with diameters less than 0.25 millimeter. These were the only 

 stations which included a significant proportion of silts and clays 

 C< 0.062 millimeter). The mean grain sizes at these two stations 

 were essentially identical. 



The first sand stations beyond the first reef (HS-4 and 

 GS-4) were again characterized by a predominance of coarse and very 

 coarse sands with similar mean grain sizes [0.829 and 0.752 milli- 

 meter) . 



At the outermost sand stations, located just inside the 

 second reef, coarse and very coarse sands predominated on both 

 transects. However, at Golden Beach, there was also a high propor- 

 tion (28.65 percent) of particles larger than 2 millimeters. This 

 fraction included many large calcareous fragments which appeared to 

 be of echinoderm origin. 



The carbonate fractions of sediments at all stations except 

 HS-2 and GS-2 were in excess of 90 percent, which reflects the 

 biogenic origin of most of these particles. 



The organic content at all sand stations was very low, 

 ranging from 0.6 to 2.3 percent and averaging only 1.7 percent 

 on each transect. 



2. Sandy- Bottom Fauna . 



Core samples from the two transects yielded 114 species of 

 benthic invertebrates, not including the oligochaete and nemertean 

 worms which were not separated into lower taxa (Table 2) . Most 

 samples were dominated by polychaete annelids which comprised 

 about one-half (49.1 percent) of the species recorded and 52.5 

 percent of the individuals. Oligochaete annelids, while not 

 identified to species, were also important components of the 

 community, comprising another 38.3 percent of the fauna. Crusta- 

 ceans, mollusks, and all other invertebrate groups included more 

 than one-half the species recorded, but only 9.2 percent of the 

 total fauna. 



The mean number of individuals (Fig. 5) and species (Fig. 6) 

 per core at each sand station, within 95 -percent confidence limits, 

 were calculated (t-test) with reference to statistical tables in 

 Rohlf and Sokal (1969) . Differences and similarities within and 

 between transects are readily apparent and are discussed below, 

 along with a more detailed description of findings at each station. 



a. Hallandale Beach . The most conspicuous feature in the 

 distribution of this fauna was a pronounced increase in both density 

 and diversity at the two outermost stations, which yielded 92 

 percent of the organisms collected (Figs. 5 and 6). Densities at 

 stations HS-4 and HS-5, located between the first and second reefs, 

 averaged approximately 30 times that of subtidal stations HS-2 and 

 HS-3 inshore of the first reef. 



Samples at intertidal station HS-1 yielded unexpectedly high 

 densities of 1,530 individuals per square meter, based on extrap- 

 olated data. However, 66.1 percent of the fauna consisted of only 

 one species, the cirolanid isopod, Eurydice littoralis . This isopod 

 is sporadically abundant on beaches in tropical areas and may occur 



