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Status of the fish communities and need for management in the Po River Delta
No full textThe term “delta”, have used as a synonym for transitional water bodies, includes the terminal stretch of rivers, estuaries, deltas, fjords and lagoons, as defined by the EU WFD directive. Wetlands are sites of high biodiversity and productivity, with great ecological interest, functional richness and great exploitation of renuwable resources. Recently, these ecosystems have suffered a serious decline worldwide due to human disturbances. The Po River delta (Adriatic Sea, Italy) and the related coastal lagoons are not an exception. In the last twenty years, extensive phenomena of eutrophication and related dystrophic crises, introduction of alien species and the development of new fishing and aquaculture practices have further contributed to the breakdown of biological communities and, in particular, of fish ones.
The aim of this study was to update the general status of the fish communities in the Po Delta of Emilia-Romagna, both in composition and trophic structure, and to identify the main problems of fisheries related to the physical evolution of the environment and the change in human activities.
The results show that freshwater and transitional water suffered from different pressures: freshwater communities are affected by a progressive invasion of exotic species, which has intensified starting from more than 30 years ago. Whereas, fish communities in transitional water do not suffer of exotic fish invasions, but their overexploitation and play a central role in fish community changes. The cases of eels and the fishery of Comacchio are presented and analized as study cases
La fauna ittica delle acque di transizione protette del Delta del Po dell’Emilia-Romagna
No full textImmunocytochemical and ultrastructural identification of adenohypophyseal cells in Ctenopharyngodon idella (Cypriniformes: Cyprinidae) during gonadal differentiation
No full textThe adenohypophysis was studied by
immunocytochemical and ultrastructural methods in
juvenile grass carp (Ctenopharyngodon idella) from
natural reproduction in Northern Italian rivers. The
adenohypophysis included the rostral pars distalis
(RPD), the proximal pars distalis (PPD) and the pars
intermedia (PI), all deeply penetrated by branches of
the neurohypophysis (Nh). The prolactin (PRL),
adrenocorticotropic (ACTH), somatotropic (GH), thyrotropic
(TSH), gonadotropic type I (GtH I) and type II
(GtH II), somatolactin (SL), melanotropic (MSH) and
endorphin (END) cells were identified with antisera
raised against piscine and human pituitary hormones.
In juveniles of 51–69 mm of total body length (TL)
with undifferentiated gonads, the PRL cells, arranged
in thick strands, occupied most of the RPD. The
ACTH and GH cells organized in cords bordering Nh
were, respectively, confined to RPD and PPD. The
TSH cells were scattered among ACTH cells in RPD
and among GH cells in PPD. Cells simultaneously
immunoreactive to anti-follicle stimulating hormone
and to anti-croaker gonadotropin were intermingled
among GH and TSH cells, which were mostly in the
dorsal PPD. The SL cells were detected in PI layers bordering the Nh. The MSH and END cells were
intermingled in PI and, unlike what observed in other
teleosts, their respective antisera did not cross-react. In
individuals of 78–112 mm TL with gonads at the
beginning of differentiation, the GtH II cells were
detected in PPD; all other cell types increased in
number. These results, supported by ultrastructural
investigations, suggest that SL and GtH II cells are
directly involved in gonadal differentiation in C.
idella
Natural recruitment contributes to high densities of grass carp Ctenopharyngodon idella (Valenciennes, 1844) in Western Europe
Full text linkIntroductions of grass carp, well known for their potentially negative ecosystem effects, have been performed in several countries around the world.
As the species was considered unable to reproduce naturally under non-native environmental conditions, little attention was initially given to its
invasive potential. We studied an area in northern-Italy where, contrary to expectations, introductions that were performed in the early 80s still exert
a considerable pressure on aquatic macrophytes. In order to reveal whether the observed population dynamics are the result of natural events or
stocking we analysed the density, age- and size-structure of the grass carp population and the migration pathways available to it. Telephone surveys
were also used to check for fish transport from national and international suppliers. We also sampled potential spawning and nursery areas for
young individuals and, when some were captured, we applied stable isotope analyses to discriminate their origin. We found that the population of
large individuals likely originated solely from early stocking. We also documented the first analytical evidence of grass carp recruitment in the
study area and, to our knowledge, in Western Europe. Therefore the species has the potential to become invasive in these areas and more detailed
studies are needed to assess this potential. Further management should account at least for natural recruitment and potential negative environmental
effects, controlling the species where needed.peerReviewe
Prima segnalazione e distribuzione di rodeo amaro, Rhodeus seiceus (Pallas, 1776), Osteichthyes Cypriniformes, nelle acque interne della provincia di Ferrara
No full textThe presence of the exotic species, bitterling, Rhodeus sericeus (Pallas, 1776), is reported for the first time in the freshwater canals of province of Ferrara, Northern Italy. The classification to the species level was supported by the morpho-meristic parameters, in agreement with the range of variability described for the species.
The specie was firstly recorded in Italy in the 1990, in the Menago river located in province of Verona, tributary of the Canal Bianco where it was found the following year, and connected to the Po river through the Governolo (MN) and Voltagrimana (RO) navigation canals. In some canals of the province of Modena it was recorded in 1996 and in the lower Secchia River in 1999, while the species was not found in the Panaro River and in the Burana basin whose homonymous canal crosses the province of Ferrara, from west to east.
The hydraulic system of artificial canals (4000 km) in the province of Ferrara (2630 Km) is divided in more sub-basins, all related to the Burana-Volano-Navigabile canal that crosses the overall territory from west to east and is used for both irrigation, driving Po River water derived at Stellata (Bondeno. FE) and drainage. The main sub-basins, considered in this study, are the Canale Burana, Po di Volano, Canal Bianco, Canale Navigabile and Canale Circondariale
Distribuzione del Gambero rosso della Louisiana nel Delta del Po
No full textL’introduzione di specie alloctone di gamberi d’acqua dolce è un fenomeno molto diffuso, che esercita significativi effetti sulle comunità residenti (Holdich, 1987; Axelsson et al., 1997), risultando addirittura più destabilizzante di forti modificazioni ambientali o fenomeni legati all’eutrofizzazione (Rodríguez et al., 2005). In molti casi, l’esplosione demografica di specie alloctone di gamberi ha portato alla riduzione o scomparsa di quelle native (ad esempio, Renai & Gherardi, 2004; Magoulick, 2004), ha fortemente modificato le comunità di invertebrati (Barbaresi & Gherardi, 2000; Gil-Sánchez & Alba-Tercedor, 2002; Renai & Gherardi, 2004), pesci (Guan & Wiles, 1997; Renai & Gherardi, 2004) ed anfibi (Axelsson et al., 1997), nonché la stessa struttura del sedimento e le caratteristiche della colonna d’acqua (Angeler et al. , 2001; Rodríguez et al., 2003).
In Italia, il Gambero rosso Procambarus clarkii (Girard) è stato evidenziato in molti corsi d’acqua nel Nord e nel Centro della penisola (Gherardi et al. , 1999), dove le popolazioni sembrano ancora in espansione. In particolare, nel Nord Italia, la comparsa di tale specie è stata riportata da molteplici servizi provinciali di gestione della fauna, del basso corso del Po (Nobile, 1997) e del suo Delta (Mazzoni et al., 1997).
Nel delta del Po (provincia di Ferrara), dove P. clarkii è stato catturato da pescatori dilettanti e professionisti a partire dal 1996, abbiamo considerato i seguenti punti:
a) la distribuzione di P. clarkii , dopo meno di una decade dall’introduzione;
b) le relazioni tra distribuzione e parametri abiotici e biotici;
c) le relazioni tra distribuzione e l’eutrofizzazione;
d) le conseguenze dell’introduzione di P. clarkii sull’assetto ecosistemico;
e) l’analisi dei parametri che discriminano i siti e che possono essere utili nel controllo della specie
Aggiornamento dello stato della popolazione di anguilla europea (Anguilla anguilla L. 1758) nelle Valli di Comacchio.
No full textEutrophication triggered changes in network structure and fluxes of the Comacchio Lagoon (Italy)
No full textCoastal lagoons, which cover about 13% of coastline, are among the most productive ecosystems worldwide. However, they are subject to significant stressors, both natural and anthropogenic, which can alter ecosystem services and functioning and food web structure. In the Comacchio Lagoon (Northern Italy), eutrophication, among other minor factors, transformed the ecosystem in the early 1980s. Here, we compiled available data for the lagoon into trophic networks (pre- and post-transformation), analyzed the ecosystem using local and global network analysis, and computed trophic fluxes of the two periods. For comparability, the networks of two periods (i.e., pre- and post- transformation) were aggregated into food webs with 23 nodes. We found differences in the trophic networks before and after eutrophication, resulting in some decrease in complexity, increase of flow diversity, and an overall shortening of the food chain. A crucial aspect of this change is the disappearance of submerged vegetation in the lagoon and the increased importance of cyanobacteria in the post-eutrophication period. We provide an approach to better understand ecosystem changes after severe disturbances which can be extended to biodiversity conservation and for the management of coastal resources in general
Controllo e stoccaggio del gambero rosso della Louisiana
No full textProgetto sperimentale per la limitazione, lo stoccaggio e lo smaltimento del gambero rosso della Louisiana a scopo di riequilibrio ittico e di conservazione delle specie autocton
Progetto per lo studio e il monitoraggio di alcuni corsi d’acqua particolarmente pregiati e collegati a zone di tutela della fauna ittica
No full textNella Delibera n. 5463 del 9 novembre 1993, vengono indicati gli orientamenti
per il ripristino e la tutela delle specie ittiche autoctone; in particolare gli indirizzi
gestionali riguardano l’istituzione di zone specifiche per la tutela della
fauna ittica, distinte in (Legge Regionale n. 11/93) Zone di ripopolamento e frega
(Zrf), Zone di protezione integrale (Zpi), Zone di protezione delle specie ittiche
(Zpsi) e Zone a regime speciale di pesca (Zrsp).
Nella Provincia di Ferrara, l’istituzione di Zrf è sicuramente l’intervento più
attuato. Tuttavia, di fronte al rapido cambiamento ambientale e di composizione
dei popolamenti ittici, risulta fondamentale disporre di un continuo aggiornamento
dello stato qualitativo delle Zrf in vigore e di una rosa di altre
eventuali aventi i requisiti di idoneità.
Una prima indagine, compiuta in Provincia di Ferrara nel triennio (1996-
1998), aveva evidenziato un netto cambiamento strutturale della comunità ittica
in numerosi siti. Sulla scorta di tali risultati, è stato attivato un progetto
che prevedeva il monitoraggio e lo studio di alcuni corsi d’acqua della Provincia
di Ferrara particolarmente pregiati e collegati a zone di tutela della fauna
ittica ed in particolare le Zrf, con particolare attenzione alle specie autoctone
di particolare pregio, come tinca e luccio e a quelle di particolare interesse
alieutico, quali pesce gatto e lucioperca
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