian Ocean from northern Kenya south around the tip of South Africa, and on the northwest coast of Madagascar. Zostera capensis has a limited distribution, which is also patchy due to a lack of suitable habitat. The area of occupancy is estimated to be less than 2,000 km².
Countries occurrence:
Kenya; Madagascar; Mozambique; South Africa; Tanzania, United Republic of
FAO Marine Fishing Areas:
Atlantic – southeast; Indian Ocean – western
Additional data:
Estimated area of occupancy (AOO) - km2:<2,000
Lower depth limit (metres):6
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Zostera capensis is common in the southern part of its range and is the only species of seagrass present in the southern region. It is a temperate species and only a small part of the range is found in the tropics, where it is rare. There have been declines documented in a number of sites throughout its range. Reports suggest that the population has been reduced by more than a third in Mozambique (Bandeira and Gell 2003). The population also has fluctuations. There is additional anecdotal information to suggest a decline in the more northerly tropical regions.

There have been a number of documented declines in the area of Z. capensis in Mozambique. In B. Pescadores the area of seagrass was 1,732 ha in 1991, and it had declined to 73 ha in 2003 (a loss of 95.8 %). This decline was due to sedimentation from flooding (Bandeira and Gell 2003). A decline was also documented in I. Inhaca from 871 ha in 1991 to 808 ha in 2003 (a loss of 7.2 %) (Bandeira and Gell 2003). There were also recorded declines in Mecufi from 3.88 ha in 1991 to 2 ha in 2003 (Bandeira and António 1996; Bandeira and Gell 2003).

In South Africa, Z. capensis occurs in 17 estuaries in southeast South Africa Coast. It consists of small individual beds, generally only a few hectares, and the total area covered by seagrass is 7.07 km² (Bandeira and Gell 2003). Some other localized declines have been reported in South Africa (J. Adams pers. comm. 2008).

In Tanzania, the total area of Z. capensis is unknown, but it has been seen in Zanzibar in 2006 (Ochieng and Erftemeijer 2003, den Hartog, pers. comm. 2006). In Kenya the total area is also unknown but the species has been seen in Shimoni near the border of Tanzania in 2004 (Ochieng and Erftemeijer 2003). The distribution in Madagascar is also unknown (den Hartog 1970).

The total area of occupancy for this species in temperate regions is very small due to available habitat.
Current Population Trend:Decreasing
Additional data:
Population severely fragmented:Yes

Habitat and Ecology [top]

Habitat and Ecology:Zostera capensis occurs mostly in estuarine waters and lagoons in muddy substrates. It also lives in muddy flats. It is a fast growing species typical for the genus Zostera. In the tropics, plants are smaller and flower more rarely. This species has a patchy and fragmented distribution given that it occurs in generally small areas of  available habitat.
Generation Length (years):4

Threats [top]

Major Threat(s): Zostera capensis exists in small areas in coastal estuaries and lagoons and is therefore particularly susceptible to coastal development in these regions. Although it is fast growing it does not colonise quickly. Flooding of estuarine areas, sedimentation and pollution are major threats to this species. Shellfish harvesting for bivalves (hand-digging) in Mozambique is also a serious threat (S. Bandeira pers. comm. 2008).

Conservation Actions [top]

Conservation Actions: There are no specific conservation measures currently in place for Zostera capensis. It was considered for inclusion in the most recent management plan of the Mombosa Marine National Park and Reserve. It is protected in coastal zone management initiatives in Tanzania by IUCN, Zanzibar (Menai Bay Conservation Project), Mafia Marine Park (by WWF) and Kinondoni Coastal Area Management Programme.

Recommended measures include transplanting for areas that have been affected by clam collection and sedimentation due to flooding, increased regulation and better management of clam collection, and better management of coastal areas for seagrass areas.

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. Zostera capensis. The IUCN Red List of Threatened Species 2010: e.T173370A7001305. . Downloaded on 23 May 2018.
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