Linkages among physical and biological properties in tidepools on the Maine Coast Adrian Jordaan & Jeffrey Crocker & Yong Chen Received: 9 July 2010 / Accepted: 31 March 2011 / Published online: 27 April 2011 # Springer Science+Business Media B.V. 2011 Abstract Tidepools experience significant gradients in ecologically relevant physical variables along the transition from ocean to terrestrial habitat (vertical axis) and from open coast to inner bays (horizontal axis). Associations amongst physical and biological variables, divided into algal, invertebrate and verte- brate (fish) groups, were examined in a tidepool survey dataset. Physical variables and the three biological groups were submitted separately to a principal component analysis (PCA). PCA scores were evaluated with Pearson correlation coefficients across the sampling units (tidepools) to identify significant correlations. Initially little structure in the data and no correlation amongst variables was present. At the onset of summer, correlations were confined amongst physical variables and algal and invertebrate components, followed in the late summer with correla- tions between invertebrate and fish components. By the fall, correlations were confined to fish and algal/ invertebrate components. Species relationships fol- lowed a seasonal cycle with a succession from little to no structure, the forming of low trophic level relation- ships in the early summer to high trophic level relation- ships in late summer-fall, and deconstruction of structure with the onset of fall-winter storms and ice scour. The seasonal pattern, and well established vertical gradient, has nested within it species composition changes along a horizontal wave energy gradient. The horizontal gradient results in a shift from species which are physiologically adapted to extreme salinities and temperatures to those which are physically adapted to high wave-energy environments. Keywords Ecological multivariate statistics . Principal Component Analysis . Tidepool fish . Intertidal . Ecosystem structure Introduction Tidepools and the intertidal zone have proven to be ideal environments to test whether ecological structure is controlled by top-down predation rates (Paine 1984; Trussell et al. 2004) and environmental variability Environ Biol Fish (2011) 92:13–23 DOI 10.1007/s10641-011-9812-4 A. Jordaan School of Marine Sciences, University of Maine, Orono 04469 ME, USA J. Crocker University of Maine, Orono, ME, USA Y. Chen School of Marine Sciences, University of Maine, Orono, ME, USA Present Address: A. Jordaan (*) School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook 11794–5000 NY, USA e-mail: Adrian.Jordaan@sunysb.edu