The physical and biological interactions discussed above result in the 

 distribution of intertidal biota into bands parallel to the water line 

 (zonation) . Zonation is a general feature along the intertidal zone of the 

 characterization area and is most easily observed on a bedrock shore where all 

 the organisms are on the substratum surface. 



Many animals found in the intertidal zone are ubiquitous; that is, they are 

 able to live in a variety of habitats and tidal heights and have a wide 

 geographic distribution. They also tend to be more resistant to stress (both 

 human-induced and natural) than other marine animals. Species distributed 

 throughout the intertidal zone of marine subsystems of the characterization 

 area at all tidal heights, in all habitats are listed in table 4-9 (Larsen and 

 Doggett, in press ) . 



Oligochaetes and nematodes are dominant species at all habitat types in the 

 characterization area except the wave-battered bedrock headlands (Larsen and 

 Doggett, in press ) . Oligochaetes had as many as 12,000 individuals/nr at a 

 single cobble-beach station. 



Class: rocky shore. 



The NWI indicates that 36% of the marine 

 intertidal area in the characterization area is composed of rocky shore. The 

 biotic communities on rocky shore vary according to the degree of wave 

 exposure. That is, wave-battered headlands and islands support a different 

 flora and fauna than is found in sheltered embayments and estuaries. For this 

 reason the discussion will be in two sections: exposed rocky shores, 

 including bedrock shores and boulder beaches, will be considered here and 

 protected rocky shores will be addressed in chapter 5, "The Estuarine System," 

 as they are most fully developed in estuaries and bays. 



Table 4-9. Species Found in all Habitats and at All Tidal Heights in the 

 Marine Intertidal Subsystem in the Characterization Area. 



Taxonomic name 



Common name 



Aschelminthes 

 Rhynchocoela: 

 Annelida: 



Mollusca: 



Arthropoda: 



Nematoda 

 Nemertea 

 Oligochaeta 

 Nereis viren s 

 Eteone longa 

 Polydora sp. 

 Littorina littorea 



Littorina obtusata 

 Mytilus edulis 

 Modiolus modiolus 

 Myra arenaria 

 Balanus balaniodes 

 Jaera sp. 



Garamarus oceanicus 

 Carinus maenus 



roundworms 



ribbon worms 



same group as earthworm 



sandworms (polychaete) 



polychaete worm 



polychaete worm 



common periwinkle 



smooth periwinkle 



blue mussel 



horse mussel 



soft-shelled clam 



barnacle 



isopod (looks like sowbug) 



amphipod (scud) 



green crab 



4-78 



