1,721,000 research outputs found
How algae influence sessile marine organisms. The tube worms case of study
No full textTube worms and phytobenthic assemblages in three infralittoral and shallow circalittoral Mediterranean benthic communities developed between 5 and 35 m depth at Punta del Lazzaretto (Giglio Island, Central Thyrrenian sea) were investigated. Despite being three algae-dominated habitats, these displayed different covering both in terms of algal layers and algal morphologies, reflecting different structural
organizations. Twenty-eight serpulid taxa have been reported, increasing both diversity and density values from most photophilic to most sciaphilous habitats. Multivariate analyses showed how algal thalli
and tube worm assemblages were strongly correlated; substrata are influenced both physically and biologically, providing different conditions for tube worm settlement
Colonization dynamic on experimental limestone substrata. The role of encrusting epilithics favouring boring polychaetes
No full textPolychaetes inhabit all the marine benthic communities and play a significant role in the degradation of calcareous substrates in marine environment. Colonization dynamics of encrusting epibenthos and polychaete assemblages on limestone experimental substrates were studied over a 3-year period in a Marine Protected Area: the Underwater Archaeological Park of Baiae (central Tyrrhenian Sea). Competitive and encrusting organisms replaced the pioneer species, dominating the epilithic community, and increasing the available surface. Polychaetes increased in species number over time. Several boring specimens of the species Polydora ciliata and Dodecaceria concharum were responsible for the bioerosion of the calcareous material. The former species characterized the early stage of the succession, whereas the latter settled during the late stages, together with the nestler species Lysidice unicornis, whose boring activity has been hypothesized. Four different surface trace morphologies attributable to boring polychaetes are here reported and described. The number of the polychaete boring traces increased according to the surface covered by ascidians, barnacles, and bryozoans. The present work provides evidence regarding positive interactions between encrusting epibenthic organisms and endolithic worms
First report on the benthic invertebrate community associated with a bronze naval ram from the First Punic War. A proxy of marine biodiversity
Full text linkHistorical traces of organisms on the seafloor, such as shells and tubes, constitute the ecological memory of ancient benthic assemblages and serve as an important resource for understanding the assembly of modern communities. Archeological shipwrecks are particularly interesting submerged substrata for both their archeological and biological implications. For the first time, we studied the species composition and life-history traits of dominant organisms in the benthic assemblage on a bronze Carthaginian naval ram, which sank more than two thousand years ago in the Southern Tyrrhenian Sea. By comparing the species composition of the ram assemblage with those of the surrounding habitats, we inferred possible colonization patterns for the ram and discussed the informative role of the shipwreck as a proxy of marine biodiversity. The ram assemblage was rich in species, including both sessile (bryozoans, serpulid polychaetes, and few bivalves) and motile (gastropods) species. Sexual reproduction with free-spawning fertilization and long-duration larvae characterized most species. The long submersion time of the ram, together with the reproductive strategies, growth forms, and motility of the dominant species were key factors shaping the community of the ram. The ram itself offers an archeological artifact of inestimable value, but our analysis revealed it to be an effective collector of fauna from the surrounding seabed. The ram community hosted species from a range of nearby natural habitats (mostly coralligenous, detritic bottoms, and zoosteracean meadows) and thus served as a proxy for marine biodiversity on the surrounding seabed. We conclude that the presence of many species on the ram that commonly occur in adjacent habitats of great environmental value was informative and highlight the important marine biodiversity in the area of the Aegadian archipelago
The bioerosion of submerged archeological artifacts in the Mediterranean Sea. An overview
Full text linkBioerosion is the destruction of hard substrates resulting from biological activity, and plays a relevant role in the ecological interactions and coastal dynamics processes. Several organisms have evolved structures and behaviors allowing them to perforate biotic and abiotic surfaces, transforming hard surfaces into particles, and contributing significantly to sediment production in the coastal and marine environment. Due to the large geographical diffusion of marine borers, bioerosion is relevant in many scientific and applied fields of interest. Most bioerosion studies have hitherto been conducted in tropical areas, where borers are a critical component of coral reef destruction. Comparatively, little information is available for the bioerosion of submerged archeological heritage. This review focuses on the bioerosion of archeological calcareous artifacts in the Mediterranean Sea, summarizing studies concerning the colonization of statues, shipwrecks, cargo, and the remains of submerged cities. The paper includes the first comprehensive listing of the archeological sites in the Mediterranean Sea where bioerosion has been assessed. The diversity of boring organisms affecting marine archeological remains and their boring patterns, the various types of bored materials, and the severity of the damage caused to heritage artifacts are also included. Both microborers (algae, fungi, and cyanobacteria) and macroborers (sponges, bivalves, polychaetes, sipunculids, and echinoids) are considered, and their roles in the structuring of endolithic assemblages are also covered. The experimental techniques currently employed to analyze bioerosion traces, helping to identify particular species and ichnospecies and their ecological dynamics, are also considered. Finally, a discussion of the current strategies proposed for the in situ protection and conservation of Underwater Cultural Heritage is provided
New records of old species. Some pelagic polychaetes along the Italian coast
No full textHoloplanktonic polychaetes constitute an exception within this taxon, which as adults colonize all the whole variety of brackish water and marine habitats. Nevertheless, they form a distinctive group in marine zooplankton and play an important role in the pelagic trophic nets. Pelagic worms are little studied, especially in the Mediterranean Sea, while information regarding the distribution of the families Typhloscolecidae and Iospilidae along Italian coasts is a century out of date. This paper deals with the state of knowledge of these polychaetes; it summarizes the previous records, updating them with the new records here reported from Tyrrhenian Sea, in order to check whether they have a bearing on Italian fauna. The findings reported in this paper confirm the presence of the Typhloscolecidae, with the species Sagitella kowalewskyi and Typhloscolex muelleri, and of the Iospilidae, with the species Phalacrophorus pictus and Iospilus phalacroides, along the Italian coasts, validating, in each case, their current presence in the Italian fauna. The main morphological features of these species and a dichotomous key for their identification are also reported
Assessment of the ecological quality (EcoQ) of Sardinian lagoons: a joint effort using multiple benthic macroinvertebrate datasets
No full textFar from early models exhibiting an overall uniformity of brackish-water benthic assemblages as monotonous biocoenoses (LEE, in the Pérès and Picard model) and a mono-factorial distinctness among basins simply based on salinity (Venice System), more recent studies have highlighted unexpected levels of environmental and biological heterogeneity of Transitional Water systems (TWs). In contrast to the large spectrum of environmental variability shown by the brackish biotopes, the Water Framework Directive requires the classification of the TWs into few ecosystem types. Thus, it is of primary importance to define the type-specific biological reference conditions in the operative process of assessing the ecological quality (EcoQ) of TWs, i.e. “to measure the health of the system compared to reference conditions” as the WFD reports. At present, three Macrotypes of TWs have been defined: two macrotypes for the tidal systems according to the salinity range variation and only one macrotype for the not-tidal systems.
The aims of this study are: a) to update, harmonize and merge into a common dataset the faunistic data available for several Sardinian lagoons; b) to single out the environmental features explaining most of the variation in the macroinvertebrate quality indicators; c) to identify possible distinct units within the not-tidal macrotype which could be functional to the TW’s monitoring, management and conservation strategies.
The TWs of Sardinia can be a pivotal case study at the regional level to address the above objectives since they cover a large range of environmental and biological conditions. This study represents a first joint effort conducted by major Sardinian Institutions (Universities and CNR) involved in the EcoQ assessment of TWs. It calls for a strong collaboration at the national level to increase efforts and resource availability, and to promote LaguNet at the Mediterranean and European scales
A multidisciplinary approach for evaluating Sabellaria bioconstructions: The case study of Torre Mileto (Northen Gargano coast, Adriatic sea)
No full textThe S. spinulosa (Leukhart, 1849) worm reef of Torre Mileto is a site of extraordinary beauty, proposed as a Site of Community Importance (SCI) to be protected by law. Recent studies highlight both the ability of this structure to increase the biodiversity of the adjacent sector of coast, and to act as a barrier to defend from coastal erosion as well as a temporary reservoir of sediments, lengthening the cycle of sand in the beach.This work shows the results of image analysis techniques on bioconstruction samples integrated with seasonal and annual monitoring. A multidisciplinary approach involving sedimentological, ecological and biological analysis techniques offers an overall view of the evolutionary state of the environment and provides quantitative data which are necessary for the protection and monitoring of this sit
Filtering activity on a pure culture of Vibrio alginolyticus by the solitary ascidian Styela plicata and the colonial ascidian Polyandrocarpa zorritensis: a potential service to improve microbiological seawater quality economically
Full text linkWe investigated and compared, by laboratory experiments, the filter-feeding activity on bacteria by the solitary ascidian Styela plicata and the colonial ascidian Polyandrocarpa zorritensis. Clearance rates and retention efficiencies were estimated by using, as only food source, the bacterial species Vibrio alginolyticus selected on account of its importance in aquaculture pathogenicity. The Cmax was 1.4±0.17Lh(-1)g(-1) DW for S. plicata and 1.745Lh(-1)g(-1) DW for P. zorritensis. The highest retention efficiency was 41% corresponding to a removed bacterial biomass of 16.34+1.71 μgCL(-1)g(-1) DW for P. zorritensis and 81% corresponding to a bacterial biomass of 32.28+2.15 μgCL(-1)g(-1) DW for S. plicata. Styela plicata resulted higher efficient than P. zorritensis in removing V. alginolyticus from seawater in experimental tanks, thus representing a more suitable biofilter to restore the quality of microbiologically contaminated waters including those where aquaculture is practiced. Present laboratory experiments represent the first contribution to the comparison of the filtration activity of the two ascidians, as well as to characterize the filtration process on bacterioplankton and pone the basis for future field works aimed to restore bacteriological polluted seawater
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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