Bioconstructional features of the coral Cladocora caespitosa (Anthozoa, Scleractinia) in the Adriatic Sea (Croatia)

Abstract

The Mediterranean endemic Cladocora caespitosa (Linnaeus, 1767) is a colonial scleractinian coral belonging to the family Faviidae and the only zooxanthellate coral from Mediterranean whose colonies may fuse in reef‐like structures (hermatypic). Recent surveys are focused on three locations where banks occur in the Adriatic Sea (Croatia): near Prvić Island in the northern Adriatic, near Pag Island in the central Adriatic and in Veliko jezero (Mljet National Park) in the southern Adriatic. The C. caespitosa bank in Veliko jezero covers an area more than 650 m2 and is thus the largest bank of C. caespitosa found to date. The strong sea currents, which occur as a result of tidal exchange in the channel, appear to favour the growth of the bank. The goal of the study was to present the influence of major environmental factors upon the build‐up process of the coral bank. Biometrical parameters in the C. caespitosa colonies like diameter of the calyces, polyp ash free dry weight (AFDW), corallite linear growth rate and index of sphericity were investigated and compared from these three locations. The morphology of coral banks from the Adriatic Sea and the disposition of the biometrical values are affected by the sea currents, temperature and sedimentation.

Growth of Mediterranean reef of Cladocora caespitosa (L.) in the Late Quaternary and climate inferences

“…The fossil Santa Teresiola coral bank probably developed under similar SST regimes which are comparable to those recorded today in the coldest regions of Eastern Adriatic Sea, where cold winds or inputs of freshwater may lower the SST temperature on the coral banks (BenoviT et al 2000;Novosel et al 2004;Montagna et al 2007;KruqiT and BenkoviT 2008). Mastronuzzi et al (2003) and Mastronuzzi (2006) concluded that the fossil C. caespitosa bank of Santa Teresiola existed in a lagoon aVected by inputs of freshwater.…”

“…In this lagoon, SST vary between 9 and 29°C and salinity shifts from 36.3 to 39 PSU (Vanibek et al 2000;KruqiT and Poqar-Domac 2003). Although the Santa Teresiola reef refers to a warm climatic phase of the Pleistocene, the diVerences between the temperature of the lagoon and the warmer open-sea temperatures of MISs 5.5 could be explained by freshwater coming from underwater, karstic springs that are common today both in Croatia and in the Taranto area (Pagliarulo and Bruno 1990;KruqiT and BenkoviT 2008). These assumptions also agree with palaeontological records of other fossil reefs found in alluvial deposits dating back as far as to the Late Pliocene (Aguirre and Jiménez 1998;Fornos et al 1996) where 'beds' of the bivalve Ostrea spp., a suspension feeder characteristic of environments with cold seawater, lower salinity and high turbidity, forms the basement or is intercalated in coral banks (Bernasconi et al 1997;Aguirre and Jiménez 1998;Dornbos and Wilson 1999).…”

“…This growth pattern, found also in the scleractinian Balanophyllia europaea by GoVredo et al (2008), seems to be characteristic of the Mediterranean species of zooxanthellate corals. However, to form a mature coral bank special environmental conditions are necessary, as outlined by KruqiT and BenkoviT (2008).…”

“…These studies also proved that the deepest colonies Fig. 1 Right: Major fossil deposits (asterisks) and living banks (circles) of Cladocora caespitosa in the Mediterranean (from: Peirano et al 1998KruqiT and BenkoviT 2008) Mastronuzzi et al (2003) have yearly growth rates related to SST despite the fact that the living depth is below the seasonal thermocline depth. Large fossil banks of C. caespitosa are known in the Mediterranean from the Late Pliocene (Aguirre and Jiménez 1998;Dornbos and Wilson 1999), from the Early Pleistocene (Bernasconi et al 1997), from the Middle and Late Pleistocene and from the Holocene (for a review see Peirano et al 1998 (Fig.…”

“…Today, living banks of coral comparable to tropical reefs were discovered in three localities along the coast of Croatia (Fig. 1) characterized by low mean annual temperatures (KruqiT and BenkoviT 2008). The greatest bank is located in one 'sea-lake' of the island of Mljet.…”