Effects of disturbance on marginal populations: human trampling on Ascophyllum nodosum assemblages at its southern distribution limit

• Type: Article in International Scientific Journal
• Date: 2009

Authors

Rita Araujo (Author) Other; Stefano Vaselli (Author) Other; Mariana Almeida (Author) Other; Ester Serrao (Author) Other; Isabel Sousa Pinto (Author) FCUP

Journal

Title: Marine Ecology - Progress Series

Vol. 378

Pages: 81-92

ISSN: 0171-8630

Publisher: Inter-Research Science Publishing

Indexing

ISI Web of Knowledge - 32 Citations

Scopus - 32 Citations

Scientific classification

FOS: Natural sciences > Biological sciences

Other information

Authenticus ID: P-003-R8Z

DOI: 10.3354/meps07814

Abstract (EN): The negative effects of disturbances on the long-term persistence of populations may be more severe in marginal populations, i.e. those occurring at the boundaries of geographical and ecological distribution ranges. Human trampling is an important source of anthropogenic disturbance for intertidal assemblages. Effects of human trampling on intertidal rocky shore assemblages dominated by Ascophyllum nodosum (L.) Le Jol. at its southern distributional limit in Europe were tested experimentally. Four different intensities of trampling disturbances were applied to experimental areas, over a period of 5 mo. Percentage cover of A. nodosum and associated organisms was quantified during the disturbance period and for a recovery period of 1 yr. The 2 highest trampling intensities drastically reduced the cover of A. nodosum. Trampling also negatively affected Fucus vesiculosus and understorey species, while indirectly allowing colonisation by ephemeral green algae. One year after the end of disturbance, A. nodosum assemblages in the highest disturbance intensity areas were still significantly different from assemblages in the control and lowest disturbance intensity areas. These results were mainly driven by a switch in the dominant canopy species, from A. nodosum to F. vesiculosus. Results obtained in this study show that disturbance by human trampling negatively affects A. nodosum assemblages and that the effects are dependent on trampling intensity. These findings highlight the risk of local extinction imposed on these populations by anthropogenic disturbance, and the consequent need for protection measures for such sensitive populations.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 12