monthly quadrat and biomass samples are listed in Table V along 

 with their abundance values (average number of individuals per 

 square meter based on twelve monthly samples in a year's period). 

 Algae and hydroids and some of the small, burrowing, annelid 

 worms could not be satisfactorily counted and are listed as Common 

 (C) , Present (P) , or Absent (0). These organisms were not used in 

 calculating similarity or diversity indices for the stations. 



Dominance diversity indices (Margalef 1957) were calculated for each 

 station (Fig. 28). They showed deeper stations were less diverse 

 than shallow stations and that diversity in Safe Harbor was lower 

 than in the turning basin or at the control station. At Station 5, 

 the deeper station was more diverse than the upper station, possibly 

 as a result of settlement by larval organisms entrained in the effluent. 

 The unusually high diversity of Stations 7A and 7B was due to a mixing 

 of faunas from Safe Harbor and the shallow water turtle grass flats. 

 The low diversity at Station 9B was caused by high siltation rates at 

 that station. 



Similarity indices (Pearson et dl 1967) were calculated between all 

 stations in Safe Harbor to determine affinities in population struc- 

 ture (Table VI). Figure 29 shows the two largest similarity indices 

 for each station. (The figured squares represent the actual relative 

 geographic position of the quadrat stations in Safe Harbor). Station 

 IB, for example, was most closely related to Stations 2A and 2B. 

 Station 2B was most closely related to Stations IB and 3C. Stations 

 2A and 3A were closely related and apparently shared a fauna similar 

 to that associated with the effluent at Stations IB and 3C. 



Based on similarity indices, the stations clustered into three main 

 groups with two intermediate stations. Stations IB, 2A, 2B, 3A, and 

 3C formed one group separated sharply at the point of effluent dis- 

 charge from a second group. Stations 4B, 5A, 5B, 6A, and 6B. The 

 third group of stations consisted of Stations 7A, 9A, 8A, lOA, and 

 lOB. Station lA showed its greatest affinities with Stations 5A and 

 6A. The fauna at Station 7B was most similar to the fauna at Stations 

 3C and 5B. Station 9B was loosely associated ^^7ith Stations 5B and 4B. 



Figure 30 shows the similarities between all of the shallow water (A) 

 stations in Safe Harbor. There were two abrupt changes in the fauna; 

 at the discharge to the desalination plant and between Stations 6A 

 and 7A. Stations 7 to 9 were in the turning basin and approach channel 

 while Stations 1 to 6 were in Safe Harbor proper (Fig. 3). At deep 

 stations (Fig. 31), the fauna remained similar from Station IB to 3C. 

 There was a marked drop in similarity between 3C and 5B at the point 

 of effluent discharge. The sharp decline in similarity shoi^m for 

 the shallow stations between the harbor and turning basin was not as 

 pronounced in the deeper stations. The similarity in faunal popula- 

 tions between Stations 7B and 9B and the harbor stations may be attri- 

 buted to the movement of effluent into deeper portions of the turning 

 basin. 



80 



