The red coral populations of the gulfs of Naples and Salerno: human impact and deep mass mortalities

Abstract

The existence of deep red coral (Corallium rubrum) banks in the gulfs of Naples and Salerno (South Tyrrhenian Sea, Mediterranean Sea) is well known in historical records due to the heavy coral harvesting that occurred during the 19th and 20th centuries, by both trawling gears and scuba diving. ) or the absence of coral were recorded in all other sites of the Gulf of Naples (including all historical re-visited banks), and a variable percentage of dead colonies was observed. This evidence suggests a huge state of stress likely favoured by the hydrodynamic conditions in the Gulf, enhancing water pollution and sedimentation rate. Finally, the documented high fishing pressure plays a major role in the hard-bottom communities' degradation. A recent mass mortality episode was also recorded along the Amalfi coast, around Li Galli Islands (Gulf of Salerno), at a depth range between 80 and 100 m, where the mortality affected 80% of the largest colonies, estimated to be around 70 years old. Several possible reasons for this mortality have been hypothesised, such as the formation of local down-welling currents inducing an unusual drop of the thermocline, or sudden warm water emissions (sulphur springs) in an area characterised by important volcanic activities, or local landslides generating turbidity currents along the steep slopes.

An overexploited Italian treasure: past and present distribution and exploitation of the precious red coral Corallium rubrum (L., 1758) (Cnidaria: Anthozoa)

“…Fishing grounds were reported around and off the Li Galli Islands and along the Amalfi Coast, between Punta Campanella and Capo di Conca, until 200 m depth (Bavestrello et al 2014b;Angiolillo et al 2015). According to Peruzy (1923), the red coral found off the city of Positano was of bad quality, due to its yellowish colour, and the harvesting was not profitable.…”

“…Today, the Portofino population is well known (Marchetti 1965;Cattaneo-Vietti & Bavestrello 2010;Bramanti et al 2014;Bavestrello et al 2014a) and protected inside the Portofino MPA. After 20 years of protection, it shows a slow recovery (Bramanti et al 2014;Bavestrello et al 2014b).…”

“…These populations were heavily harvested and depleted during the 19th century and in the early years of the 20th century: Colombo (1887) found almost no living red coral inside the Gulf. According to Liverino (1998), during and immediately after WWII, some attempts to harvest coral in the Gulf were made, but with poor results: over 60 years later, the red coral banks are still strongly suffering (Bavestrello et al 2014b;Angiolillo et al 2015).…”

“…Available data from 1978 to present, as reported by several authors Liverino 1998;Santangelo & Abbiati 2001;Bruckner 2009;Cau et al 2013;Tsounis et al 2013), have been extracted from Food and Agricultural Organization (FAO) reports that were, in turn, provided by the red coral wholesalers and manufacturers . Information regarding the bank distribution along the Italian coasts was obtained from Gaetani (1867), Panceri (1871), Targioni-Tozzetti (1880), Colombo (1887), Parona (1898), Lo Bianco (1909, Mazzarelli (1915aMazzarelli ( ,b, 1931, Mazzarelli and Mazzarelli (1918), Peruzy (1923), Scatizzi (1935), Errico and Montanelli (2008), Cattaneo-Vietti and Bavestrello (2010), Gangemi (2011Gangemi ( , 2014, Santangelo et al (2007Santangelo et al ( , 2012, Priori et al (2013), Bramanti et al (2014) and Bavestrello et al (2014b).…”

Overview of the conservation status of Mediterranean anthozoa

“…The effects of climate change in deep waters have not been fully evaluated yet. Signs of deep Red Coral mass mortalities apparently not related to climate changes have also been recently detected in the Salerno Gulf, Italy (Bavestrello et al 2014b). …”