The structure and seasonal variability of macrobenthic associations in four different patches on a Sportillo alterniflora bed at Arrozal Point, Cananéia, São Paulo State are described and compared. In the local intertidal marsh, densities of S. oltemifloro plants appear in sparsely or denscly arranged patches, both in tall and short forms. The infaunal polychaetes Copitella copitata, Isolda pulchella, Laconereis acuta accounted for 44.0% of the total individuals while epifaunal forms such as Helcobia australis, Littorina ollngulifera, Tholozidium rhombofrotalis and Sphoeromopsis mourei were the second most abundant components with 39.5%. Classilication analyses of sampling time in the same sampling patch indicated that species groups were formed basically by spatial similarity and peak densities of macrofauna and secondarily by temporal patterns. Temporal variations were evident with higher number of species in eolder months (winter and spring). Species diversity and evenness did not show clear seasonal pattcrns, although they were sigmlicantly different in sampling patchcs and time. Heleobia australis, Littorina agulifera and Anomalocardia brasilienses were dominant in tall sparse S. alterniflora with density pcaks occurring in winter/spring pcriods. Tholozodium rhombofrontalis and Sphoeromopsis mourei; were dominant in short sparse S. olterniflora with density peaks in summer. In tall, densely distributed S. altemiflora plants the higher densities occurred in winter and the dominant spccies were Nereis oligohoalina, Isolda pulchella and Copitella capitata. The species H. australis, L ongulifera and A. brasiliensis predominated in the short S. alterniflora plants denscly distributed, with faunistic peaks recorded in spring. The results suggcst that differenccs in form and aggregation of S. alternifloraimpart changes in the structure of macrobenthic fauna associated to this vegetation.
Habitat complexity; macrobenthic associalion; Spartina altemiflora marsh; Southern coast of São Paulo State; Brazil