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1.
Kevin Leleu Frédérique AlbanDominique Pelletier Eric CharbonnelYves Letourneur Charles F. Boudouresque 《Marine Policy》2012,36(2):414-422
How 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. 相似文献
2.
Abstract. The proximate composition of the various components of Posidonia oceanica is given in terms of gravimetric and energetic level and amount of plants from 2 depths at Port-Cros (Var. France). The level of proximate constituents differed little between the leaves (regardless of age) and the roots, but the rhizome contained much more soluble carbohydrate and less structural carbohydrate and ash. Because of this, the energy level in the leaves was more in terms of organic material and less in terms of total material than the energy level in the rhizome. The leaves of a P. oceanica shoot at 2 m depth in July contained 1.6 g organic material. 29.0 kJ. The weight and energy of the soluble carbohydrate in the rhizome from the base of the leaves to the 18th sheath scale decreased by ca. 40% from October to March and increased by ca. 100% from March to July. 相似文献
3.
This paper examines the distribution of unconsolidated sediment in the KwaZulu-Natal Bight located along the east coast of South Africa. Results show that there is a general shelf-wide sediment distribution of coarser grain sizes between depths of 60 and 100?m, punctuated by a broad swathe of mud offshore of the Thukela River. Seasonal changes in sediment distribution patterns are small, being restricted to seaward fining on the inner shelf off the fluvial sources. Sediment distribution reflects a partitioning between sediment populations that are current- influenced and relict (palimpsest) populations associated with submerged shorelines. Wave ravinement during the deglacial transgression, the reworking of submerged shorelines during sea-level stillstands and, to a lesser extent, the Agulhas Current system, are the dominant controls on sediment distribution. 相似文献
4.
Christine Pergent-Martini Charles-François Boudouresque Vanina Pasqualini & Gérard Pergent 《Marine Ecology》2006,27(4):310-319
The impact of fish farming facilities on Posidonia oceanica meadows was assessed from studies of intensive facilities carried out over the last few years. The disturbances caused by these fish farms were measured by means of both abiotic (light, sediment, interstitial water) and biotic variables (meadow density, leaf biometry, lepidochronology, primary production, epiphytes, reserve carbohydrates in the rhizomes), in function of increasing distance from cages and/or inside a geographically close reference site. The results showed significant degradation of these seagrass meadows in all the sectors investigated. When fish farming cages were placed above a P. oceanica bed, the meadow was severely degraded or disappeared and the sediment showed a strong increase in organic matter that could lead to anoxia phenomena. The irreversible impact of fish farming projects on P. oceanica meadows requires the application of the precautionary principle. Several recommendations (site selection, preliminary studies and monitoring over time) are suggested in order to enable piscicultural activities to be incorporated in a global process of Integrated Coastal Zone Management. 相似文献
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6.
Guillaume Bernard Charles F. Boudouresque Philippe Picon 《Estuarine, Coastal and Shelf Science》2007,73(3-4):617-629
The Berre lagoon (Provence, France), one of the largest Mediterranean brackish lagoons (155 km2), was occupied, at the turn of the 20th century, by extensive Zostera meadows (Zostera marina and probably Zostera noltii; perhaps over 6000 ha). Subsequently, the lagoon was disturbed by urban and industrial pollution and, from 1966, by the diversion of the Durance River. This resulted in a 10–49-fold and 8–31-fold increase of the freshwater and silt inputs, respectively. By means of digital analysis of aerial photographs for the years 1944, 1992, 1998 and 2004, coupled with ground truth for the last three dates, we mapped the Zostera meadows. The replacement of Z. marina by Z. noltii, the latter species being already dominant in the 1970s, was completed in 1990. In parallel to this substitution, the Zostera beds underwent a dramatic decline. Their depth limit, which was (6–9) m in the early 20th century, withdrew to 3.5, 3, 1 and less than 1 m by 1944, the 1970s, 1992 and 1998, respectively. Since 1998, Zostera must be considered as functionally extinct. The total surface area of Zostera meadows was of the order of 1.5 ha in 2004. In an attempt to alleviate disturbance, the input of freshwater and silt from the Durance River was significantly reduced from the early 1980s and 1990s respectively. Similarly, from the 1970s to the 1990s, urban and domestic pollution was drastically reduced. Despite these steps, Zostera meadows continued to shrink to near extinction. The lagoon has shifted from a system dominated by seagrass beds to a system with bare silt bottoms, which now occupy most of the lagoon. The reasons could be, in addition to continuing nutrient inputs, the resuspension of silt, no longer trapped under the seagrass canopy, during wind episodes, which are frequent in the area, and/or the release of nutrients from the bare silt habitat, which would constitute an indication of a possible hysteresis of the system. However, since 2000, the establishment of the mussel Mytilus galloprovincialis, a drop in turbidity and a slight, inconspicuous progression of Z. noltii could be the harbinger of a reverse shift of the system. 相似文献
7.
The relatively wide KwaZulu-Natal Bight between St Lucia and Durban on the north-east shelf of South Africa is characterised by several circulation features driven by the Agulhas Current, wind and coastal inputs. A large multidisciplinary programme investigated the sources and relative influences of nutrients on the shelf. Within this, and to address a critical knowledge gap, this study describes macrobenthic (<1 mm) composition and frequency from 16 stations, assigned amongst four oceanographic focus areas. The areas were predetermined across the disciplines to represent upwelling, outwelling and a semi-persistent eddy, with nutrients and primary productivity being measured at each. Environmental variables such as sediment distribution, sediment TOC and bottom water physico-chemistry were determined at a significantly larger spatial scale. Our study postulated that oceanographic focus areas support significantly different macrobenthic assemblages, and that composition and relative distribution is due to measurable habitat attributes at each. Macrofauna were relatively abundant and particularly rich at >1 000 taxa. Annelida, Arthropoda, Mollusca, Echinodermata, Sipuncula and Cnidaria (>50 taxa each) were the dominant macrobenthic groups in the bight. Annelida were dominated by the polychaete families Spionidae, Terrebelidae and Cirratullidae, which were generally associated with outwelling and a mud depocentre off the Thukela River. Two unique and distinctive assemblages were found, one in the Thukela Mouth focus area and another on the midshelf between Thukela and Durban. The latter is influenced by poorly sorted, coarse sand and with probable influences from the Durban Eddy. There assemblages were abundant, rich and specific to this habitat. Correlation, PERMANOVA and CAP analyses showed assemblage fidelity to the focus areas. Medium sand, fine sand, mud and the variance of overall sediment type were the habitat drivers underlying macrofaunal abundance distributions. 相似文献
8.
Biological pollution in the Mediterranean Sea: invasive versus introduced macrophytes 总被引：17，自引：0，他引：17
The authors have listed 85 species of macrophytes that have probably been introduced to the Mediterranean. Among them, nine species can be considered as invasive, i.e., playing a conspicuous role in the recipient ecosystems, taking the place of keystone species and/or being economically harmful: Acrothamnion preissii, Asparagopsis armata, Lophocladia lallemandii, Womersleyella setacea (Rhodophyta), Sargassum muticum, Stypopodium schimperi (Fucophyceae), Caulerpa racemosa, Caulerpa taxifolia and Halophila stipulacea (Plantae). These data fit well the Williamson and Fitter's "tens rule", which states that, on average, 1 out of 10 introduced species becomes invasive. Though some features (e.g. life traits, geographical origin) can increase the likelihood of a successful invasion, the success of invaders is far from being predictable. Since the beginning of the 20th century, the number of introduced species to the Mediterranean has nearly doubled every 20 years. Should these kinetics continue, and according to the tens rule, it can be expected that 5-10 newly introduced macrophytes shall become invasive in the next 20 years. 相似文献
9.
Thomas Belsher Alexandre Meinesz Jean Robert Lefevre Charles-François Boudouresque 《Marine Ecology》1988,9(2):157-165
Abstract. In order to simulate SPOT-typc satellite imagery, remote sensing of the Bay of San Cyprianu (Corsica) was carried out using a radiation sensor mounted in an aircraft. The resulting simulated image was calibrated using a chart of the benthos produced by SCUBA diving. We show that remote sensing by satellite should be able to resolve certain bottom types and benthic communities in water down to a depth of 12 m. 相似文献
10.
Gérard Pergent Charles-François Boudouresque Alain Crouzet Alexandre Meinesz 《Marine Ecology》1989,10(3):221-230
Abstract. Leaf sheaths in the seagrass Posidonia oceanica can persist for millcnia and they show, according to their insertion rank, cyclic variations in parameters such as thickness and tissue structure. The principal cycles are always annual, but pluriannual cycles can also be detected. Annual cycles may be changed by environmental parameters such as light, temperature, or water movement. In a fashion analogous to the study of annual tree rings (dendrochronology), the study of cyclic changes in Posidonia oceanica sheaths is thus a technique allowing the study of past yearly changes in the near-shore environment. 相似文献