68 



Ptiget Sound Marine Sta. Pub. 



Vol. 1, No. 9 



Table 2. Shozving list of algae usually found in tide pools, and their 

 relative abundance in ten typical pools 



Table 3. Composition of Fucus Association 



Fucus evanescens 



Porphyra perforata 



Rhodomela larix 

 Prionitis lyallii 

 Microcladia borealis 

 Ceratothamnion pikeanum 

 Polysiphonia sp. 

 Ulva lactuca 



DOMINANT SPECIES 



Gigartina mamillosa 



PRIMARY SPECIES 



Gloiopeltis furcata 



SECONDARY SPECIES 



Colpomenia sinuosa 

 Soranthera ulvoidea 

 Hedophyllum sessile 

 Dermocarpa fucicola 

 Corallina officinalis 



3. The Ulva Association 



This association occupies a vertical belt about 2y2-3 meters wide 

 and is divided almost equally between the littoral and sublittoral zone 

 (Plate 12). Ulva lactuca, the dominant species, cannot stand much rough 

 water, and thus is usually found in quiet spots. Its favorite place is in 

 bays which have shallow gravelly bottoms. The plant body is large and 

 easily broken, and killed by exposure to the drying sun. Often after a 

 very low tide whole beds of Ulva are exposed to the sun for hours ; thus 

 they are killed and dried. When the tide comes in again they rise to 

 the surface and drift out to sea. This is the result of the plant not 

 being able to withstand much desiccation. Ulva usually forms very 

 dense beds in quiet water. In rocky places it is usually associated with 

 other algae, among which are Cladophora arcta and Enteromorpha linsa. 



