Latitudinal variations in biometry and population density of a Mediterranean solitary coral

Abstract

Correlations between solar radiation, sea surface temperature (SST), biometry, and population density were assessed along a wide latitudinal gradient in the non-zooxanthellate solitary coral Caryophyllia inornata. Biometric parameters were more strongly correlated with temperature than with solar radiation as in previous studies on Mediterranean solitary corals. With increasing SST, populations were characterized by bigger polyps, and consequently by a higher percent area coverage and mass per square meter. Population abundance was not correlated with SST, similarly to the non-zooxanthellate solitary Leptopsammia pruvoti. Instead, the population density of the zooxanthellate solitary Balanophyllia europaea decreases with increasing SST. When extrapolating the relationships between biological parameters of the three species and SST, according to the projected seawater temperature increase, a higher tolerance to temperature for non-zooxanthellate species seems to be confirmed.

Inferred calcification rate of a temperate azooxanthellate caryophylliid coral along a wide latitudinal gradient

“…The previously formulated hypothesis that azooxanthellate Mediterranean scleractinians have a higher tolerance to high temperature than zooxanthellate corals (Caroselli and Goffredo 2014) is supported by the present findings and by previous studies on other biological parameters of C. inornata (such as population abundance, mortality and population structure stability) which are not related to temperature variations (Caroselli et al 2015(Caroselli et al , 2016. It can be argued that an adaptive shift in the symbiont community may promote higher resilience (Baker et al 2004;Fitt et al 2009), and thus, zooxanthellate scleractinians could enhance their temperature tolerance.…”

“…At each site, samples were collected using transects that consisted of 4-8 square patches of 0.1 m 2 each, 3 m apart (site and number of patches: Genova: n = 4; Calafuria: n = 8; Elba: n = 4; Palinuro: n = 6; Scilla: n = 6; and Pantelleria: n = 7). The sampling was performed within a depth range (11-16 m) known to have high population density and where the reproductive biology (Goffredo et al 2012a), biometry and abundance (Caroselli et al 2015), and growth and population demography have been studied (Caroselli et al 2016). Patches were sampled on the vault of crevices, except at the Elba site, where samples were collected under the wings of a sunken plane wreck.…”

“…Thus, the pattern suggests that fast colonization of new substratum and the strength of the corallite against mechanical stress are also both important for C. inornata, as illustrated by the Elba population. In fact, the habitat normally occupied by C. inornata is also colonized by L. pruvoti (Teixido et al 2011), which is normally present in higher densities in the crevices of the study sites (Caroselli et al 2012(Caroselli et al , 2015. However, C. inornata is the only coral present at the Elba sampling site under the wings of the sunken plane wreck and it is present with unusually high abundance (Caroselli et al 2015).…”

“…In fact, the habitat normally occupied by C. inornata is also colonized by L. pruvoti (Teixido et al 2011), which is normally present in higher densities in the crevices of the study sites (Caroselli et al 2012(Caroselli et al , 2015. However, C. inornata is the only coral present at the Elba sampling site under the wings of the sunken plane wreck and it is present with unusually high abundance (Caroselli et al 2015). A possible explanation could be that C. inornata may invest more calcification resources in linear extension than L. pruvoti, which deploys most calcification resources in increasing skeletal thickness.…”

Reproduction of the Azooxanthellate Coral Caryophyllia inornata Is Not Affected by Temperature Along an 850 km Gradient on the Western Italian Coast

“…It colonizes caves, walls, and wrecks, from the surface down to 100 m depth in dimly lit or dark environments, representing one of the main species that populate the walls and the vaults of caves and in some cases is the dominant species (Zibrowius, 1978). It is a slow growing coral with a population density that can reach thousands of individuals per m 2 and its abundance along the Western Italian coasts varies from 100 to 1500 individuals per m 2 (Caroselli et al, 2015). C. inornata is gonochoric and brooding (Goffredo et al, 2012;Marchini et al, 2015), showing peculiar traits such as a male biased sex ratio (1:3) (Goffredo et al, 2012) and the presence of embryos in coelenteric cavity and mesenteric septa of females, males, and sexually inactive individuals (without germ cells), throughout the year (Marchini et al, 2015).…”