Paramuricea clavata (Anthozoa, Octocorallia) loss in the Marine Protected Area of Tavolara (Sardinia, Italy) due to a mass mortality event

Abstract

Recent studies highlight an increase in the frequency and intensity of marine mass mortalities of several species over the past 30–40 years, mainly in tropical and temperate areas. In the Mediterranean Sea these episodes particularly affect benthic suspension feeders, such as sponges and cnidarians. The main objective of this work was to document the loss of one of the main Mediterranean seascapes, Paramuricea clavata forests at the Marine Protected Area of Tavolara Punta Coda Cavallo, Sardinia (Italy), during the summer of 2008. Data regarding colony height, density, level of damage, and microbiological community were collected at two sites. Such parameters help us understand how mass mortality mechanisms act on this ecosystem engineer. We identified a change in size class distribution following a mass mortality that leaves mainly small colonies with a decrease in habitat complexity. Several tests on water chemistry demonstrate that the mortality event was not caused by local contamination. Moreover, microbiological tests on potential pathogenic agents suggest that bacteria belonging to the genus Vibrio are present as an opportunistic and not an etiological cause of P. clavata mortality events. Possible restoration approaches are discussed.

Effects of thermal stress on early developmental stages of a gorgonian coral

“…These large events were accompanied by several others, affecting fewer species or being more localized, e.g. in summers of (Bensoussan et al 2010, Maldonado et al 2010, Cebrian et al 2011, Huete-Stauffer et al 2011, Stabili et al 2012. In general, gorgonians, which are structurally important elements of Mediterranean hard-bottom communities, were among the most affected species (Cerrano et al 2000, Pérez et al 2000).…”

“…In general, gorgonians, which are structurally important elements of Mediterranean hard-bottom communities, were among the most affected species (Cerrano et al 2000, Pérez et al 2000). Several studies assessed the immediate and delayed impacts of these events on gorgonian adult colonies (Linares et al 2005, Coma et al 2006, Cupido et al 2008, Huete-Stauffer et al 2011, including sublethal impacts on their reproduction effort (Torrents 2007, Linares et al 2008a). However, sublethal effects associated with elevated seawater temperature conditions remain poorly studied.…”

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

“…Moreover, trans-phyletic mass mortality episodes, due to summer heat-waves (caused by sea water temperatures 3-6°C above the usual values within 40 m depth), induced strong stressing conditions in several species that become prone to the proliferation of pathogenic bacteria Cerrano et al 2000;Garrabou et al 2001;Bally & Garrabou 2007;Huete-Stauffer et al 2011). In the western Mediterranean Sea, besides two large-scale episodes in September 1999 (Cerrano et al 2000;Perez et al 2000) and July 2003 (Schiaparelli et al 2007), mass mortalities occurred also in 2002, 2006(Garrabou et al 2009), always impacting shallow-water communities (above 40 m depth) where the seasonal temperature oscillations are wider.…”

Sexual structure of a highly reproductive, recovering gorgonian population: quantifying reproductive output

“…However, when subjected to overharvesting or mass mortality, which selectively affect larger colonies (Garrabou et al 2001, Cerrano et al 2005, Santangelo et al 2007, Cupido et al 2008, Huete-Stauffer et al 2011, the persistence of their populations could in large measure depend on sexual reproduction (Linares et al 2007b, Linares & Doak 2010. Under such conditions, reproductive rates, generally considered to have limited influence on long-term gorgonian dynamics, could become important factors in determining the recovery and recolonization capacity of local populations.…”