Patrice Francour

Are the Mediterranean waters becoming warmer? Information from biological indicators

The authors are biologists specializing in benthos or ichthyofauna survey. They have worked in marine protected areas or in other littoral zones of the Mediterranean Sea for a long time. The use of SCUBA diving as a sampling method allows them a great knowledge of the benthos and ichthyofauna. Charles-Francois Boudouresque is vice-chairman of the Benthos Committee of the CIESM, and chairman of the scientific committees of the National Park of Port-Cros and of the Natural Regional Park of Corsica (marine reserve of Scandola). The other authors are members of these scientific committees

Changes in Macroalgal Communities in the Vicinity of a Mediterranean Sewage Outfall After the Setting Up of a Treatment Plant

Benthic macroalgal communities of the upper rocky sublittoral were studied in 1995-1996 in the vicinity of the Marseille (Mediterranean, France) sewage outfall, 8 years after the setting up of a wastewater treatment plant and compared to a previous study carried out in 1972-1974. The number of taxa has increased, a clear stational and seasonal gradient of differentiation of the vegetation appeared, and a turf of ephemeral species is taking place of Corallina elongata at sites close to the outfall. These changes may be due to a decrease in pollutant load, the discharge of ferric chlorates used in the treatment process. However, the overall change is much less conspicuous than that described for deeper soft bottom communities, in particular the Cystoseira amantacea community is not still restored. Biological traits of this species (short distance dispersal) and the nature of most pollutants removed from the effluent (solids and organic matter) may explain this phenomenon.

Predation on Holothurians: A Literature Review

In the literature, 69 references altogether have reported 76 predators on holothurians. In terms of the number of predatory species, the most important predators are fishes (26 species), seastars (19 species), and crustaceans (17 species). Seastars are the predators most often cited as regularly ingesting large quantities of holothurians. Toxicity seems to be an effective defense against a generalized predator but, against a specialist on holothurians, escape by swimming movements or shedding of a piece of body wall are the only behaviors that occasionally end with a successful escape. Escape behaviors may be a factor in providing the apparent size refuge from predators. Impacts of predators on holothurian populations have rarely been reported or evaluated, and predation on the earliest life stage is unknown. Additional key words: Echinodermata, Holothuroidea, Asteroidea, predators, prey, fishes The importance of predation in determining or influencing community structure has been well documented from a wide range of latitudes, depths, and substrates (e.g., Dayton 1971; Virnstein 1979; Menge & Lubchenco 1981) and is considered to be often the principal factor controlling the spatial and temporal distribution of marine invertebrates (Connell 1975; Menge & Lubchenco 1981). Predation may be an important component of the population dynamics of holothurians, yet field experiments are sorely lacking. Holothurians have developed seven main types of anti-predator mechanisms (Bingham & Braithwaite 1986; Lawrence 1987): thickness of the body wall (including ossicle development), toxic and noxious skin and organs, body swelling or stiffening, evisceration or autotomy (including Cuvierian tubules), swimming, nocturnal activity, and cryptic or burrowing behavior. Kropp (1982) reported shedding of a small piece of the body wall by Stichopus in response to attack by a gastropod, which constitutes an uncommon anti-predator behavior. Brooding (i.e., the association of embryos and juveniles with an adult) is considered to increase the probability of an offsprings survival to the stage of independent existence (Lawrence 1987). Thus, brooding might be considered to be another type of anti-predator mechanism. But, as with some other marine invertebrates, the incidence of brooding in echinoderms, including holothurians, increases with latitude (Mileikovsky 1971) and is mainly restricted to antarctic and arctic holothurians (Lawrence 1987). Most holothurians display one or more of these features. These anti-predator mechanisms appear so well developed that some authors consider predation on adult holothurians to be infrequent (Massin & Jangoux 1976; De Vore & Brodie 1982; Da Silva et al. 1986). On the other hand, scarcity of young holothurians has also been attributed to predation on early life stages (Bakus 1968; Sloan 1986). Does a broad literature review support these assumptions? This paper identifies the important predators on holothurians and addresses specific as well as broader questions: is predation upon holothurians actually infrequent? which parts of holothurians are consumed? is there any evidence for or against particular behaviors being effective against predation? is predation an important component of the population dynamics of sea cucumbers? Answers to these questions could provide a better understanding of holothurian ecology and the basis for future experimental studies on the effects of predation on holothurian communities.

Impact of Caulerpa taxifolia colonization on the littoral ichthyofauna of North-Western Mediterranean sea: preliminary results

After its accidental introduction in the French waters of the Mediterranean, the green seaweed Caulerpa taxifolia is now spreading along the coast of the Alpes-Maritimes, invading various biotopes (rock, sand and Posidonia oceanica seagrass beds). During the spring and fall of 1992, we evaluated the impact of C. taxifolia on the infralittoral ichthyofauna of Cap Martin (Menton) and compared invaded and reference sites, in shallow (3-8 m) and deep (11-25 m) stations.

Conservation and restoration of marine forests in the Mediterranean Sea and the potential role of Marine Protected Areas

Cystoseira species are some of the most important marine ecosystem-engineers, forming extended canopies comparable to land forests. Such forests are sensitive to human disturbances, like the decrease in water quality, the coastal development and the outbreak of herbivores. Conspicuous historical declines have been reported in many regions and several Cystoseira species are presently protected by European Union (EU) environmental policies. The aim of this work was to synthesize the conservation perspectives of Cystoseira forests in the Mediterranean Sea, focusing on the opportunities offered by artificial restoration and highlighting the potential role of Marine Protected Areas (MPAs). MPAs give a better protection to healthy forests than non-managed sites and may be a source of propagules for natural recovery and/or for non-destructive artificial restoration of nearby damaged forests. MPAs lacking Cystoseira forests may also represent preferential sites for reforestation. We proposed a flow-chart for the conservation and a reasoned restoration of Cystoseira in the Mediterranean Sea. The successful conservation of Cystoseira forests is still possible, via raising public awareness on the role of Cystoseira and reducing human impacts on coastal ecosystems. Such actions have to be coupled with more specific large-scale management plans, encompassing restoration actions and enforcement of protection within MPAs.

Tracing sewage and natural freshwater input in a Northwest Mediterranean bay: Evidence obtained from isotopic ratios in marine organisms

Elemental carbon and nitrogen levels and isotope ratios were assessed in different biological compartments of a Northwest (NW) Mediterranean bay to trace the various sources of nutrient input from natural (river runoffs) and anthropogenic (harbor outflows, fish farms and urban sewage outfall) sources. Samples from transplanted mussels and natural sea grass communities (Posidonia oceanica leaves and epiphytes) were harvested from different locations throughout the bay during the touristic summer and rainy seasons. The results from the nitrogen analysis revealed that sewage and harbor outflow promote higher nitrogen levels, enrichment of (15)N in the tissues, and a higher seasonal variability in sea grass and epiphytes. In mussel tissues, the delta(15)N was also influenced by sewage and harbor outflow, whereas delta(13)C was influenced by terrestrial inputs. These results suggest that natural and anthropogenic nutrient inputs have a temporary and localized influence and affect the sensitivity of natural isotopic ratios to changes in hydrologic conditions, especially to rain and tourism.

An ecotoxicological approach with transplanted mussels (Mytilus galloprovincialis) for assessing the impact of tyre reefs immersed along the NW Mediterranean Sea.

Tyre artificial reefs were deposited in a marine protected area (Vallauris-Golfe Juan Bay, France) located along the NW Mediterranean coast, during the early 80s. The potential toxic effects of the tyre artificial reefs were investigated using transplantation of marine mussels, Mytilus galloprovincialis, to stations located above tyre blocks (St1, St2) or reference site (StR). Mussels transplanted to different stations presented the following sequence of mortality: St1 > St2 > StR. Principal Component Analysis, taking into account metal accumulation (cadmium, copper and zinc) and biomarker (SOD, CAT, GST and AChE activities, TBARS and MT levels, Condition Index) responses in mussel tissues indicated a clear separation between the three stations. St1 organisms were significantly more affected by tyre reefs than those from other stations. Such an integrated monitoring study represents a key approach to assess in situ the biological impact of >25 year-old tyre artificial reefs.

OCCURRENCE OF BARRED KNIFEJAW , OPLEGNATHUS FASCIATUS (ACTINOPTERYGII: PERCIFORMES: OPLEGNATHIDAE), IN MALTA (CENTRAL MEDITERRANEAN) WITH A DISCUSSION ON POSSIBLE MODES OF ENTRY

The barred knifejaw, Oplegnathus fasciatus (Temminck et Schlegel, 1844), a species native to the North Western and Eastern Central Pacific, is recorded from the central Mediterranean for the first time. Two individuals were photographed within a month of each other in Grand Harbour and in Marsamxett Harbour, Malta. It seems likely that the fish were introduced by shipping and different scenarios how this may have hap - pened are discussed.

A long-term survey of Posidonia oceanica fish assemblages in a Mediterranean Marine Protected Area: emphasis on stability and no-take area effectiveness

Marine reserves have become an important tool advocated to protect diversity, habitat or to restore depleted fish stocks. However, the links between reserve effect and temporal variability of assemblages remains equivocal. The present study presents the results obtained in a long-term series of annual surveys in the Scandola Marine Reserve (Corsica, North-western Mediterranean). An underwater visual census was performed on Posidonia oceanica seagrass beds. Species richness and density of target fish were positively affected by fishing prohibition in the no-take zone. The whole assemblage density and density of non-target and prey fish, prevailing in the seagrass bed, were not or negatively affected by fishing prohibition. Concomitantly, temporal stability was positively related to fishing prohibition. This stabilisation of the fish assemblage in the no-take zone had not been observed over rocky reefs in previous studies. This outcome may be linked to wandering predators of rocky areas, preying upon seagrass fish assemblages. In addition, the complete fishing ban appeared to be to only effective tool in restoring target fish stocks and maintaining a higher stability of the fish assemblage whereas partial fishing prohibition failed to meet this goal.

OCCURRENCE AND DISTRIBUTION RANGE OF PARABLENNIUS PILICORNIS (ACTINOPTERYGII: PERCIFORMES: BLENNIIDAE) ALONG THE FRENCH MEDITERRANEAN COAST

Ecosystem biodiversity is being altered at a worldwide scale by species loss due to extinction from human activities and species gain through intentional and accidental introductions (Sala et al. 2000). At the regional level, species gain usually equals or outpaces the losses due to extinction, suggesting that extinctions and invasions might offset one another with little net change in diversity (Sax and Gaines 2003). However, because different processes drive extinctions and invasion (e.g., overfishing versus ballast water transport), the types of species being gained and lost might differ (Byrnes et al. 2007). The combined effect of these two processes is altering the structure of coastal marine food webs, because most extinctions occur at high trophic levels, while most invasions are by species from lower trophic levels (Byrnes et al. 2007). Thus, introductions of exotic species affect plankton, macrophytes, shellfish, and crustaceans (Galil 2007). The Mediterranean sea is currently facing dramatic changes, including change in native species distribution due to climatic modification (Francour et al. 1994, Bianchi 2007), harmful algal blooms linked to increasing eutrophication (Heisler et al. 2008), fishing activity (Farrugio et al. 1993), habitat fragmentation and destruction (Airoldi and Beck 2007), and non-indigenous species invasion (Galil 2008). Consequently, Mediterranean food webs are considered to be in an advanced state of ecological degradation (Coll et al. 2008). The Mediterranean Sea is a semi-enclosed area with limited connection to two oceans: the Atlantic Ocean through the Strait of Gibraltar, and the Indian Ocean, accessed across the Red Sea through the Suez Canal, which was dug in 1869. Ben Rais Lasram and Mouillot (2009) identified the Mediterranean Sea as “the recipient of the greatest number of exotic species in the world”, with an average of one introduction every four weeks over the past five years. Zenetos et al. (2008) mention one introduction every 9 days. According Streftaris et al. (2005), the majority of these introductions are due to fouling, the release of ballast water from ships, and aquaculACTA ICHTHYOLOGICA ET PISCATORIA (2010) 40 (2): 179–185 DOI: 10.3750/AIP2010.40.2.11