winter storms. This agrees with Enright (1962) who studied the inter- 

 tidal Synohet'idiuin in southern California and found their numbers to be 

 adversely affected by storms. 



The greatest abundance of Synohelidiim was during periods 

 of low wave energy and the lowest numbers coincided with higher wave 

 energies (compare Figs. 7 and 32). There appeared to be no adverse 

 impact of beach replenishment upon intertidal populations of this 

 species group. 



(2) Euphilomedes spp. (Ostracod) . This ostracod group con- 

 sisted of two species, E. carcharodonta (distributed from British 

 Columbia to southern California) and E. longiseta (California). These 

 crustaceans occurred sporadically in large numbers. Ostracods are 

 mobile crustaceans and E. aavoharodonta is believed to be a detritus 

 feeder (Baker, 1975). This group ranked number one in abundance in the 

 3.7- and 6.1-meter depths but was only sampled once intertidally (Fig. 

 33, Table 11). 



This group was abundant only at Station B where densities 

 of over 8,000 individuals per square meter were estimated. Abundances 

 appear to be highest between June and October, but because of their 

 obvious patchy occurrence, relationships are difficult to discern. 

 However, during survey IV (postdisposal) when abundances at station B, 

 6.1 meters, increased to 6,900 per square meter; this group was scarce 

 at the 3.7-meter depth (133 per square meter). Strong aggregation is 

 evident in this species as indicated by large differences (p<.05) in 

 abundance between stations before beach deposition. 



(3) Eohaustorius spp . The taxonomy of this genus of amphi- 

 pods is poorly known for the eastern Pacific. More than one species 

 occurs in the nearshore California sediments (Smith and Carlton, 1975), 

 and at least two species were sampled at Imperial Beach, including 

 Eohaustorius washing tonianus . The abundance of this group ranked second 

 intertidally and fourth at the 6.1-meter depth (Table 11). 



Intertidal densities of Eohaustorius reached a maximum of 

 102 per square meter during survey III (June 1977, station B, concurrent 

 with beach replenishment) and remained high at this station through sur- 

 vey IV, July 1977 (Table 10). At the 3.7-meter depth the group was 

 sampled regularly with densities estimated from to 200 per square 

 meter. At the 6.1-meter depth densities also fluctuated greatly and 

 ranged from to 2,700 per square meter (Table 15). 



Intertidal abundances immediately after replenishment 

 appear to be positively correlated- Since this reponse was not ob- 

 served at station A approximately 2.5 months after the beach replenish- 

 ment operation had moved south of rock groin No. 2 or at station B less 

 than 3.5 months after replenishment, this potential enhancement of 

 abundances was of short duration. No relationship of abundance or 

 persistence to replenishment was observed at the 3.7- and 6.1-meter 

 depths. 



88 



