Benthic Macroinvertebrates 



Gangemi's 1992 study found no quantitative data linking sculpin 

 abundance with benthic macroinvertebrate density. It was 

 initially hypothesized that a direct relationship would exist 

 between sculpin density and benthic macroinvertebrate density, 

 since the literature states that invertebrates are a major 

 component of sculpin diets (Brown 1971) . This lack of a direct 

 link might be due more to sampling methodology rather than 

 results contrary to the hypothesis. Furthermore, zoobenthos have 

 various habitat preferences which may influence sculpin 

 distribution more (i.e. prey-item abundance) than benthic biomass 

 apparently does. 



Algal Density 



Findings in this study, and those of Gangemi (1992, p38) were 

 again similar; neither study found a direct relationship between 

 algal density and sculpin abundance. Gangemi indicates that as 

 sculpin abundance decreased at a number of sites, algal density 

 increased. Inversely, as algal density decreased, sculpin 

 abundance increased. A possible explanation is that sculpin were 

 cropping the algal community or feeding selectively on 

 macroinvertebrate predators of algal grazers. This would explain 

 lower algal densities at sites where sculpin densities were high. 

 Gangemi attributes the lack of an inverse relationship between 

 sculpin density and algal density at some sites to an algal 

 community dominated by a species not palatable to sculpin. 

 However, it was evident for the most part, that at sites where 

 sculpin were not present, filamentous algae was either rare in 

 abundance or not present. 



The inverse relationship between algae and sculpin might better 

 be explained by inefficient sampling methods. High algal 

 densities offer additional concealment for sculpin making it more 

 difficult to net them. This could lead to interpretations that 

 sculpin abundance was low at these sites. 



It is also plausible that sculpin prefer, or are relegated to 

 feeding on a particular algal species. Some algae may not be 

 digestible by sculpin or might possibly be too low in necessary 

 proteins for young sculpin 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. (Gangemi, 1992) 



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