. The beach system is divided into three zones based on the physical environ- 

 ment and associated resident inhabitants: the beach, surf, and nearshore zones 

 (Fig. 2). 



1. Beach Zone . 



The beach is the zone of unconsolidated material that extends landward 

 from the low water line to the foredune line. It is an area subject to harsh 

 environmental and physical changes, including a wide temperature range, 

 salinity fluctuations, and wave action that causes cycles of erosion and ac- 

 cretion. The upper beach (above mean high water, MHW) is generally dry except 

 during storms. Storms can significantly modify the physical environment by 

 eroding or accreting the upper beach and altering the beach animal communities. 

 Because of this surface environment most of the permanent residents of the upper 

 beach are burrowers. The number of species and the population size on the upper 

 beach are limited; the organisms generally have a patchy distribution. Resi- 

 dent species of the upper beach generally emerge from their burrows only at 

 night. Characteristic species are ghost crabs (Ocypode) and sandfleas 

 (Talitridae) . The lower beach (below MHW) also has a paucity of species, but 

 usually large numbers of individuals. The lower beach is characterized by 

 worms (annelids), clams (Donax) , and mole crabs (Emerita) . Plant production 

 on a high-energy beach is generally low, but may include blue-green algae and 

 diatoms . 



2. Surf Zone . 



The surf zone is the area of breaking waves; it varies in location and 

 size. Seasonal wave patterns, sediment movement, and storms are major 

 physical forces that influence the distribution and abundance of animals in 

 this zone. Most of the benthic animals in the surf are burrowers and good 

 diggers, which are excellent characteristics to maintain position in the 

 bottom. Benthic animal populations are generally small with a clustered dis- 

 tribution. As an adaptation to this unstable environment, intertidal benthic 

 organisms tend to have a short life cycle (1 to 2 years) and a high rate of 

 reproduction (Marsh, et al., 1980). The nektonic and benthic animals that 

 reside in the surf are limited by wave action, lack of cover, and food supply. 

 Some of the animals migrate onshore and offshore with the tides and seasonal 

 sediment movement. 



3. Nearshore Zone . 



The nearshore zone extends seaward of the surf zone. This is physically 

 a more stable environment than the beach or surf zone, and the fish and 

 benthic animal populations are also stable and diverse. This zone has the 

 greatest abundance of commercial and sport fish and shellfish, and is the 

 most susceptible to physical perturbation. Nearshore organisms are generally 

 less subject to impacts of waves and natural sediment movement than those in 

 the surf zone. 



III. BEACH AND NEARSHORE ORGANISMS 



A sandy beach system, despite its uniform appearance, harbors a fauna of 

 great ecological diversity. The beach system offers space for three main 

 types of populations: the epifauna and endofauna which live on, above, and 



