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Millepora squarrosa

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CNIDARIA HYDROZOA MILLEPORINA MILLEPORIDAE

Scientific Name: Millepora squarrosa
Species Authority: Lamarck 1816

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2008
Date Assessed: 2008-01-01
Assessor(s): Obura, D., Fenner, D., Hoeksema, B., Devantier, L. & Sheppard, C.
Reviewer(s): Livingstone, S., Polidoro, B. & Smith, J. (Global Marine Species Assessment)
Justification:
This species is relatively restricted range and is locally common, but is considered the least common Millepora species in the Caribbean. This species is susceptible to bleaching and is sometimes harvested for the curio and jewellery trade, and it has suffered reduction of coral reef habitat due to a combination of threats. Specific population trends are unknown, but population reduction can be inferred from declines in habitat quality based on estimates of destroyed reefs within its range (Wilkinson 2004). The estimated habitat degradation and loss of 12% over three generation lengths (30 years) is the best inference of population reduction and does not meet any of the thresholds for threatened categories. It is listed as Least Concern. It will be important to reassess this species in 10 years time because of predicted threats from climate change and ocean acidification.

Geographic Range [top]

Range Description: This species has a restricted distribution in the Caribbean. All references to it outside of the southeastern Caribbean are likely misidentifications of a growth form of M. complanata (Fenner, pers. comm.).
Countries:
Native:
Barbados; Dominica; Grenada; Saint Barthélemy; Saint Lucia; Saint Martin (French part); Saint Vincent and the Grenadines; Trinidad and Tobago; Venezuela, Bolivarian Republic of
FAO Marine Fishing Areas:
Native:
Atlantic – western central
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: This is the most restricted of the Caribbean Millepora species. It is considered common to occasional from the Dominican Republic southward through the Lesser Antilles. But has not been reported from Florida, the Bahamas, or the northern or western Caribbean (Humann and DeLoach 2006).

There is no species specific population information available for this species. However, there is evidence that overall coral reef habitat has declined, and this is used as a proxy for population decline for this species. This species is more resilient to some of the threats faced by corals and therefore population decline is estimated using the percentage of destroyed reefs only (Wilkinson 2004). We assume that most, if not all, mature individuals will be removed from a destroyed reef and that on average, the number of individuals on reefs are equal across its range and proportional to the percentage of destroyed reefs. Reef losses throughout the species' range have been estimated over three generations, two in the past and one projected into the future.

The age of first maturity of most reef building corals is typically three to eight years (Wallace 1999) and therefore we assume that average age of mature individuals is greater than eight years. Furthermore, based on average sizes and growth rates, we assume that average generation length is 10 years, unless otherwise stated. Total longevity is not known, but likely to be more than ten years. Therefore any population decline rates for the Red List assessment are measured over at least 30 years. Follow the link below for further details on population decline and generation length estimates.
For further information about this species, see Corals_SupportingDoc.pdf.
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Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: This shallow water species is often found on reef crest to depths of approximately 10 m. Millepora species are generally found in inshore areas characterized by turbidity, and exhibit a tolerance for siltation. They often occur in clear offshore sites (Lovell, pers. comm.).
Systems: Marine

Threats [top]

Major Threat(s): This species has been reduced from historical baselines, but probably not much more than 10% except locally on some reefs. This species has been affected in past bleaching events but appears to recover more rapidly than most scleractinian species (Precht, pers. comm.).

This genus is generally not found in aquarium trade, but is sometimes collected for curio and jewellery trade. This genus is generally susceptible to bleaching. They are some of the first hard corals to bleach but are resilient, being some of the first to recruit after the bleaching.

In general, the major threat to corals is global climate change, in particular, temperature extremes leading to bleaching and increased susceptibility to disease, increased severity of ENSO events and storms, and ocean acidification. In addition to global climate change, corals are also threatened by disease, and a number of localized threats. The severity of these combined threats to the global population of each individual species is not known.

Coral disease has emerged as a serious threat to coral reefs worldwide and is a major cause of reef deterioration (Weil et al. 2006). The numbers of diseases and coral species affected, as well as the distribution of diseases have all increased dramatically within the last decade (Porter et al. 2001, Green and Bruckner 2000, Sutherland et al. 2004, Weil 2004). Coral disease epizootics have resulted in significant losses of coral cover and were implicated in the dramatic decline of acroporids in the Florida Keys (Aronson and Precht 2001, Porter et al. 2001, Patterson et al. 2002). Escalating anthropogenic stressors combined with the threats associated with global climate change of increases in coral disease, frequency and duration of coral bleaching and ocean acidification place coral reefs at high risk of collapse.

Localized threats to corals include fisheries, human development (industry, settlement, tourism, and transportation), changes in native species dynamics (competitors, predators, pathogens and parasites), invasive species (competitors, predators, pathogens and parasites), dynamite fishing, chemical fishing, pollution from agriculture and industry, domestic pollution, sedimentation, and human recreation and tourism activities.

Conservation Actions [top]

Conservation Actions: These non-scleractinian corals are listed under Appendix I and II of CITES. There are no records in the CITES database of exports of non-scleractinians by weight. Parts of this species distribution fall within several Marine Protected Areas within its range.

Recommended measures for conserving this species include research in taxonomy, population, abundance and trends, ecology and habitat status, threats and resilience to threats, restoration action; identification, establishment and management of new protected areas; expansion of protected areas; recovery management; and disease, pathogen and parasite management. Artificial propagation and techniques such as cryo-preservation of gametes may become important for conserving coral biodiversity.

Having timely access to national-level trade data for CITES analysis reports would be valuable for monitoring trends this species. The species is targeted by collectors for the aquarium trade and fisheries management is required for the species, e.g., Marine Protected Areas, quotas, size limits, etc. Consideration of the suitability of species for aquaria should also be included as part of fisheries management, and population surveys should be carried out to monitor the effects of harvesting.

Citation: Obura, D., Fenner, D., Hoeksema, B., Devantier, L. & Sheppard, C. 2008. Millepora squarrosa. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 25 July 2014.
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