| Abstract | We present an example of how an invasion by a non-native cyprinid (common bream, Abramis brama (Pisces: Cyprinidae), hereafter bream) in a natural shallow lake in southern Europe (Lake Montorfano, northern Italy) may have adversely affected the state of the lake's ecosystem. In less than two decades, bream became the most abundant species and characterized by a stunted population with asymptotic length 33.5 cm, an estimated mean length at first maturity of 19.6 cm, a total mortality rate of 0.64 year(-1) and a diet overwhelmingly dominated by microcrustaceans. Following bream establishment, nutrients and phytoplankton biomass rose, the proportion of Cyanobacteria by numbers increased markedly and water transparency decreased. Total zooplankton abundance increased with a marked increase in small cladocerans and copepods, whereas the abundance of large herbivorous cladocerans did not change. The coverage of submerged macrophytes declined, as did the abundance of native pelagic zooplanktivorous fish. The composition of the fish community shifted towards a higher proportion of zoobenthivorous species, such as bream and pumpkinseed (Lepomis gibbosus). Our results indicate that bream affected water quality through bottom-up mechanisms, while top-down effects were comparatively weak. Selective removal of bream and perhaps stocking of native piscivores might improve the ecological status of the lake. |
| Text | 308875 2013 10.1007/s10530 013 0433 z ISI Web of Science WOS 000322576600015 Scopus 2 s2.0 84881024720 Invasive alien species IAS Electrofishing Multi mesh survey gill nets CPUE Cyprinids Ecosystem functioning Recent invasion by a non native cyprinid common bream Abramis brama is followed by major changes in the ecological quality of a shallow lake in southern Europe Pietro Volta; Erik Jeppesen; Barbara Leoni; Barbara Campi; Paolo Sala; Letizia Garibaldi; Torben L.Lauridsen; Ian J.Winfield Volta, Pietro CNR ISE, Pallanza Verbania Jeppesen, Erik Department of Bioscience, Aarhus University, Vejlsøvej 25, 8600 Silkeborg, Denmark Leoni, Barbara Universita` degli Studi di Milano Bicocca, Milan, Italy Campi, Barbara CNR ISE, Pallanza Verbania Sala, Paolo CNR ISE, Pallanza Verbania Garibaldi, Letizia Universita` degli Studi di Milano Bicocca, Milan, Italy Lauridsen, Torben L. Greenland Climate Research Centre GCRC , GreenlandInstitute of Natural Resources, Kivioq 2, P.O. Box 570, 3900 Nuuk, Greenland Winfield, Ian J. Centre for Ecology Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP, UK We present an example of how an invasion by a non native cyprinid common bream, Abramis brama Pisces Cyprinidae , hereafter bream in a natural shallow lake in southern Europe Lake Montorfano, northern Italy may have adversely affected the state of the lake s ecosystem. In less than two decades, bream became the most abundant species and characterized by a stunted population with asymptotic length 33.5 cm, an estimated mean length at first maturity of 19.6 cm, a total mortality rate of 0.64 year 1 and a diet overwhelmingly dominated by microcrustaceans. Following bream establishment, nutrients and phytoplankton biomass rose, the proportion of Cyanobacteria by numbers increased markedly and water transparency decreased. Total zooplankton abundance increased with a marked increase in small cladocerans and copepods, whereas the abundance of large herbivorous cladocerans did not change. The coverage of submerged macrophytes declined, as did the abundance of native pelagic zooplanktivorous fish. The composition of the fish community shifted towards a higher proportion of zoobenthivorous species, such as bream and pumpkinseed Lepomis gibbosus . Our results indicate that bream affected water quality through bottom up mechanisms, while top down effects were comparatively weak. Selective removal of bream and perhaps stocking of native piscivores might improve the ecological status of the lake. 15 Published version Articolo Biol_Invasions_15_2065_2079.pdf Articolo in rivista Kluwer Academic Publishers 1387 3547 Biological invasions Biological invasions CAMPI BARBARA pietro.volta VOLTA PIETRO TA.P04.016.004 Ecologia teorica e applicata degli ecosistemi acquatici |
