1,721,125 research outputs found
A comparative study of the mollusc communities of a Mediterranean saltwork (Marsala, Western Sicily.
No full textSaltworks are peculiar artificial ecosystems and holds great interest for basic research. In fact the cooling vat
(the first pond of the evaporating series) is a good example of a relatively closed area and can be considered
an excellent in the field open-air laboratory, namely a mesocosm reproducing a simplified model of the
natural condition of hyperaline lagoons.
The aim of the present work was to analyse the structure, composition and distribution of molluscan
assemblages and to identify the faunistic relationships between the cooling vat and the neighbouring basin of
Stagnone di Marsala, beside considering exchanges between saltwork, Stagnone di Marsala and sea, on soft-
bottom, covered by Cymodocea nodosa. In structural terms, two molluscan communities can be identified.
As regard the saltwork, the community was always characterized by halolimnobic and euryaline species
such as Ventrosia ventrosa, Loripes lacteus, Abra segmentum and Pirenella conica. while the community
inhabiting Stagnone was composed mainly of marine taxa; here a good exchange with the sea is confirmed
by the high values for species richness and diversity gives rise mainly to the presence of marine taxa: e. g
Jujubinus striatus, Dikoleps nitens, Rissoa paradoxa, R. similis, Columbella rustica etc.
The saltwork molluscan assemblage doesn’t seem to be similar to that of the Stagnone. The low specific
richness, the high abundance and the low evenness, showed a pioneer stage of colonization, being poor in
species and dominated by taxa with high abundance and low evennes
Seascape characterization of a Mediterranean vermetid reef: a structural complexity assessment
No full textIn the Mediterranean Sea, vermetid reefs can modify coastal seascapes forming platforms in the intertidal zone of rocky coasts. With their three-dimensional and seaward-expanding structure, these bioconstructions support high biodiversity levels and provide important ecological functions and ecosystem services. In this study, we perform a first structural characterization of a vermetid reef seascape (hereafter, vermetid reefscape) and quantitatively assess the degree of their contribution to the structural complexity of the coastal seascape. Aerial images of a vermetid reef coast were acquired in the Marine Protected Area of Capo Gallo-Isola delle Femmine (Southern Tyrrhenian Sea) by means of unmanned aerial vehicle technology. In the seascape, the outer reef, platform, and coast classes were identified and digitized in GIS environment. The resulting vermetid reefscape was analysed by means of FRAGSTATS software using metrics belonging to the "area-edge", "shape", and "aggregation" categories. To quantitatively assess the structural complexity, the edge density, area-weighted perimeter area ratio, and landscape shape index metrics were applied to the seascapes with and without the vermetid reefs to simulate a sea level rise scenario. In addition, the effect of their presence in terms of coast length (i.e., total edge) was statistically tested using the Wilcoxon signed rank test. The outer reef had the highest total edge value (5,785.6 m) and, at the same time, the lowest class area (1,040 m(2)). It was also the patchiest, and the most fragmented and geometrically complex class in the seascape. Overall, the bioconstruction positively contributed to the structural complexity of the seascape with higher values of coastal area (12%), edge density (139%), area-weighted perimeter-area ratio (90%), and landscape shape index (66%). The Wilcoxon test revealed a statistically significant effect of the vermetid reefs presence on the coastal total edge (z = 3.9, p < 0.005), with a large effect size (r = 0.74). The results showed an overall higher structural complexity of the vermetid reefscape, indicating that its loss would lead to a significantly less complex seascape, entailing detrimental effects on the supported biodiversity levels and the valuable ecosystem services provided
Decreasing in patch-size of Cystoseira forests reduces the diversity of their associated molluscan assemblage in Mediterranean rocky reefs
No full textCanopy-forming seaweeds of the genus Cystoseira (Fucales, Phaeophyceae) form diverse and productive habitats along temperate rocky coasts of the Mediterranean Sea. During the last decade, Cystoseira forests have retracted their range considerably due to many interacting environmental, biological and anthropogenic pressures. We investigated how reducing in patch-size of C. montagnei affects their associated molluscan communities at the shallow northwest rocky shores of Palermo (Sicily, Italy). Molluscs were sampled from the fronds of individual thalli, clumps of 3 and 5 thalli of C. montagnei over an annual vegetative cycle (May–September) in two sites within the Marine Protected Area “Capo Gallo-Isola delle Femmine”. We measured five substrate attributes of the alga (thallus volume, canopy volume, interstitial volume, algal surface, and biomass) and explored their relationships with the diversity of the associated molluscan assemblage. A total of 3756 individuals of molluscs were collected, belonging to 30 families and 57 species, being Rissoidae the most speciose family and Barleeidae the dominant in terms of abundance. The molluscan assemblage on C. montagnei displayed significant spatial and seasonal variations, with the maximum number of individuals and species in summer, whereas evenness and diversity displayed maximum values in spring. The abundance, species richness and diversity of the molluscan assemblage decreased with decreasing in patch-size of C. montagnei, regardless of the vegetative phase of the alga or the sites considered in the study, while evenness showed an opposite trend. The substrate attributes of C. montagnei changed over the vegetative cycle of the alga and showed a similar pattern across sites with values that tended to decrease in autumn during the quiescence phase of the alga. Variation in patch-size of C. montagnei affected also the substrate attributes of the individual alga, with individual thalli becoming smaller with increasing patch-size. The algal surface of a single thallus of C. montagnei ranged on average from 956 cm2 in spring to 289 cm2 in autumn. Furthermore, algal surface together with thallus volume and dry weight were the substrate attributes that explained better the variation of the number of molluscan individuals and species. Overall, our results suggest that the reduction of both patch-size and algal substrate of C. montagnei forests altered the structure and composition of its associated molluscan assemblage. We argue that a reduction or loss of Cystoseira forests could probably trigger bottom-up effects in rocky shores habitats, with consequences for the whole ecosystem structure, functioning and services provided to humans
The Effects of Non-Indigenous Macrophytes on Native Biodiversity: Case Studies from Sicily
Full text linkBiological invasions are widely recognized as a major threat to native biodiversity, ecosys tem functioning and services. Non-indigenous species (NIS) may in time become invasive (invasive alien species (IAS)), determining significant environmental, socioeconomic and human health impacts such as biodiversity loss and ecosystem service degradation. The Mediterranean islands, particu larly Sicily and the circum-Sicilian islands (northwestern Mediterranean Sea), which are important hotspots of biodiversity, are notably vulnerable to anthropogenic pressures such as biological in vasions. Therefore, monitoring NIS distribution as well as understanding their effects on native
biodiversity is critical in these areas for planning effective conservation strategies. Here, we report four different case studies from Sicily that highlight how NIS may affect native biodiversity and habitats. The first three case studies were carried out within Marine Protected Areas (MPAs) and highlight (1) the ability of Caulerpa cylindracea to promote the establishment of other NIS, including biofouling worms belonging to the genus Branchiomma; (2) how the shift in habitat from the native Ericaria brachycarpa to the invasive Asparagopsis taxiformis may drastically erode the primary producer biomass and associated biodiversity; and (2) that the presence of Lophocladia lallemandii can affect the
molluscan assemblage inhabiting the canopy-forming Gongolaria montagnei. The fourth case study, performed along the northwestern coast of Sicily, shows how Halophila stipulacea can affect the growth of the co-occurring native seagrass Cymodocea nodosa. Overall, these case studies demonstrate various ways in which NIS can interact with native biodiversity and habitats. Furthermore, they emphasize that MPAs are ineffective at preventing the introduction and spread of NIS
Meiofauna associated with vermetid reefs: the role of macroalgae in increasing habitat size and complexity
Full text linkWe present the first dataset of meiofauna associated with vermetid reefs (biogenic constructions of Mediterranean intertidal habitat) in two areas along the northern coast of Sicily, Italy. The vermetid reefs are characterized by a horizontal extension from the shore towards the open sea and can be divided into three zones (the inner margin, the cuvette zone and the outer margin) which differ in hydrodynamic features. We studied the spatial distribution of meiofauna along the horizontal axis of the vermetid reefs, investigating the communities inhabiting the sediment inside cuvettes (shallow pools inside the “cuvette zone”) located between the inner and the outer margins of the reefs. We observed an increase in meiofaunal abundance from the inner to the outer part of the reef (from 1808 ± 80 to 2992 ± 512 ind. 100 cm−2) in both areas. Moreover, we studied meiofaunal communities associated with the most abundant macroalgae (Cystoseira sp., Jania rubens, Palisada perforata, Dictyota sp. and Padina pavonica) living on the reefs, investigating the influence of habitat size (biomass) and identity (complexity) of macroalgae. We found that meiofauna varied in abundance (from 446 ± 51 to 1758 ± 231 ind. 100 cm−2 on P. perforata and Cystoseira sp., respectively), on different macroalgae, and that the habitat size significantly influenced these abundances, but its effect was dependent on macroalgal identity. In fact, we observed a positive correlation between meiofaunal abundance and algal complexity (fractal dimension). The high algal cover in the “cuvette zone” of the reefs could contribute to make this zone more suitable for meiofauna, in particular close to the outer margin where we found more complex macroalgae (i.e. Cystoseira sp.). These results confirm that vermetid reefs, with their structural complexity, may play an important role in structuring benthic fauna in intertidal habitats
BOAT ANCHORING ON POSIDONIA OCEANICA BEDS IN A MARINE PROTECTED AREA (ITALY, WESTERN MEDITERRANEAN): EFFECT OF ANCHOR TYPES IN DIFFERENT ANCHORING STAGES
No full textThe neglected status of the vermetid reefs in the Mediterranean Sea: A systematic map
Full text linkStudied since late 1800, vermetid reefs are marine bioconstructions of well-acknowledged importance in the Mediterranean Sea. Despite their persistence being jeopardized in the whole basin, recent studies have referred to this bioconstruction as a neglected habitat. In this study, we assessed the neglected status of the Mediterranean vermetid reefs in the scientific literature producing a systematic map through a multi-method bibliometric protocol. Scopus and Web of Science databases were jointly used for data collection. Vermetid reefs publication rate (i.e., number of publications per year) was investigated compared to the other Mediterranean bio-constructions using ANOVA analysis and Zero-Inflated Poisson regression. Later, VOSviewer software was used to perform a bibliometric network analysis and for mapping visualization. The analysis aimed at investigating gaps, patterns, and trends of the vermetid reefs together with the other main Mediterranean bioconstructions (i.e., Astroides calycularis, Cladocora caespitosa and coralligenous formations, and sabellariid and Lithophyllum reefs). The ANOVA analysis of the number of publications from 1966 to 2020 found statistically significant differences between coralligenous and vermetid reefs publication rates in the 2006-2010, 2011-2015, and 2016-2020 timeframes and pointed out a clear before/after-2010 pattern in coralligenous publication rate, which was also confirmed by the Zero-Inflated Poisson regression model. The bibliometric network analysis of the bio-constructions literature revealed the same temporal pattern, with the vermetid reefs poorly investigated and weakly connected to newer research lines and conservation topics. Instead, coralligenous showed strong con-nections with biodiversity conservation and was indicated as a recent research hotspot. Overall, the results of this study confirm previous references of the vermetid reefs as a neglected habitat and, among others, show an increasing research interest in the coralligenous topic
Towards a local mass mortality of the Mediterranean orange coral Astroides calycularis (Pallas, 1766) in the Pelagie Islands Marine Protected Area (Italy)
No full textIn late summer 2020, a widespread mortality event severely affected colonies of the Mediterranean endemic orange coral Astroides calycularis in the Pelagie Islands (Strait of Sicily, southern Mediterranean Sea). The degree of the mortality impact at seven study sites of the archipelago (five within the Pelagie Islands Marine Protected Area) was quantified by estimating the proportion of affected colonies in populations of A. calycularis. Five of the seven surveyed sites revealed a low degree of impact, but Punta Ruperta and Cala Creta (both on the island of Lampedusa) showed a medium impact with values of 32.3% and 30.5% of affected colonies respectively. The 2020 mortality event coincided with a longer lasting and warmer anomalous summer period, with sea surface water reaching the highest temperatures recorded in the last decade across the archipelago. Given the alarming climatic predictions for the near future, new mortality events could occur, causing potentially new local extinctions in the Mediterranean Sea. In this context, the role of marine protected area management becomes crucial to detect mortality events of vulnerable species
How do non-indigenous species affect native species and habitats?
No full textBiological invasions are a key driver of global change, affecting biodiversity and natural ecosystem functioning. Non-indigenous species (NIS) with significant established and expanding populations have the potential to become invasive, with serious environmental, socio-economic, and/or human health consequences. Mediterranean Islands (including Marine Protected Areas “MPAs”), important hotspots of biodiversity, are particularly vulnerable to NIS invasions. Understanding the effects of NIS species on biodiversity, as well as their current distribution and expansion trends, is therefore critical for creating effective conservation strategies. Here, we present three different case studies
from Sicily (North-Western Mediterranean Sea) that highlight how NIS species interact with native species and the habitat where they settle. The first case study, carried out along the coast of Favignana Island (Egadi Islands MPA), highlights how the ability of Caulerpa cylindracea to form multi-layered mats trapping the sediment promotes the establishment of other NIS, including the biofouler worm Branchiomma bairdi. The second case study, performed along the North-Western coast of Sicily, shows how Halophila stipulacea can inhibit the growth of the co-occurring native seagrass Cymodocea nodosa. Finally, the third study case, undertaken along the coast of Favignana Island,
highlights how the shift in habitat from the native Ericaria brachycarpa to the invasive Asparagopsis taxiformis may drastically erode primary producer biomass and associated biodiversity. Overall, our findings not only emphasize the negative effects of NIS on native habitats, but also confirm that MPA protection does not limit the introduction and spreading of NIS
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