566 E. Biological Oceanography OLR (1988) 35 (6)

El80. Biochemistry

88:3549 Hay, M.E., J.E. Duffy, C.A. Pfister and William

Fenical, 1987. Chemical defense against different marine herbivores: are amphipods insect equiv- alents? Ecology, 68(6): 1567-1580.

The effect of various concentrations of pachy- dictyol-A and dictyol-E (from the brown seaweed DictYota dichotoma) on feeding by three herbivores that co-occur with DicO, ota in coastal North Caro- lina was evaluated. Dictyol-E significantly reduced fish and urchin consumption, but had no effect on amphipods. Pachydictyol-A significantly reduced fish grazing at relatively high concentrations, but had no effect on urchins and significantly increased amphipod grazing. Predation and herbivory by fishes may be major factors selecting for amphipods that can live on and eat seaweeds that are unpala- table to fishes. Univ. of North Carolina, Inst. of Mar. Sci., Morehead City, NC 28557, USA.

88:3550 Hay, M.E., William Fenical and Kirk Gustafson,

1987. Chemical defense against diverse coral-reef herbivores. Ecology, 68(6):1581-1591.

Five secondary metabolites from tropical marine algae and one compound from a sea-hare were coated onto the seagrass Thalassia testudinum and placed on coral reefs. Laboratory feeding assays with Piadema antillarum were also conducted. The fol- lowing compounds significantly reduced the amount of Thalassia eaten by both Diadema and reef fishes: stypotriol, from the brown seaweed Stypopodium zonale; pachydictyol-A, produced by several genera of brown seaweeds; elatol, from the tropical red alga Laurencia obtusa; and isolaurinterol, produced by several species of Laurencia. Pharmacological and crude bioactivity tests suggest that several of these function as general toxins. Inst. of Mar. Sci., Univ. of North Carolina, Morehead City, NC 28557, USA.

E220. Invertebrates (except E230-Crusta- cea, E240-Protozoa)

88:3551 Rosman, Ian, G.S. Boland and J.S. Baker, 1987.

Eplfannai aggregations of Vesicomyidae on the continental slope off Louisiana. Deep-Sea Res., 34(11A): 1811-1820.

Two species of bivalve Vesicomyidae living at a depth of 940 m in the central Gulf of Mexico were

photographed, counted and measured. These spe- cies, related to bivalves in chemoautotrophic com- munities in the Gulf of Mexico and at hydrothermal vents in the Pacific Ocean, occurred here in two apparently distinct aggregations clearly visible on the sea floor surface. Living vesicomyids were generally found amid dead shells and occurred in densities of 0.5-9.6 individuals per m 2. Distribution of living individuals within aggregations was patchy. Living clams appear to plow actively through a substrate of silty clay, leaving behind distinctive, curving furrows up to 205 cm in length. Estimates of density, size distribution and spatial distribution provide a basis for detection of change in the aggregations over time and for comparison with similar aggregations. Dept. of Oceanogr., Texas A&M Univ., College Station, TX 77843, USA.

E230. Crustacea

88:3552 Barthel, K.-G., 1986. The position of dominant

copepod species in the food web of typical water bodies of the Greenland Sea. Ber. Inst. Meeresk. Christian-Albrechts-Univ., 158:107pp. (In Ger- man, English abstract.)

Carbon and lipid content of adult and subadult stages of the dominant copepods in ice-covered and ice-free areas and food uptake under in-situ con- ditions were determined, along with particulate concentrations in the upper 300 m. Seawater par- ticulate concentration was very low under the ice cover while values were much higher in the marginal ice zone. Carbon and lipid content of animals from ice-covered areas suggest a poor nutritional situation for herbivorous zooplankton; ice algae were appar- ently not an appropriate or sufficient food source. At the marginal ice zone and in the East Greenland shelf polynya food was abundant due to phyto- plankton blooms. In the very productive ice-edge region a significant portion of newly formed algal cells could be utilized by the herbivorous copepods. Inst. fur Meeresk., Abteilung Mar. Planktol., Dusternbrooker Weg 20, D-2300 Kiel 1, FRG.

88:3553 Belk, Denton, 1987. Embryonic cuticles of Artem/a

during diapanse and hatching: insights from comparison with other Branchinpoda. J. crus- tacean Biol., 7(4):691-696. Biol. Dept., Our Lady of the Lake Univ., San Antonio, TX 78285, USA.