Similarity of rocky intertidal assemblages along the Pacific coast of Japan: effects of spatial scales and geographic distance |
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Authors: | Masahiro Nakaoka Norihiko Ito Tomoko Yamamoto Takehiro Okuda Takashi Noda |
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Institution: | (1) Graduate School of Science and Technology, Chiba University, Inage, Chiba 263-8522, Japan;(2) Faculty of Fisheries Sciences, Kagoshima University, Kagoshima, Japan;(3) Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Japan |
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Abstract: | Factors and processes affecting community structures operate at various spatial and temporal scales. We analyzed how similarities
of rocky intertidal assemblages vary at different spatial scales using a nested, hierarchical sampling design. Intertidal
assemblages consisting of algae, sessile animals, and mobile animals were censused on five rock walls at each of five shores
chosen within each of six regions along the Pacific coast of Japan, encompassing 1,800 km of coastlines. Based on this sampling
design, similarities in assemblages were calculated using both qualitative (presence/absence) and quantitative (percent cover
and density) data, and compared at three spatial levels: (1) rock level (the finest spatial scale, encompassing several to
hundreds of meters), (2) shore level (the intermediate spatial scale, encompassing several to tens of kilometers), and (3)
region level (the broadest spatial scale, encompassing hundreds to thousands of kilometers). Cluster analysis showed that
assemblages were categorized into distinct regional groups except for the two southern regions, but they did not separate
clearly from each shore. A nested analysis of similarities revealed significant variation in similarities among regions and
among shores within each region, with the former showing greater variation. Similarity was negatively correlated with geographic
distance at the regional level but not at the shore or the rock levels. At the regional level, similarity decreased more rapidly
with distance for mobile animals than sessile organisms. The analyses highlighted the importance of broad-scale abiotic/biotic
factors such as oceanic current conditions and biogeographic factors in determining observed patterns in similarity of rocky
intertidal assemblages. |
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Keywords: | Geographic distance Hierarchical design Marine benthic organisms Multivariate analyses Pacific coast of Japan |
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