Robert R.L. Guillard

Reduction of marine phytoplankton reproduction rates by copper and cadmium

Abstract The reproduction rates of 38 clones of marine phytoplankton were measured in media in which free cupric ion activity was controlled at different levels using a NTA-cupric ion buffer system. The major trend among species in their resistance to copper toxicity was a phylogenetic one, with cyanobacteria being the most sensitive, diatoms the least sensitive, and coccolithophores and dinoflagellates intermediate in sensitivity. The reproduction rates of most of the cyanobacteria were reduced at cupric ion activities above 10 −12 M, while most eukaryotic algae still had maximum reproduction rates at 10 −11 M. Four species, Emiliana huxleyi (Lohm.) Hay & Mohler, Skeletonema costatum (Grev.) Cleve, Thalassiosira pseudonana (Hustedt) Hasle & Heimdal and Thalassiosira oceanica (Hustedt) Hasle were particularly resistant to copper, being able to reproduce well at the highest cupric ion activities tested, 10 −9.5 M and 10 −9.2 M. There was no major difference, however, between neritic and oceanic species in their sensitivity to copper. The sensitivity of 20 species of marine phytoplankton to free cadmium ion activity was measured in a similar manner using an NTA-cadmium ion buffer system. As observed with copper, the prokaryotic cyanobacteria were the most sensitive to cadmium toxicity, diatoms were the least sensitive, and coccolithophores and dinoflagellates were intermediate. All cyanobacteria tested were dead at a cadmium ion activity of 10 −9.3 M whereas the reproduction rates of most of the eukaryotic algae were not reduced significantly until 10 −8.3 M. Comparison of these data with natural concentrations in sea water implies that cadmium is not an important ecological factor in unpolluted waters but natural copper concentrations may inhibit the reproduction of some phytoplankton species, especially cyanobacteria, in upwelled sea water. Copper may influence the seasonal succession of species.

Microwave treatment for sterilization of phytoplankton culture media

Abstract A standard microwave oven for the sterilization of phytoplankton culture media and apparatus was tested. Elimination of bacterial, algal, and fungal contaminants is achieved in

Coccoid eukaryotic marine ultraplankters with four different HPLC pigment signatures

Pigment compositions of 16 coccoid eukaryotic ultraplanktonic clones isolated from coastal and oceanic waters were investigated by high‐performance liquid chromatography (HPLC). Four distinct pigment signatures were observed, and clones were classified into subgroups based on the presence or absence and relative abundances of selected chlorphylls and carotenoids. The first subgroup (5 clones) was pigmented like chlorophyll b‐containing higher plants and resembled true chlorophycean algae. The second subgroup (3 clones) contained chlorophyll b and relatively high levels of prasinoxanthin, a carotenoid characteristic of certain members of the Prasinophyceae (sometimes grouped as the Micromonadophyceae). The third subgroup (5 clones) was pigmented in a similar fashion but had a twofold lower prasinoxanthin‐to‐chlorophyll a ratio and an unidentified carotenoid. The fourth subgroup (3 clones) lacked chlorophyll b and was pigmented like certain members of the Chrysophyceae (e. g. 19′‐butanoyloxyfucoxanthin‐containing Pelagococcus subviridis Norris) Online diode array spectral analysis of selected clonal extracts revealed the presence of Mg 2,4‐divinylphaeoporphyrin a5 monomethyl ester‐like and chlorophyll c‐like pigments in representatives of the prasinophyte‐like and chrysophyte like clones, respectively. These findings plus the occurrence of chlorophyll b, prasinoxanthin and 19′‐butanoyloxyfucoxanthin in the North Atlantic Ocean suggest that chrysophyte‐ and prasinophyte‐like organisms can be important biomass components of marine phytoplankton.

Rôles of temperature, salinity, and light in seasonality, growth, and toxicity of ciguatera-causing Gambierdiscus toxicus Adachi et Fukuyo (Dinophyceae)

Abstract The ciguatera-causing dinoflagellate Gambierdiscus toxicus Adachi et Fukuyo reached maximum abundance in the Florida Keys when the water temperature was ≈ 30°C; populations were over half maximum when temperature lay in the interval 27–30°C. In laboratory unialgal culture experiments, temperatures >29 and 1.4 × 10 16 quanta . cm -2 · s -1 (≈ 11% of full sunlight). Under optimum combinations of the aformentioned parameters, growth rates > 0.5 division · day -14 could be sustained and led to unusually high yields in large scale cultures of up to 360 mg (dry weight) · 1 -1 . Cultures grown at 27°C were more toxic than those at 21°C (3515 ± 500 cells · MU -1 vs. 16536 ± 2400 cells · MU -1 , sd). Cultures were also still capable of producing toxins at inhibiting high irradiance levels.

Additional carotenoid prototype representatives and a general chemosystematic evaluation of carotenoids in prasinophyceae (chlorophyta)

Abstract Quantitative carotenoid analyses of 3 additional species representing each of three pigment types of Prasinophyte algae grown in pure culture are reported. The carotenoids were characterized by chromatographic (TLC, HPLC), spectroscopic (visible and mass spectroscopy, and, in part, 1H NMR, circular dichroism), and chemical methods. Preprasinoxanthin was isolated for the first time and the structure of 6′-hydroxysiphonaxanthin 19-(trans-Δ2-dodecenoate) was elucidated. The presence of siphonein, identified as siphonaxanthin 19-(trans-Δ2-dodecenoate) in Prasinophyceae was confirmed. Small amounts of the corresponding trans-Δ2-decenoates were present. Authentic siphonaxanthin 19-(trans-Δ2-dodecenoate) was isolated from Codium fragile for comparison. Pyramimonas amylifera belonged to the siphonein type. Prasinococcus capsulatus produced carotenoids of the prasinoxanthin/uriolide type, whereas Nephroselmis olivacea only contained common green algal carotenoids. A chemosystematic evaluation is made on the basis of 13 species examined by methods including mass spectroscopy and supplemented by less documented literature data on 26 species. Plausible biosynthetic routes are proposed from structural interrelationships, including chiralities. The Prasinophyceae displays a diversified carotenoid complement; 30 carotenoids have been identified, 14 of which are peculiar to this algal class. Three carotenoid prototypes emerge: type 1, producing only common green algal type carotenoids; type 2 with additional carotenoids of the siphonaxanthin series; and type 3 with additional carotenoids of the prasinoxanthin/uriolide series. Carotenoids with e- and γ-end groups are abundant. The 7,8-dihydro feature of the unique uriolide series is compatible with unprecedented cyclization of the least unsaturated end group of neurosporene by an e-cyclase.

Carotenoid Distribution Patterns in Bacillariophyceae (Diatoms)

The distribution of carotenoids in 10 species of diatoms was determined qualitatively and quantitatively. Monoacetylenic carotenoids (diatoxanthin and diadinoxanthin, 12–43% of total), allenic carotenoids (fucoxanthin and fucoxanthinol, 49–81% of total), monoepoxides (diadinoxanthin, fucoxanthin and fucoxanthinol, 79–91% of total) and β,β-carotene (3–8% of total) were identified and analysed by methods including TLC, HPLC, MS, VIS and cochromatography with authentic standards. Trace amounts of echinenone and canthaxanthin were obtained from Navicula pelliculosa. Chemosystematic considerations are made.

Phaeocystis sp. clone 677-3—a tropical marine planktonic prymnesiophyte with fucoxanthin and 19′-acyloxyfucoxanthins as chemosystematic carotenoid markers

Abstract Unialgally cultured cells of the tropical isolate Phaeocystis sp. clone 677-3 (class: Prymnesiophyceae) were analysed qualitatively and quantitatively for carotenoids. Together with β,β and β-carotene, the acetylenic xanthophylls diatoxanthin and diadinoxanthin (isolated as diadinochrome) and the allenic apocarotenoid 19-hexanoyloxyparacentrone 3-acetate were present as minor carotenoids. The main TLC fraction was a mixture of fucoxanthin and its two derivatives 19′-hexanoyloxyand 19′-butanoyloxyfucoxanthin. Phaeocystis sp. clone 677-3 shares the possession of 19′-acyloxyfucoxanthins with four other members of the Prymnesiophyceae, one member of the Chrysophyceae and three members of the Dinophyceae. This carotenoid distribution pattern supports the suggestion that chloroplasts of 19′-acyloxyfucoxanthin-containing dinoflagellates are of prymnesiophycean or chrysophycean origin. The presence of 19′-Acyloxyfucoxanthins in Phaeocystis sp. clone 677-3 distinguishes this clone from other north temperate ones previously examined, supporting the idea that the genus comprises more than one species. Some morphological, oecophysiological and chemical features of potential use for the classification of the different subtaxa within Phaeocystis are briefly discussed. It is suggested that the carotenoid distribution pattern should be included in future taxonomic studies on Phaeocystis spp.

TAXONOMIC AFFINITIES OF MARINE COCCOID ULTRAPHYTOPLANKTON: A COMPARISON OF IMMUNOCHEMICAL SURFACE ANTIGEN CROSS-REACTIONS AND HPLC CHLOROPLAST PIGMENT SIGNATURES1

Immunological grouping, determined by affinities of polyclonal antibodies to surface antigens of intact cells, was used to characterize 19 clones of marine coccoid ultraplankton. The resulting cross‐reactive antigen groups corresponded to pigment‐groups as defined by HPLC analysis of chloroplast pigments (carotenoids and chlorophylls). Because immunological cross reactions are specific at the species level in groups of algae having well defined morphological criteria, we suggest that immunological methods can be used to recognize algae presently indistinguishable by standard morphological criteria, and especially in oceanographic applications involving qualitative cell enumerations of the ultraplankton.

The influence of some cembranolides from gorgonian corals on motility of marine flagellates

Abstract Crassin acetate, eunicin and eupalmerin acetate, three cembranolides (14-member ring diterpenoid lactones) derived from Caribbean gorgonians, were tested for their effect on a variety of marine flagellates. Included were three isolates of the genus Symbiodinium whose nonmotile forms occur as symbiotic zooxanthellae in coral reef organisms. Eunicin at a concentration of 5 ppm in seawater immobilized most of the flagellates tested. At 10 ppm eucinin immobilized in 10 min three organisms not affected within 24 h at 5 ppm. Crassin acetate and eupalmerin acetate were found active in limited testing.