Venezia, Italy
Venezia, Italy

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Scarton F.,SELC soc. coop. | Cecconi G.,Thetis Consorzio Venezia Nuova | Valle R.,Rialto Inc.
Wetlands Ecology and Management | Year: 2013

Colonization of newly created habitats is a challenge for waterbird populations in a changing world. Knowing which habitat characteristics are required by waterbird populations is a research challenge for rational management of the new ecosystems and their aquatic bird populations. Since 1989 intertidal dredge islands have been built in the lagoon of Venice using sediments coming from regular dredging of lagoon channels and inlets. Kentish Plover, a species declining in Europe, readily uses these new sites as soon as they become available. Between 2005 and 2007, 75 dredge islands were surveyed each year and the number of breeding pairs of Kentish Plover estimated. Each year about one-third of available dredge islands was used by Kentish Plover. Between 34 (in 2005) and 131 (in 2007) breeding pairs were found, and possible differences in vegetation and morphological characteristics between occupied and unoccupied sites were investigated. Only age, mean elevation above sea level and extension of bare ground were statistically different; Kentish Plover preferred younger sites, with higher elevation and with larger areas of bare ground. The largest groups of breeding pairs, up to thirty pairs, were found on islands which also supported colonies of Little Terns. In the study period dredged islands supported about 60 % of the total breeding population of the lagoon of Venice and 4-6 % of the estimated Italian population. Along coastal sites where human pressure on beaches is particularly heavy, man made habitats such as dredge islands may become a valuable alternative breeding site for this and other species of conservation concern. Management works aimed at promoting the occurrence of this species at selected dredge islands have been made in the lagoon of Venice. © 2012 Springer Science+Business Media Dordrecht.

Scarton F.,SELC Soc. Coop. | Cecconi G.,Thetis SpA | Cerasuolo C.,Thetis SpA | Valle R.,Rialto Inc.
Ecological Engineering | Year: 2013

Since 1989, intertidal dredge islands have been constructed in the Venice Lagoon using sediments originating from regular dredging of lagoon channels and inlets. Between 2005 and 2007, 75 dredge islands were surveyed in each year and the number of breeding pairs of seabirds and shorebirds estimated. The results showed that, of the 13 species that nested at least once, eight represented more than 1% of their total Italian population, sometimes even higher than 10%. Our results indicated that the majority of birds prefer site dimensions of between 10 and 30. ha, even if some species use small or very small (<1. ha) sites particularly heavily. Most of the other environmental variables we measured concurred in explaining species' occurrence and abundance. Redshank and Shelduck selected sites with high vegetation coverage, whereas sites with lower vegetation were preferred by Kentish Plover and Little Tern. More pairs than expected were observed at sites between 25 and 30. ha. These sites have a considerable wealth of habitat types, becoming suitable for species with contrasting nesting habitat requirements. Density of breeding pairs ranged between one and four pairs/10. ha; these values compare well with those observed in natural habitats existing in the Venice Lagoon, and support the opinion that dredge islands are a good alternative to natural sites. Along coastal sites where human pressure on beaches is particularly heavy, man-made habitats such as dredge islands may become a valuable alternative breeding site for those seabirds and waders of conservation concern. The results presented allow an assessment of the importance of dredge islands for breeding waterbirds over a short to medium period. They may also be used to estimate the expected richness and abundance of breeding birds that will use intertidal man-made sites, when these are built in a temperate coastal marsh. © 2013 Elsevier B.V.

Falace A.,University of Trieste | Curiel D.,University of Trieste | Bandelj V.,SELC Soc. Coop. | Solidoro C.,National Institute of Oceanography and Applied Geophysics - OGS | And 2 more authors.
Botanica Marina | Year: 2012

We sampled macroalgal assemblages on 37 rocky outcrops in the northern Adriatic over the last 2 decades by SCUBA. Macroalgal assemblages were rich (173 taxa), but there was high variability in the number of species and coverage. The morphology of the outcrops, the distance from the coast and the depth were identified as the main factors accounting for this variability. Both the mean total algal coverage (14.8%) and encrusting layer coverage (8.0%) were low when compared to typical Mediterranean coralligenous habitats. Four main groups of algal assemblages were distinguished on the basis of their species composition and coverage. Groups 1 and 3 were located inshore off the Lido inlet and south of it, and had, respectively, low or intermediate total algal cover. Group 2 included outcrops situated offshore from the Venice lagoon along with all outcrops off the Grado-Marano lagoon; these had the highest total algal cover. Finally, group 4 included assemblages comprising algae that were widespread on outcrops in the inshore habitats of the Venice lagoon, between Malamocco and Chioggia inlets. Offshore outcrops subject to low turbidity and eutrophication levels had several characteristic Mediterranean coralligenous taxa.

Each year between 1989 and 2008, I monitored Common Tern colonies in the lagoon of Venice (Italy). This population nests only on salt marsh islets, which are subjected to flooding during high tides. The number of breeding pairs decreased significantly from 832 to 109, with an average rate of decrease of -10.1%. Overall, 188 colonies were found, ranging from two to 583 pairs; median colony size was 57 pairs, and it decreased significantly. The mean turnover rate was high at 41.5%, and it ranged each year between 7.7% and 60%. The observed trends could be attributed to the increase in mean sea level that occurred over the last 20 years (0.5 cm/yr). In the May-June period, the number of days with high tides leading to a complete flooding of the breeding site increased. Between 1989 and 1998 there was on average 4.4 days with floodings. This increased to 8.4 days between 1999 and 2008. Therefore, sea level rise could be a major contributor to declining Common Tern populations in the lagoon of Venice. © Society of Wetland Scientists 2010.

Scarton F.,SELC Soc. Coop | Montanari M.,SISSAD
Journal of Coastal Conservation | Year: 2015

Man-made habitats provide suitable nesting, resting and feeding habitats for many birds at coastal sites. Despite intensive study outside Europe, very few data are available to date on the bird communities that exploit artificial intertidal sites along the European coasts. Between July 2009 and December 2010, 32 ornithological surveys were performed at six artificial intertidal sites in the lagoon of Venice (Italy). Overall, 101 species (with 23,399 birds) were observed, about a third of those occurring in the lagoon of Venice; 58 of these species were of conservation concern. Ten species comprised about 80 % of the total; bird abundance was the highest during the post-breeding migration and wintering period. Multivariate analysis identified similarity among sites, seasons and observed behaviours. Dredge islands were mostly used by waders as foraging sites, when surrounding tidal flats were still flooded. In winter the six dredged islands supported about 2 % of the dunlins Calidris alpina occurring in the whole lagoon of Venice and about 10 % of the grey plovers Pluvialis squatarola. Since the study sites comprised just the 6 % of the total dredge island area available in 2009–2010, the results indicate as large fractions of these shorebird populations might exploit the dredge island habitats for foraging. Among the newly created habitats, intertidal ponds and inner tidal flats were the most heavily used by birds, followed by dykes and mounds with ruderal vegetation. Maintenance of the habitat mosaic is a need for a conservation- based management of the dredge islands. © 2015, Springer Science+Business Media Dordrecht.

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