INTERTIDAL ZONATION PATTERNS OF MACROINFAUNA OVER A RANGE OF EXPOSED SANDY BEACHES IN SOUTH-CENTRAL CHILE

Ten sandy beaches, covering a range from reflective to dissipative con ditions, were sampled in south-central Chile to determine whether diff erent beach morphodynamic states support different macroinfaunal zonat ion patterns. Three patterns were distinguished through examination of kite diagrams and analysis using multivariate techniques: (1) in refl ective beaches with coarse sand, a single zone of air-breathing crusta ceans was located above the drift line; (2) a reflective beach with fi ner sands exhibited 2 faunal zones due to the addition of a second zon e of cirolanid isopods below the drift line; and (3) in intermediate a nd dissipative beaches 3 faunal zones were delineated, the above 2 plu s a broad zone covering the lower shore. Species representative of the se zones are Orchestoidea tuberculata and Excirolana braziliensis in t he upper shore, E. hirsuticauda and E. monodi in the middle shore and Emerita analoga and Bathyporeiapus magellanicus in the lower shore. Th is study also showed that zones were ordinated along an intertidal gra dient of sediment water content. The 3 zone pattern agrees with the wo rldwide scheme proposed by Dahl (1952; Oikos 4: 1-27). Body-size compa risons showed that individual sizes in some species differed across th eir intertidal distribution.