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Bertuzzi, Cantone and Nuova Valleys

 


 

Environment

The complex commonly known as Bertuzzi Valleys is constituted by three basins of brackish water: Bertuzzi Valley-Nuova Valley (1385 ha) and Cantone Valley (550 ha).  It stretches out immediately southward of the Po di Volano, between Vaccolino, Lido di Volano, the Lake of Nations (Lago delle Nazioni) and the reclaimed San Giuseppe Valleys.  The complex corresponds to a vast body of water formed by the submersion of the southern wing of the medieval Po di Volano delta; numerous coastal sandbars mark the progressive eastward development of the delta.  A collection of sandbars, likely formed around the 10th century, mark the present-day eastern border of the valley complex, now home to the northern-most segment of the Strada Sopraelevata or “Elevated Road.”

Due to subsidence and a lack of new sediments supplied by the Po di Volano (a branch that has progressively declined since the 12th-century breach at Ficarolo), submerged areas have expanded ever-farther across the territory, with water flowing both from the interior, in a series of river breaches, and from the sea.  The most elevated areas of the aforementioned sandbars constitute the humps that now characterize the valley’s body of water; they are arranged in a subparallel formation.  The Dosso Bertuzzi, or “Bertuzzi Hump,” is one of the most interesting exemplars.    

The bottom and more superficial layers of many islands are composed of loam, silt and bioclastic materials; deeper down, one encounters sandy sediments.

The southern boundary Is constituted by the Gorgadello (or Rotta Zambusi) Canal, which divided Bertuzzi Valley from the Valli Basse di S. Giuseppe, now drained.  The canal was one of the principal means by which seawater returned to the territory; in fact, it allowed these valleys to communicate with Volano Valley (now the Lake of Nations), which has itself often been open to the sea.  A pump system in the Volano estuary is used to turn over the waters of Bertuzzi Valley (Bondesan in Corbetta 1990).

The Bertuzzi Valley complex belonged to the Societa’ per la Bonifica dei Terreni Ferraresi—or “Society for the Reclamation of Ferrarese Terrains”—until 1998, when it was sold to two private companies that manage the complex independently for the purpose of extensive fishing and hunting.  Following the construction of the Val Cantone embankment (1998-99), the complex was separated hydraulically into two basins: Cantone Valley(550 ha) and Nuova Valley- Bertuzzi Valley (1385 ha).  The only lavoriero (an ancient fishing instrument) still functioning up through 1998 was in Nuova Valley: the entire complex is thus called both Bertuzzi Valley, for the largest basin, and Nuovo Valley, for the valley containing the lavoriero

The average depth is about 50 cm, but some zones reach 1.5-2 meters in correspondence to the sub-lagoonal canals.  Water temperature varies over the course of the year between zero and 30 degrees Celsius, but during particularly harsh winters the upper layers of water can freeze.  The salinity level is typical of that of a brackish valley, with winter lows and summer highs, during periods of intense evaporation.  The salinity in Bertuzzi Valley increased from 5-6% in 1967 to 17-22% in 1978 and 25-35% in 1994, with summertime peaks exceeding 50% (Jiang et al 1995). 

Until the projects carried out in the late 1990s, freshwater rich in nutrients flowing from the Volano struggled to spread across the valley interior; for this reason, an abrupt drop in nutrients and a scarce incidence of freshwater upon salinity levels occurs as one proceeds westwards (Rossi and Carrieri 1995).  In Bertuzzi Valle, macroalgae and macrophytes tend to capture nutrients, with consequent low concentrations in microalgal biomass: a characteristic that renders the waters of Bertuzzi Valley among the cleanest and highest in quality of the entire Delta del Po, notwithstanding the difficulties in hydric circulation.  The efforts carried out by the new owners in the 1998-2001 period are finalized to the improvement of hydraulic circulation; this will likely result both in a magnification in the emergence of new natural communities and an increase in fisheries production.

 

 

 

Flora

Vegetation is often scarce or absent in open bodies of water, but in some positions—largely to the east or west of Dosso Bertuzzi—submergent grasslands of Ruppia cirrhosa grow, without algal components (Sint. Ruppietum cirrhosae) or with Ulva, Chaetomorpha, Cladophora and Ceramium algal components, as in the open waters near the entrance to the Nuova Valley fishing station (Sint. Ruppietalia). 

A halophile and halotolerant vegetation dominates the Bertuzzi Valley complex; for further details, see Corticelli (1999).  From the constantly submerged zones near the humps to the more elevated, emerged zones of the humps, a succession of diverse vegetable associations ensues.  Perennial Sarcocornia deflexa, of great naturalistic value (Sint. Sarcocornietum deflexae), grows in conditions of pronounced hygrophilia; at higher levels and in conditions of lesser hygrophilia, vegetation is dominated by Arthrocnemum fruticosum (Sint. Puccinellio festuciformis- Sarcocornietum fruticosae), often accompanied by Juncus maritimus, Puccinellia palustris, Arthrocnemum glaucum and Halimione portulacoides.  Soils wet in summer and long-flooded in winter host grasslands of Puccinellia palustris (Sint. Limonio narbonensis-Puccinellietum festuciformis) and a poor floristic variety, generally composed of Aster tripolium (high naturalistic value).  In elevated positions with rarely flooded soils, one finds communities of extremely great naturalistic value composed of Artemisia coerulescens and Limonium serotinum (Sint. Limonio narbonensis- Artemisietum coerulescentis), in which Agropyron elongatum and Inula crithmoides are common.  Dense meadows dominated by Elytrigia atherica—heterogenous in variety and rich in ruderalis, nitrophilous and halophile species—grow on the summit of shoals and artificial humps.  On the highest humps, in the vicinity of the Nuova Valley fish farms, shrubbery (Sint. Prunetalia spinosae) characterized by Prunus spinosa, Crataegus monogyna, Ligustrum vulgare, Cornus sanguinea, Coronilla emerus, Rhamnus catharticus, Rubus sp., Rosa sp. and Euonymus europaeus grows (Corticelli 1999, Pellizzari and Pagnoni 1998).  Thermophile scrubland (Sint. Quercion ilicis)—dominated by Holm oaks (Quercus ilex) and featuring Phillyrea angustifolia, Asparagus acutifolius, Clematis flammula, Rubia peregrina, Ruscus aculeatus, Osyris alba and Rosa sempervirens mixed with mesophyll species—grew on the Dosso Bertuzzi until the mid-1980s.  The settlement of a large colony of wintering and nesting Cormorants produced an enormous quantity of excrement that provoked the death of the largest arboreal exemplars and the deterioration of scrubland (Sint. Prunetalia  spinosae) composed of Prunus spinosa, Crataegus monogyna, Ligustrum vulgare, Cornus sanguinea, Coronilla emerus, Rhamnus catharticus, Rubus sp., Rosa sp., and Euonymus europaeus.  Invasive alien species such as Phytolaca americana also grow in the scrubland, thus conferring to the zone an extremely low naturalistic value.   

 

 

Fauna

Bertuzzi Valley hosts extraordinarily important animal communities, above all with regard to avifauna,   although the total number of both individuals and of wintering species has notably declined since the late 1990s; scientific studies of an eventual correlation between environmental deterioration, the crisis in fisheries production and the reduction in avifauna are lacking, but it is probable that the phenomena are related.  The presence of hunting activities (in the central areas of the three basins) and the problems of hydric procurement and hydraulic circulation are probably at the heart of this situation.  From an avifaunistic point of view, the Bertuzzi Valley complex falls short of its potential.  In neighboring Cannevie-Porticino Valley, hunting is forbidden and the hydraulic circulation system is superior; in this valley, Eurasian Coots and anatids enjoy a winter concentration of 98 individuals per hectare, versus only five individuals per hectare for Nuova Valley (data winter 1998-99). 

The avifauna that winters, nests and migrates in Bertuzzi Valley renders it one of the most crucial wetland environments in Italy; it has been inserted into the list of Ramsar Zones.  Little Grebes, Great Crested Grebes, Black-necked Grebes, Eurasian Coots, Mallards, Eurasian Teals, Gadwalls, Northern Shovelers, Common Pochards, Little Egrets, Great Egrets and Grey Herons regularly winter in Bertuzzi Valley.  The woods of Dosso Bertuzzi host a dormitory of wintering Cormorants (Phalacrocorax carbo sinensis) that represented 99% of the Delta’s total until 1999.  The progressive demolition of perches as trees die out has driven the wintering Cormorants to spread across different dormitories (Sacca di Scardovari, Argenta, AGIP platforms across the territory surrounding Ravenna, etc.).  The current wintering population of the entire Delta del Po numbers about 3,500 individuals; concentrations in single dormitories vary from year to year. 

 

Colonies of Charadriiformes, frequently mixed, are settled on the internal humps (dossi del Cavallo, dossi della Vigna, dossi Le Guardate, dossi di Paron Paolo, dossi di Valle Nuova).  In Italy, the seagull (Larus ridibundus) nesting colony numbered about 780 pairs in 1984, 71% of which were concentrated in the Comacchio Valleys (including Bertuzzi).  The Delta del Po of Emilia Romagna presently hosts 350-600 pairs; the size at each site varies from year to year.  The Mediterranean Gull (Larus melanocephalus) is also present in Italy, especially in the Delta del Po.  The gull settled in Italy for the first time in 1978 (Comacchio Valleys); two pairs colonized Bertuzzi Valley in 1982.  The population (divided in half between Comacchio Valleys and Bertuzzi Valley) increased from 360 in 1986 to 1,927 pairs in 1994, before slightly declining to 857 pairs in 1998. 

Significant nesting colonies on the national level include the Common Tern (Sterna hirundo), with 750 pairs in 1994, Little Tern (Sterna albifrons), with 40-100 pairs, and Caspian Gull (Larus cachinnans), with 300 pairs. The Snowy Plover (Charadrius alexandrinus), with 3-15 pairs, Common Redshank (Tringa totanus), with 50 pairs divided amongst the brackish wetlands of the Delta del Po in Emilia Romagna, Black-winged Stilt (Himantopus himantopus), Common Moorhen (Gallinula chloropus), Eurasian Coot (Fulica atra) and Western Marsh Harrier (Falco aeruginosus) also nest here.  The Cormorant, with 80 pairs in 1994, Little Egret, with about 200 pairs, and Great Egret, with two couples in 1995, all nest on the Dosso Bertuzzi (Costa 1998, Toso et al. 1998).  During the migration season, other particularly common species are the Dunlin (Calidris alpina), Ruff (Philomachus pugnax), Little Stint (Calidris minuta), Spotted Redshank (Tringa erithopus), Common Redshank (Tringa totanus), Black-tailed Godwit (Limosa limosa), Common Greenshank (Tringa nebularia) and Eurasian Curlew (Numenius arquata). 

The area is quite important for the wintering of anatids and Eurasian Coots, and is an important regional site for the the Eurasian Teal in particular. 

Since the mid-1990s, hundreds of Greater Flamingos have frequented the south-central area of Bertuzzi Valleys, and it represents a zone of the delta where one can most easily spot them.  The flamingo population is constantly growing both here and in the rest of the delta. 

The Mediterranean killifish and Adriatic dwarf goby maintain significant, long-standing presences (Costa 1998).

 

 

 

To visit

The area is privately owned, visible only from the Acciaioli embankment, where a turret (open Saturday and on holidays) allows for the observation of the biotope.  From here, interior humps dominate the perspective, most notable of which is the Dosso Bertuzzi.  Flamingos are easy to spot.  On the Acciaioli embankment, along the eastern side of Nuova Valley, there is a piece of land (sandbar) where Delta-Camargue horses roam in a semi-wild state and one can observe birds from a small tower. 

  

Typology Lagoons and brackish valleys
Cartography CTR 1:25.000 – 187SE; 205 SE
Extension 1935 ha
Municipality Comacchio
Property Private
Management Private

 

Obligations

Landscaping restrictions pursuant to L. 431/85, now abrogated by D.L. 490/1999, currently in force.  The site is included within the limiting boundaries of the Delta Park, pursuant to L.R. 27/1998 and to the Volano-Mesola-Goro Station Plan of 1991 and 1997.  The 1997 Territorial Plan inserts the central part of the Valley in the Pre-park Zone (PP.SMT and PP.SMT.G1), and its outer zones in Zone B (B.SMT).  This same principle is applied by the 1991 Plan, although individual boundaries differ from the previous ones.Ramsar Zone known as “Residual valleys of the Comacchio district” (13100 ha) instituted by D.M. 13/07/1981, published in GU n. 203 of 25/07/1981.The complex forms part of the Site of Community Interest (IT4060002) known as “Bertuzzi Valley and adjacent bodies of water,” instituted by D.M. 13 July 1981 (G.U. n. 203 of 25/7/81).Special Protection Zone (IT4060004) pursuant to DIR 79/409 EEC (2570 ha).  Site of Community Interest (IT4060004) known as “Bertuzzi Valley, Porticino Valley, Cannevie,” identified pursuant to DIR 92/43/EEC (=SPZ 2570 ha)
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