Halichondria

Abstract: In this paper we report and describe material of Halichondriidae sampled at 11 different stations in the Brazilian northeastern coast. Halichondria (Halichondria) marianae sp. nov. is a massively encrusting sponge, with firm texture, soft, fleshy, but compact and compressible. Color in vivo is dark green, becoming grayish or brown after fixation in ethanol; the spicules are smooth oxeas. Amorphinopsis atlantica from the Northeastern Brazil is thickly encrusting to massively, also with firm texture, color in vivo is usually yellow to dark green and both distributed in different regions, brownish after fixation in ethanol; the spicules are smooth oxeas and styles. A taxonomic study of these samples is given, including description and illustrations.

Abstract: The predatory activities of fishes are thought to have little impact on the distribution and abundance of sponges on Caribbean coral reefs. To test this premise, 15 species of sponges were transplanted from mangrove and grassbed habitats, where spongivorous fishes are rare, to shallow patch reefs, where spongivorous fishes are common. Twelve of these 15 sponge species could also be found in cryptic locations, but not in conspicuous locations, on nearby reefs. After 3 d, there was significant loss of wet mass of uncaged sponges versus caged sponges for nine sponge species because of consumption by spongivores, primarily angelfishes. A mean of >50% of the sponge tissue was consumed for seven species: Chondrilla nucula, Chondrosia collectrix, Geodia gibberosa, Halichondria sp., Halichondria melanodocia, Myriastra kalitetilla, and Tedania ignis. These results, in addition to other recent data on the chemical defenses of Caribbean reef sponges against generalist predatory fishes, suggest that predation plays an important role in structuring the reef sponge community and that predation limits the distribution of some Caribbean sponges.

Abstract: From the marine sponge Halichondria panicea a lectin was isolated and characterized The homogeneous lectin (composed of protein to 807% and of neutral carbohydrates to 141%) had a molecular weight of 78,000 (determined by gel filtration) and consisted of four subunits with a molecular weight of 21,000 each (determined by gel electrophoresis in the presence of sodium dodecyl sulfate) The hemagglutinating activity was only slightly dependent upon ionic strength and incubation temperature and did not require divalent cations, but it was inhibited by reagents for thiol groups The Halichondria lectin was completely inhibited in hemagglutination competition experiments in the presence of fetuin, D-galacturonic acid, D-glucuronic acid, polygalacturonic acid, or L-fucose The purified Halichondria lectin did not cause reaggregation of dissociated H panicea cells From the same sponge species bacteria were isolated and identified as Pseudomonas insolita These bacteria were cultivated in marine broth 2216 Under these culture conditions the bacteria grew only in the presence of the homologous lectin; the lectin-caused effect was not abolished by D-glucuronic acid or D-galacturonic acid However, after addition of a polysaccharide-containing fraction isolated from P insolita, the lectin-caused, growth-promoting effect was abolished Other lectins were found to exhibit no growth-promoting effect On the basis of colony counts, P insolita was the predominant bacterial species in the sponge extract; 19 X 10(6) Pseudomonas colonies were measured in extracts isolated from 1 g of sponge The assumption of an interrelationship between the sponge and the bacterium is supported by the results indicating that the Halichondria lectin has no effect on the growth of such bacteria isolated from six other marine sponge species Evidence is presented which indicates that the Halichondria lectin is not utilized during growth of the Pseudomonas species Lectin activity was detected on the surface of mucoid cells from H panicea From the data obtained the possibility is discussed that the Halichondria lectin is a basis for a symbiotic relationship between the sponge and the bacterium Images