check on the adequacy of a sampling methodology. Since variation was low 

 at the 20-meter control station, temporal changes were confidently studied 

 and partitioned into the three groups proposed by Masse (1972) . 



Because of the bottom stability and general accessibility of the 20- 

 meter control station, ancillary studies were made on the vertical distri- 

 bution of the infauna (Oliver, 1973), the effect of experimental mass 

 accumulation of sediment, larval settling, and fish predation. Although 

 the faunal assemblage differed between the control station and the dis- 

 posal area, it did provide an adequate and important measure of the natu- 

 ral variations within a benthic assemblage. 



The control transect was located perpendicular to the shoreline on a 

 gently sloping sandflat approximately 1.6 kilometers south of the Monterey 

 Canyon head (Fig. 1). The transect consisted of three stations at 6-, 

 10-, and 20-meter depths. Prevailing winds and waves approached from the 

 northwest, although the largest winter storms often approached from the 

 south. Currents were primarily tidal, with a net southerly flow. Veloc- 

 ities often reached 50 centimeters per second (Broenkow and McKain, 1972). 

 During many low tides a plume of suspended material from the Elkhom 

 Slough and Moss Landing Harbor reaches the control area. Turbidity varies 

 seasonally, and is usually highest in the winter because of storms. The 

 Salinas and Pajaro Rivers also add a large amotmt of particulate matter 

 in the winter rainy season. Yearly temperature fluctuations are presented 

 in Figure 9. Upwelling in the Monterey Canyon head causes periodic tem- 

 perature changes in most seasons; a variation of 4° Celsius occurred in 

 one tidal cycle. The standing stock of chlorophyll in shallow water fluc- 

 tuates with the seasons. High chlorophyll values occur in spring and 

 summer; low values in the winter (Fig. 9) . 



The bottom sediment is mostly fine sand. Seasonal changes at the 

 beach move sand to depths of at least 10 meters (Fager, 1968; Oliver, 

 1973) . Large waves create a dense layer of suspended sand that oscil- 

 lates inshore and then offshore. The intensity of movement and resuspen- 

 sion of sediments decrease with increasing water depth. 



Development of the sampling plan began in March 1971. The first reg- 

 ular sampling was in July 1971 and the last in May 1973. Generally, 8 

 replicate cores were taken from each station per sampling period; 10 cores 

 were taken in March 1972. All sampling was done by divers using scuba. 

 The corers were 1.4-kilogram coffee cans which were opened at both ends 

 and could be capped underwater and easily transported. Depth of corer 

 penetration was 15 centimeters, and the surface area sampled was 0.018 

 square meter (15-centimeter diameter). With few exceptions, biological 

 data are presented as number of animals per core or sample (eight cores) . 

 Ninety-six percent of the individuals were found about 10 centimeters in 

 the sediment at the 10-meter station, and 93 percent (excluding one 

 species) at the 20-meter station (Table 3) . Samples were washed through 

 a 0.5-millimeter mesh screen. The residue was stained with rose bengale 

 and preserved in 10-percent Formalin. All animals were sorted from the 

 debris under a dissecting microscope, transferred to 70-percent ethanol 



