Architectural characteristics of two bed types of the seagrass Posidonia oceanica over different spatial scales |
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Authors: | JA Borg MJ Attrill AA Rowden PJ Schembri MB Jones |
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Institution: | aSchool of Biological Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK;bDepartment of Biology, University of Malta, Msida MSD06, Malta;cNational Institute of Water and Atmospheric Research, P.O. Box 14-901 Wellington, New Zealand |
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Abstract: | Seagrass beds occur in various morphological forms, ranging from small patches to continuous meadows. The endemic Mediterranean seagrass Posidonia oceanica forms dense and extensive stands that occur in several different morphotypes, including reticulate (seagrass interspersed with a different habitat type, such as bare sand) and continuous beds. This study, undertaken in the Maltese Islands, examined whether reticulate and continuous P. oceanica beds, located adjacent to each other and at similar depths, had different within-bed architectural characteristics. Five commonly used architectural measures (shoot density, number of leaves per shoot, mean leaf length, mean leaf width and shoot biomass) were measured from P. oceanica shoots collected from the two bed types at three different spatial scales: (1) tens of metres (‘small’ scale); (2) hundreds of metres (‘medium’ scale); and (3) kilometres (‘large’ scale). Results of 2-factor ANOVA (factor 1=bed type; factor 2=sampling locality) carried out at the three spatial scales indicated significant differences between the two bed types in shoot density (P<0.01) and leaf length (P<0.05) at the small scale, and in leaf number (P<0.05) at the large scale. Significant interactions were also apparent for shoot density (at the large scale) and for shoot biomass (at the medium scale). However, the results obtained did not indicate consistent architectural differences between the two P. oceanica bed types over the spatial scales considered. Spatial variations in within-bed architectural characteristics observed were therefore thought to be attributable mainly to the influence of local environmental factors. The findings are discussed with reference to the conservation and management of P. oceanica habitat. |
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Keywords: | Posidonia oceanica seagrass architecture seagrass bed type seagrass landscapes Maltese islands |
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