bluuebunny/crossref_metadata_2025 huggingface dataset:
PATTERNS OF INTERSPECIFIC INTERACTIONS IN THE ULVA‐DOMINATED INTERTIDAL COMMUNITY IN A SOUTHERN COAST OF KOREA
Authors: Bhang Y.J. , Kim J.H.
Published: March 2003

In the southern coast of Korea, rocky intertidal zones where green tide commonly occurs are dominated by Ulva pertusa, red algal turf (a mixed stand of Gigartina intermedia and Gigartina teedii) and species of Enteromorpha with highly opportunistic occurrence. To investigate their interspecific interactions, a field experiment was carried out using press effect of one species removal from permanent plots (20 x 20cm) set up on two different tidal heights. Mechanisms of interaction were also attempted using artificial plants to test the possible effects of shading, scouring, allelopathy of U. pertusa on the turf algae. The turf‐forming red algae lowered the abundance of U. pertusa presumably by inhibiting the recruitment of U. pertusa; this effect was consistent along the tidal height. However, the greater abundance of Enteromorpha was observed in the presence of turf in the upper zone, indicating a positive effect of turf on Enteromorpha. Once U. pertusa was successfully recruited and grown to the adult plant, it inhibited the growth of turf by shading, which was effective both in winter and summer regardless of desiccation stress. No scouring and allelopathic effects of U. pertusa on the turf were detected. When an open substrate was provided, Enteromorpha colonized the space faster than any other species in the upper zone, but the turf was the fastest one followed by U. pertusa and Enteromorpha in the lower zone. Results indicated that patterns of interaction represented a complex network with no ultimate winner and the outcomes of interaction varied over time and space.
PRELIMINARY FLUORESCENCE AND ULTRASTRUCTURAL OBSERVATIONS IN DICTYOSPHAERIUM PULCHELLUM (CHLOROCOCCALES, CHLOROPHYCEAE)
Authors: Rodríguez M.C. , De La Peña G. , Leonardi P.I.
Published: March 2003

Dictyosphaerium pulchellum is a common freshwater phytoplankter. After cell division, autospores remain attached to each other in a characteristic fashion through the remnants of the partially hydrolyzed mother cell walls (tracts), originating up to 64‐celled colonies immersed in abundant mucilage. Staining with ruthenium red and toluidine blue revealed mucilage acid properties, probably due to uronic acids in polysaccharides. Tracts and cell walls were Periodic Acid‐Schiff positive and showed fluorescence with calcofluor white, indicating the presence of fibrillar polysaccharides of the type cellulose and beta‐mannans. Intense fluorescence with berberine suggested some hydrophobic coating of fibrillar polysaccharides. Though cell walls proved to be acetolysis resistant, no secondary fluorescence was observed with primuline, suggesting that the hydrophobic polymer in the cell wall differed from algaenan. Ultrastructural observations revealed no trilaminar structure in the cell wall, but ruthenium red stained sections exhibited a “zipper‐like” band in the outermost cell wall layer both in autospores and mother walls. The cells have a large cup‐shaped chloroplast containing a single pyrenoid with the matrix traversed by double thylakoids and circled by starch plates. A lobulated nucleus occupied the concavity of the chloroplast. Dictyosomes appeared closely related with the nuclear envelope. Several vacuoles scattered in the cytoplasm and close to the nucleus showed electron dense content, which could also be observed in the periplasmalemmal space. Fluorescent dye quinacrine also showed active vesicle traffic.
A CANDID ASSESSMENT OF SYSTEMATICS IN THE LAMINARIALES: MUDDLED MORPHOLOGIES AND SKETCHY SEQUENCES
Authors: Saunders G.W. , Lane C.E. , Mayes C.
Published: March 2003

Algae of the Alariaceae, Laminariaceae and Lessoniaceae are the largest, most complex, and, arguably, most fascinating of the seaweeds. It is, therefore, a profound paradox that these species remain in taxonomic chaos despite the contemporary emphases on systematics. Setchell and Gardner established the classification system in 1925, recognizing these families on the basis of clear morphological features. At that time, however, they acknowledged that some species had features consistent with placement in two families, or that obscured logical placement in any of the families. Ironically, the problems noted by Setchell and Gardner have been ignored and the system has become entrenched in kelp literature. Initial molecular studies highlighted the shortcomings noted by Setchell and Gardner, and further indicated that little of the morphology‐based system was natural. It was obvious that the diagnostic morphological features, presence or absence of sporophylls and ontogenetic splitting, were ‘noisy’ being gained and lost independently many times in kelp evolution. Despite the insights of the initial molecular studies, they had limitations and key relationships remained unresolved. The investigations used the Internal Transcribed Spacers (ITS) of the ribosomal cistron that have phylogenetic limitations owing to their short length, which is exacerbated by the many variable regions that can't be aligned confidently and must be removed prior to phylogenetic analyses. Many molecular publications have appeared subsequent to the first ITS results, and their contribution towards elucidating kelp phylogeny will be assessed. Current investigations using the Large Subunit ribosomal DNA (LSU) for kelp systematics will also be discussed.
A PROPOSAL FOR A NEW RED ALGAL ORDER, THE THOREALES
Authors: Sheath R. G. , Müller K. M. , Sherwood A.R.
Published: March 2003

The freshwater red algal genera Nemalionopsis and Thorea are currently classified in the family Thoreaceae of the Batrachospermales. However, these two genera differ from other members of the order in having multiaxial thalli. The phylogenetic relationships of the genera were investigated using a combination of DNA sequence analysis (rbcL and 18S rRNA genes) and transmission electron microscopy. In both gene trees, Nemalionopsis and Thorea form well supported clades (87–100% bootstrap values) separate from other members of the Batrachospermales as well as taxa from the Acrochaetiales, Palmariales, and Nemaliales. In addition, analysis of the secondary structure of the 18S rRNA gene in Nemalionopsis and Thorea reveals an additional helix, which is not present in any of the other taxa within the Rhodophyta. Pit plugs of the Thoreaceae also differ from those of other members of the Batrachospermales in not having an outer cap layer that is not universally domed. Based on these findings, it is proposed that Nemalionopsis and Thorea represent a distinct taxonomic group that should be recognized as a new order, the Thoreales.
INTRA‐CELLULAR AND EXTRA‐CELLULAR TOXINS IN THE RED TIDE DINOFLAGELLATE, GYMNODINIUM BREVE
Authors: Blum P. C. , Henry M. S. , Pierce R. H. , Payne S. R. , Lyons J.I.
Published: March 2003

The marine dinoflagellate, Gymnodinium breve (Davis), produces several neurotoxins that cause neurotoxic shellfish poisoning (nsp), massive fish kills and respiratory irritation in marine mammals and humans. The common method for discerning toxic levels of G. breve for public health advisories is enumeration of live cells in a given water mass. In this study, laboratory cultures, as well as natural blooms, were added to a stirred ultra‐filtration cell concentrator to separate viable cells containing intra‐cell toxins from ambient water containing extra‐cell toxins. Methods were validated using various mixtures of lysed and whole G. breve laboratory culture. Extractions and recovery of brevetoxins were done using a C‐18 bonded‐phase glass fiber extraction disc eluted with methanol. Total PbTx toxin concentrations were quantified by HPLC/UV using a C‐18 column and an 85:15 methanol:water (1 ml min−1) isocratic elution at 215 nm. This method of separation and extraction was subsequently applied to water samples collected during natural blooms along two different areas of the Florida Gulf coast. The results indicated that early stages of G. breve blooms contained primarily intra‐cell toxins with extra‐cell toxins increasing as the bloom progressed, even though very few viable G. breve cells were present. This suggests that enumeration of cells alone may be insufficient and additional toxin quantitation is necessary.
WHAT DOES COMBINING MOLECULAR DATA SETS TELL US ABOUT DIATOM ORIGINS AND PHYLOGENY?
Authors: Theriot E.C. , Goertzen L.
Published: March 2003

The past several years have seen an abundance of molecular sequence data gathered on heterokont algae and other stramenopiles with the goal of resolving phylogenetic relationships among major groups. The original focus was on SSU rDNA sequence, but lately a significant number of sequences of plastid and mitochondrial encoded genes (specifically rbcL and coxI) have been made available. Of particular interest to us has been the origin of diatoms and the relationship of diatoms to other stramenopiles. According to most claims based on morphological data, typically viewed from a non‐rigorous evolutionary taxonomy standpoint (i.e. not with explicit cladistic or phylogenetic systematic methodology), diatoms are closely related to silica‐scaled golden brown algae (chrysophytes or synurophytes). SSU rDNA sequence data, however, often place diatoms at the base of the heterokont alga tree, and chryso/synurophytes at the tip with eustigmatophytes, for example, as the chryso/synurophyte sister group. More recent analysis of rbcL sequences, however, supports the traditional classification. It is not automatically to be assumed that there is incongruence between the sequences, however. Taxon sampling is different in the different analyses, methods of analysis are often different, assumptions used to “filter” data are different, etc. Moreover, the relative strength of signal appears to be different in the data sets. We will present an analysis of combined SSU, rbcL and coxI data, an analysis of taxon‐sampling issues, and review underlying assumptions and methodologies in an attempt to a) better understand the results of prior studies and b) reconcile the different hypotheses.
SPECIES COMPOSITION AND SEASONAL PERIODICITY OF MACROALGAL SPECIES IN CORPUS CHRISTI BAY, TEXAS
Authors: Agan J.C. , Lehman R. L.
Published: March 2003

Benthic algal sampling from selected sites along Corpus Christi Bay and from one site at the Port Aransas, Texas south jetty was completed between April 1999 and February, 2000. Species composition, seasonal periodicity, and fluctuations in temperature and salinity were determined. This is the first comprehensive study of benthic macroalgae conducted in Corpus Christi Bay, which is shallow, turbid, and lacks natural hard substrate. Man‐made jetties are necessary for suitable floral attachment. Macroalgae are affected by changes in salinity as freshwater inflows are followed by periods of drought, which increase salinity. These effects are most notable where freshwater enters at the south end near Oso Bay and at the north end at Nueces Bay. Previous Texas algal collections described species of Enteromorpha, Ulva, Gelidium, and Gracilaria as the most dominant plants of the area. This supports the current study with the additions of Hypnea musciformis and Centroceras clavulatum. Dominant plants at the Port Aransas jetty include Ulva fasciata, Padina gymnospora, and Hypnea musciformis. The Rhodophyta including Gracilaria, Gelidium, and Centroceras clavulatum dominate the bay and do so throughout the year. Chlorophytes, although few in species richness, are important to benthic coverage and biomass. Phaeophyta are found predominantly at the Port Aransas jetty with Sargassum, Dictyota dichotoma, and Petalonia fascia being most abundant. A transition occurs in species composition as the water temperature changes seasonally. Hincksia, Ectocarpus, and Petalonia fascia are found only during the cooler months.
PSEUDOFILAMENTOUS GREEN ALGAE FORM INDEPENDENT CHLOROPHYTE AND STREPTOPHYTE LINEAGES
Authors: Buchheim  , Buchheim J.A.
Published: March 2003

The pseudofilamentous condition in green algae has been characterized as the formation of a linear array of autospores. Although it is likely that this characterization will be found to be an over‐simplification, it serves as a logical starting point for a study of diversity among pseudofilamentous taxa. Therefore, given that molecular phylogenetic analyses have revealed that coccoid, autospore‐formers are found in a number of independent green algal lineages, it is reasonable to expect that pseudofilamentous taxa are likely to be found in a number of distinct lineages. In order to test this hypothesis, data from the nuclear‐encoded 18S r  RNA gene were collected from several pseudofilamentous, green algal genera (Geminella, Gloeotila, Hazenia, Interfilum, Microspora, and Sphaeroplea) and incorporated into an 18S rRNA database of chlorobiont taxa. Results from phylogenetic analyses of these data support (1) an alliance of Interfilum, two Geminella isolates, and Klebsormidium within the streptophyte lineage, (2) an alliance of two Geminella isolates and Microspora as a sister group to the ulvophycean/chlorophycean/trebouxiophycean clade or as a sister group to trebouxiophycean taxa, (3) an alliance of Hazenia with ulotrichalean taxa, (4) of Gloeotila with trebouxiophycean taxa and (5) an alliance of Sphaeroplea with chlorophycean taxa. These data confirm that the filamentous condition has evolved in a number of independent lineages. Moreover, these data further illustrate that the extent of molecular variability within the green algae is far from fully appreciated.
MONITORING THE PERSISTENCE OF GIANT KELP AROUND SANTA CATALINA ISLAND USING A GEOGRAPHIC INFORMATION SYSTEM
Authors: Bushing W.W.
Published: March 2003

Geographic information systems (GIS) facilitate monitoring and analysis of population distributions at spatial and temporal scales differing from those employed in conventional field monitoring. This study utilizes a GIS‐based gap analysis of a network of marine reserves around Santa Catalina Island relative to the regional ecology, disturbance regime, and persistence of giant kelp (Macrocystis pyrifera), a keystone species in the nearshore, marine environment. Catalina's orientation and greatly‐dissected coastline create diverse microhabitats with respect to storm exposure, temperature, light regime and topographic factors. GIS overlay methods applied to multi‐temporal kelp distribution maps generated a model representing the spatial “persistence” of kelp. Correlations between the kelp's geographic distribution and persistence, the disturbance regime and physical variables conferring resistance to or recovery from it were drawn. This analysis identified regions of persistent kelp under disturbance regimes markedly different from those in the existing reserves, suggesting the designation of additional reserves in unprotected areas is ecologically warranted.
EFFECT OF LIGHT QUALITY ON POLYSACCHARIDE YIELD AND COMPOSITION OF TWO RED ALGAE
Authors: Carmona R. , Vergara J.J. , Lahaye M. , Niell F.X.
Published: March 2003

Two species of agarophytes, Gelidium sesquipedale (Clem.) Born. et Thur. and Gracilaria tenuistipitata var. liui (Zhang & Xia), have been cultured in chemostat systems under different light qualities to study the response of growth and polysaccharide yield and composition to certain wavelengths. The yield of galactans, methoxyl groups and sulphate content in the agar as well as the starch concentration of these species are controlled by light quality in a different way, presumably because of their patterns of growth. The polysaccharide characteristics will be discussed in relation to the growth and metabolism of those algae.
NEW AND RARE CHRYSOPHYTES FROM WYOMING AND COLORADO LAKES
Authors: Aguiar R. , Kugrens P.
Published: March 2003

Colorado and Wyoming lakes with high pH values generally ranging from 8 to 10 are dominated by phytoplankton belonging to the chrysophytes, diatoms and cryptomonads. Our studies on phytoplankton diversity in Dowdy, South Delaney Buttes and Cowdrey Lakes in Colorado and Diamond and Twin Buttes Lakes in Wyoming have yielded several isolates of rare or new chrysophytes. These isolates were examined with light microscopy, SEM, TEM, and novel information regarding their structure is presented. Proposed new species belong to the genera Saccochrysis, Prymnesium and Chrysochromulina. Chrysophytes that were examined for the first time include Monochrysis aphanaster, Uroglenopsis, and a mixotrophic species of Ochromonas, which ingests small diatoms. Probable new species are the following: Saccochrysis sp. nov. differs in chloroplast structure, cell shape and cell number/colony, and absence of a posterior vacuole; Prymnesium sp. nov. is the first freshwater form examined with EM and differs in scale morphology; and Chrysochromulina sp. nov. is similar to Chrysochromulina parva but lacks scales. The ultrastructure of M. aphanaster is unique and appears to be a member of the Chrysophyceae. It has two flagella, one of which is emergent, while the other is hidden within an invagination of the cytoplasm. Diacronema and Sarcinochrysis spp. from these lakes also were isolated and reinvestigated, and some unique cellular features will be discussed.
POLYPHOSPHATE AND SILICEOUS GRANULES IN THE GAMETOPHYTES OF THE RED ALGA PORPHYRA PURPUREA (BANGIOPHYCEAE)
Authors: Chopin T. , Morais T. , Belyea E. , Belfry S.
Published: March 2003

Variations of the different phosphorylated fractions in tissues of starved and fresh plants of Porphyra purpurea, a representative of the Bangiophyceae, over a 72 hour incubation period in pulse‐enriched seawater (15 μM phosphorus and 25 μM nitrogen) were analyzed and compared to those in Chondrus crispus, a representative of the Florideophyceae, considered the more advanced of the two classes of the Rhodophyta. Differences point towards P. purpurea being a much more metabolically active phosphorus “pump” than C. crispus, with a higher phosphorus turnover rate, in which the orthophosphate fraction is predominant and acid‐soluble and acid‐insoluble polyphosphates are not as significant storage pools. Confirmation of the presence of acid‐insoluble polyphosphates, detected by chemical analyses, in the form of cytoplasmic granules was obtained by transmission electron microscopy and energy dispersive X‐ray microanalysis. The granules in P. purpurea were, however, much smaller (20 to 110 nm in diameter) than those in C. crispus (around 1 μm, but some larger than 2 μm in diameter). Larger granules (290 to 310 nm in diameter) were also observed. Their surface was more uniformly electron‐opaque without the reticulated or globular appearance of typical polyphosphate granules. Energy dispersive X‐ray microanalysis demonstrated that they were siliceous granules. To our knowledge, this is the first report in algae of such structures whose occurrence and metabolic role remain enigmatic.
BUILDING A SPECIES PHYLOGENY FOR THE GENUS COLEOCHAETE (COLEOCHAETALES) USING THE GENES RBCL AND ATPB
Authors: Cimino  , Delwiche C.F.
Published: March 2003

The freshwater green alga Coleochaete Breb. (Coleochaetaceae; Coleochaetales) is a key streptophyte genus and is important to the understanding of the evolutionary origin of embryophytes (land plants). To date only a few species have been available from public culture collections. To facilitate research on this genus we have isolated 17 previously uncultured species of Coloechaete from material collected in the United States, Puerto Rico, and the Dominican Republic. Sequences for the genes rbcL and atpB were determined for these new isolates of Coleochaete (and for existing cultures) and combined with sequences from representative other streptophytes. Phylogenetic analyses indicate that Coleochaete, along with Chaetosphaeridium and Chara, are closely related to embryophytes and constitute a ‘higher streptophyte’ clade. At least four well‐supported lineages exist within Coleochaete. Characteristic growth forms have been identified for these four lineages, with important characters including aspects of thallus establishment, thallus habit, zygote development and hair sheath position. These data provide an improved understanding of species diversity and character evolution in the genus Coleochaete, and facilitate examination of hypotheses concerning character evolution in the streptophytes.
HABITAT HETEROGENITY ON TROPICAL ROCKY SHORES: A SEAWEED STUDY IN SOUTHERN BRAZIL
Authors: Coimbra C.S. , Berchez F. A.S.
Published: March 2003

The main concepts in coastal community ecology have been proposed to explain relatively plain substrate, specially at temperate zones. We show that, on a irregular tropical substratum (a complex system of quarry stones with diverse shapes and sizes), the classical community zonation scheme is only applicable if we simplify the tridimensional substrate arrangement to a single dimensioned universe: the topographic level. Thus, the continuous spatial distribution implicited in “zones” notions is nonexistent. Our study was conducted on a rocky shore at Ubatuba (São Paulo State, Brazil) during one year. Percentual coverage was estimated using the quadrat method located by random coordinates. The topographic level was determined for each sampling element. Analysis of spatial splitting revealed large‐scale stratification of the shore into dominiums related to topographical level: 1) Upper Dominium (represented by Chthamalus sp. and Tetraclita spalactifera); 2) Transition Level (composed of Gymnogongrus griffithsiae, Gelidium aff. pusillum and often Centroceras clavulatum);. and 3) Lower Dominium (mainly Sargassum vulgare and occasionally Padina gymnospora, Dictyopteris delicatula and Grateloupia doryphora). These dominiums cannot be recognized as “bands” or continuous “zones” in a landscape view of the community. Otherwise, these bands could be observed on a small scale on each large quarry stone.
THE FISH POND EXPERIMENT: CHAPTER TWO
Authors: Coleman A.W.
Published: March 2003

Forty years ago, after 1 1/2 years of weekly surveys, a Baltimore fishpond was inoculated with three identifiable clones of Pandorina morum. The results of subsequent recollection attempts are published in Amer. Naturalist 118:761 (1981). More recently, molecular analyses have permitted characterization of the P. morum population that was endemic to the pond. The results, and their comparison with those from other P. morum sites, challenge some longstanding assumptions concerning the importance of various lifehistory stages to the introduction and maintenance of algal populations in temperate freshwater locales.
THE PHYLOGENETIC RELATIONSHIPS OF THE PHAEOTHAMNIOPHYCEAE, WITH COMMENTS ON CERTAIN CAPSOID MEMBERS OF THE CHRYSOPHYCEAE
Authors: Andersen R.A. , Bailey J.C. , Daugbjerg N.
Published: March 2003

The Phaeothamniophyceae was based upon ultrastructure, pigment analysis and rbcL gene sequences. Recently we have successfully obtained SSU rDNA sequences from members of this relatively new class. These sequences corroborate the phylogenetic relationship of the Phaeothamniophyceae as a close relative of the Phaeophyceae and Xanthophyceae. Additionally we show that the “walled”Chrysocapsa epiphytica is a synonmym of Tetrasporopsis fuscescens and belongs in the Phaeothamniophyceae. Conversely, “wall‐less” taxa such as Chrysocapsa vernalis, Dermatochrysis, and Chrysonebula belong within the Chrysophyceae. Furthermore, we suggest that the capsoid Tetrachrysis dendroides is a synonym of Stichogloea globosa and belongs within the Phaeothamniophyceae. We will also report new findings for other genera (e.g. Phaeobotrys, Phaeothamnion, Phaeoschizochlamys, Stichogloea). It appears that the capsoid habit evolved independently in the Phaeothamniophyceae and the Chrysophyceae, thus providing a new example of convergent evolution for thallus organization.
EFFECT OF NITROGEN ADDITION ON A MIXED SPECIES PHYTOPLANKTON BLOOM
Authors: DeYoe H. , Buskey E. , Jochem F. , Villareal T.
Published: March 2003

The Laguna Madre of Texas is a hypersaline lagoon that in recent years has been dominated by the brown tide alga, Aureoumbra lagunensis although a Synechococcus‐like sub‐dominant is typically present. Dominance of A. lagunensis is thought to be due at least in part to its nitrogen competitive abilities. A mesocosm study was performed to determine if an increase in ambient nitrogen concentration would lead to a shift in the dominant alga. Twelve fiberglass cylinders enclosing 1.2 cubic meters of Laguna Madre water were deployed for 16 days. Four times during this period, ammonium was added (N+ mesocosms) to half the mesocosms to achieve a post‐addition concentration of approximately 40 mM. The average initial particulate N/P ratio was 40/1 (SD = 2.9) which recent evidence indicates is within the range of N/P ratios for N‐limited A. lagunensis. In control mesocosms, total cell biovolume (TCB) of A. lagunensis cells dropped after 4 days by a factor of four and then increased to a level slightly above the day 0 value by day 16. In N+ mesocosms, A. lagunensis TCB was unchanged after 4 days then doubled by day 16. Despite the differences in final yield, growth rates of A. lagunensis in the two treatments were similar. The Synechococcus‐like organism, showed a four‐day lag before TCB in both treatments increased although at a slower rate in the control mesocosms. By the end of the experiment, TCB of A. lagunensis was two to six‐times greater than that of subdominant. Despite the nitrogen treatment, A. lagunensis retained dominance.
ALGAE AS WATER QUALITY INDICATORS FOR A DYSTROPHIC POND
Authors: Ferguson E. , Mosto P. , Nordone N. , Perez C.Iii. , Wojs J.
Published: March 2003

The physico‐chemical, bacteriological, and algal composition of R.U.Bi.S. Pond were studied since March 1999. The pond, located in Cape May County, NJ, is a dystrophic body of water, with high sediment:water ratio and organic matter content creating anoxic conditions during fall and early winter. Water quality indicators based on periphytic algae and water quality indices that are specific to R.U.Bi.S. Pond are being developed. Such indicators could be used for similar bodies of water and for the restorability of this dystrophic ecosystem integrity. Two sampling sites were studied. Samples were collected weekly, using a periphytometer, for seasonal analysis of succession. Samples for water chemistry, bacteriology, and periphytic algae were collected bi‐monthly. The predominant algal species found during summer ‘99 were Phormidium, Oscillatoria, Chlorella, and Eunotia. During fall ‘99, the predominant species were Oscillatoria and Phormidium. In winter, the community was dominated by Chlorella and Chlamydomonas. Species present year‐round were Nitzschia, Oedogonium, Eunotia, and Navicula. Data analysis indicated variations among the two sampling sites, with total cell counts and species diversity higher at the northern site. Algal cell counts, chlorphyll a concentrations, species diversity, and D.O. levels were greatest during summer. Biomass, hardness, HPCs and total organic carbon peaked during the fall. Nutrients, pH, and coliforms remained constant during the study period. The predominant algae found were pollution‐tolerant genera, categorizing the pond as highly dystrophic. Species diversity indices indicated that water quality decreased during the fall/winter months, with the southern site being more environmentally stressed than the northern site.
LET THERE BE LIGHT (BUT NOT TOO MUCH): MOLECULAR EVOLUTION OF LIGHT‐HARVESTING COMPLEXES
Authors: Green B.R.
Published: March 2003

The light‐harvesting antennas common to all photosynthetic eukaryotes belong to two protein familes: the Chl a‐binding core complex family (e.g. CP47, CP43), and the LHC superfamily, whose members bind a variety of Chls. The former are all chloroplast‐encoded and have high sequence similarity to their cyanobacterial homologs; the latter are all nucleus‐encoded and have a much more complex relationship with each other and their (presumed) cyanobacterial ancestors. Phylogenetic analysis of the LHC superfamily protein sequences show that they follow the endosymbiotic history of their hosts and suggest that the ancestral cyanobacterial genes were copied to the nucleus soon after the establishment of the primary endosymbiosis. Both families have members whose role appears to be related to photoprotection rather than light‐harvesting, suggesting that these families may have originated as stress‐response proteins. In support of this, all members of the LHC superfamily bind significant amounts of carotenoid, and much of the variation between them resides in the bewildering array of different carotenoids they bind. In fact, it has been suggested that this family originated as carotenoid‐binding proteins and only later acquired Chl (Gantt, E. 1998; Photosynthesis: Mechanisms & Effects I, pp. 239‐246).
THE ROLE OF CARBONIC ANHYDRASE IN THE FORMATION OF MOUGEOTIA (CHAROPHYCEAE) BLOOMS IN ACIDIC ENVIRONMENTS
Authors: Arancibia‐Avila P.E. , Coleman J.R. , Russin W.A. , Wilcox L.W. , Graham J. M. , Graham L.E.
Published: March 2003

Mougeotia sp, a dominant component of a metaphytic algal bloom‐forming alga in an experimentally acidified lake (Little Rock Lake, Vilas Co. WI) was isolated to analyze pH effects on carbonic anhydrase (CA) activity, localization, and algal morphology. A potentiometric method was used to assess internal and external CA activities using two CA inhibitors, ethoxyzolamide (EZA) and acetazolamide (AZA) in cultures grown at pH 5 and pH 8. External and total CA activities at pH 8 were significantly greater than those at pH 5, but internal CA activities were not significantly different at both pH levels. The non‐penetrating inhibitor AZA inhibited external CA activity at pH 8, whereas EZA, which inhibits internal CA activity in some green algae, did not inhibit Mougeotia CA activity, possibly because of permeability problems. Ultrastructural immunogold labeling with a polyclonal antibody for Chlamydomonas external CA suggested that an antigenically‐similar enzyme was located in the periplasmic space and inflated end walls of Mougeotia grown at both pHs. This antibody, labeled the Mougeotia chloroplast, but not the pyrenoid and cytoplasmic peripheral regions. Activity measurements, inhibitor results, and localization data were consistent with the operation of a carbon concentrating mechanism (CCM) at both pH levels. Growth form, cell dimensions, chloroplast morphology, and cell wall ultrastructure were significantly different in cultures grown at both pH levels. These features probably contributed to the ability of Mougeotia to form blooms in acidified waters. A polyclonal antibody to pea chloroplast CA did not label Mougeotia, suggesting evolutionarily significant differences in the plastid CA systems of this alga and higher land plants.
A REEXAMINATION OF THE SYSTEMATICS OF THE ACROCHAETIALES (RHODOPHYTA) USING LARGE‐SUBUNIT RDNA SEQUENCE DATA
Authors: Harper J.T. , Saunders G.W.
Published: March 2003

The taxonomic history of the red algal order Acrochaetiales is chaotic. There is no consensus in the literature as to how many genera should be recognized or in the assignment of the over 400 species to these genera. Morphological and anatomical studies have provided a suite of possible characters to delineate genera within this order, but there have been major discrepancies in the assessment and use of these features. The phylogenetic placement of the Acrochaetiales has also been the focus of debate. Once thought to be the most ancestral florideophyte lineage, recent molecular systematic studies have illustrated that this order is a derived lineage closely related to the Nemaliales and Palmariales. Phylogenies using sequences of the small‐subunit (SSU) rDNA have strongly supported two very divergent lineages within a possibly polyphyletic Acrochaetiales. The relationships between these two groups and among other closely related rhodophyte orders were not resolved. We have generated large‐subunit (LSU) rDNA sequence data for representatives of the Acrochaetiales and related taxa. Distance and parsimony phylogenies based on LSU and combined SSU and LSU data will be presented. The increased phylogenetic signal afforded by this approach will shed light on previous conundrums in the systematics of this group.
THE PRESENCE OF CALLOSE IN THE PRIMARY ZYGOTE WALL OF CHLAMYDOMONAS MONOICA AND THE EFFECTS OF ITS DEGRADATION ON ZYGOTE DEVELOPMENT
Authors: Bai  , VanWinkle‐Swift K.P.
Published: March 2003

Chlamydomonas monoica constructs a temporary primary wall around its developing zygotes. This study aimed to confirm callose as a component of the primary wall, as well as to note the effects of primary wall degradation on zygote development. Glucanase, specific for the β‐1,3 glycosidic bonds comprising callose, was added to mating media at concentrations ranging from 5 to 1 mg ml−1 and light microscope observations were made as the zygotes developed. The overall health of the zygotes was assessed by comparing their ability to germinate after exposure to chloroform vapors. The bright staining of the primary wall with aniline blue, specific for β‐1,3 polysaccharides, suggested the presence of callose. This was further supported by the adverse effects of glucanase on zygote development. After mating, declining levels of intact zygotes were found as their maturation continued, and dead immature zygotes accumulated in the treated cultures. Twelve days after mating, when the zygotes were plated for germination, fully mature zygotes were identified in only the lowest of the six enzyme concentrations. In addition, germinating zygotes from the treated cultures showed increased sensitivity to killing by chloroform vapors relative to untreated zygotes. These results suggest that callose is a key component in the primary zygote wall, and that its degradation negatively affects zygote maturation. Electron microscopy will be used to help determine whether structural defects in the primary wall occur as a result of glucanase treatment, and whether such defects affect secondary zygospore wall assembly.
THE COLONIAL GREEN ALGA ASTREPHOMENE GUBERNACULIFERA DISPLAYS A CHEMORESPONSE TO ACETATE
Authors: Hoops H.J. , Cocina A.E. , Binder D.S. , Widjaja A.
Published: March 2003

Astrephomene gubernaculifera is a colonial green alga capable of growth on sodium acetate in the dark. Because heterotrophic organisms often have mechanisms to detect and respond to food sources, we tested the response of A. gubernaculifera to a number of potential chemoeffectors. Acetate elicits strong chemoaccumulation in three different behavioral assays. However, there was no chemoaccumulation in response to the carbohydrates xylose, ribose, glucose, galactose, mannose, arabinose, fructose, maltose, lactose, and sucrose; the amino acids asparagine, arginine, cysteine, glutamine, glycine, histidine, isoleucine, lysine, phenylalanine, serine, threonine, and hydroxyproline; or glycerol. Interestingly, A. gubernaculifera did respond to propionate. This compound is structurally related to acetate, but is incapable of supporting growth in the dark. This implies that the chemosensory response in A. gubernaculifera is not the direct result of metabolic changes but rather involves a specific chemical receptor and subsequent internal signaling pathway. We are presently analyzing swimming patterns in colonies exposed to changes in acetate concentration to test several alternate models that could lead to chemoaccumulation.
QUALITATIVE AND QUANTITATIVE STUDIES OF THE SWIMMING BEHAVIOR OF HINCKSIA IRREGULARIS SPORES (PHAEOPHYCEAE)
Authors: Iken K.B. , Amsler C.D. , Greer S.P. , McClintock J.B.
Published: March 2003

The swimming behavior of spores of the brown alga Hincksia irregularis was analyzed using computer‐assisted motion analysis. We distinguished five main swimming patterns: straight paths, search circles, orientation, gyration, and wobbling. We suggest different functional values for the individual swimming patterns. Straight paths, search circles, and orientation are different but all may be important in small‐scale movements in the benthic boundary layer. As such, they could enable a spore to find a suitable microenvironment for germination and growth. Gyration occurs during the initial reversible phase of adhesion that can lead to settlement. Wobbling is typical for irritated or mechanically damaged spores and does not seem to be a typical pattern associated to settlement. The dominant swimming patterns changed with spore age (10 ± 5 to 60 ± 5 min of spore age), with young spores mainly swimming in straight paths and search circles and older spores in orientation and gyration. This change in swimming patterns can be quantified by speed (decrease over time) and rate of change of direction (increase over time). Based on these results, we suggest that computer‐assisted motion analysis of the swimming behavior of H. irregularis spores can be used to develop bioassays with both ecological and technological relevance.
A NOVEL BIOFOULING ASSAY USING COMPUTER‐ASSISTED MOTION ANALYSIS OF HINCKSIA IRREGULARIS SPORE SWIMMING
Authors: Iken K.B. , Greer S.P. , Amsler C.D. , McClintock J.B.
Published: March 2003

Computer‐assisted motion analysis of the swimming behavior of spores of the brown alga Hincksia irregularis was used in a novel antifouling bioassay. Newly released spores were exposed to water soluble compounds of organic and aqueous body wall extracts of two sympatric sea stars, Astropecten articulatus and Luidia clathrata. Changes in the swimming behavior of H. irregularis spores were quantified by changes in speed (decrease at extract exposure) and rate of change of direction (increase at extract exposure). Sea star extracts were tested at natural concentrations (mg extract/g wet weight) and at approximate 10‐, 100‐, and 1000‐fold dilution. Significant effects (p ≤ 0.05) were observed at 1000‐fold dilution of the natural concentration in both extracts of A. articulatus, and at 100‐ and 10‐fold dilution of the aqueous and organic extract, respectively, in L. clathrata. Germination of spores after short time exposure (30 min) to sea star body wall extracts indicates that compounds were not toxic but affected spore mobility, a factor that plays an important role during spore settlement. We suggest that this assay is very useful for bioassay‐guided fractionation of extracts because it is very sensitive and requires only small amounts of extracts or isolated compounds.
FATTY ACIDS IN PHOTOTROPHIC AND MIXOTROPHIC GYRODINIUM GALATHE‐ANUM (DINOPHYCEAE)
Authors: Adolf J.E. , Place A.R. , Lund E. , Stoecker D.K. , Harding L.W.
Published: March 2003

Fatty acids were measured in G. galatheanum grown either phototrophically, or mixotrophically with Storeatula major (Cryptophyceae) as prey. G. galatheanum, like many photosynthetic dinoflagellates, contains high amounts of n‐3 long‐chain‐polyunsaturated fatty acids (LC‐PUFA) such as docosahexaenoic acid (DHA, 22:6n‐3) and the hemolytic toxic fatty acid 18:5n‐3. We hypothesize that a benefit of phagotrophy in G. galatheanum is the acquisition of precursor linolenic acid (18:3n‐3) that fuels LC‐PUFA synthesis. Phototrophs grew at 0.37 d−1, while mixotrophs grew at 0.40 d−1 with a feeding rate of 0.62 d−1. Photosynthesis was lower in mixotrophs (3.7 pg C cell−1 h−1) than phototrophs (4.9 pg C cell−1 h−1). DHA levels were higher in mixotrophs [3.7 (+/− 0.11) pg cell−1] than phototrophs [3.0 (+/− 0.16) pg cell−1] and prey [0.4 (+/− 0.01) pg cell−1]. 18:5n–3 levels [1.7 (+/− 0.03) pg cell−1] were similar in phototrophs and mixotrophs. An intermediate in n‐3 LC‐PUFA synthesis, 20:4n‐3, accumulated in mixotrophs [0.6 (+/− 0.27) pg cell−1] relative to phototrophs (not detected) and prey [0.03 (+/− 0.002) pg cell−1]. Low ratios of linolenic acid to DHA in phototrophic G. galatheanum (0.14) relative to mixotrophic G. galatheanum (0.29) and prey (2.14) are consistent with substrate limitation of LC‐PUFA synthesis in phototrophs. Accumulation of 20:4n‐3 suggests incomplete conversion of linolenic acid to DHA, possibly due to conditions in batch culture. We conclude that precursors for n‐3 LC‐PUFA biosynthesis in G. galatheanum may be acquired through ingestion of S. major, and may partially control feeding/photosynthesis in mixotrophic populations.
EFFECTS OF SUSPENDED SEDIMENT ON BIOMASS AND CELL MORPHOLOGY OF CLADOPHORA GLOMERATA (CHLOROPHYTA) IN THE COLORADO RIVER, ARIZONA
Authors: Wilson Kevin P. , Shannon Joseph P. , Blinn Dean W.
Published: March 2003

This study assessed changes in biomass, filament length, and cell morphology in Cladophora glomerata (L.) Kütz. along a suspended sediment gradient in the Colorado River below Glen Canyon Dam, Arizona. Suspended sediments ranged from 2.0 mg·L−1 at Lees Ferry (Rkm 0.8) to 4.2 mg·L−1 at Gorilla Island (Rkm 352). There was a 74% decrease in Cladophora biomass along the river transect through Grand Canyon National Park and a significant decrease in filament and cell length, but cell width increased. Similar changes in cell morphology occurred after 19 days when C. glomerata was transplanted from a low suspended sediment site (2.0 mg·L−1) at Lees Ferry to a habitat with high suspended sediments (≥20.0 mg·L−1). Cell length increased and cell width decreased when plants were transplanted back to the low suspended sediment habitat for 24 days. In situ studies with reduced light in the absence of suspended sediments showed no change in cell morphology. These in situ experiments imply that changes in cell morphology by C. glomerata in waters with high suspended sediments are adjustments in structural integrity to accommodate the abrasive force of suspended particles. Our study suggests that cell dimensions in Cladophora might be too plastic under varying environmental conditions to be used in taxonomic determinations.
TETREUTREPTIA POMQUETENSIS (EUGLENOPHYTA), A PSYCHROPHILIC SPECIES: GROWTH AND FATTY ACID COMPOSITION
Authors: McLachlan J. L. , Curtis J. M. , Boutilier K. , Keusgen M. , Seguel M. R.
Published: March 2003

Tetreutreptia pomquetensis McLachlan, Fritz et Seguel, a quadriflagellated euglenoid isolated from a shallow‐water embayment of the southeastern Gulf of St. Lawrence, is a common winter species where habitats are ice covered for 4 to 5 months. Growth in culture, which was similar to that of many euryhaline species, was limited at normal seawater salinities to temperatures between ∼0° and 7° C, and the alga could not be maintained at 10° C; thus, it is a strict psychrophile. The maximum growth rate (μ≅ 0.35·days−1) was around 5° C and, given its size (∼100 μm length), high productivities are indicated. The major fatty acids (FAs) identified were 18:4ω3, 16:4ω3, 20:5ω3, and 16:0. The overall FA spectrum does not align closely to other euglenoids but may reflect more the low growth temperature. The presence of 18:5ω3 is unusual, as this FA had been known previously only from dinoflagellates and haptophytes. The two most abundant sulfoquinovosyl diacylglycerols (SQDGs) had pairings of [18:4/16:0] and [18:4/18:4] and together constituted 80% of the total SQDGs. The latter pairing is unique, not having been previously recognized. The FA data support the hypothesis that the degree of unsaturation is indicative of low temperatures and membrane integrity.
KLEPTOPLASTIDY IN THE TOXIC DINOFLAGELLATE PFIESTERIA PISCICIDA (DINOPHYCEAE)
Authors: Lewitus Alan J. , Glasgow Howard B. , Burkholder JoAnn M.
Published: March 2003

The ichthyotoxic dinoflagellate Pfiesteria piscicida Steidinger et Burkholder has a complex life cycle with several heterotrophic flagellated and amoeboid stages. A prevalent flagellated form, the nontoxic zoospore stage, has a proficient grazing ability, especially on cryptophyte prey. Although P. piscicida zoospores lack the genetic capability to synthesize chloroplasts, they can obtain functional chloroplasts from algal prey (i.e. kleptoplastidy), as demonstrated here with a cryptophyte prey. Zoospores grown with Rhodomonas sp. Karsten CCMP757 (Cryptophyceae) grazed the cryptophyte population to minimal densities. After placing the cultures in near darkness where cryptophyte recovery was restricted and further prey ingestion did not occur, the time‐course patterns in growth, prey chloroplast content·zoospore−1, and prey nucleus content·zoospore−1 were followed. Ingested chloroplasts were selectively retained in the dinoflagellate, as indicated by the decline and, ultimately, near absence of cryptophyte nuclei in plastid‐containing zoospores. Chloroplasts retained inside P. piscicida cells for at least a week were photosynthetically active, as indicated by starch accumulation and microscope‐autoradiographic measurements of bicarbonate uptake. Recognition that P. piscicida can function as a phototroph broadens our perspective of the physiological ecology of the dinoflagellate because it suggests that, at least during part of its life cycle, P. piscicida’s growth and survival might be affected by photoregulation and nutritional control of photosynthesis.
SUBMISSION AND RETRIEVAL OF AN ALIGNED SET OF NUCLEIC ACID SEQUENCES
Authors: Brawley Susan H.
Published: March 2003

An important part of many studies published in the Journal of Phycology is the construction and analysis of an alignment of related nucleotide sequences. These alignments are valuable to other investigators, especially when the data provide a basis for more than one possible alignment. Publication of alignments, however, is prohibitively expensive, and the data are difficult to retrieve and use in this form. Several electronic archives for these alignments now exist, and information is provided here on the submission and retrieval of alignments at the National Center for Biotechnology Information (NCBI), the European Bioinformatics’ Institute (EBI), and TreeBASE. Emphasis is placed on the use of Sequin and Entrez at the NCBI, because these programs have been modified recently and they provide a fluid and integrated system to submit and retrieve sequence and alignment records and related information. Other useful features of Entrez (e.g. free Medline searches) are noted.
OLIGOAGARS ELICIT A PHYSIOLOGICAL RESPONSE IN GRACILARIA CONFERTA (RHODOPHYTA)
Authors: Weinberger Florian , Friedlander Michael , Hoppe Hans‐Georg
Published: March 2003

Gracilaria conferta (Schousboe ex Montagne) J. et G. Feldmann responded with an oxidative burst and rapid increases in respiration and halogenating activity when agar, agarose, or the agarose degradation products neoagarotetraose and neoagarohexaose were added to the growth medium. In contrast, carrageenan, oligocarrageenans, neoagarobiose, l‐galactose, d‐galactose, and several other mono‐ and oligosaccharides did not have any effect. Sixfold increases in respiration were observed 3 min after addition of neoagarohexaose. The response could only be induced in species of the genera Gracilaria and Gracilariopsis. Neoagarohexaose also elicited a release of hydrogen peroxide in less than 15 min, resulting in an immediate increase in algal brominating activity. Bleached thallus tips appeared a few hours after the addition of neoagarohexaose. This effect was dependent on the release of hydrogen peroxide and exposure to light. Exposure to light and oligosaccharide elicitors increased the production of reactive oxygen species, which reached destructive concentrations when both mechanisms were simultaneously active. Concentrations of 0.1 to 3.3 μM agarose or agars were sufficient to trigger an increase in respiration, an oxidative burst response, and tip bleaching. However, higher concentrations of neoagarohexaose and neoagarotetraose were necessary to elicit the responses, indicating that the alga is more sensitive to oligoagars with degrees of biose‐polymerization > 3. The extremely short reaction time and high specificity indicate that intermediates of agar degradation are recognized by Gracilaria as messengers when microbial degradation of its cell wall occurs. The physiological responses may represent the early stages of algal defense mechanisms involved in repression of pathogen ingress.