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Comacchio Valleys





The Comacchio valleys constitute the vastest complex of brackish wetland zones in the Emilia-Romagna region.  

The principal basins are the Fossa di Porto valleys, Lido di Magnavacca, Cona Valley and adjacent basins; Campo Valley and Sottolido; and the basins of the Saline di Comacchio, Fattibello and Spavola Valley, Capre Valley, Furlana Valley (Lavadena Valley, Pastorina Valley, Bru Valley, Ussarola and Smarlacca Valley).  To these are added the remains of valleys not in communication with these: Molino Valley, Zavelea Valley (also known as the Fossa di Porto Oasis), Vene di Bellochio and Sacca di Bellochio.  To the south, the Comacchio Valleys Station includes the Reno River and Volta Scirocco floodplain.


A bit of history


In the Etruscan and Roman period, the principle estuary channels of the Po (Padus-Eridanus) and Santerno (Vatrenus) emptied into the sea in the area between Comacchio and Primario.  The dominant environment was therefore fluvial-marshy, and briny morasses were limited to zones in proximity to the coast.  In the Middle Ages, with the crisis and extinction of the Padus-Eridanus and ensuing temporary elevation of the sea level, subsidence was no longer compensated for by the supply of new sediments: salty seawater begin to enter and the briny morass environment extended for kilometers, culminating in the complete submersion of the Mezzano in the 16th century.

The current Comacchio Valleys are therefore the residual of a lagoon complex that reached its maximum extent in the 16th century, when it covered about 50,000 hectares of surface.  This surface area progressively declined with the reclamation efforts begun in the mid-19th century and survived into the late 1960s.  Numerous remnants of coastal sandbars and riverbeds are still visible throughout the valleys, and are often used to delimit single basins (Bodesan in Corbetta 1990, Caputo 1974). 


Some data

The depth of the Comacchio Valleys varies greatly: 60 cm on average, with a maximum of 1.5-2 meters.  Clays, silts, bioclastic materials, and (more rarely) sand constitute the sea bottom.  Communication with the sea occurs through the Porto Garibaldi Canal, Logonovo Canal and Bellocchio-Gobbino Canal.  Communication is difficult for the last two channels because the estuaries frequently fill up with sand.  Pollution phenomena and administrative impediments render challenge the replenishment of the Fossa di Porto valleys and Lido di Magnavacca with freshwater from the Reno River.  Salinity varies over the course of the year, as well as from one basin to the next (and sometimes within a single basin), due both to climatic and weather reasons (evaporation and precipitation) and to the hydraulic regime utilized in the each case.  In general, salinity diminishes from north to south due to the influence of the waters of the Reno.  Various problems, together with the aforementioned difficulties in replacing the waters, have notably compromised the situation of these valleys in recent years.


A delicate environment

The first evident modification of lagoon waters, relative to the 1970s, has been an increase in the turbidity of the water due to the drastic reduction of the macrophytic and macroalgal components (Ruppia and Lamprothamnium) in favor of the abundant flourishing of phytoplankton, composed principally of picocyanobacteria (Sorokin et al. 1996a and 1996b), and of Nannochloropsis sp. (Andreoli et al. 1998).  Repercussions have occurred at all levels:  the modification and simplification of the floral and faunal communities at every level of the trophic network, and a fall in ichthyic production (Boldreghini et al. 1992, Cataudella and Rossi 1998, Piccoli 1998, Rossi and Cataudella 1998, Volponi et al. 1998).

Numerous studies of water quality in the Comacchio Valleys have been undertaken (Cognetti et al. 1975, Colombo 1972, Sorokin et al. 1996a and 1996b, Dallochio et al. 1998).  The cited works describe a current situation of notable environmental deterioration, but scientific proof regarding causes for the deterioration has not been found.  Regarding the environmental impact of intensive ranching practices, one study by Cavallini (1980) found that eutrophication had not influenced the terminal basin of Campo Valley and that the significant quantity of organic substances released had only a limited impact upon Ussarola Valley, a small basin used for water settling.  Sorokin et al. disagreed, arguing that an “ecological disaster” is underway in Comacchio Valleys, responsibility for which must be sought in the development of intensive ranching practices in the 1970s and 80s.  The report of Dallocchio et al. (1998) is more cautious, affirming that “lacking data prior to the 1960s, it is not possible to attribute to any single factor the cause of the changes manifested in this extremely delicate environment.”




The Comacchio Valleys exhibit typical halophile and halotolerant communities, of which we provide only a schematic description here; for a detailed description, see Corticelli (1999).  The majority of the lagoon pools, flooded year-round, now display little or no vegetation.  In some places—the Campo Valley above all—submergent meadows of Rupphia cirrhosa (Sint. Ruppietum cirrhosae) have taken root, with more or less extensive algal components constituted by Ulva, Chaetomorpha, Cladophora, and Ceramium (Sint. Ruppietalia). 


Ruppia populations of a certain breadth are present in the Cona and Verdone Valleys, sheltered by the eastern edge of the Boscoforte peninsula and the Dosso Fuori; minor areas are found to the east of Dosso Lungo, to the south of the Casone Fossa di Porto, in the basins around Ca’Ussarola (Campo Valley) and in numerous tanks of the former SIVALCO installation (Campo Valley).  Zostera noltii, already identified as rare, is now present only in Lido di Magnavacca Valley, in the shelter of the Marasetto embankment.  The dramatic decline of submergent vegetation is likely due in large part to the permanent turbidity of the water, which impedes the passage of an adequate amount of light (Piccoli 1998).

In brackish waters on sandy substrates—in Fossa di Porto above all—submergent populations of Lamprothamnium papulosum (green algae of the Charophyceae family), of great naturalistic value, are present.  These populations, once widespread, are now quite rare.  Drastically reduced in the last decades, they are sporadically sighted in Fossa di Porto and more densely, in the tanks of the former SIVALCO installation (Campo Valley).

A community of pioneer annual halophytes is settled into the long-inundated briny soils.  Because it is dominated by Salicornia veneta, a native species of the High Adriatic (Sint. Salicornietum venetae), the the community is of great naturalistic value.  On the crest of humps or inconspicuous shoals, in sandy loam soils and in marked hydrophylic conditions, a perennial halophilic vegetation characterized by Sarcocornia deflexa (Sint. Sarcocorniertum deflexae) grows: ecosystems of limited distribution and great naturalistic value.  On the same level, but in soils rich in organic substances and bivalvia shells, an annual halophyte community dominated by Suaeda maritima and Bassia hirsuta, of great naturalistic value, is present (Sint. Suaedo maritimae-Bassietum hirsutae).  At a higher level, in conditions of lesser hydrophylia, vegetation is dominaed by Arthrocnemum fruticosum (Sint. Puccinellio festuciformis-Sarcocornietum fruticosae), often accompanied by Juncus maritimus, Puccinellia palustris, Arthrocnemum glaucum and Halimione prtulacoides.  On the summit of shoals and artificial humps, dense meadows dominated by Elytrigia atherica grow (Corticelli 1999, Piccoli 1998).



The large colonies of gulls and nesting terns on the interior humps of Comacchio Valleys are of international importance, with colonies that represent a very high percentage of Italy’s nesting population.  Of particular importance are the colonies of Common Terns (1000-1500 pairs), Little Terns (50-220 pairs), Sandwich Terns (322-407 pairs), Mediterranean Gulls (571-1927 pairs), Common Gulls (350-600 pairs), Yellow-legged Gulls (1100 pairs), Gull-billed Terns (100-150 pairs), Lesser Crested Terns (1-2 pairs since 1985) and Slender-billed Gulls (55 pairs).  The nesting of the Eurasian Spoonbill is very important on an international level; the Tre Motto hump is the only site they regularly occupy in Italy (about 20 pairs). 

On a national level, important nesting populations include the Pied avocet, Common Redshank (with 50 pairs divided between the wet brackish zones of the Po in Emilia Romagna), Kentish Plover (26-66 pairs in Salina di Comacchio), Black-winged Stilt, Great Egret (6 pairs in 1995), and several species of anatids: in particular the Common Shelduck, Northern Shoveler, Gadwall and Common Pochard (100 pairs), present in populations that in most cases exceed 50% of the Italian total.  From 1981 to 1983, one or two pairs of Black-tailed Godwits also nested here.

The environmental deterioration of the Valleys has revealed itself in the drastic decline of wintering anatids.  The Common pochard in particular was very common in the 1970s (more than 30,000 individuals, according to Boldreghini et al. 1992).  Nevertheless, the Comacchio Valleys remain one of the principle Italian sites for the migration and hibernation of many Grebes, Herons, Charadriiformes and Coots; such contingents of wintering anatids as the Mallard, Gadwall, Eurasian Wigeon, Northern Shoveler, Common Pochard and Tufted Duck are quite important.  The hibernation of Goldeneye Ducks, generally concentrated at Fossa di Porto, is also of notes.

The populations of Mediterranean killifish and Adriatic dwarf gobies are historical and important (Costa 1998). 


To visit         

Free access to the Comacchio Valleys district is not permitted.

Historical-naturalistic excursions into the valley depart from Foce Station, to the south of Fattibello a Valley.

A naturalistic itinerary and open-air ethnographic museum, thanks to the restoration of original materials and structures, illustrates traditional activities and the daily life of the valley’s fishers through the mid-20th century.  A boating itinerary (departures at 9 AM, 11 AM, 3 PM and 5 PM) winds along the Ungola Canal—in antiquity, one of the minor branches of the delta—with stops and visits to the dairy factories of the valley.

From Casone Foce, it is possible to walk or bicycle along the banks of the Fattibello Valley, the Spavola Valley (eastwards) and the Fosse Canal (westwards), arriving at the Casone di Donnabona or Zavelea Valley, or visiting the Saline di Comacchio.



Lagoons and brackish valleys


CTR 1:25.000 – 205 SE, 205 SW, 223 NW, 223 NE


14,383 ha


Comacchio, Argenta, Ravenna


Comacchio municipality; Autonomous State Monopoly Corporation (Saline di Comacchio), Merchant Navy Branch (Sacco di Bellochio N.), former state company of public forests (Sacca di Bellocchio S.), private ownership (Furlana Valley and adjacent, S. Clemente Island and south vein of Bellcohio), Emilia Romagna Regione (Volta Scirocco, Zavelea Valley).


Delta del Po Park Emilia Romagna, Autonomous State Monopoly Corporation, former state company of public forests (ASFD), private




Landscape restrictions pursuant to L. 1497/1939 and environmental restrictions pursuant to L. 431/1985; currently subject to the restrictions of D.L. 490/1999.

The following Fauna Protection Oases have been instituted in the area: Bosco Forte (500 ha), instituted by del. GP n. 849/7822 of 19/08/1981; Fossa di Porto (1300 hectares), instituted by del. CP n. 300/10016 of 01/08/1979 and modified in its boundaries by del GP n. 966/7920 of 31/05/1989; Zavalea (170 ha), instituted by del. GP n. 966/7920 of 31/05/1989; Cona Valley (200 ha), instituted by del. GR n. 973/8004 of 31/05/1989; Ussarola Valley (380 ha), instituted by del GP n. 850/7823 of 19/08/1981; Vacca Valley (760 ha), instituted by del. GP n. 851/7824 of 19/08/1981; Fattibello Valley (650 ha), instituted by del. GP n. 250/5778 of 30/07/1981; Lidi Ferraresi Sud, instituted by del. GP n. 20/29480 of 04/08/1975 and later modified. 

The “Comacchio Valleys and adjacent territories” are a Ramsar Zone (13,500 ha), instituted by DM 13/07/1981 and published in G.U. n. 203 of 25/07/1981

The Pre-park, C and B Zones of the “Comacchio Historical Center” and “Comacchio Valleys” stations of the Delta del Po Park, pursuant to LR 27/1988 and included within the limiting boundaries of the Station Territorial Plans of Del. C.P. Ferrara 88/25001 of 25/06/1997 and of Del. C.P. Ferrara 119/10013 of 01/07/1991, in force in obligatory defense pursuant to LR 11/1988.

Special Protection Zone (IT4060002) pursuant to DIR 79/409 EEC (12745 ha) and Site of Community Importance (IT4060002) pursuant to DIR 92/43/EEC (12745 ha).

The Saline di Comacchio have been selected as natural areas to be preserved, pursuant to DM 03/05/1993, and as such are subject to the precise preservation measures provided for in the decree. 



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