1,721,022 research outputs found
Can epiphytic vegetation be used as an indicator of the recovery state of Cystoseira s.l. forests? A study carried out along the Conero Riviera (N Adriatic).
No full textDeep-sea mobile megafauna of Mediterranean submarine canyons and open slopes: analysis of spatial and bathymetric gradients
No full textEverything you wanted to know about regime shifts in the marine environment and have not dared to ask, yet
Full text linkBiochemical composition of a meso-bathyal lobster (Polycheles typhlops, Heller 1862 Decapoda, Palinura, Polychelidae)
No full textTo characterise some traits of the life strategies of Polycheles typhlops, a deep-sea small lobster usually encountered as by-catch within deep trawls in the Southern Tyrrhenian Sea (Mediterranean Sea), we analysed the biochemical composition of the caudal muscles of 49 specimens collected in March and April 2007. Differences in the biochemical composition between females and males were weak, but relevant differences in protein (>90% of the organic C) and lipid (4-6%) contents were observed between developmental stages both in females and males. These differences are likely to be related to different food items and/or to the metabolic shifts associated with their reproduction. We argue that this deep-sea lobster could cover a relevant role in the meso-pelagic food webs and attract future commercial interest
Meiobenthos in earthen ponds used for semi-intensive shrimp farming (New Caledonia, South Pacific)
No full textWe analysed the temporal variability of meiobenthic (meiofauna and protists) abundance and community structure in the sediments of two shrimp farms located in New Caledonia. In each farm, sediment samples were collected weekly from February to June 2006 at two ponds, and analysed for quantity and composition of sedimentary organic matter, meiofaunal abundance, taxa richness and community composition. Independently of the initial conditions, sedimentary contents of biopolymeric C and total phytopigment varied significantly during shrimp rearing, although not consistently in the two ponds. Changes in the quantity and biochemical composition of sedimentary organic matter were associated with changes in total meiofaunal abundance and taxa richness, as well as in total and rare (<1% of total abundance) meiobenthic community composition. We show that the slight eutrophication of the sediment during the shrimp rearing cycle determined significant effects on the meiofaunal community composition as well as on the relative importance of metazoan vs. protists abundance. The results of this study suggest that the study of meiobenthic communities represents a reliable descriptor of the environmental quality of shrimp farming ponds
Potentially combined effect of the invasive seaweed Caulerpa cylindracea (Sonder) and sediment deposition rates on organic matter and meiofaunal assemblages
Full text linkThe seaweed Caulerpa cylindracea (Sonder) is one of the most successful marine bioinvaders worldwide. Caulerpa cylindracea can influence the quantity and biochemical composition of sedimentary organic matter (OM). However, it is still unknown if the effects of C. cylindracea on both OM and small metazoans (i.e. meiofauna) can change according to different sediment deposition rates. To provide insights on this, we investigated the biochemical composition of sediments along with the abundance and composition of meiofaunal assemblages in sediments colonized and not-colonized by the seaweed C. cylindracea under different regimes of sediment deposition. Our results show that the presence of the invasive alga C. cylindracea could alter quantity, biochemical composition, and nutritional quality of organic detritus and influence the overall functioning of the benthic system, but also that the observed effects could be context-dependent. In particular, we show that the presence of C. cylindracea could have a positive effect on meiofaunal abundance wherever the sediment deposition rates are low, whereas the contextual presence of high to medium sedimentation rates can provoke an accumulation of sedimentary organic matter, less favourable bioavailability of food for the benthos, and consequent negative effects on meiofauna
Trophic conditions and meiofaunal assembalges in the Bari Canyon and the adjacent open slope
No full textDue to their topographic features, submarine canyons are generally sites of intense shelf-slope exchanges of water and material, fuelling the deep basins with large quantities of sediment exiting from the continental shelf. In order to provide new insights about the role of submarine canyons in controlling the relationships between food availability and benthic biodiversity patterns along the continental slope, we investigated the quantity and the biochemical composition of sediment organic matter and the abundance of meiofaunal assemblages in the sediments along two different branches of a canyon and in an adjacent open slope located in the Bari margin (Adriatic Sea). Our results highlight that even twin branches within the same canyon may exhibit very large differences in the quantity, depth-related patterns and biochemical composition of sediment organic matter as well as of meiofaunal abundance. We also report here that the trophic relationships in the canyon sediments are tightly connected with the hydrodynamic conditions and that the steeper and the more flushed the canyon the more hostile environment for the benthos
Organic matter composition, metazoan meiofauna and nematode biodiversity in Mediterranean deep-sea sediments
No full textTo identify the relationships between the abundance and biodiversity of deep-sea meiofauna and their food resources in the Tyrrhenian Sea (Mediterranean Sea), we have investigated the quantity and biochemical composition of sediment organic matter, the metazoan meiofauna abundance and biomass, and the nematode biodiversity at meso- (>50 km) and/or local (<1 km) scales. Sediment samples were collected at four deep-sea sites (from 3430 to 3581 m in depth), two of which were close to two seamounts. The analysis of variance revealed significant differences at both the meso- and local scales (i.e. between sites and between stations at each site), and showed that the variability at the mesoscale was much higher than that at the local scale. The values of all of the investigated variables were generally lowest in sediments surrounding the seamounts, suggesting a role for these submersed structures in the abundance of the metazoan meiofauna and their resources. The nematode assemblage composition changed significantly across the four sites. Among the 96 identified nematode species, 14 were exclusively seen in sediments around the two seamounts, and only three species were present at all sampling stations. Differences in the trophic structures of the nematode assemblages were also linked with differences in the biochemical composition of sediment organic matter. These results indicate that high β-diversity in soft sediments around deep seamounts is associated with diversification of the benthic food webs, and suggest that while making the sediments poorer for food availability for benthic consumers, the presence of seamounts enhances the biodiversity in neighbouring sediment
Towards an Ecosystem-Based Marine Spatial Planning in the deep Mediterranean Sea
Full text linkThe deep sea covers about 79% of the Mediterranean basin, including habitats potentially able to deliver multiple ecosystem services and numerous resources of high economic value. Thus, the deep Mediterranean Sea represents an important frontier for marine resources exploitation, which is embedded within the European Blue Growth Strategy goals and agendas. The deep sea is crucial for the ecological functioning of the entire basin. For this reason, the deep Mediterranean deserves protection from the potential cumulative impacts derived from existent and developing human activities. Marine Spatial Planning (MSP) has been identified as key instrument for spatially allocating maritime uses in the sea space avoiding spatial conflicts between activities, and between activities and the environment. Indeed, MSP incorporates the ecosystem-based approach (EB-MSP) to balance both socio-economic and environmental objectives, in line with the Maritime Spatial Planning Directive and the Marine Strategy Framework Directive. Despite MSP is under implementation in Europe, the Directive is not applied yet for the managing and monitoring of the environmental status of the deep sea. In the Mediterranean, deep areas fall both in internal and territorial waters, and in High Seas, and its management framework turns out to be complicated. Moreover, a certain level of cumulative impacts in the deep Mediterranean has been already identified and likely underestimated because of paucity of knowledge related with deep-sea ecosystems. Thus, the implementation of scientific knowledge and the establishment of a sustainable management regime of deep-sea resources and space are urgent. This study aims at reflecting on the best available ecological knowledge on the deep Mediterranean to incorporate conservation objectives in EB-MSP. We propose a framework to include key ecological principles in the relevant phases of any EB-MSP processes taking in consideration existing socio-economic and conservation scenarios in the region. We add the uncertainty principle to reflect on the still unexplored and missing knowledge related to the deep Mediterranean. Here, we resume some guidelines to overcome limits and bottlenecks while ensuring protection of deep-sea ecosystems and resources in the Mediterranean Sea
High Meiofaunal and Nematodes Diversity around Mesophotic Coral Oases in the Mediterranean Sea
No full textAlthough the mesophotic zone of the Mediterranean Sea has been poorly investigated, there is an increasing awareness about its ecological importance for its biodiversity, as fish nursery and for the recruitment of shallow water species. Along with coastal rocky cliffs, isolated coralligenous concretions emerging from muddy bottoms are typical structures of the Mediterranean Sea mesophotic zone. Coralligenous concretions at mesophotic depths in the South Tyrrhenian Sea were investigated to assess the role of these coralligenous oases in relation to the biodiversity of surrounding soft sediments. We show here that the complex structures of the coralligenous concretions at ca. 110 m depth influence the trophic conditions, the biodiversity and assemblage composition in the surrounding sediments even at considerable distances. Coral concretions not only represent deep oases of coral biodiversity but they also promote a higher biodiversity of the fauna inhabiting the surrounding soft sediments. Using the biodiversity of nematodes as a proxy of the total benthic biodiversity, a high turnover biodiversity within a 200 m distance from the coralligenous concretions was observed. Such turnover is even more evident when only rare taxa are considered and seems related to specific trophic conditions, which are influenced by the presence of the coralligenous structures. The presence of a high topographic complexity and the trophic enrichment make these habitats highly biodiverse, nowadays endangered by human activities (such as exploitation of commercial species such as Corallium rubrum, or trawling fisheries, which directly causes habitat destruction or indirectly causes modification in the sedimentation and re-suspension rates). We stress that the protection of the coralligenous sea concretions is a priority for future conservation policies at the scale of large marine ecosystems and that a complete census of these mesophotic oases of biodiversity should be a priority for future investigations in the Mediterranean Sea
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