Scillitani G., Liuzzi C., Lorusso L., Mastropasqua F., Ventrella P. (curatori), 2013. Atti IX Congresso Nazionale della Societas Herpetologica Italica (Bari - Conversano, 26-30 settembre 2012). Pineta, Conversano (BA). Herpetofauna of the Northern Adda Regional Park (SCI IT2030005 Palude Di Brivio, Lombardy, Northern Italy): management and conservation issues ANNA RITA DI CERBO 1, 2, CARLO M. BIANCARDI 1, 3 1 Centro Studi Faunistica dei Vertebrati, Società Italiana di Scienze Naturali, corso Venezia 55, 20121 Milano, Italy. 2 Corresponding author: E-mail: bombinatoridae@gmail.com 3 Corresponding author: E-mail: carlo.biancardi@gmail.com Riassunto. Erpetofauna del Parco regionale dell Adda Nord (SIC IT2030005 Palude di Brivio, Lombardia, Italia settentrionale): aspetti di gestione e conservazione. La Palude di Brivio (SIC IT2030005, Parco Adda Nord) è un area umida della rete Natura 2000, inserita fra il corso del Fiume Adda e due centri urbani (Calolziocorte e Brivio). Tra il 2010 e il 2011 sono stati compiuti rilevamenti sull erpetofauna presente nel SIC e aree limitrofe. In totale vengono segnalate 8 specie di anfibi e 10 di rettili, di cui il 72.3% sono state riconfermate o rinvenute per la prima volta nel corso del presente studio. Quasi tutte le specie sono prioritarie a livello regionale e oltre il 60% godono di protezione comunitaria. La Palude di Brivio può essere considerata un hot spot di biodiversità da salvaguardare. Tuttavia, nel corso dello studio sono stati evidenziati diversi fattori di rischio per le comunità animali, tra cui il parziale isolamento dell area, una forte pressione antropica che insiste sull area con anche varie forme di inquinamento e introduzione di specie alloctone. Keywords. Amphibians, Reptiles, Risk factors, Habitat management INTRODUCTION Habitat loss and degradation of residual habitat are among the major threats to wildlife (He & Hubbell, 2011). At landscape scale, isolation and even fragmentation of single patches can lead to a decrease in species richness, abundance of individual species, reduction of genetic diversity that could seriously affect the ecosystem biodiversity (Hamer & McDonnel, 2008). Amphibians and reptiles are particularly vulnerable to habitat fragmentation, being generally characterized by limited dispersal abilities, and, especially amphibians, needing both aquatic and terrestrial ecosystems (Cushman, 2006). To limit this phenomenon the European Council promoted the Natura 2000 Network. In Lombardy, the Regional Ecological Network (REN) project has been recently launched, and rivers and adjacent zones have been indicated as main corridors and branches of the
138 A. R. Di Cerbo and C. M. Biancardi REN. The Palude di Brivio (SCI IT2030005) is enclosed in the REN (sector 69), and it constitutes one of the most important residual wetlands in the western Lombard Alps. This study is a part of a wider project aimed to define the wildlife community, the risk factors for species and habitat in the SCI, and to provide conservation and management actions for the authority of the Northern Adda Park. MATERIAL AND METHODS The Palude di Brivio (surface: 302 ha) is a wetland of international relevance, within the framework of the Ramsar Convention (1971). The SCI is bounded by the river Adda and two urbanised areas (Calolziocorte and Brivio) and is included in the Northern Adda Regional Park. It hosts habitats of community importance associated to freshwater environments (NATURA 2000 habitat codes 3140, 3150, 3260, An. 1, 92/43/EEC), natural and semi-natural grassland formations (6410, 6510), alkaline fens (7230), alluvial forests (91E0). The wetlands (7 artificial ponds, several temporary pools, cane fields, small ditches and oxbows) represent refuges and connection corridors to the natural river strip. The study has been carried out from February 2010 to June 2011 inside the SCI boundaries and in a buffer area (about 1 km width) along its eastern border. The presence of amphibians and reptiles has been investigated using the following methodological approaches: Visual Encounter Survey, Systematic Sampling Survey along line transects, Plot Survey including freshwater habitat, Calling Survey and Roads Monitoring (for techniques explanation see Dodd, 2010). Data on species and habitats have been collected. Each record has been georeferenced using a GPS device (Garmin Dakota 20), and mapped in a GIS (QGIS, v.1.6.0, 2010). Amphibian call surveys have been performed using a professional hydrophone (SS03 SeaPhone), a digital recorder (Micro-track II, M-Audio), at a sample rate of 44.1 khz and 16 bit resolution, and a directional microphone (NTG2, Røde). Sounds were analysed using a FFT (Fast Fourier Transformations) length of 512 points width using the freeware softwares SoundRuler (v. 0.9.6.0., 2007) and Audacity (v. 1.3.14, 2011). RESULTS Overall, 8 amphibian and 10 reptile species have been reported in the study area, 72.3% of which were reconfirmed or firstly recorded during our surveys (Table 1). The majority of them (87.5% of amphibians and 80% of reptiles) are classified as priority species at regional level (value 8 in Table 1; ref. D.G.R. n. 7/4345, 20 April 2001), and 61.1% are protected by the Habitat Directive (Annex II and/or IV of the European Directive 92/43 CEE). Based on our survey, the northern sector of the study area shows the higher richness of species, this is probably due to the larger variety of aquatic habitats available. The site occupancy by amphibians has been shown according to each habitat typology (Fig. 1). Interesting data for conservation and management of wetlands especially concern the species enclosed in the annexes II and IV of the Habitat Directive.
Herpetofauna of the Northern Adda Regional Park 139 Table 1. Check List of amphibians and reptiles. : data form NATURA 2000; : literature, : this study; A: adults, L: larval phase; Y: young; E: eggs; I: inside the SIC; O: outside Species Data Type Sample Type Location Regional Priority Habitat Directive Triturus carnifex, A I 10 II, IV Lissotriton vulgaris - O 10 Bufo bufo, A, L, E I, O 8 Bufo balearicus - 9 IV Hyla intermedia,, A, L, E I, O 10 IV Rana dalmatina,, A, L, E I, O 10 IV Rana latastei,, A, L, E I, O 12 II, IV Pelophylax kl. esculentus, A, L, E I, O 5 Emys orbicularis - I 14 II, IV Trachemys scripta A I Anguis fragilis - I 8 Lacerta bilineata - I 8 IV Podarcis muralis,, A, Y I,O 4 IV Hierophis viridiflavus,, A, Y I,O 8 IV Zamenis longissimus, A I 10 IV Natrix natrix, A, Y I,O 8 Natrix tessellata, Y I 11 IV Vipera aspis A O 9 Fig.1. Site occupancy according to amphibian species.
140 A. R. Di Cerbo and C. M. Biancardi Triturus carnifex was rare and only found inside artificial ponds and cane fields located in the northern part of the SCI. Rana latastei and Rana dalmatina were widespread and surveyed in the following habitat types: artificial ponds, small channels, cane fields, temporary pools, mostly during the reproductive period (February-April) and in forest habitats, mostly during late spring and summer. The two brown frogs were often found syntopic and during the reproductive season they have been recognized by the underwater calls analysis (Fig. 2). Similarly, H. intermedia was recorded mostly during the call surveys, both in spring (till June) and autumn (September-October), mainly near the cane field. Surveys revealed low abundance of reptiles in the SCI, apart from the Common wall lizard and the Grass snake. In addition, some relevant species (e.g. Emys orbicularis) have not been reconfirmed (see Table 1), while Vipera aspis, found in an open area bordering on the SCI, was not previously reported in the study area. The scarcity of some amphibians and reptiles can be related to some of the threats detected and quantified both during the survey sessions and using GIS land use layers. Edge effect and habitat fragmentation resulted the main risk factors on the boundary of the study areas. The most relevant risk factors for the herpetofauna, are reported in Table 2. Alien invasive species (954) found at the ponds and rivers are recognized to be the main direct drivers of biodiversity loss and included in the black list of Delivering Alien Invasive Species Inventory for Europe (DAISIE, 2009). Trachemys scripta, Myocastor coypus and Procambarus clarkii, were widespread in the protected area. In particular, the invasive allochthonous terrapin was recorded inside the artificial ponds and the oxbows, and along the bank of the Adda River. The drying up of the wetlands (951) and flooding (840) in forest and grassland represent two relevant risk factors. Both events are related to the water use and management of the Adda River northwards the protected area. According to Naiman & Decamps (1997), the flooding is a highly relevant risk factor for invertebrate fauna and small vertebrate, especially reptiles, causing mortality and a transitory reduction of their habitats. The filling up of the marshes, due to the scarce management of the cane fields, was a limiting factor to species richness. This factor can be clearly observed at the Isolone del Serraglio and has likely driven the local extinction of the autochthonous freshwater turtle E. orbicularis. The freshwater terrapin had been signaled until early 90s inside the SCI, but all the following turtle sightings are questionable and perhaps referable to T. scripta (La Viola et al., 1996). The practice of fire to control the cane overgrowth has been previously applied in this area, even if it is currently forbidden (L.R. n.10, 31 March 2008). Fire (180) directly kills animals but also modifies and reduces the habitat surface for animals living in riparian and forest zones. Accidental fires or arsons still remain among the major risks in forest and grassland habitats of the SIC. Similarly, we observed harvesting activities (102) affecting reptiles (e.g. one Asp viper killed by mowing activities in a grassland located within the urban area of Calolziocorte). Aquatic pollution due to industrial drain water and sewers was recorded during our surveys and also reported by La Viola (1996) in the northern part of the SCI and in some marsh areas inside the buffer zone, probably driving the decrease of the urodele species. Last of all, the network of transportation infrastructures (502) and the high level of industrial urbanization (411) act as barriers among populations or have a trap effect for
Herpetofauna of the Northern Adda Regional Park 141 Table 2. Risk factors for the herpetofauna in the study area, location and impact rate. FW: freshwater; FO: forest, GR: grassland; A: high, B: medium, C: low; Area (%): percentage of the SCI area involved, blank when referred to an external threat affecting the SCI biocoenosis. Code Impact Factor Habitat Intensity Area(%) 102 Harvesting / Mowing FW, FO, GR C 10 140 Grazing FW, FO, GR C 10 180 Fire FW, FO, GR A 50 290 Illegal hunting-fishing FO,FW C 20 400 Urban areas FW, FO, GR A 411 Industries FW, FO, GR A 5 424 Other dump areas FW, FO C 430 Rural structures FW, FO, GR B 501 Pathways and cycle tracks FO, GR C 5 502 Roads and highways FO, GR B 625 Gliding GR C 20 701 Water pollution FW C 5 840 Flooding FO, GR A 70 951 Drying up FW B 75 954 Alien species GR, FW B 100 961 Competition FW B 60 963 Disease transmission FO, FW B 60 966 Conflicts due to species introductions GR, FW B 60 967 Conflicts with domestic species FW, FO C 100 Fig. 2. Oscillograms (top traces) and power spectrum (bottom traces) of a one-note underwater advertisement call of R. latastei (left) and of R. dalmatina (right). Time scale in seconds, amplitude expressed as sound pressure in Pascal, frequency in kilohertz.
142 A. R. Di Cerbo and C. M. Biancardi animals (Glista et al., 2008). For instance, the collected data of the Common toad in the area were mainly based on dead specimens, recorded during the road monitoring. But road mortality also affected brown frogs and several reptiles. DISCUSSION On the basis of our results, Palude di Brivio can be considered an hotspot for Lombard herpetofauna, hosting a wide variety of species, including priority amphibians and reptiles at regional and European level. However, the protected area is enclosed in a complex mosaic of anthropic land-use patches (urban, agro-industrial), while the zone close to the river is included in the REN. In this landscape matrix, the importance of the SCI seems to be particularly important for priority species like R. latastei (All. II and IV Habitat Directive, All. II Bern Convention, regional priority species according to the L.R. n. 10/2008). The role of corridors to sustain an adequate natural level of connectivity among populations has been frequently debated in conservation biology (e.g. Marsh & Trenham, 2001; Denoël & Lehmann, 2006; Hamer & McDonnell, 2008). In this case, the fluvial strip represents the main corridor for herpetofauna along the north-south axis of the SCI. Our study assessed that Italian agile frog is quite common in the SCI and southward along the wetlands near the Adda River (Corbetta, Giovine, Di Cerbo, pers. com.). At regional level, the area represents a crucial node towards western and southern populations (Bernini et al., 2004). For these reasons the terrestrial and aquatic habitat management and conservation are fundamental to maintain the connectivity within the distribution area of this species. The provided risk factors for herpetofauna will be useful to activate measures aimed to preserve species and habitats in the protected area and buffer zone. In fragmented landscapes, habitat connectivity becomes crucial to maintain wildlife populations, especially when the complex landscape matrix is a mosaic of suitable and unsuitable patches for the species. Therefore, we provided the Park authority some management actions and conservation measures to preserve habitats and strengthen the natural corridors along the north-south and eastern axes, connecting the protected area with the surrounding environment. ACKNOWLEDGEMENTS This work was funded by the Northern Adda Park. We are particularly grateful to Dr. S. Saladini (Director) and Dr. G. Defilippis (Resp. for Nat. Res.). We would like to thanks A. Corbetta, C. Crespi and G. Giovine for delivering their information. REFERENCES Bernini, F., Bonini, L., Ferri, V., Gentilli, A., Razzetti, E., Scali, S. (2004): Atlante degli Anfibi e dei Rettili della Lombardia. Monografie di Pianura n. 5. Provincia di Cremona, Cremona.
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