ROCKY INTERTIDAL STUDIES 



INTRODUCTION 



The intertidal zone and near-shore waters are among the most productive regions of the world (Mann 

 1973). Intertidal algae provide food directly and indirectly to snails, crabs, and other benthic invertebrates, 

 as well as to fish, shore birds, and man (Paine 1980; Edwards et al. 1982; Menge 1982). Some algae, 

 Ascophyflum nodosum for example, release a large portion of their annual biomass as detritus and dissolved 

 nutrients (.lossclyn and Mathieson 1978). Other algae, primarily annual species, are consumed directly. 

 I^rge perennial algae also contribute to the intertidal community's physical structure by providing shade 

 and protection to much of the shore biota, and attachment space for epiphytes (Lewis 1964; Stephenson 

 and Stephenson 1972; Menge 1975; Lobban et al. 1985). 



CJradients of many parameters affecting shore populations result in universal patterns of zonation 

 (C^hapman 1946; I^wis 1964; Zaneveld 1969; Stephenson and Stephenson 1972). Some of these parameters 

 can be quantified and characterized over time, and some can be experimentally manipulated in an effort 

 to determine causal relationships (Connell 1961; Paine 1966; Dayton 1975; Menge 1975). 



Rocky intertidal communities have certain attributes that make them ideal subjects for ecological 

 assessment (MYAPCo 1978; Wilce et al. 1978; IJLCo 1983; PSNII 1985). The stability of rocky shores 

 permits establishment of permanently marked sampling areas. A discrete segment of a community, in 

 many cases the same individual plants and animals, can be studied by successive observations. Some 

 shore species are long-lived, capable of integrating effects of environmental conditions over their life spans. 

 The presence of ephemeral species, which respond quickly to environmental conditions, reflects environ- 

 mental change or instability. Sessile and slow-moving species arc continuously exposed to potential 

 impacts; others arc motile, whose occurrence and abundance at a locality indicates the suitability of the 

 environment at a given time. Many intertidal species show precise seasonal patterns of occurrence, 

 abundance, and reproductive status. These seasonal patterns allow a multitude of spatial and temporal 

 biological comparisons (Vadas et al. 1978; Schneider 1981). 



