The influence of the rock mineralogy on population density of Chthamalus (Crustacea: Cirripedia) in the Ligurian Sea (NW Mediterranean Sea)

Settlement, recruitment and survival of sessile marine species are driven by many biotic and abiotic factors. Among them, substrate mineral composition is generally a neglected topic, despite it proved to be a relevant contributing variable in driving the structure of benthic communities. Thanks to their ecology, Chthamalus species are a good proxy to test the role of substrate in affecting settlement and final population density on exposed rocky shores. Differences in the number of individuals were analysed in eight localities along the Eastern Ligurian Riviera (north-western Mediterranean Sea), from Portovenere to Manara Cape. In this sector of the Ligurian littoral, the coast is constituted by different rocks characterised by variable concentrations of calcite, silicates and quartz. This situation constitutes an ideal setting to evaluate the influence of mineral composition of the rocks in structuring the epilithic macrobiota communities in energetic splash zones and under similar physical pressures. Rocks rich in calcites turned out to be more suitable for Chthamalus species than substrates containing high amounts of silicates, and of quartz in particular. Additionally, also the grain size of the main mineral component of the rocks, determining in turn the surface roughness seemed to influence barnacle densities, with a significant preference for finer-grained substrates

The sub-fossil red coral of Sciacca (Sicily Channel, Mediterranean Sea): colony size and age estimates

The Mediterranean red coral, Corallium rubrum (L.), has been a valuable economic resource for more than 2000 years. The Sicily Channel and surrounding areas are one of the most famous red coral fishing grounds of the whole region, hosting the deepest ever found living colonies and large sub-fossil red coral deposits; the so-called Sciacca banks are a unique location in the whole Mediterranean Sea. In this paper, a morphometric description of this sub-fossil population is presented for the first time from studies of colonies in the collection of several coral factories from Torre del Greco (Naples), with radiocarbon age estimations and growth rate evaluations. From the results of this study, after several thousand years Sciacca red coral colonies maintained the organic matrix structure with evident annual discontinuities, allowing estimations of the annual growth rate (about 0.3 mm/year) and the average population age (about 33.5 years). These resulting data are similar to the values determined for deep-dwelling living red coral populations. The radiocarbon dating evidenced a range of ages, from 8300 to 40 years before 1950 CE, mostly falling between 2700 and 3900 YBP, suggesting that colonies accumulated over a wide span of time. In view of the tectonically active nature of the area, several catastrophic events affected these ancient populations, maintaining them in a persistent state of early-stage, structurally similar to the those in current over-exploited areas

Demographic parameters of two populations of red coral (Corallium rubrum L. 1758) in the North Western Mediterranean

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LTER-AMP-Portofino (Mar Ligure): variabilità stagionale ed interannuale delle forzanti meteo-climatiche, delle variabili fisico-chimiche e biologiche del comparto pelagico

L’area marina costiera antistante il Promontorio di Portofino è stata inserita nella rete ILTER – International Long Term Ecological Research dal 2007, grazie ai numerosi studi ecologici che si susseguono nell’area dagli anni ’80, ed in particolare dal 1999, quando è iniziata la raccolta sistematica delle principali variabili fisiche e chimico-biologiche lungo la colonna d’acqua e delle principali forzanti meteo-climatiche. L’analisi dei dati ha messo in evidenza un incremento della temperatura media lungo la colonna d’acqua negli ultimi anni rispetto al decennio precedente (1985-1995) ed in particolare un progressivo aumento della temperatura superficiale nelle stagioni primaverili ed autunnali, che ha portato ad un ampliamento del periodo caldo. L’area di studio è inoltre caratterizzata da una forte variabilità interannuale: sono state registrate importanti anomalie termiche nell’estate 2003 e nei periodi autunnali e primaverili del 2006-2007 con temperature superficiali più elevate rispetto alla media del periodo, dovute a due importanti anomalie termiche atmosferiche. Negli ultimi anni, le precipitazioni annuali sono sempre al di sotto della media climatica, ad eccezione del 2002, con conseguente modificazione della struttura termo-alina dell’area di studio. Le variabilità riscontrate si riflettono sui popolamenti planctonici, modificando le risposte delle comunità, in particolare nel periodo tardo primaverile. L’area conserva, comunque, le caratteristiche oligotrofiche tipiche del Mar Ligure: infatti, pur mostrando una evidente variabilità interannuale, la biomassa planctonica media nello strato superficiale continua a rimanere bassa, con una tendenza a diminuire negli ultimi anni