Comparing the flora represented by the 1986 

 collections to those collected in each of the pre-op 

 years (Table 2), there was a tendency at most 

 stations for red algae to comprise a smaller pro- 

 portion of the total flora found since Unit 3 began 

 operation than in the pre-op period. In most 

 cases, the relative decrease in the number of red 

 algal species was attributed to the absence (in the 

 3-unit operational period, to date) of some small, 

 rarely found plants. At all stations except FE, 

 the proportion of reds in 1986 was within one 

 percentage point of previous years' values, and 

 the decrease is not regarded as a major community 

 change. At FE, however, the proportion of red 

 algae in 1986 (35%) was 10 percentage points 

 lower than the pre-op summary, and the number 

 of red algal species (22) was at least 7 less than 

 in any previous year except 1985 (Table 2). 



These patterns represent a continuation of spa- 

 tial and temporal trends that have occurred at FE 

 since the opening of the second quarry cut in 

 August 1983 (NUSCO 1985), and are different 

 from those identified at the other sampling sites. 

 Many perennial species and associated epiphytes 

 at FE were eliminated in the summer of 1984 

 when water temperatures exceeded 28 °C. Com- 

 munity changes resulting from elevated water tem- 

 peratures included the loss of established popula- 

 tions of perennial macroalgae such as Chondrus 

 crispus, Ascophyllum nodosum, and Fucus 

 vesiculosus, and increased abundance and persis- 

 tence of opportunistic species such as the greens 

 Codir^m fragile and Enteromorpha flexuosa. Ele- 

 vated temperatures at FE also caused a decrease 

 in the number of brown algal species, thereby 

 decreasing the proportion of browns relative to 

 reds and greens (cf. Schneider 1981; Quarry Study 

 in NUSCO 1987). Changes at FE were identified 

 both as a decrease in species number (from a total 

 of 80 species in 1982 to 50 in 1985), and as a 

 shift in divisional proportions (more greens, fewer 

 browns and reds). 



Local spatial and temporal distribution patterns 

 are also apparent when the qualitative algal col- 

 lections are presented as number of species in 



each division (Table 2). Number of species in 

 each division and total number of species at each 

 station during the Unit 3 operational period gen- 

 erally fell within the range of previous years. 

 Fewer species have been collected in the 19 

 months since Unit 3 began operation than were 

 found in the 7 years of pre-op studies. Continued 

 collection during the 3-unit operational period 

 will augment the 3-unit species list. 



Relationships between the pre-op and 3-unit 

 operational floras may also be represented graph- 

 ically (Fig. 3). When division proportions of the 

 overall flora were analyzed, proportions were sim- 

 ilar and independent of species number. Relative 

 species proportions m the first 12 months of the 

 3-unit operational period (45:26:29) were virtually 

 identical to those of the pre-op summary (Fig. 

 3). The local flora proportions continue to be 

 similar to those of other researchers in the north- 

 west Atlantic (Vadas 1972; Wilce et al. 1978; 

 Schneider et al. 1979; Mathieson et al. 1981; 

 Mathieson and Hehre 1986). 



In brief, the algal flora of the Millstone area, as 

 represented by collections in the 3-unit operational 

 period to date, was similar to that reported for 

 2-unit operating conditions. The community 

 changes described at Fox Island-Exposed were 

 attributed to elevated water temperatures resulting 

 from opening the second quarry cut, not from 

 start-up of Unit 3. However, most of these 

 changes have persisted during 3-unit operations, 

 as water temperatures close to 28 "C have occurred 

 at FE in summer. The FE community has shown 

 some response to the periodic incursion of 

 ambient-temperature water that occurs near the 

 time of high tide (see Temperature section); e.g., 

 Fucus persists throughout the year, and isolated 

 Chondrus plants have been collected. However, 

 Ascophyllum has not recolonized, and Codium 

 and Enteromorpha remain the most abundant spe- 

 cies at FE. Continued monitoring at FE and at 

 nearby stations (e.g., FS, MP) will allow us to 

 determine whether the observed thermal effects 

 will remain within present bounds. 



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