considered critical to the benthic fauna. Although the SPM and turbidity 

 values obtained were generally high and varied widely between the nearshore and 

 offshore stations, there was little variation between the surface and bottom at 

 any given station, probably because of the wind-induced vertical mixing which 

 occurred immediately prior to and during nearly all sampling periods. 



Turbidity values for 21 July 1980 (App. B) and the turbidity plume visible 

 in Figure 2 collectively suggest that the harbor breakwaters may increase tur- 

 bidity in the vicinity of the harbor, by causing the resuspension of beach 

 sediment, when littoral currents exceed some miminum velocity. 



4. Macrozoobenthos . 



The composition of the macrozoobenthos in the study area is similar to 

 that recorded by Teter (1960), McKim (1962), and Schuytema and Powers (1966) in 

 samples taken from the nearshore waters of Lake Huron. 



The macrozoobenthos communities were compared before, immediately after, 

 and 1 year after beach nourishment by using Morisita's index value of community 

 similarity calculated for each station. The index values (Table 7) indicate 

 that the macrozoobenthos communities at station 1 in 1980 differed in 9 of 18 

 comparisons from the communities present at station 1 in 1981. At stations 2 

 to 4, however, the index values indicated that the macrozoobenthos communities 

 in 1980 were similar or highly similar in 51 of 54 comparisons to the macrozoo- 

 benthos communities present in 1981 . The dissimilarity among the benthos com- 

 munities at station 1 occurred at the reference transects I and VI, as well as 

 at transects II, III, IV, and V, which were with the area most likely to be 

 affected by beach nourishment. Also the variability in density estimates for 

 oligochaetes and chironcmids at transect III, stations 2 and 3, is in part 

 reflective of the highly variable substrate found here. It is concluded there- 

 fore that the beach nourishment activities were not responsible for this 

 dissimilarity. A more likely explanation is that the unstable substrate at 

 station 1 on all transects caused the macrozoobenthos to occur there in such 

 low densities that the communities present were often dissimilar. 



5. Fish . 



Gillnet and seine catches made during the present study indicate that the 

 fish cOTimunity in the vicinity of the Lexington Harbor is typical of that in 

 the nearshore waters of lower Lake Huron. Lists of species taken before and 

 after beach nourishment activities were conducted differed little and the 

 species that dominated the catch in 1980 were also the most abundant species in 

 1981 . The major exception was the gizzard shad which was taken in very large 

 numbers only in October 19 80, immediately after beach nourishment was 

 accomplished, and was virtually absent from the catch at other times. The 

 sporadic appearance of large numbers of gizzard shad in the nearshore waters of 

 the Great Lakes in the fall, (Edsall and Yocom, 1972; Caroots, 1976; Goodyear, 

 1978; Werner and Manny, 1979) appears typical of the species. Thus the large 

 catch made in October 1980 is probably unrelated to the beach nourishment 

 activities earlier in the month. The virtual absence of gizzard shad from the 

 catches in November 1981 may reflect the tendency for the species to be more 

 abundant in the nearshore waters in October than in November, as reported by 

 Caroots (1976). 



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