The changing biogeography of the Mediterranean Sea: from the old frontiers to the new gradients

Work partly done in the frame of the project ‘The impacts of biological invasions climate change on the biodiversity of the Mediterranean Sea’ funded by the Italian Ministry of the Environment.Peer Reviewe

Expansión del alga verde Caulerpa taxifolia (Caulerpales, Chlorophyta) en el Mediterráneo: Consecuencias posibles de un proceso ecológico de gran importancia

9 páginas, 1 figura.-- Contribución a "Topics in marine Benthos ecology", R.Sardà y J.D. Ros (eds.).[EN] Caulerpa taxifolia, a green alga with a circumtropical distribution, was observed for the first time in the Mediterranean in 1984. At present it covers an area of 1000-2000 ha, which is increasing by a factor of 2 to 10 annually. The Mediterranean plants have some morphological and physiological differences from their tropical counterparts; they colonize a wide range of biotopes, from surface to 20-30 meters depth, and have been collected down to 100 meters depth. Caulerpa taxifolia outcompetes native seaweeds due to its high growth rate, its total substrate occupation, its improved light access, the increased sedimentation rates it creates, and the synthesis of secondary metabolites (mono and sesqui-terpenes). The concentration of these metabolites changes seasonally, and strongly affects grazing by the sea-urchin Paracentrotus lividus. The assemblages dominated by Caulerpa taxifolia show a reduced number of other alga1 species and a low diversity. Populations of sea-urchins, fishes, amphipods and polychaetes are also affected. Based on preliminary studies, some special features concerning the functioning of an hypothetic future ecosystem dominated by Caulerpa taxifolia are predicted. If Caulerpa taxifolia continues to spread into the Mediterranean at present rates, we will witness a major ecological event, with a strong decrease of eco-diversity (and perhaps of bio-diversity, too) in Mediterranean coastal waters.[ES] El alga clorofícea Caulerpa taxifolia, especie propia de mares tropicales, fue observada por vez primera en el Mediterráeo en 1984. Actualmente ocupa una superficie de 1000 a 2000 ha. pero progresa con rapidez aumentando su área de invasión en un factor anual de 2 a 10. Los ejemplares mediterráneos presentan características morfológicas y fisiológicas distintas a los ejemplares recogidos en aguas tropicales. En el Mediterráneo, Caulerpa taxifolia coloniza una gran variedad de biotopos, entre la superficie y los 20-30 metros de profundidad, habiéndose recolectado hasta los 100 metros de profundidad. Caulerpa taxifolia compite ventajosamente con las especies indígenas gracias a su rapidez de crecimiento, modo de ocupación del substrato, acceso a la luz, aumento de la sedimentación, y la síntesis de metabolitos secundarios (sesqui- y mono-terpenos). La concentración de estos metabolitos varía mucho a lo largo del año y ello afecta al consumo por el erizo Paracentrotus lividus. Las poblaciones de Caulerpa taxifolia presentan un reducido número de otras especies algales y una baja diversidad. También resultan negativamente afectadas las poblaciones de erizos, peces, anfípodos y poliquetos. En base a los datos actualmente disponibles se predicen algunas particularidades en el funcionamiento de un posible ecosistema dominado por Caulerpa taxifolia. Si la expansión de esta especie continua al ritmo actual asistiremos a un acontecimiento ecológico de primera magnitud para el Mediterráneo, caracterizado por un fuerte descenso de la ecodiversidad y, quizás también, de la biodiversidad de las zonas costeras.This study has been funded by a Life Project (LIFE 92-3/INT/13/A).Peer reviewe

The management of artisanal fishing within the Marine Protected Area of the Port-Cros National Park (northwest Mediterranean Sea): a success story?

The Port-Cros National Park, France (northwest Mediterranean Sea), established in 1963, is a Marine Protected Area (MPA) where, unlike no-take areas, artisanal fishing has been permitted (except trawling), owing to social and economic pressures. Nevertheless, restrictions on artisanal fishing have increased through a fishing charter (1999). In the meantime, recreational fishing was progressively banned, which has helped as a management tool to make the restrictions on artisanal fishing acceptable in social terms. Monitoring of the artisanal fishing (2000–2005) reveals the stability of the fishing fleet (9–13 vessels); of the fishing effort [number of fishing sets per day between 3.4 (+2.1) and 6.9 (+3.4) in spring, and 3.0 (+1.7) and 5.2 (+2.7) in summer]; and of yields [catch per unit effort between 1.27 (+0.72) and 1.68 (+1.44) kg 100 m of net 21 d 21]. Furthermore, based on an analysis of available data, artisanal fishing does not jeopardize the conservation objectives of the MPA, so that, from 1963 to date, the issue has changed from “What can be done to ban commercial fishing? ” to “Is there any reason to ban commercial fishing?”

Fishers' perceptions as indicators of the performance of Marine Protected Areas (MPAs)

International audienceHow users perceive the performance of Marine Protected Areas (MPAs) is fundamental for the social acceptance of these zones. Moreover, their perceptions may be relevant for monitoring the effects of MPAs on extractive activities. This study analyzes artisanal fishers' perceptions of the performance of a north-western Mediterranean coastal MPA, which encompasses two no-take zones (NTZs). Three viewpoints have been considered: the effect on the personal activity of fishers, the effect on the local fishery and the effect on the ecosystem. In order to test the hypothesis that biomass export (spillover) - which had previously been evidenced from the two NTZs - may influence fishers' perceptions of NTZ effects, fishers' perceptions were compared with both declared and observed fishing activity over an one-year period. The results show that negative perceptions of NTZs are either nil or are negligible. Most fishers are aware of the beneficial effects of NTZs on ecosystems and fisheries. However, they remain to be convinced of the beneficial effects of the NTZs on their own activity. For instance, the proximity of a NTZ appears never to be involved in the choice of a fishing spot. This partial lack of correspondence between scientific expectation and fishers' perceptions is discussed in the light of fishing habits in the zone adjacent to NTZs, and takes into account fishing grounds, targeted species and seniority (defined as the number of years the fisher has been fishing within the MPA). All three factors appear to influence fishers' perceptions. For example, having a positive perception about a NTZ and spending more time fishing in the adjacent zone are habits that can be associated with fishers with less seniority. Fishers' perceptions obviously indicate the social acceptance of the MPA and are an essential monitoring tool for MPA managers. However, perceptions cannot be seen as a substitute for scientific monitoring, as both approaches are clearly complementary

Unexpected headless and tailless fish in the stomach content of shortfin mako Isurus oxyrinchus.

The stomach content of 113 individuals of shortfin mako Isurus oxyrinchus was analyzed. Individuals were sampled at landing in Vigo (Spain) and captured by sea-surface long-liners in the vicinity of the Azores Archipelago and between Azores and the Iberian Peninsula, in March and October 2012, and March 2013. Teleosts constituted the dominant item, mainly Atlantic saury Scomberesox saurus (87% of teleost prey). Among them, 94% were deprived of both head and the caudal fin, while the flesh and bones of the body were preserved. The presence of eye's lenses, the number of which was consistent with the number of fish remains, likely rules out the elimination of the heads before ingestion. There is no obvious explanation for this unexpected and unrecorded pattern of digestion

Métiers, effort and catches of a Mediterranean small-scale coastal fishery: The case of the Côte Bleue Marine Park

The overexploitation of fishery resources has led to a major fisheries crisis. In this context, artisanal fisheries, and in particular small-scale coastal fisheries, appear as relevant alternatives for a sustainable use of coastal resources. Marine Protected Areas (MPA) are more and more used as management tools for these fisheries, as protection effects and targeted access regulations may benefit to commercial fishers. Managers and scientists need then quantitative information not only to adapt their management to the fishing activity present on their territory, but also to estimate the effects of MPA management on it. This study provides catch and effort estimates that are essential for appraising and managing the artisanal fishery in the Côte Bleue Marine Park (CBMP), a French Mediterranean MPA including two No-Take Zones of different age and size. A field protocol was defined and implemented between July 2009 and June 2010 within the CBMP. Seven métiers were identified and characterized by target species, gear type, fishing grounds and fishing periods. During the one-year studied period, 3512 fishing trips and 4645 fishing operations were performed by 30 active boats in the Côte Bleue fishing territory, amounting to 9500 km of immersed nets. In total, approximately 130 tons of catch were landed in the six CBMP harbors, out of which 58% depend on the three main species caught on the Côte Bleue: hake (Merluccius merluccius), gilthead seabream (Sparus aurata) and common sole (Solea solea). The presented methodology could be part of a long term monitoring requiring close collaboration with local fishers. It enables adaptive management with respect to changes in fishing pressure (from inside and outside the MPA) that may impact the environment and its resources

Blitzkrieg in a marine invasion: Caulerpa racemosa var. cylindracea (Bryopsidales, Chlorophyta) reaches the Canary Islands (north-east Atlantic)

On the basis of morphological and genetic studies (rDNA ITS1, 5.8S, ITS2, and a 18S rDNA intron), we confirm here that Caulerpa racemosa var. cylindracea (Sonder) Verlaque, Huisman et Boudouresque, a southwestern Australian taxon recently introduced into the Mediterranean Sea also occurs in the Canary Islands. This is the first report of C. racemosa var. cylindracea in the Atlantic. It was observed for the first time in the Canary Archipelago in 1997–1998. The speed and regional scale of expansion (north Atlantic Ocean and the Mediterranean Sea) of this invasive species appear to be among the most dramatic ever recorded. The possible outcome of this introduction in the Atlantic is discussed