ISLANDINIUM BREVISPINOSUM SP. NOV. (DINOFLAGELLATA), A NEW ORGANIC‐WALLED DINOFLAGELLATE CYST FROM MODERN ESTUARINE SEDIMENTS OF NEW ENGLAND (USA)1

Modern estuarine environments remain underexplored for dinoflagellate cysts, despite a rapidly increasing knowledge of cyst distributions in open marine sediments. A study of modern estuarine sediments in New England has revealed the presence of Islandinium brevispinosum sp. nov., a new organic‐walled dinoflagellate cyst that is locally common and probably of heterotrophic affinity. Resistance of this cyst to standard palynological processing indicates its geological preservability, although fossils are not yet known. Previously assigned species of the genus Islandinium are characteristic of polar and subpolar environments today and cold paleoenvironments in the Quaternary. The present record of I. brevispinosum extends the ecological and geographical range of this genus into the warm temperate zone, where I. brevispinosum occupies specific environments with reduced salinities and elevated nutrient levels.     

SEASONAL VARIABILITY IN POLYUNSATURATED ALDEHYDE PRODUCTION POTENTIAL AMONG STRAINS OF SKELETONEMA MARINOI (BACILLARIOPHYCEAE)1

The cosmopolitan bloom‐forming diatom Skeletonema marinoi Sarno et Zingone is known to produce toxic polyunsaturated aldehydes (PUAs) in response to cell damage that can affect a diverse suite of organisms, including grazing species and competitor plankton species. The production of PUAs in nine different S. marinoi strains isolated at three different times of the year (spring, summer, and autumn) was assessed in relation to the predominant conditions at the time of isolation from Gullmar Fjord, Skagerrak. During the initial stages of growth, PUA production potential of S. marinoi was generally the highest in summer strains, although there was a substantial variation among strains isolated at the same time. Spring strains, however, showed a strong capacity for increased PUA production potential in later stage cultures with diminishing nutrient levels, reaching amounts similar to those observed in summer strains. In contrast, PUA production potentials of summer and autumn strains did not change significantly from the original values. There is negligible grazing pressure during the spring bloom in Gullmar Fjord, but a potential for high competition for resources, such as nutrients, toward the later stages of the bloom. In contrast, grazing pressure is much greater during summer and autumn, and there may also be nutrient limitation at this time. The PUA production potentials of S. marinoi appear to reflect the ecological conditions at the time of isolation with higher production potentials in strains isolated when conditions were likely to be less beneficial for survival.     

GYMNODINIUM COROLLARIUM SP. NOV. (DINOPHYCEAE)—A NEW COLD‐WATER DINOFLAGELLATE RESPONSIBLE FOR CYST SEDIMENTATION EVENTS IN THE BALTIC SEA1

A naked dinoflagellate with a unique arrangement of chloroplasts in the center of the cell was isolated from the northern Baltic proper during a spring dinoflagellate bloom (March 2005). Morphological, ultrastructural, and molecular analyses revealed this dinoflagellate to be undescribed and belonging to the genus Gymnodinium F. Stein. Gymnodinium corollarium A. M. Sundström, Kremp et Daugbjerg sp. nov. possesses features typical of Gymnodinium sensu stricto, such as nuclear chambers and an apical groove running in a counterclockwise direction around the apex. Phylogenetic analyses based on partial nuclear‐encoded LSU rDNA sequences place the species in close proximity to G. aureolum, but significant genetic distance, together with distinct morphological features, such as the position of chloroplasts, clearly justifies separation from this species. Temperature and salinity experiments revealed a preference of G. corollarium for low salinities and temperatures, confirming it to be a cold‐water species well adapted to the brackish water conditions in the Baltic Sea. At nitrogen‐deplete conditions, G. corollarium cultures produced small, slightly oval cysts resembling a previously unidentified cyst type commonly found in sediment trap samples collected from the northern and central open Baltic Sea. Based on LSU rDNA comparison, these cysts were assigned to G. corollarium. The cysts have been observed in many parts of the Baltic Sea, indicating the ecologic versatility of the species and its importance for the Baltic ecosystem.     

SEASONAL VARIABILITY OF PHYSICOCHEMICAL AND RHEOLOGICAL PROPERTIES OF ULVAN IN TWO ULVA SPECIES (CHLOROPHYTA) FROM THE BRITTANY COAST1

The seasonal variability in the extraction yield, physicochemical characteristics, and rheological properties of ulvan from two Ulva species contributing to Brittany “green tides” has been studied. These seaweeds were collected in the water column for Ulva armoricana Dion, de Reviers et Coat and on hard substrata for Ulva rotundata Bliding. The maximum ulvan extraction efficiency was not related to the maximum ulvan content in the seaweeds, but with the active growth period of the seaweeds. Ulvan chemical structure, macromolecular characteristics, and rheological properties were affected by both species and seasons. The proportion of high‐molecular‐weight ulvan was the major factor positively correlated with the gelling properties. Characteristics of ulvan from U. rotundata subjected to tides were more affected by seasons than ulvan from U. armoricana living in a more constant environment. These results point to several useful recommendations concerning Ulva sp. biomass collected with regard to ulvan characteristics and uses.     

AKINETE PRODUCTION OF ANABAENA LEMMERMANNII AND A. CYLINDRICA (CYANOPHYCEAE) IN NATURAL POPULATIONS OF N‐ AND P‐LIMITED COASTAL MESOCOSMS1

A strong biomass increase of two Anabaena species was observed in natural plankton community enclosed into nine large mesocosms (51 m³) and manipulated with mineral nutrients and an organic carbon source during a 3‐week period in the coastal Baltic Sea. The water column and settled material from the bottom of the mesocosms were sampled at 2‐day intervals. Planktonic populations of Anabaena lemmermannii Richter and A. cylindrica Lemmermann and sedimentation rates of akinetes to the bottom were quantified. Comparing mesocosms with artificially induced nitrogen and phosphorus limitation, we found that during the third week of the experiment, the population size of A. lemmermannii was clearly higher in nitrogen‐limited units (by a factor of 2.4), whereas the production rate of akinetes was higher in the phosphorus‐limited units (by a factor of 2.5). Input of freshly produced A. lemmermannii akinetes to the benthos was on average 15 × 10⁶ and 6 × 10⁶ cells· m^?2·d^?1 in the P^? and N^? limited mesocosms, respectively. Our estimates of specific akinete production rate of A. lemmermannii in P^? and N^? limited mesocosms revealed an even larger divergence (a factor of 5.5), being on average 2.4 and 0.4 akinetes·10^?3 vegetative cells^?1·d^?1, respectively. The phosphorus addition effectively reduced akinete production of A. lemmermannii. Differences in the nutrient manipulation had no apparent effect on the biomass and akinete production of A. cylindrica. The akinete production pattern of A. cylindrica revealed a 1‐week delay compared with the vegetative population peak, whereas such a delay was not obvious in A. lemmermannii.     

A STRESS‐INDUCED PROTEIN ASSOCIATED WITH THE GIRDLE BAND REGION OF THE DIATOM THALASSIOSIRA PSEUDONANA (BACILLARIOPHYTA)1

We report the characterization of a cell‐surface protein isolated from the centric diatom Thalassiosira pseudonana Hasle and Heimdal. This protein has an apparent molecular weight of 150 kDa, is highly acidic, and is intimately associated with the cell wall. Although originally identified in cells experiencing copper toxicity, it is also induced by silicon and iron limitation but not by phosphate or nitrate limitation. Using immunofluorescence techniques, the 150‐kDa protein was localized to the girdle band region and covered the elongated girdle band region of morphologically aberrant cells suffering from copper toxicity. Although having biochemical similarities to girdle band associated proteins identified in pennate diatoms known as pleuralins, the 150‐kDa protein is not a sequence homolog and is predicted to have a number of unique features, such as chitin binding domains and a possible RGD cell attachment motif. Results presented here suggest that this protein is normally cell cycle regulated and may be involved in stabilizing cells during the division process.     

IDENTIFICATION AND ASSESSMENT OF DOMOIC ACID PRODUCTION IN OCEANIC PSEUDO‐NITZSCHIA (BACILLARIOPHYCEAE) FROM IRON‐LIMITED WATERS IN THE NORTHEAST SUBARCTIC PACIFIC1

We identified and investigated the potential toxicity of oceanic Pseudo‐nitzschia species from Ocean Station Papa (OSP), located in a high‐nitrate, low‐chlorophyll (HNLC) region of the northeast (NE) subarctic Pacific Ocean. Despite their relatively low abundances in the indigenous phytoplankton assemblage, Pseudo‐nitzschia species richness is high. The morphometric characteristics of five oceanic Pseudo‐nitzschia isolates from at least four species are described using SEM and TEM. The species identified are Pseudo‐nitzschia dolorosa Lundholm et Moestrup, P. granii Hasle, P. heimii Manguin, and P. cf. turgidula (Hust.) Hasle. Additional support for the taxonomic classifications based on frustule morphology is provided through the sequencing of the internal transcribed spacer 1 (ITS1) rDNA. Pseudo‐nitzschia species identification was also assessed by the construction of ITS1 clone libraries and using automated ribosomal intergenic spacer analysis (ARISA) for environmental samples collected during the Subarctic Ecosystem Response to Iron Enrichment Study (SERIES), conducted in close proximity to OSP in July of 2002. Based on ITS1 sequences, the presence of P. granii, P. heimii, P. cf. turgidula, and at least five other putative, unidentified Pseudo‐nitzschia ITS1 variants was confirmed within iron‐enriched phytoplankton assemblages at OSP. None of the oceanic isolates produced detectable levels of particulate domoic acid (DA) when in prolonged stationary phase due to silicic acid starvation. The lack of detectable concentrations of DA suggests that either these strains produce very little or no toxin, or that the physiological conditions required to promote particulate DA production were not met and thus differ from their coastal, toxigenic congeners.     

DISCOVERY OF A FERTILE PELAGOPHYCUS×MACROCYSTIS(PHAEOPHYTA) PUTATIVE HYBRID AND SUBSEQUENT PRODUCTION OF F2 SPOROPHYTES IN THE LABORATORY1

A fertile putative hybrid of Pelagophycus porra (Lem.)Setch. × Macrocystis pyrifera (L.) was discovered in Big Fisherman Cove, Santa Catalina Island, California, in March 1986. The plant possessed a single, solid primary stipe that bifurcated into two secondary stipes, each with a hooked-shaped pneumatocyst. A total of 15 blades, 14 with sori, were produced on two to three dichotomies above and below each pneumatocyst. Gametophyte development of spores released from sori and the resulting early sporophtes (2–3 mm) were typical of Laminariales. Gametophytes appeared within a day of spore germination, 500-cell stage sporophytts within 3–4 weeks, and 2–3 mm sporophytes within 5–6 weeks. The cultures expired before branching patterns could be determined.     

THE PERFORMANCE OF SPRAY‐IRRIGATED ULVA LACTUCA (ULVOPHYCEAE,CHLOROPHYTA) AS A CROP AND AS A BIOFILTER OF FISHPOND EFFLUENTS1

The seaweed Ulva lactuca L. was spray cultured by mariculture effluents in a mattress‐like layer, held in air on slanted boards by plastic netting. Air‐agitated seaweed suspension tanks were the reference. Growth rate, yield, and ammonia‐N removal rate were 11.8% · d^?1, 171 g fresh weight (fwt) · m^?2 · d^?1, and 5 g N · m^?2 · d^?1, respectively, by the spray‐cultured U. lactuca, and 16.9% · d^?1, 283 g fwt · m^?2 · d^?1, and 7 g N · m^?2 · d^?1, respectively, by the tank U. lactuca. Biomass protein content was similar in both treatments. Dissolved oxygen in the fishpond effluent water was raised by >3 mg · L^?1 and pH by up to half a unit, upon passage through both culture systems. The data suggest that spray‐irrigation culture of U. lactuca in this simple green‐mattress‐like system supplies the seaweed all it needs to grow and biofilter at rates close to those in standard air‐agitated tank culture.     

DEVELOPMENT OF SEQUENCE CHARACTERIZED AMPLIFIED REGION MARKERS FROM INTERSIMPLE SEQUENCE REPEAT FINGERPRINTS FOR THE MOLECULAR DETECTION OF TOXIC PHYTOPLANKTON ALEXANDRIUM CATENELLA (DINOPHYCEAE) AND PSEUDO‐NITZSCHIA PSEUDODELICATISSIMA (BACILLARIOPHYCEAE) FROM FRENCH COASTAL WATERS1

Harmful algal blooms are a serious threat to shellfish farming and human health all over the world. The monitoring of harmful algae in coastal waters originally involved morphological identification through microscopic examinations, which was often difficult unless performed by specialists and even then often did not permit identification of toxic species. More recently, specific molecular markers have been used to identify specific phytoplankton species or strains. Here we report on the use of the intersimple sequence repeat (ISSR) technique to develop specific sequence characterized amplified region markers (SCAR) and to identify with these tools two toxic species in French coastal waters, the diatom Pseudo‐nitzschia pseudodelicatissima (Hasle) Hasle and the dinoflagellate Alexandrium catenella (Whedon and Kofoid 1936), Balech 1985. Six polymorphic ISSR regions were selected among amplified fingerprints of a representative sample of phytoplankton species. After cloning and sequencing the selected polymorphic ISSR regions, pairs of internal primers were designed to amplify a unique and specific sequence designed as a SCAR marker. Of the six selected SCAR markers, three were specific to P. pseudodelicatissima and one for A. catenella. The SCAR marker specificity was confirmed by using basic local alignment search tool comparison, by experimental assays on different strains from 11 countries, and by checking that the sequence amplified was the expected one. When tested on water samples collected along the French shores, the four specific SCAR markers proved to be efficient tools for fast and low‐cost detection of toxic phytoplankton species.     

RAPID ASSEMBLY OF A WOUND PLUG: STAGE ONE OF A TWO‐STAGE WOUND REPAIR MECHANISM IN THE GIANT UNICELLULAR CHLOROPHYTE DASYCLADUS VERMICULARIS (CHLOROPHYCEAE)1

Upon injury, selected coenocytic algae are capable of forming temporary wound plugs to prevent detrimental cytoplasmic loss. Wound plugs of Dasycladus vermicularis ([Scropoli] Krasser) were harvested 5 min post‐injury and dried. The plug material contained 94% water and can be considered a hydrogel. The gel plug extended several millimeters from the cut end and filled the space inside the cell wall, which resulted from cytoplasmic retraction. Total organic carbon included 55% sugars, 5%–15% protein, and 0.18% lipids. The major sugars were glucose, galactose, mannose, and galacturonic acid. Fluorescein isothiocyanate‐lectins specific for these sugars were localized around the plug matrix. Sulfur content calculated as sulfate corresponded to 17% of the carbohydrate by weight, and sulfated material was detected in plugs by Alcian Blue staining. Formation of the initial plug occurred within 1 min of injury and was not significantly perturbed by the addition of ionic, antioxidant, or chelating agents to the seawater medium. However, addition of exogenous d (+)‐galactose and d (+)‐glucose prevented formation of the nascent gel plug. Wound plugs that were allowed to form from 10 min up until 24 h post‐injury were isolated and incubated with selected biochemical probes to identify the biochemical processes involved in plug formation. The operative strategy in Dasycladus to prevent “cytoplasmic hemorrhage” required availability of sequestered carbohydrate and lectin precursor components throughout the thallus for plug assembly. Once the initial assembly had commenced, additional biochemical interactions were initiated (as a function of time) to promote structural integrity.     

A FORENSIC AND PHYLOGENETIC SURVEY OF CAULERPA SPECIES (CAULERPALES,CHLOROPHYTA) FROM THE FLORIDA COAST,LOCAL AQUARIUM SHOPS,AND E‐COMMERCE: ESTABLISHING A PROACTIVE BASELINE FOR EARLY DETECTION1

Baseline genotypes were established for 256 individuals of Caulerpa collected from 27 field locations in Florida (including the Keys), the Bahamas, US Virgin Islands, and Honduras, nearly doubling the number of available GenBank sequences. On the basis of sequences from the nuclear rDNA‐ITS 1+2 and the chloroplast tufA regions, the phylogeny of Caulerpa was reassessed and the presence of invasive strains was determined. Surveys in central Florida and southern California of >100 saltwater aquarium shops and 90 internet sites revealed that >50% sold Caulerpa. Of the 14 Caulerpa species encountered, Caulerpa racemosa was the most common, followed by Caulerpa sertularioides, Caulerpa prolifera, Caulerpa mexicana, and Caulerpa serrulata. None of the >180 field‐collected individuals (representing 13 species) was the invasive strain of Caulerpa taxifolia or C. racemosa. With one exception (a sample of C. racemosa from a shop in southern California belonged to the invasive Clade III strain), no invasive strains were found in saltwater aquarium stores in Florida or on any of the internet sites. Although these results are encouraging, we recommend a ban on the sale of all Caulerpa species (including “live rock”) because: morphological identification of Caulerpa species is unreliable (>12% misidentification rate) and invasive strains can only be identified by their aligned DNA sequences, and because the potential capacity for invasive behavior in other Caulerpa species is far from clear. The addition of the Florida region to the genetic data base for Caulerpa provides a valuable proactive resource for invasion biologists as well as researchers interested in the evolution and speciation of Caulerpa.     

EVOLUTION OF MICROALGAE IN HIGHLY STRESSING ENVIRONMENTS: AN EXPERIMENTAL MODEL ANALYZING THE RAPID ADAPTATION OF DICTYOSPHAERIUM CHLORELLOIDES (CHLOROPHYCEAE) FROM SENSITIVITY TO RESISTANCE AGAINST 2,4,6‐TRINITROTOLUENE BY RARE PRESELECTIVE MUTATIONS1

The increasing rates of global extinction due to human activities necessitate studies of the ability of organisms to adapt to the new environmental conditions resulting from human disturbances. We investigated the evolutionary adaptation of a microalga to sudden environmental change resulting from exposure to novel toxic chemical residues. A laboratory strain of Dictyosphaerium chlorelloides (Naum.) Kom. and Perm. (Chlorophyceae) was exposed to increasing concentrations of the modern contaminant 2,4,6‐trinitrotoluene (TNT). When algal cultures were exposed to 30 mg·L ^{? 1} 1 Received 9 July 2001. Accepted 23 July 2002.
TNT, massive lysis of microalgal cells was observed. The key to understanding the evolution of microalgae in such a contaminated environment is to characterize the TNT‐resistant variants that appear after the massive lysis of the TNT‐sensitive cells. A fluctuation analysis demonstrated unequivocally that TNT did not facilitate the appearance of TNT‐resistant cells; rather it was found that TNT‐resistant cells appeared spontaneously by rare mutations under nonselective conditions, before exposure to TNT. The estimated mutation rate was 1.4 × 10 ^{? 5} mutants per cell division. Isolated resistant mutants exhibited a diminished fitness in the absence of TNT. Moreover, the gross photosynthetic rate of TNT‐resistant mutants was significantly lower than that of wild‐type cells. Competition experiments between resistant mutants and wild‐type cells showed that in small populations, the resistant mutants were driven to extinction. The balance between mutation rate and the rate of selective elimination determines the occurrence of about 36 TNT‐resistant mutants per million cells in each generation. These scarce resistant mutants are the guarantee of potential for adaptation.