investigation (Hales and Calder, 1979). Stomachs were removed from the 
demersal species and preserved for laboratory analysis. In the laboratory, 
the stomachs were washed in tap water and transferred to 50% isopropanol, 
and contents of individual stomachs were sorted by taxa and counted. 
Colonial forms and fragments of animals were counted as one organism 
unless abundance could be estimated by counting pairs of eyes (crustaceans) , 
otoliths (fishes), or other parts. Any food items (i.e., fish remains) 
that might have been bait in blackfish traps were not included in the 
analysis. Volume displacement of food items was measured using a graduated 
cylinder, or estimated by using a 0.1-cm2 grid (Windell, 1971). 
4. Hydrographic Sampling 
During every sampling period, surface and bottom water samples were 
collected at all stations except SEI, which could not be reached by boat. 
Samples were obtained using a Van Dorn bottle and the parameters measured 
were temperature, salinity, dissolved oxygen, and water clarity. Water 
temperature was measured from stem thermometers mounted inside the Van 
Dorn bottles. Salinity was measured using a Beckman Model RS7B induction 
salinometer, or a YSI Model 33 S-C-T meter. Dissolved oxygen was 
measured using a YSI Model 51-B Dissolved Oxygen Meter, or by the modified 
Winkler titration method (Strickland and Parsons, 1972). Water clarity 
was measured using a Secchi disk. 
5. Data Analysis 
Community structure was evaluated through comparisons of species cover 
or abundance, diversity indices, and cluster analysis. Where appropriate, 
abundance estimates obtained from replicate sampling were statistically 
compared using the non-parametric Mann-Whitney U test. Only the motile 
macroinvertebrates were counted since most of the sessile fauna and flora 
observed on the jetties were colonial. 
Diversity indices used in the analysis of motile macroinvertebrates 
included Shannon's index (H') and measurements of species richness (SR) 
and evenness (J') as described by Margalef (1958) and Pielou (1975). 
The expressions for these indices are as follows: 
s 
H' =-7 a logy a 
i=1 
h 
where s is the number of species and P; is the proportion of the LE 
species in a collection, 
SR = (s - 1) 
log, n 
where s is the number of species and n is the number of individuals 
in a collection, and 
au = H' 
logs 
14 
