We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
The Effects of Grazing by the Limpet, Acmaea Insessa, on the Kelp, Egregia Laevigata, in the Intertidal Zone.
- Authors
Black, Robert
- Abstract
The limpet Acmaea insessa lives on and east only the kelp Egregia. In the intertidal zone around Santa Barbara, California, USA the grazing activities of this limpet caused extensive and conspicuous damage to the majority of the larger Egregia. Severe damage weakened the main axis of the algae and was associated not only with loss of parts of Egregia, but also with one-third of the individuals found cast ashore; the remaining two-thirds suffered detachment from the substratum. The distribution of Acmaea insessa among Egregia was not uniform. Settlement of the limpet on experimental groups of algae was greater on old, post-reproductive Egregia than on new Egregia, was greater on crowded algae than on isolated algae, and was greater on individuals with adult limpets already on them than on individuals without limpets. The density of limpets increased with increasing algal length. Results of these settlement patterns were that crowded algae suffered limpet-related mortality than isolated algae, and loss of parts of individuals was more prevalent among large algae. These risks associated with loss and mortality of Egregia were countered by better survival and faster growth of small limpets in grazing scars than on intact surfaces. Experimental tests of other effects of limpet on Egregia revealed that damage by the limpet did not affect growth rate of algae or the timing and numbers of reproductive sporophylls. However, Egregia did respond to loss of parts by producing more branch rachises than those plants remaining intact. Evidence from this and other studies suggests that, although isolated Egregia suffered less mortality from limpets and had several other advantages over crowded algae, their large size was associated with mortality by detachment which may have balanced or outweighed the advantages of isolation. Loss of rachises because of grazing damage, a form of pruning by the limpet, could have served the beneficial function of preventing an Egregia from becoming so large that it was susceptible to detachment. Egregia has several escape mechanisms from the prudent predator Acmaea insessa.
- Subjects
EGREGIA; ALGAL reproduction; GRAZING; GEOGRAPHICAL distribution of algae; ALGAL growth
- Publication
Ecology, 1976, Vol 57, Issue 2, p265
- ISSN
0012-9658
- Publication type
Article
- DOI
10.2307/1934815