OLR (1987) 34 (12) E. Biological Oceanography 1067

occurred in cages lacking Callianassa. Benthic microalgae accumulated on the surface in the absence of Callianassa, but were relatively more abundant at depths of 15 to 25 cm in their presence. Bacterial numbers increased between 30 and 100% in the presence of Callianassa, and meiofaunal numbers declined in proportion to the density of Callianassa. Taken in conjunction with published work on the detrimental effects Callianassa spp. have on corals, suspension-feeders and seagrasses, these results emphasize the powerful role Callianassa plays in structuring the communities of soft sediments. Zool. Dept., Univ. of Cape Town, Rondebosch 7700, South Africa.

g7:6990 Caine, E.A., 1987. Potential effect of f lo~ng dock

on a South ~ estnary. J. expl mar. Biol. Ecol, 108(1):83-91. Dept. of Mar. Sci., Univ. of South Carolina, Beaufort, SC 29902, USA.

87:6981 Davis, A.N. and R.T. Wilce, 1987. Algal diversity in

relation to physkal distmboee: a m o J c of successional stages in a subtidal cobble habitat. Mar. Ecol.-Prog. Set , 37(2-3):229-237.

Regression analyses of cobbles with attached algae (collected 4-5 m below MLW and segregated into four size categories representing a gradient of disturbance frequency) determined the relationship between cobble size and diversity and life-form of attached algae. Small (2 cm diam.), frequently disturbed cobbles are dominated by crustose algae and juvenile uprights and exhibit low diversity. Cobbles of 4.5 cm diam., dominated by crustose algae and annual uprights, are disturbed less fre- quently and have a higher diversity. Cobbles of 7 cm diam., disturbed infrequently, exhibit the highest diversity with equal amounts of crustose algae, annual uprights, and perennial uprights. The largest cobbles (9.5 cm diam.) are the least disturbed, exhibit lower diversity than intermediate size cob- bles, and are dominated by perennial upright species, representing the climax condition in this habitat. These patterns support the intermediate disturbance hypothesis and suggest that this com- munity is maintained in a non-equilibrium state. Dept. of Botany, Univ. of Massachusetts, Amherst, MA 01003, USA.

87:6982 Johnson, S.C. and R.E. Scheibling, 1987. Structure

and dynamics of epifannal amemblages on inter- tidal macroalgae ~ y / / u m nodosmu and Fucus ves/tm/os~ in Nova Seotia, Canada. Mar. Ecol.-Prog. Ser., 37(2-3):209-227.

Epifauna abundance and species composition show pronounced seasonal variation. Total density de- clined by 2 orders of magnitude between summer and winter. Harpacticoid copepods and their nauplii, nematodes, and halacarid mites were numerically most important throughout the study (May 1983- June 1984). Density was positively correlated with epiphytic algal biomass for most epifaunal taxa. Cluster analysis and multidimensional scaling also indicate that epifaunal sample groupings were strongly related to epiphyte biomass. Dept. of Biol., Dalhousie Univ., Halifax, NS B3H 4Jl, Canada.

87:6983 MarineUi, R.L. and B.C. Coull, 1987. Structural

complexity and juvenile fish predation on meiobenthos: an experimental approach. J. expl mar. Biol. Ecol. 108(1):67-81.

Juvenile spot (Leiostomus xanthurus) predation/dis- turbance on meiofauna and effectiveness of simu- lated worm tubes as refuges were assessed in laboratory experiments with intact natural estuarine sediments and three densities of worm tube mimics. No statistically significant predation on meiofaunal taxa in the habitat containing no tube mimics occurred. Mortality was significant for three of six taxa in the 'low complexity' habitat and three of six taxa in the 'high complexity' habitat. Evidence from more complex habitats suggests structure promotes mortality for certain meiofaunal taxa, resulting from predator/prey refuge interactions that make certain prey more vulnerable, or from a predator's ability to forage more efficiently amidst structure. Belle W. Baruch Inst. for Mar. Biol., Univ. of South Carolina, Columbia, SC 29208, USA.

87:6984 Pawlik, J.R., M.T. Burch and William Fenical, 1987.

Patterns of chemical defense among Caribbean coraJs: a p]i-eliminary survey. J. expl

mar. Biol. Ecol., 108(1):55-66.

Caribbean wrasse were used to determine the palatability of food pellets coated with freshly- extracted, lipid-soluble metabolites of 37 types of Caribbean gorgonian corals. Extracts of 19 types (51%) were highly unpalatable, four types (11%) were moderately unpalatable and 14 (38%) were palatable to fish in feeding assays. Gorgonians of the genera Pterogorgia and Eunicea were consistently highly unpalatable, those of Plexaurella were palatable and those of Piexaura were most frequently palatable. Serial dilutions of extracts from seven representative unpalatable types revealed that extracts inhibited fish feeding at pellet concentrations near or below metabolite concentrations in gorgonian soft tissue. Erythropodium caribaeorum and Pseudopterogorgia