Polychaete Diversity Related to Different Mesophotic Bioconstructions along the Southeastern Italian Coast (original) (raw)
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Deep Sea Research Part I: Oceanographic Research Papers, 2019
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 tenfold 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.
Diversity, 2020
The knowledge on the hard bottom polychaete assemblages in the Northern Adriatic Sea, a Mediterranean region strongly affected by environmental pressures, is scarce and outdated. The objective of this paper was to update the information on polychaete diversity and depict their patterns of natural spatial variation, in relation to changes in algal coverage at increasing depth. Hard bottom benthos was quantitatively sampled by scraping off the substrate from three stations at Sveti Ivan Island (North Adriatic) at three depths (1.5 m, 5 m and 25 m). Polychaete fauna comprised 107 taxa (the majority of them identified at species level) belonging to 22 families, with the family Syllidae ranking first in terms of number of species, followed by Sabellidae, Nereididae, Eunicidae and Serpulidae. Considering the number of polychaete species and their identity, the present data differed considerably from previous studies carried out in the area. Two alien species, Lepidonotus tenuisetosus, whi...
Non-indigenous polychaetes along the coasts of Italy: a critical review
Mediterranean Marine Science, 2020
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 r...
Marine Biology, 2003
This study reports on the distribution of polychaete assemblages along a depth gradient from 5 to 25 m, along a stretch of rocky coast near Otranto (South Adriatic sea, Italy). Three depths were sampled in May and November 2000. At each depth three sites (about 100 m apart) were sampled by scraping off three replicate quadrats of 20·20 cm. The experimental design enabled identification of across-and along-shore spatial patterns of variation of polychaete assemblages. A total of 4,168 specimens, belonging to 152 taxa were collected. Multivariate analysis showed that the polychaete assemblages differed significantly among depths with the clearest differences between the shallowest sites (5 m) and the deeper ones (15-25 m). A considerable source of variation among sites at each level of the shore was also exhibited by the analyses, with the greatest differences among sites within depths recorded at 5 m. The species most contributing to the differentiation of assemblages among depths and sites within each depth were identified. Some potential causes of the observed differences are hypothesized and discussed. The importance of quantitative observation to provide the context for studying the underlying ecological processes is also stressed.
Ecology and spatial distribution of selected polychaete species from the Italian continental shelf
Italian Journal of Zoology, 2011
Data from several research and monitoring projects carried out between 1999 and 2009, for a total of 26 study areas located along the Italian continental shelf (Mediterranean Sea), were extracted from ISPRA's data set, to revise and update the existing information on the ecology and spatial distribution of 20 selected soft-sediment polychaete species. The species were selected taking into account their spatial distribution and ecological role in the benthic assemblages and the existence of voucher specimens deposited in ISPRA's reference collection. Samplings were taken at 872 stations on soft sediments, at depths ranging from 1 to 155 m. Surface sediment composition data were available at each site. The number of specimens from the selected species was extracted at each site, and relative abundance (%)calculated. The spatial distribution of each species was investigated according to the biogeographical zones identified in the Italian Seas. The distribution of five species (Aponuphis bilineata, A. brementi, A. fauveli, Nothria conchylega, and Onuphis eremita) was updated. Several species that were previously considered to be characteristic of a specific biocenosis, sensu Pérès & Picard (1964), e.g. Diopatra neapolitana, Ditrupa arietina, Notria conchylega and Sternaspis scutata, were found to be distributed over a wider bathymetric and granulometric range of surface sediments. Indicator Species Analysis highlights that the distribution of 17 selected species depends on definite granulometric characteristics of the sediment. This new relevant information outlines the important contribution of environmental monitoring programmes to scientific knowledge.
Sardá, R., Serrano, L., Labrune, C., Gil, J., March, D., Amouroux, J.M., Taboada, S., Bonifácio, P. and Grémare, A. 2014. Shallow-water polychaete assemblages in the northwestern Mediterranean Sea and its possible use in the evaluation of good environmental state. Memoirs of Museum Victoria 71: 289-301.
1991
The exislence of i.\ boundary between midlittor<l.l and infraJittof<l.l polychaete assembl.ages was investigated at four stations exposed 10 different degrees of wave action around the coasts of Capraia Island (Tuscan Archipelago -'ryrrhenian Sea). Three samples were taken from each station: above, below and passing across the zero level. Filly-onc species ofpolychaetes were found, and lour polychaete assemblages were recognized: 1) exposed infra!iuorai and midlittoraJ, 2) semi-exposed infralittoral, 3) sheltered midlittora!, and 4) ~hellered infra!ittora!. The main factors inl1uencing their composition and structure were considered to be physical disturbances (emersion and wave action) and predation pressure; also alga! cover turned out to play an important role. A discontinuity between midlittora! and infra!ittora! zones was not clearly demonstrable at all the stations and the existence of a polychaete midlitwr!,1 assemblage is likely to be a local event rather than a genera! fea· ture.
Marine Environmental Research, 2018
Biological Traits Analysis (BTA) was used to identify functional features of infaunal polychaete assemblages associated with contamination in two Italian coastal areas: the harbour of Trieste (Adriatic Sea) and the Mar Piccolo of Taranto (Ionian Sea). The analysis was performed on 103 taxa, collected at four stations in each area. The two areas differed in species composition. The low diversity and the presence of stress-tolerant species in more polluted sites were not reflected in functional diversity, due to species contributing little to community functions or being functionally redundant. Sand and clay fractions were significant drivers of trait category expressions, however other environmental parameters (depth, total organic carbon and nitrogen, and Hg in sediments) influenced trait composition. Motile was the prevalent trait in environments with coarse sediments, and tube-builder were related to fine-grained ones. Motile endobenthic and burrower were essential traits for living in contaminated sediments. Epibenthic and sessile polychaetes dominated at stations subjected to high organic loads. BTA offers an integrative approach to detect functional adaptations to contaminated sediments and multiple anthropogenic stressors.