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Grazing Patterns of the Periwinkle and Their Effect on Sessile Intertidal Organisms
Author(s) -
Petraitis Peter S.
Publication year - 1983
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1939972
Subject(s) - littorina , barnacle , balanus , intertidal zone , biology , ecology , abundance (ecology) , herbivore , gastropoda , crustacean
The periwinkle, Littorina littorea, a common gastropod herbivore in the New England intertidal, strongly affects two abundant, sessile organisms, the green alga Enteromorpha and the barnacle Balanus balanoides. At very low densities, Littorina can maintain initially bare areas clear of Enteromorpha while higher densities are required to eliminate established patches. At low periwinkle densities, Enteromorpha interferes with Balanus settlement, while at high densities, Littorina appears to dislodge newly settle barnacle cyprids. Balanus abundance is greatest at intermediate Littorina densities. Experimental manipulation of periwinkle behavior through the use of partial cages shows that Enteromorphia can persist due to an interaction between snail behavior and surface irregularities. Certain areas are consistently missed which would normally be reached by a randomly moving grazer. There is no such refuge for Balanus. These results suggest that behavior—mediated effects may play an important role in maintaining diversity in the rocky intertidal.