John J.A. McLaughlin

SYMBIODINIUM MICROADRIATICUM FREUDENTHAL, A REVISED TAXONOMIC DESCRIPTION, ULTRASTRUCTURE.

The ultrastructure of Symbiodinium microadriaticum in vitro and in the type host Condylactis and Casseopeia is described and contrasted with previous observations on symbionts from Anemonia sulcata and the Pacific Tridacnidae. Its type description is emended with new electron microscopic observations and with a list of alternate hosts, including their distributions.

Effects of Five Metals on Susceptibility of Striped Bass to Flexibacter columnaris

Abstract Exposure of young striped bass Morone saxatilis (weight, 8.5–34 g) to a mixture of arsenic, cadmium, copper, lead, and selenium at 4 and 10 times the average environmental concentrations of 1–3 μg/L protected the fish from experimental infection with Flexibacter columnaris, the causal organism of columnaris disease. In four trials, all striped bass died within 7 d after a 2-min exposure to 5 × 106 F. columnaris cells in untreated water. In contrast, no fish died after a single days exposure to the metal mixture followed by infection with F. columnaris and a second exposure to the metals for seven more days. When striped bass were exposed 5 d to individual metals, copper protected against infection and cadmium offered marginal protection but was slightly toxic after 2 d exposure. Arsenic increased susceptibility to infection, and lead and selenium were without an apparent effect.

Serological investigation of the fish pathogen Edwardsiella ictaluri, cause of enteric septicemia of catfish.

The serological relationships among 32 isolates of Edwardsiella ictaluri obtained from fish were studied. The strains were extremely homogeneous in protein and lipopolysaccharide preparations as observed by sodium-dodecyl-sulfate polyacrylamide gel electrophoresis. Only minor variations were observed in the structural O-side chain subunits in three isolates; however, such variation did not preclude antigenic recognition by two E. ictaluri antisera in either microagglutination or Western blot immunoassays. The antigenic homogeneity of E. ictaluri was further demonstrated by microagglutination assays with both formalin-killed and heat inactivated cellular antigens. The minimal degree of antigenic variability observed suggested that most isolates of E. ictaluri compose a single antigenic serotype.

The association of phytoflagellate blooms in lower New York bay with hypertrophication

Abstract Large quantities of nutrients, including organic substances, in treated and untreated wastes, are discharged into the New York estuary. The possible relationship between annual phytoflagellate blooms in Lower New York Bay and the urban hypertrophication was investigated by means of tests of the utilization of a wide variety of organic C, N, and P compounds by the dominant phytoplanktonic organisms. Carbon compounds were tested at 50, 25, and 5 mg C l ; nitrogen compounds at 1.4, 0.7, and 0.14 mg N l ; and phosphorus compounds at 0.5, 0.25, and 0.1 mg P l . The results from the lowest concentration are considered of greatest environmental relevance. At the low concentrations Massartia rotundata (Lohmann) Schiller used 11, Olisthodiscus luteus Carter 14, and Prorocentrum micans Ehrenberg 15 of 20 organic carbon compounds; M. rotundata used 14, O. luteus 7, and P. micans 14 of 16 organic nitrogen compounds; M. rotundata used 6, O. luteus 8, and P. micans 7 of 8 organic phosphorus compounds. These results, together with complementary data indicating utilization of organic substances during blooms, suggest a bloom-hypertrophication association.

Differences of ammonia metabolism in symbiotic and aposymbiotic condylactus and cassiopea spp.

Abstract Patterns of the excretion of ammonia in aposymbiotic and symbiotic Condylactus and Cassiopea species suggest that zooxanthellae remove host-produced ammonia. Greater amounts of ammonia are removed by zooxanthellae present in Cassiopea exposed to light whereas symbionts in Condylactus remove larger amounts of ammonia in animals in the dark. The results also indicate that the rate of ammonia production by the animal is affected by light, although there are significant specific differences. It is suggested that the involvement of zooxanthellae in the re-cycling of nitrogen enhances the ecological efficiency of Condylactus and Cassiopea.

A mathematical model of PCB bioaccumulation in plankton

Abstract In batch experiments exposing individual plankton constituents to Aroclor 1254 PCB, the rate at which the organism approaches partitioning equilibrium appears to be partly size-dependent while the extent of PCB accumulation is species-specific. The sorptive desorptive kinetics of PCB in these experiments can be described mathematically by a first-order expression. Employing this expression in a model plankton food web permits examination of the role of feeding and sorptive processes in determining PCB body burden under various environmental conditions. When ingestion rates exceed desorption and excretion rates, a consuming organism accumulates PCB above levels predicted by equilibrium partitioning relationships. Feeding-induced oscillations in PCB body burden could thus obscure the reduction of soluble PCB concentration which determine a “baseline” PCB body burden. Unless referenced to a specific set of biological and environmental conditions, the importance of direct partitioning from water vs. food uptake appears to be a moot topic.

QUANTITATIVE AND QUALITATIVE STUDIES OF GUT FLORA IN STRIPED BASS FROM ESTUARINE AND COASTAL MARINE ENVIRONMENTS

Examination of the intestinal contents of 130 striped bass (Morone saxatilis) collected from the Hudson River and Long Island Sound during May to October 1981 showed that opportunistic fish pathogens—especially Aeromonas hydrophila—predominated in samples from both locations. Other isolates from both groups of striped bass included Vibrio, pseudomonads, flavobacteria, Alcaligenes, and enterics. Small numbers of Micrococcus, Bacillus, Corynebacterium, and Acinetobacter were also isolated. Total numbers of bacteria in the intestines were 100 to 1,000 times higher in striped bass from the Hudson River than in those from Long Island Sound.

Salinity influence on the ecology of phytoflagellate blooms in lower new york bay and adjacent waters

The possible role of salinity in phytoflagellate blooms in New York Harbor estuarine and oceanic waters was examined by culture studies of the dominant species. Massartia rotundata (Lohmann) Schiller (=Katodinium rotundatum (Lohmann) Loeblich III) grew best in the range 24–30‰, Olisthodiscus luteus Carter in the range 10–36‰, and Prorocentrum micans Ehrenberg in the range 27–36‰. The optimum ranges for all three species sufficiently match the characteristic bay-ocean range (17–32‰) to eliminate salinity tolerance as a major factor in bloom development. Laboratory simulation of the change from brackish-river to ocean water salinities, by culture preconditioning at 20‰ or at 30‰ before inoculation into a salinity gradient, shows stress effects on growth, especially in Massartia rotundata and Olisthodiscus luteus. It is speculated that salinity stress may temporarily affect the development of particular blooms of these two species.

Water-soluble vitamins in cells and spent culture supernatants of Poteriochromonas stipitata, Euglena gracilis, and Tetrahymena thermophila

Vitamins B6 and B12, biotin, folates, riboflavin, nicotinate, pantothenate, biopterin, and vitamin C (l-ascorbate) were assayed in Poteriochromonas stipitata, Euglena gracilis, and Tetrahymena thermophila cells grown in defined media and in spent culture supernatants. P. stipitata and E. gracilis synthesized, stored and excreted folates (mainly as 5-methyltetrahydrofolate), B6, riboflavin, pantothenate, nicotinate, biopterin, and ascorbate. E. gracilis synthesized and stored biotin. T. thermophila did not synthesize the above vitamins except for B12, biopterin, and ascorbate; it excreted biopterin and stored B12 and ascorbate. Thiamin was left of consideration because all 3 organisms are thiamin auxotrophs. Possible ecological implications of these findings are considered.

Nutrient availability for zooxanthellae derived from physiological activities of Condylactus spp

Abstract Differences in phosphate metabolism of symbiotic and aposymbiotic Condylactus suggest that the host animal makes available quantities of phosphate to support growth of zooxanthellae. Nitrite may serve as a nitrogen source for symbionts as indicated by host removal of nitrite from sea water. The presence of zooxanthellae is responsible for removal of phosphate from sea water in the dark whereas there is excretion during light periods. There is a greater uptake of nitrite from sea water in the light compared with the dark in symbiotic animals. Since nitrate is removed from sea water by aposymbiotic animals, the presence of nitrate reducing bacteria is proposed.