A physically derived exposure index for marine shorelines

Abstract A new exposure index is described which can be derived from wind velocity, direction, duration and the effective fetch. Effective fetch is calculated from actual fetch modified by shoreline and offshore extents of shaIlow water. The index is calculated from the sum of these components for each unobstructed 22.5 degree compass sector of the shoreline. Data are presented for tests of the index as a predictor for littoral zonation phenomena in Bermuda and the Bayof Fundy, Canada. For the zones in both locations the index satisfies the majority of variance in the data. The vertical distribution of species is weIl modeIled in many cases, but not for others. In many cases significantly better fits are obtained if the basic index is modified using a component for shore slope. The index is useful as a numerical index of exposure which can be derived from standard weather data and hydrographic charts. It is also useful in pointing out littoral species that either do not respond to exposure, or respond in ...

[1]  B. Menge,et al.  Organization of the New England Rocky Intertidal Community: Role of Predation, Competition, and Environmental Heterogeneity , 1976 .

[2]  J. Harger.  THE EFFECT OF WAVE IMPACT ON SOME ASPECTS OF THE BIOLOGY OF SEA MUSSELS , 1970 .

[3]  B. Menge,et al.  Competition for Food between Two Intertidal Starfish Species and its Effect on Body Size and Feeding , 1972 .

[4]  A. Southward.  THE ZONATION OF PLANTS AND ANIMALS ON ROCKY SEA SHORES , 1958 .

[5]  P. Dayton.  Experimental Evaluation of Ecological Dominance in a Rocky Intertidal Algal Community , 1975 .

[6]  J. Crothers.  Variation in dog‐whelk shells in relation to wave action and crab predation , 1983 .

[7]  B. Menge,et al.  Species Diversity Gradients: Synthesis of the Roles of Predation, Competition, and Temporal Heterogeneity , 1976, The American Naturalist.

[8]  Joseph H. Connell,et al.  Effects of Competition, Predation by Thais lapillus, and Other Factors on Natural Populations of the Barnacle Balanus balanoides , 1961 .

[9]  P. Keddy.  Quantifying a within-lake gradient of wave energy in Gillfillan Lake, Nova Scotia , 1984 .

[10]  Joseph H. Connell,et al.  Community Interactions on Marine Rocky Intertidal Shores , 1972 .

[11]  B. Muus.  A field method for measuring “exposure” by means of plaster balls , 1968 .

[12]  J. R. Lewis.  THE ROLE OF PHYSICAL AND BIOLOGICAL FACTORS IN THE DISTRIBUTION AND STABILITY OF ROCKY SHORE COMMUNITIES , 1977 .

[13]  Willard Bascom,et al.  Waves and beaches: The dynamics of the ocean surface , 1964 .

[14]  R. Paine,et al.  The Pisaster-Tegula Interaction: Prey Patches, Predator Food Preference, and Intertidal Community Structure , 1969 .

[15]  Joseph H. Connell,et al.  A Predator‐Prey System in the Marine Intertidal Region. I. Balanus glandula and Several Predatory Species of Thais , 1970 .

[16]  A. Demetropoulos,et al.  Exposure to wave action: Measurements of an important ecological parameter on rocky shores on Anglesey , 1968 .

[17]  M. L. Thomas.  Littoral community structure and zonation on the Rocky shores of bermuda , 1986 .

[18]  R. Paine,et al.  THE EFFECTS OF GRAZING BY SEA URCHINS, STRONGYLOCENTROTUS SPP., ON BENTHIC ALGAL POPULATIONS1 , 1969 .

[19]  W. J. Syratt,et al.  An exposure scale for marine shores in western Norway , 1978, Journal of the Marine Biological Association of the United Kingdom.

[20]  J. G. Field.  The ‘Turbulometer’—An Apparatus for Measuring Relative Exposure to Wave Action on Shores , 1968 .

[21]  Martin W. Johnson,et al.  The oceans : their physics, chemistry, and general biology , 1943 .

[22]  Mark W. Denny.  A simple device for recording the maximum force exerted on intertidal organisms1 , 1983 .

[23]  P. Dayton.  Competition, Disturbance, and Community Organization: The Provision and Subsequent Utilization of Space in a Rocky Intertidal Community , 1971 .

[24]  J. Connell.  The Influence of Interspecific Competition and Other Factors on the Distribution of the Barnacle Chthamalus Stellatus , 1961 .

[25]  Mark W. Denny.  Forces on intertidal organisms due to breaking ocean waves: Design and application of a telemetry system1 , 1982 .

[26]  H. B. Moore.  The biology of Balanus balanoides. IV. Relation to environmental factors , 1935 .

[27]  A. Test.  Flowering Behavior and Natural Distribution of the Eastern Ragweeds (Ambrosia) as Affected by Length of Day , 1945 .

[28]  John R. Lewis,et al.  The ecology of rocky shores , 1964 .

[29]  T. A. Stephenson,et al.  The universal features of zonation between tide-marks on rocky coasts , 1949 .

[30]  B. Foster.  Desiccation as a factor in the intertidal zonation of barnacles , 1971 .