Inter-Research > MEPS > v553 > p33-48  
Marine Ecology Progress Series

via Mailchimp

MEPS 553:33-48 (2016)  -  DOI:

On the very edge: faunal and functional responses to the interface between benthic seagrass and unvegetated sand assemblages

R. S. K. Barnes1,2,*, S. Hamylton3

1School of Biological Sciences and Centre for Marine Science, University of Queensland, Brisbane 4072, Queensland, Australia
2Biodiversity Program, Queensland Museum, Brisbane 4101, Queensland, Australia
3School of Earth & Environmental Sciences, University of Wollongong, Wollongong 2522, New South Wales, Australia
*Corresponding author:

ABSTRACT: Changes in macrobenthic spatial structure were investigated across the precise 0.5 m wide boundary zone between intertidal seagrass and unvegetated sand in Moreton Bay, Queensland, Australia. Faunal abundance and species density in the marginal seagrass were only slightly reduced relative to local non-boundary areas. Although gradual diminution in seagrass faunal abundance occurred towards the interface and a few locally dominant species were absent from the boundary zone, most transition was far from gradual, instead being exactly coincident with the specific 0.1 m interface between the 2 habitats. Over this distance, faunal abundance and species density fell by 56 to 60% (from 1412 to 625 m-2 and from an estimated 42 species per sampling horizon to 17, respectively). Dominant seagrass species were abundant right up to the interface itself, but their densities had fallen by 82% a further 0.1 m into the adjacent sand. Functional-group density and diversity mirrored these changes, decreasing over the same distance by 30 to 36%. Spatial analysis showed that adjacent cores along lattice sampling horizons, although spaced further apart, were more similar to each other than were those oriented across horizons, even though these were contiguous. Characteristic high animal species richness in the seagrass relative to adjacent sand appears to be not so much related to characteristics of the seagrass habitat as a whole rather than to the presence or absence of individual plants. Asymmetrically, distributions of species characteristic of the sand stopped somewhat in advance of the interface, leaving a marginal sand zone dominated by generalists occurring at equal (low) species and population density across both habitats.

KEY WORDS: Benthos · Biodiversity · Ecotone · Edge effects · Sandflat · Seagrass

Full text in pdf format
Supplementary material 
Cite this article as: Barnes RSK, Hamylton S (2016) On the very edge: faunal and functional responses to the interface between benthic seagrass and unvegetated sand assemblages. Mar Ecol Prog Ser 553:33-48.

Export citation
RSS - Facebook - - linkedIn