Cladocora caespitosa 

Scope: Mediterranean
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Cnidaria Anthozoa Scleractinia Faviidae

Scientific Name: Cladocora caespitosa (Linnaeus, 1767)
Regional Assessments:
Common Name(s):
English Mediterranean Pillow Coral, Bushy Coral, Thin Tube Coral
Spanish Madrépora Mediterránea
Taxonomic Source(s): WoRMS Editorial Board. 2015. World Register of Marine Species. Available at: http://www.marinespecies.org. (Accessed: 16 April 2015).
Taxonomic Notes:

Even though the species was considered as part of the Faviidae, this affiliation has been considered dubious and the species has most recently been placed within Caryophylliidae (Romano and Cairns 2000, Cairns et al. 2001) and now within Scleractinia incertae sedis (Hoeksema and Cairns 2013).

Assessment Information [top]

Red List Category & Criteria: Endangered A4a (Regional assessment) ver 3.1
Year Published: 2015
Date Assessed: 2014-10-01
Assessor(s): Casado de Amezua, P., Kersting, D., Linares, C.L., Bo, M., Caroselli, E., Garrabou, J., Cerrano, C., Ozalp, B., Terrón-Sigler, A. & Betti, F.
Reviewer(s): Fine, M., Otero Villanueva, M. & Allen, D.J.
Contributor(s): Kružić, P., Zavalaga, C., Templado, J., Jimenez, C., Chefaoui, R. & Kersting, D.

Mediterranean regional assessment: Endangered (EN)

This species is primarily found in the Mediterranean Sea, with a small number of records from the adjacent eastern Atlantic Ocean (the Atlantic coasts of Morocco and Portugal). In the Mediterranean Sea the species is widespread and can be locally abundant. This coral can form extensive banks, but can also exist as scattered, non-reef forming colonies.

This is a long lived, colonial species, with an estimated generation length of 30 years. The most extensive populations described to date, inhabiting the Adriatic Sea and Columbretes Islands, have been reported to have severely declined during the past decades, impacted by a range of threats. For example, over nine years the population in the Columbretes Islands declined by between 55 to 80%. Other subpopulations have also been impacted, including the subpopulations from the Gulf of La Spezia, Dardanelles (Marmara Sea, Turkey) and Cyprus, although quantitative measures of declines are not available. Although declines can not be measured over the past three generation lengths (~90 years), the main threat to this species, global climate change resulting in warming seawater temperatures, is expected to continue and perhaps worsen, in the near future. Populations can recover from the mortality events through recruitment of new individuals to existing colonies and the establishment of new colonies, however the recruitment rate for this long-lived species is extremely low and not able to compensate for the increasing mortality rates. Within a three generation length that includes the past and present, it is inferred that the population will decline by at least 55% to perhaps as high as 80%, as has been documented in the banks at the Columbretes Island. Although these declines nearly reach the threshold for Critically Endangered, the non-reef forming colonies throughout the Mediterranean Sea are persisting at present levels of mortality. Therefore, this species is assessed as Endangered under criterion A4a for the Mediterranean region. 

Continuous monitoring of the species populations is highly recommended. This species should be re-evaluated in five years to include additional information and to determine the effects of continued or increased threats from climate change and direct anthropogenic impacts.

Geographic Range [top]

Range Description:

Cladocora caespitosa can be considered as part of the recent fossil history of the Mediterranean Sea. Since the Pliocene, C. caespitosa has been the only species that develops monospecific reef-like structures in the Mediterranean Basin. The oldest fossil records of banks of C. caespitosa are those described by Aguirre and Jiménez (1998) from the Upper Pliocene shallow marine deposit of the Almería-Nijar basin (southeastern Spain). This coral species became very common in some Quaternary peri-Mediterranean basins and diverse Holocene and Pleistocene fossil banks have been described from several areas (e.g., Cuerda et al. 1986, Fornós et al. 1996, Kühlmann 1996, Bernasconi et al. 1997). Furthermore, Laborel (1987) mentioned the existence of extensive dead banks of C. caespitosa (dated around 2500-3000 years ago) on the coasts of Tunisia and Corsica.

The currently known Cladocora caespitosa distribution range covers the entire Mediterranean Basin and adjacent areas of the Atlantic including Olhao in Portugal and Agadir in Morocco (Zibrowius 1983, Schiller 1993). Despite the extensive distribution of dispersed colonies, only in a few locations do the colonies form beds (i.e., great numbers of distinct subspherical colonies 10–30 cm in diameter) or banks (i.e., large formations reaching several decimeters in height and covering several square meters in surface area) (Peirano et al. 1999). Living banks and/or beds of this coral have been recorded in: Tunisia (Zibrowius 1980); the Gulf of Atalanti and some places of the Aegean Sea (Laborel 1987); the Gulf of La Spezia, Ligurian coasts (Morri et al. 2000, Peirano et al. 2001, 2005, Rodolfo-Metalpa et al. 2005); in the Adriatic Sea: in Mljet National Park, other localities of the Croatian and Slovenian coasts (Schiller 1993, Kružić and Pozar-Domac 2002, Kružić and Benkovic 2008) and in the Bay of Piran (Schiller 1993); the northwestern Mediterranean: the Columbretes Islands, Medes Islands and Cap de Creus (Kersting and Linares 2012); the Levantine Sea, Cyprus (Jiménez et al. 2014); the Marmara and northern Aegean Sea, Turkey (Öztürk  2004, Özalp and Alparslan 2011). Large spreading banks of the species have also been found in the Balearic Islands, in the localities of Minorca (Fayos pers. comm. 2014) and Mallorca (Cap Blanc (R. Aguilar pers. comm. 2014)), and at Banyuls-Sur-Mer in France (Romans pers. comm. 2014).

Some colonies of the species has also been found in Lebanon, North Israel, Lybia (Bomba bay) and Egypt (Bitar and Zibrowius 1997, Badalamenti et al. 2011, Kashta et al. 2011, Pitacco et al. 2014).

Countries occurrence:
Albania; Croatia; Cyprus; France (Corsica, France (mainland)); Gibraltar; Greece; Israel; Italy (Italy (mainland), Sardegna, Sicilia); Lebanon; Libya; Malta; Monaco; Montenegro; Morocco; Slovenia; Spain (Baleares, Spain (mainland)); Syrian Arab Republic; Tunisia; Turkey (Turkey-in-Asia, Turkey-in-Europe)
FAO Marine Fishing Areas:
Mediterranean and Black Sea
Additional data:
Continuing decline in area of occupancy (AOO):No
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:10000-20000
Continuing decline in extent of occurrence (EOO):YesExtreme fluctuations in extent of occurrence (EOO):Yes
Lower depth limit (metres):40
Upper depth limit (metres):5
Range Map:133142-3

Population [top]


Following the available information, the most important sites known for this taxon in terms of colony cover and extent are those found in Mjlet National Park (Croatia, Adriatic Sea, Kružić and Benkovic 2008) and in the Columbretes Islands Marine Reserve (Spain, NW Mediterranean; Kersting and Linares 2012). Cladocora caespitosa is a long-lived species showing slow dynamics (low recruitment and natural mortality rates) (Kersting and Linares 2012, Kersting et al. 2014b); thus, significant impacts to its mortality rates may easily overcome its capacity to recover through recruitment (Kersting et al. 2014b).

However, only in a very few cases have Cladocora caespitosa populations have been described in terms of cover, distribution, health status and population dynamics (Schiller 1993, Peirano et al. 2001, Kružić and Benkovic 2008, Kersting and Linares 2012, Kersting et al. 2013b, Kersting et al. 2014b).

Information on both size and population trend is only available currently for the population of the Illa Grossa Bay (Columbretes Islands, NW Mediterranean; Kersting and Linares 2012; Kersting et al. 2013a, 2014b). Detailed information on population size and/ or structure is also available for populations of the Adriatic coasts in the islands Prvić, Pag and Iz and in the Mjlet National Park as well as for the populations inhabiting the Marmara Sea (Özalp 2013).

Population genetic studies of the species in the western Mediterranean basin (Casado-Amezúa et al. 2014) suggest that populations of Cladocora caespitosa are highly dependent on self-recruitment. On the other hand, the genetic connectivity among the populations seems to be related to sporadic dispersal events. These features indicate a reduced resilience of the populations mainly driven by the high levels of self-recruitment.

Cladocora caespitosa population from Columbretes Islands

Size The Cladocora caespitosa population in the Illa Grosa Bay (Columbretes Islands) is formed by a combination of banks and separate colonies (beds) with a highly aggregated distribution between 5 and 30 m of depth. The cumulative cover area of C. caespitosa in the bay was estimated to be approximately 2,900 m2. Regarding the growth rates obtained for this population (~ 2.5 mm year-1) some of the coral colonies in the Columbretes could reach ages up to 300 years (Kersting and Linares 2012).

Population trends The population in the Illa Grossa Bay has lost between 55 % and 80 % of its cover due to recurrent mortalities related to warming and extreme summer temperatures (Kersting et al. 2013b). This climate-induced necrosis has been recorded over nine summers from 2003 to 2012, in two mortality periods (2003-2006 and 2008-2012). The first mortality period and especially the summer of 2003 triggered high necrosis values in this population, while impacts over the second period were milder. This shows that extreme hot summers such as in 2003 have a significant impact on this population. Furthermore, the summer of 2003 had delayed effects in the following summers resulting in an increase in the recorded necrosis rates, even if seawater temperature showed mild thermal anomalies (Kersting et al. 2013b). Given these results and the increase in frequency and persistence of extreme events projected for the 21st century in the Mediterranean Sea (Déqué 2007, Diffenbaugh et al. 2007), recurrent mortality episodes could likely be repeated and will threaten this species, which, due to its slow dynamics, will most likely not be able to cope with elevated mortality rates (Kersting et al. 2014b).

This population is also being impacted by two invasive algae (Caulerpa racemosa and Lophocladia lallemandii). Even if no lethal effects of these algae have been detected on Cladocora caespitosa in Columbretes, sublethal effects derived of the algal invasion on other stages of the life cycle of C. caespitosa, like recruitment and juvenile survival, cannot be disregarded (Kersting et al. 2014a).

Populations of Cladocora caespitosa in the Adriatic Sea

Size The most extensive population of the species occurs in Veliko Jezero (Mljet National Park, southern Adriatic) at 6-18 m depth, where the bank has a large coverage of 650 m2 (Kružić and Pozar-Domac 2003). Average coral growth rate has been estimated on a range of 1.92-4.19 mm/ year; and the age of the banks has been estimated to be 46-312 years (Kružić and Pozar-Domac 2002).

Three other banks of the species have been described in the Adriatic Sea. The banks close to Prvić Island (Kvarner region, N Adriatic Sea) occur between 11-19 m depth and cover a size of about 190 m2. Its average growth rate has been estimated as 3.08 mm/year, and the age of the bank estimated at 194 years. The bank near Pag Island (central Adriatic), occurs between 15-21 m depth and covers 120 m2. Its average coral growth rate has been estimated in 3.06 mm/ year and age estimated of the bank in 294 years. (Kružić and Benković 2008). More recently, a bank near Iz Island (central Adriatic) has been described, occurring between 12-16 m depth and covering an area of 150 m2 (Kružić and Požar-Domac 2007).

Population trends Anthropogenic activities such as industrial and sewage discharges, trawling and other fishing activities and coastal works development have cause a major decline of Cladocora caespitosa in the eastern Adriatic Sea during the last decades. A negative correlation has been observed in this populations between sea surface temperature and coral carbonate density (Kružić et al. 2012), that would mean an attenuation of calcification probably due to an inhibition of the photosynthetic process carried out by zooxanthellate at higher temperatures.

During 1954-1958 high input of phosphates into the seawater decreased coral growth on the Mljet coral bank in the Veliko Jezero Lake. This event was related to the experimental fertilization of Mljet’s Veliko Jezero Lake in 1953, in which, around 17 tons of phosphates (117 kg/hectare) were discharged into the lake.

During the summers 1997 and 1998, the increased temperatures caused polyp necrosis in 10% colonies at the Mljet bank (Kružić et al. 2012)

During 2001-2005 more than 90% of Cladocora caespitosa colonies from the bank near Iz Island died in the vicinity of tuna farms. This might be due the increase of nitrites and nitrates concentrations. This increase in nutrients enhanced phytoplankton and macroalgal blooms, thus decreasing the light available for the benthic communities. Increased levels of nutrients also led to higher levels of filamentous algae.

Populations of Cladocora caespitosa from the Marmara Sea

Size Populations in the Dardanelles and Marmara Sea are formed by beds of colonies varying from 8-96 cm diameter. The colonies occur at 2-23 m depth and the total spreading area that colonies covered in Dardanos region is 27 m2. In Soğandere region the total area is 3 m2. The total coverage for the other areas is less than 2 m2. In the Dardanelles (Marmara Sea) there are many individual Cladocora caespitosa colonies, not forming a large coral bank. Unlike colonies found in the Mediterranean sea, colonies in this area are not closely ordered and the formation could not be considered as a big bank reef of Cladocora caespitosa (Özalp 2013).

Population trends According to the latest observations performed in the late 2013 (B. Özalp pers. obs.), the necrosed extent of the colonies is about 50% of the colony area. It is thought that the physico-chemical conditions and the seasonal abnormal changes have an effect on this problem. Although short-term surveys show an increase in bleaching, more extensive scientific investigation focusing on population dynamics and colony condition and regular monitoring of ecological features need to be undertaken in the coming years.

Other relevant information from smaller populations of Cladocora caespitosa

Beds of Cladocora caespitosa have been also found in the Gulf of La Spezia (northern Tyrrhenian Sea) in the localities of Fiascherino Bay, Punta Bianca and Bocca di Magra. Beds of the species are mainly formed by colonies within a range of 20-65 cm in diameter (Periano et al. 1999). Colonies from this population have been found to range from 9-63 years old. A bank of Cladocora caespitosa has been recorded in the Gulf of La Spezia (Morri et al. 2000) however with no population information available. A three years monitoring study of the colonies at Fiascherino Bay during period 1997-1999 period showed at the end of the study about 50% of the colonies completely dead (Rodolfo-Metalpa et al. 2005), associated with an increase on seawater temperature during the summer period.

Monitoring studies of Cladocora caespitosa populations in Cyprus have shown that some beds have been heavily impacted by warming events in 2010 and 2012, with a high percentage of necrosed colonies (Jimenez pers. comm. 2014).

Populations of C. caespitosa around Medes Islands and Cap de Creus (NW Mediterranean Sea), comprise disperse colonies, and are not currently impacted by climate-induced mortality and invasive species. However, it is important to note that they are found at deeper waters, below 20-25 m depth, where the incidence of these and other impacts is lower and the recorded mortality of the colonies is almost nil (Kersting and Linares pers. comm. 2014).

Large spreading banks of the species have been found in the Balearic Islands, in the localities of Cala Galdana (Minorca; at 5-10 m depth, Fayos pers. comm.) and Cap Blanc (Mallorca, 36 m depth, R. Aguilar pers. comm. 2014), as well as in Banyuls in France (Romans pers. comm. 2014), however with no population data available.

Current Population Trend:Decreasing
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:

Cladocora caespitosa occurs on a wide range of substrata, a range of depths (commonly from 5 to 40 m depth), and hydrodynamic conditions (Zibrowius 1980). In Cyprus, the species occurs in the first meters of depth (1-5 m) (Hadjioannou pers. comm. 2015), whilst in several western Mediterranean locations, such as Medes Islands and Cap de Creus, the species is commonly found below 20 m depth in dim light conditions (Kersting 2013). The capacity of the species to tolerate a range of environments and to withstand seasonal abiotic factors such as temperature and light, typical of temperate seas as the Mediterranean, is probably related to the ability of this species to regulate autotrophy and heterotrophy depending on the environmental light conditions, as suggested by Hoogenboom et al. (2010).

Cladocora caespitosa may occur in a wide range of habitats, from shallow photophilic communities to circalitoral assemblages, however, the equilibrium between hydrodynamic protection and high water exchange through strong currents seems to enhance the development of extensive C. caespitosa populations, as occurs in the Mjlet National Park and Columbretes Islands (Kružić and Benkovic 2008, Kesting and Linares 2012).

The high prevalence of macroalgae has been considered a limiting factor in the development of this coral (e.g., Peirano et al. 1998, Rodolfo-Metalpa et al. 1999). However, the coral has been shown to be able to successfully compete with those algae in some localities, as happens in the Illa Grossa Bay where algal cover is high and most of the coral colonies and banks occur within the infralitoral photophilic algal community (Kersting and Linares 2012, Kersting 2013); whilst in other localities such the Adriatic and Marmara seas, the presence of algae (mainly C. racemosa) has been observed to impact the growth of the species (B. Özalp pers. comm. 2014, Kružić and Požar-Domac 2007).

The sexual reproduction of the species has been recorded in situ in the Adriatic Sea (Kružic et al. 2008), where the coral has been described as hermaphroditic at colony and polyp levels. Spawning has been observed to occur coinciding with increasing Summer water temperature and correlated with the lunar cycle. Eggs are released by the polyps in a mucus coating as clumps of eggs, that binds them together, while sperm are freely released (Kružic et al. 2008). In the western Mediterranean, histological analyses have shown that the coral is gonochoric (Kersting et al. 2013c). Spawning time has been observed to differ significantly between the Adriatic Sea and the western Mediterranean; in the former, spawning was observed at the beginning of Summer, coinciding with rising sea water temperatures (Kružic et al. 2008), whilst in the western Mediterranean spawning seems to occur at the end of the Summer coinciding with the cooling of sea water temperature (Kersting et al. 2013c). These notable differences in reproductive biology between these two regions should be further investigated.

Based on average sizes and growth rates of the species, we assume that average generation length is 30 years. Average longevity is not known, but likely to be more than 100 years. In the Adriatic Sea and Columbretes Islands, colonies of already 300 years have been described.

Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):30

Use and Trade [top]

Use and Trade: The species is not used for commercial purposes

Threats [top]

Major Threat(s):

Cladocora caespitosa is a long-lived species showing slow dynamics, therefore being highly limited in its capability of recovery from impacts of diverse nature (Kersting et al. 2014b).

Cladocora caespitosa mass mortalities related to seawater warming and summer heat waves have been reported in several Mediterranean sites (Perez et al. 2000, Rodolfo-Metalpa et al. 2005, Garrabou et al. 2009, Kružić et al. 2012, Kersting et al. 2013b, Hadjioannou pers. comm. 2015, Istael as Fine pers.comm. 2015). Increasing sea water temperature in shallow waters, as well as short times recorded between mortality events have severe consequences for the viability of the affected C. caespitosa populations. These populations also show a dramatic decrease in its biomass, along with a very slow recovery.

Seawater temperatures recorded during the summer 2003 were the warmest in the last 30 years (Garrabou et al. 2009). During these years, not only were temperatures high, but the warm and stable conditions lasted for an unusually long time (more than one month). In the case of Columbretes Islands population, a positive correlation between temperature and mortality rates in Cladocora caespitosa colonies was observed over this period (Kersting et al. 2013b). These recurrent mortalities are expected to affect over 50% of the colony cover in this area during the next decade (Kersting et al. 2013b).

The presence of the invasive algae Caulerpa racemosa has been reported in Mjlet National Park (Kružić et al. 2012), Columbretes Islands (Kersting et al. 2014a) and Dardanos region (B. Özalp pers. comm. 2013), and the spread of these invasive algae over the most important known populations of this coral is concerning. In the case of Columbretes Island population, another invasive algal species has been also observed, Lophocladia lallemandii.

No lethal effects derived from C. racemosa and L. lallemandi invasions have been detected in the C. caespitosa population from the Columbretes Islands, the adult colonies of this species being capable of successfully competing with the algae. However sublethal effects derived of the algal invasion on other stages of the life cycle of C. caespitosa, like recruitment and juvenile survival cannot be disregarded (Kersting et al. 2014a)

In some areas around the Dardanos region, C. racemosa occurs at shallow depths down to 18 m. Populations of C. caespitosa of this region have been badly impacted by this invasive algae. In some instances colonies of the coral are completely covered by the algae, causing negative effects such as tissue necrosis (B. Özalp pers. comm. 2013). A more intensive study is being undertaken at this site in order to distinguish between the potential damage of increasing seawater temperature and algae coverage of the colonies.

In Israel several mortality events have been reported in the annual surveys (M. Fine pers. comm. 2015): In Sdot-Yam (Israel) the last Cladocora colony died in 1995 and the species is now absent from this site. Similarly, the extensive Cladocora rims at a depth of 10 m in Akko went nearly extinct and the substrate was taken over by invasive bivalves (Spondylus). In Rosh- Hanikra at the northern most part of the Israeli coast, the Cladocora population has also decreased dramatically over the last decade.

Negative impacts resulting from eutrophication have been described in some C. caespitosa populations (e.g., Croatia and Cyprus; Kružić and Požar-Domac 2007, Hadjioannou pers.comm. 2015). Anthropogenic activities such as industrial and sewage discharges, trawling and other fishing activities and coastal development have caused a major decline of Cladocora caespitosa in the eastern Adriatic Sea. In the eastern Adriatic Sea, the high input of phosphates during 1954-1958 into the seawater decreased coral growth on the Mljet coral bank in the Veliko Jezero Lake. This event was related to the experimental fertilization of Mljet’s Veliko Jezero Lake in 1953, in which around 17 tonnes of phosphates (117 kg per hectare) were discharged into the lake, thus increasing nitrites and nitrates concentrations and enhancing phytoplankton and algal blooms.

Trawling and dredging are probably the most destructive impacts currently affecting marine bioconstructors, including the coral Cladocora caespitosa, resulting in physical damage to coral colonies and habitat destruction. Small scale line fisheries, such as in the Dardanelles Strait, cause localized impacts as a result of boat anchors.

High sedimentation rates due to beach replenishing or dredging may cause the collapse of colonies. On the other hand, increase of water turbidity may be accompanied by an elevation of the deepest limit of distribution of this coral.

Conservation Actions [top]

Conservation Actions:

There are no direct conservation measures in place for this species. The species is present within protected areas in the Mediterranean, such as Columbretes Islands, Mljet Islands, Cape Palos and Cabo de Gata.

In general, the main conservation actions for C. caespitosa should be:

  • Extend the current knowledge on the taxonomy, distribution, population, and ecology of the species, especially at known localities where the information is lacking.
  • Identify and describe new sub-populations.
  • Ensure the protection of the main subpopulations of C. caespitosa identified to date. At these locations, damage to the colonies by threats such as anchoring, fishing, recreational diving, dredging activities, should be controlled.
  • Information on the main traits of Cladocora caespitosa populations, their health status and local threats is lacking for most sites. Once this information is available, long-term monitoring programs of biotic and abiotic factors should be implemented in order to monitor population trends, especially relevant in the actual context of global change impacts.

Another important conservation action for this species is to include the species under protection by national laws, EU Directives and international conventions in the protection lists. Despite the rapid decline of shallow Cladocora caespitosa populations, currently this species is only included in the Annex 1 of Habitats Directive (Directive 92/43/CEE) under Habitat 1170 “Reefs” and listed on CITES Appendix II.

Citation: Casado de Amezua, P., Kersting, D., Linares, C.L., Bo, M., Caroselli, E., Garrabou, J., Cerrano, C., Ozalp, B., Terrón-Sigler, A. & Betti, F. 2015. Cladocora caespitosa. The IUCN Red List of Threatened Species 2015: e.T133142A51214584. . Downloaded on 20 November 2017.
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