38 



Algal Density 



The filamentous algae community was also hypothesized to be a critical component 

 for sculpins both as a food resource and as protection from predation. However, no direct 

 relationship between algal density and sculpin abundance was evident. In fact, as sculpin 

 abundance decreased at a number of sites, algal density increased. The inverse also held 

 true, as algal density decreased, sculpin abundance increased. One explanation for this 

 inverse relationship between sculpin abundance and algal density would be that sculpins 

 were possibly cropping the algal community or sculpins were selectivley feeding on 

 macroinvertebrate predators of algal grazers. Thus, algal densities would be lower at sites 

 where sculpin densities were high. 



The lack of an inverse relationship between sculpin density and algal density at some 

 sites could be attributed to an algal community dominated by a species not palatable to 

 sculpins. However, It was evident, for the most part, that at sites where sculpins were not 

 present, filamentous algae was either rare in abundance or not present. 



The inverse relationship between algae and sculpins might better be explained by 

 inefficient sampling methods. High algal densities offer additional concealment for 

 sculpins making it more difficult to net them, thus, possibly leading to interpretations that 

 sculpin abundance was low at these sites. 



It is also plausible that sculpins prefer or were relegated to feeding on a particular algal 

 species. Some algae may not be digestible for sculpins or might possibly be too low in 

 necessary proteins for young sculpins to pass through a critical age class. If this were the 

 case then sculpin density and distribution might be greatly influenced by the algal 

 community. Further studies in sculpin distribution should examine sculpin stomach 

 contents as well as the algal community at study sites. 



