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Este artículo contiene 31 páginas, 19 figuras, 3 tablas., The morphological reexamination of specimens previously identified as Laonice bahusiensis Söderström, 1920 from North European and Mediterranean collections, supported by the molecular analysis of freshly collected material, enabled the recognition of four different species in the region: the genuine L. bahusiensis, L. irinae n. sp. from North European waters, and L. grimaldii n. sp. and L. mediterranea n. sp. from the Mediterranean Sea. The morphology of these species is described and illustrated, and their distributions are clarified based on old and new materials. A key for their identification is also provided. The Bayesian analysis of the COI sequences (483 bp) showed that these four species form a clade, namely the L. bahusiensis species complex, morphologically characterized by the continuous dorsal crests on postbranchiate chaetigers in the adults. The genetic p-distances between the species of the complex ranged from 13.27% to 17.99%, while the intraspecific variability ranged from 0.6% to 1.57%. Together with the sister species Laonice cirrata (Sars, 1851), the L. bahusiensis complex formed the Laonice (Laonice) clade, which is morphologically characterized by the prostomium fused with the anterior peristomial margin. However, the monophyly of the L. bahusiensis complex, as well as that of the clade Laonice (Laonice), needs to be further supported through the analysis of a greater set of genes from a larger number of species.

Aphanius fasciatus is a small fish occurring in Mediterranean brackish environments. In Cyprus it is known from three localities separated by long stretches of coast. The genetic diversity of these populations was evaluated using fragments of two mitochondrial genes. A comparison with the other available data showed that Cyprus populations represent a distinct lineage. The other lineages are concentrated in a relatively small area between the Strait of Sicily and the Western Ionian Sea, while all other areas include a subset of these lineages, suggesting that the aforementioned area might have acted as a glacial refugium. Landlocked North-African populations diverge from all other populations, suggesting that they might have originated in the Late Pleistocene, during transgression events of the Mediterranean Sea in North-African inland water bodies. The genetic diversity of A. fasciatus varied across different Cyprus populations, with a pattern mirroring the degree of environmental degradation, which likely affected population genetic variability through demographic reductions. The three Cyprus populations showed genetic uniqueness, suggesting the need of population-based management practices; the low genetic diversity of two populations, and the number of threats affecting them, suggest that the species should be considered endangered at national level and deserves protection measures.

Knowledge of the diversity of deep-sea polychaetes in the Mediterranean Sea is still scarce and fragmentary, due to the absence of comprehensive taxonomic revisions of several families, with the majority of recent works relying on higher level taxonomy. In the present work samples were collected with a box-corer along the Sardinian Slope, a bathyal escarpment area located in the western Mediterranean Sea, at seven depth levels separated from each other by a 300 m interval, ranging from 600 to 2400 m. Samples were sifted with a 0.3 mm mesh, and polychaetes were identified at the lowest taxonomic level and characterised from the biogeographic and tropho-functional point of view. Ninety-seven taxa were recorded, 60 of which identified at the species level; eight taxa are likely to be undescribed species, possibly endemic to the Mediterranean Sea, whereas another seven are reported for the first time for the Mediterranean Sea. The majority of taxa shows an Atlantic-Mediterranean or strictly Mediterranean distribution, thus confirming the similarity between Atlantic and Mediterranean deep-sea assemblages, but also the unicity of the latter. Conversely, cosmopolitan taxa, usually considered common in deep-sea assemblages, represented a minor component. The trophic guild composition of the assemblage varied along the slope, with shallower assemblages (600–900 m) including a relatively high percentage of predators and microphagous omnivores, while deeper assemblages (1500–1800 m) showed a > 90% percentage of deposit- and filter-feeders, with the 1200 m assemblage characterised by intermediate features. This outcome suggests that in the presently investigated area, the environmental conditions of shallower samples allow the stable occurrence of at least two trophic levels, whereas deeper assemblages depend mainly on organic matter coming from shallower levels and from the water column. The examined polychaete assemblages are characterised by low density and a complete absence of dominance, with the evenness index J’ ranging from 0.72 to 1; the wide ranges of the H’ index (0.50–2.67) and of Hill's N1 (1.65–14.65) suggest a high variability at low spatial scale. If compared to Atlantic deep-sea polychaete assemblages the assemblage studied shows an almost ten-fold lower organism abundance, but species diversity is only two- to four-fold lower, suggesting that biodiversity in Mediterranean deep-sea environments is possibly underestimated. Diversity of polychaete assemblages in the deep Mediterranean Sea is likely to be underestimated due to their low density, and adequate sampling strategies should be planned to have a better insight into the functioning and diversity of these communities.

A pilot study, using the dataset from the research network ‘FLT Med Net’, which regularly monitors transborder regions in the Mediterranean Sea using ferries as platform for systematic surveys, was undertaken to assess common bottlenose dolphin range and population trends within the Natura 2000 EU marine site “Tutela del Tursiops truncatus”. The site was recently designated by the Tuscany Region (Italy) within the requirement of the EU Habitats Directive. In order to evaluate the conservation status of bottlenose dolphin according to the surveillance scheme of the Directive, two six-year periods (2007-2012; 2013-2018) were compared to assess trends in distribution-occurrence (range); Sightings Per Unit of Effort and Density (population). In total, 18146 NM were surveyed along two fixed transects, recording 90 sightings of Tursiops truncatus and a total of 268 specimens. Between the two periods, slight but not statistically significant differences were assessed, with decreasing trend in range and population of the species; no variation was detected in mean group sizes. Travelling was the most common behaviour, and juveniles were present in 20% of the sightings, concentrated during spring and summer. The consistent FLT Med Net dataset was found to be appropriate to evaluate important parameters for the assessment of trends in the conservation status of Tursiops truncatus at the Natura2000 site scale.

In coastal marine ecosystems coralline algae often create biogenic reefs. These calcareous algal reefs affect their associated invertebrate communities via diurnal oscillations in photosynthesis, respiration and calcification processes. Little is known about how these biogenic reefs function and how they will be affected by climate change. We investigated the winter response of a Mediterranean intertidal biogenic reef, Ellissolandia elongata exposed in the laboratory to reduced pH conditions (i.e. ambient pH – 0.3, RCP 8.5) together with an extreme heatwave event (+1.4 °C for 15 days). Response variables considered both the algal physiology (calcification and photosynthetic rates) and community structure of the associated invertebrates (at taxonomic and functional level). The combination of a reduced pH with a heatwave event caused Ellisolandia elongata to significantly increase photosynthetic activity. The high variability of calcification that occurred during simulated night time conditions, indicates that there is not a simple, linear relationship between these two and may indicate that it will be resilient to future conditions of climate change. In contrast, the associated fauna were particularly negatively affected by the heatwave event, which impoverished the communities as opportunistic taxa became dominant. Local increases in oxygen and pH driven by the algae can buffer the microhabitat in the algal fronds, thus favouring the survival of small invertebrates.

Recent research hypothesised that the Siculo-Tunisian Strait might fit, at least for some species, the picture of a genetic transitional zone instead of a sharp genetic break between the Western and Eastern Mediterranean basins. The present study aimed at using the common Octopus, Octopus vulgaris as an empirical test-case to evaluate this hypothesis. To accomplish this goal, 458 new sequences of the mitochondrial gene cytochrome c oxidase subunit I were used. Combining the new sequences with those available on public databases, we assembled a dataset containing 920 sequences to investigate the spatial genetic patterns across 34 Mediterranean populations of O. vulgaris. The genetic structure of this species was assessed combining analysis of molecular variance and Median-Joining networks. Results supported the hypothesis of a complex spatial genetic pattern across the Sicilian channel. Contemporary factors, such as marine currents, likely affect the species’ genetic structuring across this area. Overall, our results highlighted that focusing the attention on the whole transitional area rather than on a unique genetic break might help to detect similar patterns across different species. Finally, acknowledging the occurrence of complex spatial genetic patterns across transitional zones may improve stock identification and management practices for commercially valuable species.

Marine litter, that is solid materials deliberately or accidentally released into marine and coastal environments, is a growing issue both at local and global scale. In particular, litter accumulation on beaches represents a relevant problem in touristic coastal areas. The DPSIR framework, already applied to tackle other environmental issues, can help in analysing the origin, impact, and possible solution of material stranded on the beach allowing a holistic approach in the “one health” perspective. It was applied in a popular sandy bathing location in the North-Western Tuscany (Italy). Information and data on origin and fate of beach-stranded material as well as existing local strategies were retrieved from a stakeholders’ network. In summer 2020, a monitoring campaign was performed to evaluate the sanitary state of the shoreline and the impact of this material on coastal habitat. In a 7-year period (2014-2020), a mean amount of 1.548,3 tons of beach-stranded material have been collected and treated to separate sand (55%), organic green fraction (31%), and anthropogenic debris (2%), while 12% weight-loss was attributable to evaporation. Analysis of historical environmental data revealed that shoreline accumulation of this material was associated with low atmospheric pressure, medium-strong winds, and storms. Preliminary monitoring data showed that the green fraction was mainly represented by wood and terrestrial plants with little quantity of the seagrass Posidonia oceanica, while most of the anthropogenic debris was rubber and metal. Microbial pollution of beached material was at least one order of magnitude higher than the surrounding environment (sand and seawater) for total coliforms, Escherichia coli, intestinal enterococci, and total fungal load. Overall, our results indicate a potential impact of beach-stranded material in this coastal area, with possible health risk for human population. The instruments already in place for the management of beached material, although consistent, could be further improved.

Non-indigenous species (NIS) represent one of the most relevant threats to biodiversity, ecosystem functioning and human activities, and their occurrence and spread have been the subject of numerous works and revisions. However, the information available is rather confused for several taxa, including polychaetes, which are characterised by having a high number of cryptogenic and questionable species. This work aims at providing a revised checklist of alien polychaetes occurring along the coasts of Italy, based on the examination of newly collected and deposited material and on the critical analysis of published and gray literature, and whenever possible on the re-examination of historical material. Of the 86 polychaete species reported as NIS in Italian waters, 25 are confirmed as alien species, while 3 are cryptogenic, and 40 should be considered questionable. Finally, 18 species were excluded from non-indigenous species checklists, either because they are native, or because they represent misidentifications of other species. The high number of cryptogenic and questionable species points at the need of molecular studies and taxonomic revisions for the majority of polychaete taxa reported as NIS, in order to clarify their taxonomy, origin, introduction pathways and spreading patterns.

The paraonid polychaete Aricidea fragilis Webster, 1879, a typically west-Atlantic species, is reported from the Mediterranean Sea on the basis of several individuals, from the Adriatic and Tyrrhenian Sea. Its differences with the other Mediterranean Paraonidae, and in particular with the morphologically close Aricidea suecica meridionalis Laubier & Ramos, 1974, are briefly discussed. The possible status of A. fragilis as an alien species in European waters is analysed. The scarcity of historical records, the relatively restricted distribution, and the population dynamics observed in European waters strongly support the hypothesis of an introduction, despite the wide temporal interval between the first record of the species in the 1930s and the currently ongoing range expansion and population explosion. Here we precautionarily suggest considering A. fragilis a cryptogenic species.

Non-biodegradable and compostable plastic bags on beaches negatively affect the development of coastal dune vegetation by drastically reducing seedling emergence and growth.

A phyllodocid polychaete belonging to the genus Eulalia is reported from Nuevo Gulf, Patagonia (South-western Atlantic Ocean) with abundant populations thriving in the intertidal zone. Morphological and molecular data allowed assigning this population to Eulalia clavigera (Audouin & Milne-Edwards, 1834), a species typically occurring along the north-eastern Atlantic coast. The absence of genetic structuring between north-eastern and south-western Atlantic E. clavigera strongly supports a non-native origin of the Patagonian population. Conversely, the majority of the Mediterranean Eulalia cf. clavigera analysed in this study turned out to belong to a different, probably undescribed species, suggesting that the diversity and taxonomy of green Eulalia is more complex than previously supposed. The high adaptation capabilities to stressed environments showed by E. clavigera, along with its possible high impact on native assemblages through predation, compel to carefully monitor its spread along the Patagonian coasts.

Coralline algae represent the most important bioconstructors in the Mediterranean Sea and are currently impaired by the effects of climate change (CC), particularly by global warming (GW) and ocean acidification (OA). We studied the effects of these two drivers on Ellisolandia elongata, an intertidal coralline algae that is known to host a rich biodiversity of associated fauna. We cultured turfs of E. elongata in experimental conditions of increased temperature and OA (using the values of the IPCC scenario RCP- 8.5 expected for 2100: actual mean temperature +3 °C and pH=7.78), and estimated alteration of algal linear growth and community structure, focusing especially on peracarid crustaceans and annelids. Our findings revealed a decrease in linear growth, yet with no significant changes on structural integrity, and a simplification of associated community, in particular for peracarids. Our study contributes to understand community-level response to CC drivers, highlighting the vulnerability of the fauna associated to an important Mediterranean marine habitat.

Despite almost two centuries of research, the diversity of Mediterranean deep-sea environments remain still largely unexplored. This is particularly true for the polychaete family Syllidae. We report herein 14 species; among them, we describe Erinaceusyllis barbarae n. sp., Exogone sophiae n. sp. and Prosphaerosyllis danovaroi n. sp. and report Parexogone wolfi San Martín, 1991, Exogone lopezi San Martín, Ceberio & Aguirrezabalaga, 1996 and Anguillosyllis Day, 1963 for the first time from the Western Mediterranean, the latter based on a single individual likely belonging to an undescribed species. Moreover, we re-establish Syllis profunda Cognetti, 1955 based on type and new material. Present data, along with a critical analysis of available literature, show that Syllidae are highly diverse in deep Mediterranean environments, even though they are rarely reported, probably due to the scarce number of studies devoted to the size-fraction of benthos including deep-sea syllids. Most deep-sea Syllidae have wide distributions, which do not include shallow-waters. 100 m depth apparently represents the boundary between the assemblages dominated by generalist shallow water syllids like Exogone naidina Ørsted, 1843 and Syllis parapari San Martín & López, 2000, and those deep-water assemblages characterised by strictly deep-water species like Parexogone campoyi San Martín, Ceberio & Aguirrezabalaga, 1996, Parexogone wolfi San Martín, 1991 and Syllis sp. 1 (= Langerhansia caeca Katzmann, 1973).

In the Mediterranean Sea, Cystoseira species are the most important canopy-forming algae in shallow rocky bottoms, hosting high biodiverse sessile and mobile communities. A large-scale study has been carried out to investigate the structure of the Cystoseira-dominated assemblages at different spatial scales and to test the hypotheses that alpha and beta diversity of the assemblages, the abundance and the structure of epiphytic macroalgae, epilithic macroalgae, sessile macroinvertebrates and mobile macroinvertebrates associated to Cystoseira beds changed among scales. A hierarchical sampling design in a total of five sites across the Mediterranean Sea (Croatia, Montenegro, Sardinia, Tuscany and Balearic Islands) was used. A total of 597 taxa associated to Cystoseira beds were identified with a mean number per sample ranging between 141.1 ± 6.6 (Tuscany) and 173.9 ± 8.5(Sardinia). A high variability at small (among samples) and large (among sites) scale was generally highlighted, but the studied assemblages showed different patterns of spatial variability. The relative importance of the different scales of spatial variability should be considered to optimize sampling designs and propose monitoring plans of this habitat.

Antarctic plunderfishes are demersal species inhabiting the continental shelf of the Ross Sea, with sympatric distributions and similar morphology. Assuming these species are potential competitors for food, we aimed to quantify food overlap among them and to test the existence of factors involved in prey resource partitioning. Dietary composition and feeding niche breadth were estimated through stomach contents analysis of some species of Artedidraco sampled in the western Ross Sea. The fish community consisted of a wide range of feeders, from specialists like A. glareobarbatus and A. shackletoni, which fed exclusively on epifaunal polychaetes, to generalists like A. loennbergi and A. skottsbergi, which fed on a variety of prey. Although all species relied exclusively on benthic prey, diet diversity and prey type largely differed from each other, both contributing to reduce prey overlap and food competition. In a few cases, relatively high food overlap was observed between species with different spatial distributions. Based on our data and on previous studies, prey resource partitioning in plunderfishes is therefore established through morphological and behavioural adaptations, either by differential development of sense organs and trophic structures or by different diet composition and spatial distribution within the shared benthic habitat.

The census of natural populations provides relevant information for both conservation purposes and environmental monitoring. In the present work, natural populations of the killifish Aphanius fasciatus (Teleostei: Cyprinodontidae) were censused in the Italian territory. The historical distribution of the species was reconstructed with the aid of bibliographic material and museal samples, in order to evaluate the extent of changes in its distribution. Three periods (pre-1990s, 1990s, post-1990s) and five habitat types (lagoons/coastal ponds, saltworks, canals, river mouths, inland water bodies) were considered. Overall, we recorded the presence of A. fasciatus in 82 localities, the majority of which are lagoons/ponds. The species showed a widespread decline and sometimes local population extinction, due to habitat degradation and competition with the introduced poeciliid Gambusia holbrooki. With a few exceptions, A. fasciatus is currently extinct in inland waters, being mainly present in coastal br...

The polychaete assemblages from an escarpment area in the western Ionian Sea are characterised in terms of species richness, evenness and trophic composition. Moreover, the first occurrence of the genus Barantolla in the Mediterranean Sea, and of Lumbrinerides carpinei and Exogone (Parexogone) campoyi in Italian waters, is reported. Aricidea trilobata Laubier and Ramos, 1974 is redescribed on the basis of new material with the new name Aricidea (Acmira) jeaneteae, together with a brief description of two deep-water species belonging to the genus Levinsenia.

This study provides data on the genetic structuring of the pipefish Syngnathus abaster in the western Mediterranean and Adriatic Seas. A total of 109 specimens were collected in brackish-water biotopes. The control region and three other regions of the mitochondrial genome were analysed. The most relevant result was the high genetic structuring found by Bayesian inference (BI), maximum likelihood (ML) and network analyses, which were consistent in showing three well-separated clusters of S. abaster populations. Furthermore, BI and ML did not support the monophyly of the taxon S. abaster. These results suggest the occurrence of a species complex in the study area, whose differentiation may have occurred since the Pleistocene. The results also show a very high genetic variability at the inter-population level, with no shared haplotypes among sites. Evolutionary forces due to the fragmented nature of the brackish-water habitats may account for the high genetic divergence found among the groups and populations. Finally, although dispersal by rafting over long distances may occasionally occur, this study suggests linear stepping-stone model of colonization to be most likely. The complexity of the results obtained suggests that further studies are needed to elucidate the phylogeny of S. abaster.

Pinctada imbricata radiata (Leach, 1814) was the first Lessepsian bivalve reported in the Mediterranean Sea where it is progressively expanding westward. Its native range includes the Indian Ocean and western Atlantic. The present study provides the first insight into the species’ phylogeographic structure, by analysing sequences of a 385-bp region of the mitochondrial gene coding for the subunit I of the cytochrome c oxydase (COI). Sixty-four individuals collected at seven Mediterranean localities were sequenced; in addition, eight COI sequences of individuals from the species’ native range (Persian Gulf) were retrieved from GenBank. Overall, we detected 10 haplotypes. Samples from both the native range and invaded localities were characterised by low levels of haplotype and nucleotide diversity (total h = 0.351, total π = 0.0013). Significant genetic divergence was found between Persian Gulf and Mediterranean Sea samples, whereas very shallow genetic structuring was observed within the Mediterra...

Exogenous application of plant growth regulators (PGRs) may be an effective technique for increasing the rooting ability and the growth of vegetative fragments (cuttings) of plants used in dune restoration programs. Various concentrations (0, 50 and 100 mg l −1 ) of two auxins, alpha-naphtaleneacetic acid (NAA) and indole-3-butyric acid (IBA), and two cytokinins, 6-furfurylaminopurine (Kinetin) and 6-benzylaminopurine (BAP), were applied separately to cuttings of two widely used species for restoration, Ammophila arenaria and Sporobuls virginicus . Root development and production of new buds in cuttings were examined under laboratory conditions one month after application. Cuttings were also examined one year after transplanting into a sandy substratum under natural conditions, to test for possible long term effects of PGRs on plant establishment success and growth. The response of the two study species to PGRs differed substantially. In A. arenaria the auxin NAA at 100 mg l −1 reduced the time for root initiation and increased the rooting capacity of cuttings, while the cytokinin Kinetin at 50 mg l −1 facilitated root growth. No auxin had effect on rooting or growth of S. virginicus cuttings, but treatment with 100 mg l −1 Kinetin resulted in higher rooting success than the control. One year after planting, the cuttings of A. arenaria treated with 100 mg l −1 NAA showed a higher establishment success (90% vs. 55%) and produced more culms and longer roots than the control; those treated with cytokinins did not differ in the establishment success from the control, but had longer roots, more culms and rhizomes. On the other hand, the cuttings of S. virginicus treated with 100 mg l −1 Kinetin showed a higher establishment success (75% vs. 35%) and had more culms than the control. Therefore, in restoration activities that involved A. arenaria, a pre-treatment of cuttings with NAA would be beneficial, as it allows the production of a higher number of well-developed plants with high survival potential and greater area cover. In contrast, a pre-treatment of cuttings of S. virginicus with Kinetin would achieve more acceptable plant survival rates. This easy and low cost-effective technique may be extended to other dune plant species and applied on a large scale to improve the chance of dune restoration success.

Phylogeographical analysis of Paracentrotus lividus was carried out by means of sequencing the mitochondrial cytochrome b gene (1143 bp) of 260 individuals collected at 22 Mediterranean and four Atlantic localities. Against a background of high haplotype diversity and shallow genetic structuring, we observed significant genetic divergence between the Adriatic Sea and the rest of the Mediterranean, as well as between the Mediterranean and the Atlantic sample groups. Furthermore, on the largest spatial scale, isolation by distance was detected. Three main haplogroups were identified by network and Bayesian assignment analyses. The relative proportions of haplogroups were different in the four regions considered, with the exception of Western and Eastern Mediterranean that showed a similar pattern. This result together with the outcome of Snn statistics, analysis of molecular variance and network analyses allowed to identify three weakly differentiated populations corresponding to the Atlantic, Western + Eastern Mediterranean, and Adriatic seas. Analyses of mismatch distribution and neutrality tests were consistent with the presence of genetic structuring and past demographic expansion(s). From a fisheries perspective, the results obtained in the present study are consistent with genetic sustainability of current exploitation; local depleted stocks are recurrently replenished by recruits that may have originated from nonharvested areas. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 910-923.

The pleated ascidian Styela plicata (Lesueur, 1823) is a solitary species commonly found in ports and marinas around the world. It has been recorded in the Mediterranean region since the mid-19th century. In the present work, the species’ genetic diversity was analysed, employing a 613-bp portion of the mitochondrial cytochrome c oxidase subunit I (COI) gene from 149 individuals collected in 14 ports along Italian coasts at spatial scales ranging from 1 to approximately 2200 km. Haplotype and nucleotide diversity values were h = 0–0.933 (total h = 0.789) and π = 0–0.145 (total π = 0.0094), respectively. A general southward trend of increasing within-population genetic diversity was observed. Analysis of molecular variance revealed significant genetic structuring but no significant differences were detected among basins, and no isolation by distance was found. Our data were integrated with the COI sequences available from previous studies and re-analysed in order to investigate the possible routes of introduction of this ascidian into the Mediterranean Sea. The presence of the two COI haplogroups detected in previous molecular investigations on S. plicata at intercontinental spatial scale was confirmed in the Mediterranean Sea. The results revealed multiple introductions of S. plicata, although some locations appear to have experienced rapid expansion from few founding individuals with reduced genetic diversity. However, continuous introductions would confound the pattern deriving from single founder events and make it difficult to estimate the time needed for gene diffusion into established populations. This mixing of effects creates difficulties in understanding the past and current dynamics of this introduction, and managing this alien invasive ascidian whose genetic structure is continuously shuffled by vessel-mediated transport.

Variation in the number and distribution of paragnaths in populations of the ragworm, Hediste diversicolor, from 14 localities across a large part of its European range was analysed. Significant inter‐population variation was revealed by ANOVA applied to (i) the number of paragnaths in each zone of the pharynx, (ii) the number of paragnaths in each of the two belts (maxillary and oral), (iii) the total number of paragnaths on the pharynx and (iv) the measures of asymmetry for paired zones. No geographical pattern of morphological variation was detected by multidimensional scaling on population centroids and no signals of morphological population substructuring were found. Explanations of variation in paragnath number and pattern among populations may reflect local differences in diet or dominant mode of feeding. Factor analysis suggested that the two belts of the pharynx behave as separate functional units in feeding activities. The comparison with two samples of the other nereidid, Perinereis cultrifera,...

An investigation of the genetic variability of Octopus vulgaris, an intensively harvested species, was carried out using a mi crosatellite locus as genetic marker. Samples from one eastern At lantic and nine Mediterranean locations were analysed. In each population, the number of alleles at locus Ov06 varied from four to seven and was 21 overall. Observed and expected heterozy‐gosity values ranged from 0.310 to 0.655 and 0.506 to 0.841, re spectively. Permutation tests and the positive average value of FIS showed significant departures from the Hardy‐Weinberg equilibri um, due to a deficit of heterozygotes. FST showed high levels of genetic divergence among the populations. Genetic distance val ues ranged from 0.0004 to 7.1520. Isolation‐by‐distance was not evident either by the Mantel test or multidimensional scaling. Mi crosatellite results are consistent with a previous allozyme study, and suggest that the common octopus does not form a single panmictic unit in the Mediterranean. From a fisher...

The small-spotted catshark Scyliorhinus canicula is a small demersal chondrichthyan distributed on continental shelf and uppermost slope waters of the Mediterranean Sea and north eastern Atlantic Ocean. It has commercial value in some European regions, whereas in other it is considered a bycatch species. Species’ genetic structure was analysed by means of 578 bp mitochondrial COI sequences. A total of 192 individuals (122 obtained in the present work and 70 retrieved from GenBank) from 11 Mediterranean and 1 Atlantic locations were considered. Overall, we detected 27 COI haplotypes, seven of which were newly found. Moreover, a high number of haplotypes were location- and/or region-private. Low values of nucleotide diversity (total π = 0.0027) and moderate to high haplotype diversity (h = 0.500–0.920, total h = 0.827) were found. Significant genetic structuring in the study area was highlighted by AMOVA, Φ-statistics and Bayesian assignment analyses. The Atlantic sample was genetically divergent from Western Mediterranean counterparts and the Adriatic samples diverged from Eastern Mediterranean ones. Instead, Western and Eastern Mediterranean were not significantly divergent, suggesting that the Strait of Sicily is not effective in restricting past or current gene flow. No pattern of isolation by distance was detected. From a fisheries perspective, our results represent the first evidence of genetic structuring in S. canicula and are consistent with the presence of multiple genetic stocks in the study area. Further genetic analyses coupled with a fine grained sampling design are needed to precisely identify the borders of genetic stocks. These data provide a significant contribution for the planning of a long-term effective management policy, which could ensure sustainability of resource exploitation and stock viability.

Differentiation between two samples of the polychaete Perinereis cultrifera collected in a brackish-water habitat and in an adjacent marine site at Elba Island (Italy) was assessed by morphological (number of paragnaths on the zones of the pharynx) and genetic (allozymes) approaches. Mean number of paragnaths differed significantly in zones IIl, IIr, III and V by t-test (PD=0·185±0·018) and the mean value of the coancestry coefficient (Θ=0·381± 0·123, P

Diversity, distribution and biomass patterns of polychaetes were studied in the shallow soft bottoms off Terra Nova Bay (Ross Sea, Antarctica). Benthic samples, collected in the austral summer 1989–1990, were sampled using a Van Veen grab at 14 stations distributed between 23- and 194-m depth. A total of 5,768 individuals of polychaetes belonging to 77 species were found. The species richness recorded was high, despite the few biotopes investigated at Terra Nova Bay in this study, especially when compared to that recorded from previous investigations in the same area and from the whole Ross Sea (146 species). Despite the high number of species found, only a few species accounted for 76% of the total abundance: Tharyx cincinnatus (27%), Spiophanes tcherniai (23%), Leitoscoloplos mawsoni (18%) and Laonice weddellia (5%) were mainly distributed in the deeper stations (below 100-m depth), while Aglaophamus ornatus (3%) was the only species abundant in the shallowest stations (above 50-m depth), characterized by gravels and coarse sands. Species richness, diversity and evenness showed an increase with depth. Abundances ranged between 40 to over 12,000 ind/m2. Biomass values ranged between 0.9 to 176 g/m2 (wet weight). A trophic-guild classification revealed the occurrence of various feeding categories that were, however, numerically dominated by deposit feeders with both discretely motile epiand endobenthic forms, and sessile ones. Both the Bray-Curtis similarity and Correspondence (C.A.) analyses showed stations ordered according to depth and to the local dominance of some species. Both poorly and well-structured polychaete assemblages occurred and they seemed related to depth-related factors, such as degree of environmental disturbance (shallowest bottoms vs deep ones), heterogeneity of the substrate and habitat complexity (gravel and coarse sands vs mixed sediment. The richest and most diverse assemblages of polychaetes were those occurring below 140-m depth, where the substrate was dominated by medium sands, often mixed with a mosaic of rocks and boulders.

A study of feeding ecology in Trematomus hansoni Boulenger 1902 and Trematomus loennbergii Regan 1913 was carried out from samples collected in the austral summer 1990–1991 off Terra Nova Bay, Ross Sea. T. hansoni was caught between 35 and 566 m and T loennbergii between 311 and 543 m. Stomach contents analysis shows that T. loennbergii relies on a wider range of prey than T. hansoni. Fish and decapods are the main food resources of T. loennbergii, which feeds also on epifaunal and tube-dwelling polychaetes. T. hansoni mostly relies on fish resources that are made up of juvenile stages of fish and eggs. Despite the common area occupied by the two species, the interspecific competition is mostly mitigated due either to taking different prey or to taking different amounts of the same prey.

The polychaete Hediste diversicolor is characterised by a high degree of genetic structure among populations. The genetic differentiation has been related to the presence of cryptic species, corresponding to Atlantic and Mediterranean lineages whose divergence may have been driven by vicariance and/or selection. In this study we used DNA inter-simple sequence repeat (ISSR) markers to validate the genetic structure in nine populations from the north-western Mediterranean. We also analysed patterns of genetic differentiation among Mediterranean and Atlantic samples to assess the occurrence of further cryptic species in the north-western Mediterranean . We compared our results with previous mitochondrial DNA data to assess whether nuclear and mitochondrial genetic patterns were consistent. Analysis of ISSR banding patterns showed (1) a geographical structuring within the north-western Mediterranean, and (2) a sharp genetic differentiation between Atlantic and Mediterranean groups of populations, confirming the findings from previous mitochondrial DNA survey. The pattern of genetic variability found in the north-western Mediterranean is unlikely to reflect the occurrence of cryptic species in this area. On the other hand, our results are consistent with the occurrence of two cryptic species in the Mediterranean and Atlantic, whose genetic differentiation may have been driven by vicariance. Finally, this study further highlights the usefulness and effectiveness of ISSR markers for monitoring genetic diversity in aquatic invertebrates.

An investigation into the feeding habits of two demersal nototheniids, Trematomus bernacchii and T. centronotus, showed that the most important prey were polychaetes, molluscs and euphausiids for T. bernacchii and polychaetes and amphipods for T. centronotus. Epifaunal (e.g. Barrukia cristata) and tube-dwelling polychaetes (Amphicteis cfr. midas and Amythas membranifera) were common in the diet of both species. Bivalvia including Adamussium colbecki were found in the diet of T. bernacchii. Epifaunal gastropods (Trochidae) were an occasional prey for T. centronotus. Amphipods (mainly Acanthonotozomatidae) and the euphausiid Euphausia frigida were the main crustacean food of T. centronotus and T. bernacchii respectively. Our data suggest a difference in the feeding behaviour of the two nototheniid species, although both appear capable of feeding on common epibenthic invertebrates.

The spatial scale of life-history and demographic variation was investigated in the opportunistic polychaete Ophryotrocha labronica La Greca and Bacci. Individuals were collected along the Italian coasts from three thermally different biogeographical regions of the Mediterranean Sea. For each region, populations from four harbours were considered, and for each harbour, two sites were examined. Life-history and demographic traits were investigated after one generation under a common garden experiment, and their variation at the three spatial scales was assessed. All the traits showed high variability with regard to site. A number of life-history and all demographic traits also varied according to the biogeographical region. Conversely, no differences were found between harbours, suggesting that geographical isolation did not contribute to phenotypic variation. Results confirmed the central role of local conditions for the evolution of life history in species colonizing heterogeneous environments, but they also pointed to the importance of large-scale factors in shaping the phenotypic responses of O. labronica, demonstrating the need for a multi-scale approach for obtaining a good measure of natural variation in widespread opportunistic species.

The present study reports new records of the invasive pygmy mussel Xenostrobus securis in six brackish-water localities in the western Mediterranean. Until now X. securis, whose native range includes southern Australia and New Zealand, was also known from the northern Adriatic Sea and southern France. Along the coast of northern Tuscany (Italy) X. securis invaded brackish-water canals in the area between the port of Leghorn and the mouth of the Arno River. Moreover, this mussel has been found in one inner site of the Gulf of Olbia (north-eastern Sardinia, Italy) and at the mouth of the Fluvia River (northern Catalonia, Spain). As an ecosystem engineer, X. securis is an ecologically important species, heavily altering pre-existing benthic communities. Given that its presence in other western Mediterranean sites is highly possible, we recommend a closer monitoring of brackish-water biotopes.

Biological zonation in brackish habitats is usually related to the gradients of several factors, of which salinity is often taken as the most important. In contrast, recent papers, mainly on Mediterranean lagoons, have emphasized the role of other factors such as water movement and trophic status. In this paper, the distribution of polychaetes in the Orbetello lagoon (a poly-hyperhaline pond on the northern Tyrrhenian coast) is compared with the gradients of a number of environmental parameters. Polychaete distribution turned out to be under the control of a variety of highly interrelated factors. The study of biotic zonation as a function of a single driving factor is thus overly simplistic even when dealing with ‘simple’ environments, as lagoons are often defined. Several factors and their synergistic effects must always be taken into account. Summary A total of 79 species was collected from 13 sites in the Orbetello lagoon, comprising both brackish-water and marine species as well as a large number of species typical of organically enriched habitats. Through correspondence analysis, three major polychaete assemblages were recognized, linked to three different zones of the lagoon: 1) the channels connecting the lagoon to the sea; 2) the western lagoon; 3) the eastern lagoon (including a small part of the western lagoon situated near the town of Orbetello). Such a zonation was shown - by Trend Surface and linear correlation analyses - to be consistent with the spatial trends of a number of environmental parameters such as vivification/confinement, water movement, dissolved oxygen, poikilohalinity, and poikilothermy (in the order of importance); in contrast, salinity (minimal values), sediment grain size, and primary productivity showed little or no relation to polychaete distribution. However, almost all environmental parameters were significantly correlated with each other, thus making it impossible to identify the principal factor. This demonstrates that biotic zonation cannot be explained as the resultant of the action of a single driving factor (e. g., salinity or confinement), even in environments which are usually considered to be relatively simple from a synecological point of view, such as brackish habitats. Both the synergism among the various abiotic factors and the influence of biotic interactions must always be taken into account.

A new species of Schroederella (Polychaeta, Orbiniidae, Protoariciinae) collected in the Mediterranean Sea is described. This is the first record of the genus Schroederella in the Mediterranean Sea. 5. laubieri n. sp. is clearly distinguished from the other two species of the genus, S, pauliani and S. berkeleyi, by the distribution of hooks and the dimensions of the parapodial appendices and anal cirri.

A new species of Cephalocarida belonging to the genus Lightiella is described. Like all known species of Lightiella, the new species is characterized by reduction of trunk segment 8, which also lacks both pleura and thoracopods. The diagnostic characters of the species are: (1) one seta on the inner distal corner of the penultimate endopodal segment of second maxilla and thoracopods 1–5; (2) only one claw on the distal segment of the endopod of thoracopod 6. A cladistic analysis of 27 morphological characters was used to estimate the phylogeny of all species of Lightiella, with all other cephalocarid species used as outgroups. The discovery of this species in the Mediterranean fills a gap in the distribution of the genus and of the entire class. © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society, 2006, 148, 209–220.

Ophelia bicornis sensu lato is a polychaete living in intertidal sandy habitats of Mediterranean and European Atlantic coasts, whose systematics have been strongly debated in the past few decades. In the present work the count of nephridiopores was coupled with genetic analysis carried out with DNA markers (inter simple sequence repeats) for a total of 30 individuals collected at six Italian beaches. Exact test, analysis of molecular variance, non-metric multidimensional scaling and assignment tests clearly separated individuals with five nephridiopore pairs from those with six pairs. This finding validated results of a recent allozyme study in which O. bicornis sensu lato was split into O. bicornis sensu stricto (six nephridiopore pairs) and O. barquii (five nephridiopore pairs). This paper represents a further contribution to the estimation of biodiversity within marine invertebrates.

Macrofaunal communities and specific bulk properties of organically enriched sediments were investigated in the coastal lagoon of Cabras (Sardinia, western Mediterranean) on a grid of twenty-nine sampling stations, in spring 2001. Species composition and community structure indicated poor and heterogeneous macrofaunal communities, characterized by few predominant taxa typical of degraded environments, such as Polydora ciliata, Tubificidae nc and Neanthes succinea, distributed differently in some areas of the lagoon. Sediments were homogeneously muddy, with a mean silt + clay content of 93%. The analysis of specific grain size intervals within the mud fraction, however, highlighted a marked spatial variability of sediment particle distribution. Simple associations included a positive relationship of both Ficopomatus enigmaticus and Corophium sextonae, patchily distributed along the shores, with sediment sorting (σ), an index of sediment selection due to hydrodynamic energy. By contrast, inner areas, charac...

Two samples of Aphanius fasciatus collected in the Pilo pond (northern Sardinia, Italy) and in an adjacent pool of small surface area were analysed morphologically (235 individuals) and genetically (a subsample of 58 individuals). The aims of the present study were (i) to test the hypothesis that different predation pressures may be associated with morphological and/or genetic differences between samples from each habitat and (ii) to assess the level of divergence between the two populations. Morphological analysis was based on the relative size of fins because it has been shown to be associated with predation pressure. The relative caudal fin area (caudal fin area/total body surface) was smaller in specimens from the pool, in both males and females, whereas no differences were found for the dorsal and anal fin areas. Caudal fins with higher aspect ratio (fin depth/fin length) were found in fish from the pool but not in the pond, due to a higher fin depth. We hypothesised that specimens from the pool would show smaller caudal fin area, since they are subject to lower predation pressure. Random amplification of polymorphic DNA (RAPD) analysis revealed a relatively high degree of both within- and between-sample genetic heterogeneity. The pond and pool samples exhibited heterozygosities, which did not differ significantly by t-test. Between-sample genetic divergence was highlighted by the coancestry coefficient (theta = 0.301 +/- 0.059, P < 0.001) and analysis of molecular variance (AMOVA) (variance between sites = 41%, P < 0.001). Genetic divergence between sites with a relatively high genetic diversity within both samples suggested that the population in the pool did not originate from a single colonisation event with a small number of founders. The genetic divergence between the two populations is consistent with their differences in fin size., Deux échantillons de l’espèce Aphanius fasciatus, collectés dans l’étang de Pilo (nord de la Sardaigne, Italie) et dans une mare voisine, ont été analysés morphologiquement (235 individus) et génétiquement (un sous-échantillon de 58 individus). Les objectifs sont : 1) de tester l’hypothèse selon laquelle des pressions de prédation différentes seraient associées à des différences morphologiques et/ou génétiques entre les échantillons de chaque habitat ; 2) de déterminer le niveau de divergence entre les deux populations. L’analyse morphologique est basée sur la taille relative des nageoires car il a été démontré qu’elle dépendait de la pression de prédation. La surface relative de la nageoire caudale (surface de la nageoire caudale/surface totale du corps) est plus petite chez les spécimens de la mare aussi bien chez les mâles que chez les femelles alors qu’aucune différence n’est trouvée pour les surfaces des nageoires dorsale et anale. Les nageoires caudales à l’aspect plus haut (profondeur/longueur) se rencontrent chez les poissons de la mare mais pas chez celle de l’étang. Nous supposions que les spécimens de la mare présenteraient une surface de la nageoire caudale inférieure puisqu’ils sont soumis à une moindre pression de prédation. Une analyse par la méthode random amplification of polymorphic DNA (RAPD) révèle un degré d’hétérogénéité génétique relativement élevé aussi bien au sein d’un échantillon qu’entre les échantillons. Les échantillons de l’étang et de la mare présentent des hétérozygoties qui ne diffèrent pas significativement en utilisant le test-t. La divergence entre échantillons est mise en lumière par le coefficient de co-lignage (θ = 0,301 ± 0,059, P < 0,001) et le test Amova (variance entre sites = 41 %, P < 0,001). La divergence génétique entre sites avec une diversité génétique relativement élevée au sein des deux échantillons suggère que la population de la mare n’est pas issue d’une seule colonisation avec un faible nombre de fondateurs. La divergence génétique entre les deux populations est cohérente avec la différence de taille de leurs nageoires.

Pinna nobilis is the largest endemic Mediterranean marine bivalve. During past centuries, various human activities have promoted the regression of its populations. As a consequence of stringent standards of protection, demographic expansions are currently reported in many sites. The aim of this study was to provide the first large broad-scale insight into the genetic variability of P. nobilis in the area that encompasses the western Mediterranean, Ionian Sea, and Adriatic Sea marine ecoregions. To accomplish this objective twenty-five populations from this area were surveyed using two mitochondrial DNA markers (COI and 16S). Our dataset was then merged with those obtained in other studies for the Aegean and Tunisian populations (eastern Mediterranean), and statistical analyses (Bayesian model-based clustering, median-joining network, AMOVA, mismatch distribution, Tajima’s and Fu’s neutrality tests and Bayesian skyline plots) were performed. The results revealed genetic divergence among three distinguishable areas: (1) western Mediterranean and Ionian Sea; (2) Adriatic Sea; and (3) Aegean Sea and Tunisian coastal areas. From a conservational point of view, populations from the three genetically divergent groups found may be considered as different management units.

This study examined spatial relationships between rocky shore polychaete assemblages and environmental variables over broad geographical scales, using a database compiled within the Census of Marine Life NaGISA (Natural Geography In Shore Areas) research program. The database consisted of abundance measures of polychaetes classified at the genus and family levels for 74 and 93 sites, respectively, from nine geographic regions. We tested the general hypothesis that the set of environmental variables emerging as potentially important drivers of variation in polychaete assemblages depend on the spatial scale considered. Through Moran's eigenvector maps we indentified three submodels reflecting spatial relationships among sampling sites at intercontinental (>10000 km), continental (1000-5000 km) and regional (20-500 km) scales. Using redundancy analysis we found that most environmental variables contributed to explain a large and significant proportion of variation of the intercontinental submodel both for genera and families (54% and 53%, respectively). A subset of these variables, organic pollution, inorganic pollution, primary productivity and nutrient contamination was also significantly related to spatial variation at the continental scale, explaining 25% and 32% of the variance at the genus and family levels, respectively. These variables should therefore be preferably considered when forecasting large-scale spatial patterns of polychaete assemblages in relation to ongoing or predicted changes in environmental conditions. None of the variables considered in this study were significantly related to the regional submodel. Fil: Benedetti Cecchi, Lisandro. Università degli Studi di Pisa; Italia Fil: Iken, Katrin. University of Alaska; Estados Unidos Fil: Konar, Brenda. University of Alaska; Estados Unidos Fil: Cruz Motta, Juan. Universidad Simón Bolívar; Venezuela Fil: Knowlton, Ann. University of Alaska; Estados Unidos Fil: Pohle, Gerhard. Huntsman Marine Science Centre; Canadá Fil: Castelli, Alberto. Università degli Studi di Pisa; Italia Fil: Tamburello, Laura. Università degli Studi di Pisa; Italia Fil: Mead, Angela. University of Cape Town; Sudáfrica Fil: Trott, Tom. Suffolk University; Estados Unidos Fil: Miloslavich, Patricia. Universidad Simón Bolívar; Venezuela Fil: Wong, Melisa. Bedford Institute of Oceanography; Canadá Fil: Shirayama, Yoshihisa. Kyoto University; Japón Fil: Lardicci, Claudio. Università degli Studi di Pisa; Italia Fil: Palomo, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentina Fil: Maggi, Elena. Università degli Studi di Pisa; Italia

A new species, Platynereis nadiae sp. n. (Polychacta: Ncrcididac), from thc Mediterranean Sea is described. It is clearly distinguished from the other Platynereis species by the distribution and the morphology of the homogomph falciger setae and by the structure of thc tcntacular cirri.

The macrozoobenthic community in the northern Adriatic Sea, south of the Po river, along the Emilia-Romagna region coast, was sampled in 1985. Sampling site was central to a highly eutrophicated area with greatly increased intensity and frequency of dystrophic events over recent decades. The sampled community differs from all those described in the same area in a period (1934–1936) previous to the actual degree of eutrophication. Large abundances of species indicative of unstable bottoms, such as the bivalve Corbula gibba and the polychaete Lumbrineris latreilli were recorded. Moreover, the community structural features indicate a state of immaturity, such as in early successional stage communities. The increased frequency of acute dystrophic events and consequent shortening of the time between successive disturbances is proposed as the cause of biocenosis modification and its current structure and composition.

Some specimens of the genus Onuphis Aud. et M-Edw were collected on sandy bottoms in the Gulf of Follonica in Italy, and having the same characteristics they were considered a new species: Onuphis falesia. This new species differs from Onuphis eremita (a similar species of the same habitat) in several features, e.g., the branchiae become bifid from the 20th-25th setiger to the last segments, and the tube encrusted with small stones and shell fragments. Onuphis falesia is characterized, like many Onuphinae, by their wide variation in some features during different stages of development.

Along the vertical cliff of Romito (Leghorn, Italy) 97 polychaete species were found from 0 to 6 m depth. Three depth related communities could be identified by trends in structural parameters (abundance, number of species, and diversity), by changes in species composition, and by the distribution of ecological and trophic groups. Such a zonation is consistent with the principal models proposed for the Mediterranean and seems mainly related to algal conditioning of the substrate.

Experiments were carried out during autumn 1998 and spring 1999 at four selected sites in the Venice Lagoon in order to estimate the major bioturbation modes, and for quantitative analysis of the contribution of various taxa to these modes. Fluorescent sediment particles (63–350 micrometres) were supplied as a tracer pulse input at the sediment surface. Tracer depth profiles obtained after 15 and 20 days were simulated with a diffusion-advection-non-local transport model. This allowed the rates of biodiffusion, bioadvection, and RS, a non-local transport coefficient to account for the displacement of sediment by regeneration, to be estimated. A combination of fresh water and marine organisms were responsible for the recorded sediment reworking, which was dominated by both types of non-local transports (conveying and regeneration). Considering all the sampling sites and seasons, biodiffusion ranged from 0.87 +/-0.02 to 3.17 +/-0.92 sq cm/y-1, bioadvection from 0.12 +/-0.09 to 27.41 +/-2.47 cm/y-1 and RS from 0.00 +/-0.00 to 5.47 +/-1.09 g/cm-2/y-1 (mean +/-SE, n=3). A multiple regression analysis was applied to identify the contribution from individual species to sediment transport types. Biodiffusion resulted from the combined activity of polychaetes such as Spio decoratus and meiobenthic harpacticoïd copepods, while the polychaete Hediste diversicolor was mainly responsible for regeneration. Conveying processes were driven by another polychaete, Capitella capitata. Despite heterogeneity in the benthic community composition, biodiffusion and regeneration rates did not vary significantly between sites or season, with only bioadvection found to be higher in spring than in autumn.

Species belonging to the genus Amphicorina are reported from some areas of the Mediterranean Sea, with the description of the new species A. grahamensis. The description of another species, Amphicorina sp., close to an Australian taxon, together with the redescriptions of A. pectinata, A. persinosa, and A. armandi are also given; the variability of this last taxon, probably deriving from misidentiflcations, is also considered. Examined specimens were prevalently from the Italian coast, and in particular from the Adriatic Sea. © 1999 Taylor & Francis Group, LLC.

Rocky intertidal platforms at Asinara Island Marine Protected Area (Italy, Mediterranean Sea) were experimentally trampled to assess the impact of human visitation on polychaetes. Trampling at two different experimental intensities (60,120 steps/20x20 cm quadrat) and controls were applied at two locations (“no-entry, no-take” zones) of the MPA. One day after the experimental trampling, benthic samples were collected and the polychaetes counted and identified. Overall 1146 individuals were collected; Salvatoria clavata, Polyophthalmus pictus, Syllis prolifera, Amphiglena mediterranea, Fabricia stellaris, Platynereis dumerilii and Sphaerosyllis taylori were the most abundant species. Analyses of variance on all polychaetes and on each of the important polychaete species showed a significant higher abundance in controls than in trampled plots. Given the short-term decline in abundance, these results suggest that polychaetes are vulnerable even to the lowest experimental level of trampling. Las plataformas rocosas intermareales del Área Marina Protegida (AMP) de la Isla de la Asinara (Cerdeña, Italia), fueron experimentalmente pisoteadas para evaluar el impacto de la presencia humana sobre las comunidades de poliquetos. Se aplicaron dos diferentes intensidades experimentales (60,120, pasos sobre una superficie de 20x20cm) y control en dos zonas (zonas definidas como “no-entry, no-take”) de la AMP. Un día después de la perturbación experimental, se recogían muestras bentónicas identificando y cuantificando los poliquetos. Un total de 1.146 poliquetos fueron recogidos; Salvatoria clavata, Polyophthalmus pictus, Syllis prolifera, Amphiglena mediterranea, Fabricia stellaris, Platynereis dumerilii y Sphaerosyllis taylori fueron las especies más abundantes. El análisis de la variación global de los poliquetos y de sus especies permitieron observar una abundancia significativamente superior en las áreas de control que en las parcelas pisoteadas. Considerando en el corto plazo la disminuciòn de la abundancia, estos resultados sugieren que los poliquetos son vulnerables, includo en el nivel experimental más bajo probado. &nbsp