FACTORS LIMITING EDAPHIC ALGAL BIOMASS AND PRODUCTIVITY IN A GEORGIA SALT MARSH1,2

A “planted core” system was developed to test the effect of short term (1–2 weeks) experimental manipulation of environmental parameters on edaphic microalgae under field conditions. A large number of small cores (surface area = 7 cm²) were collected, randomized and replanted in the marsh in fiddler crab exclosures with appropriate experimental treatments. Daily enrichment of the cores with NH₄⁺ resulted in significant increases in edaphic primary productivity and levels of chlorophyll a in both summer and winter seasons in the short-Spartina marsh. Enrichment with a complete nutrient solution caused no further increases. Nutrient enrichment of creekbank sediments was much less stimulatory to the resident algal assemblage. In both sites, but especially in the creekbank, the removal of fiddler crab grazers resulted in significant increases in chlorophyll a and productivity. Experimental manipulation of light intensity showed that the average light intensity reaching the sediment surface was saturating for chlorophyll production in the short-Spartina marsh. A reciprocal transplant experiment involving unfertilized cores from the short-Spartina marsh and creekbank marsh demonstrated that NH₄⁺ inputs occurring in the creekbank site rapidly alleviated nitrogen limitation of edaphic algae from short-Spartina marsh. Algae in creekbank cores incubated in the short-Spartina marsh were unable to sustain high productivity once the original standing stock of NH₄⁺ declined.     

REPRODUCTION AND SYSTEMATICS OF THE MARINE ALGA DERBESIA (CHLOROPHYCEAE) IN NEW ENGLAND1,2

The morphology, gross cytology, reproduction, and habitat ecology are described for Derbesia marina based on observations of New England field populations and laboratory cultures of this plant. These data, and additional observations on cultures of several other species of Derbesia from elsewhere and on type and other important collections, have been used to evaluate the systematic relationship of New England Derbesia with other species of this genus. The single Derbesia species in New England is referred to D. marina. The systematic criteria previously used to distinguish species within Derbesia are reviewed and interpreted within the context of the present investigation. In systematic studies, we stress the importance of the use of sporangial and chloroplast morphology, the presence or absence of pyrenoids, and reproductive history. Two types of life history are reported for D. marina in New England: (1) A form of D. marina collected at 20 m reproduces directly with stephanokontous zoospores growing into sporophytic plants of Derbesia morphologically identical to their parent thalli. (2) On the other hand, at least some New England, populations of D. marina have retained the genetic potential for producing a sexual generation (Halicystis ovalis), even though the latter is unknown for the coast of northeastern North America.³ Gametophytes (H. ovalis) were produced directly from enlargement and subsequent differentiation of uncleaved lateral sporangia in 2 cultured populations of New England D. marina. A single female and numerous male vesicles formed in this manner produced gametes, but neither fertilization nor parthenogenesis occurred; thus the entire life history was not completed in culture. The occurrence of the directly reproducing deep water form of D. marina is presented as evidence for speciation of a sporophyte (Derbesia) independent of its alternate gametophyte (Halicystis). An hypothesis is advanced to explain the source and means for expression of genetic variability necessary for speciation in a population of nonsexually reproducing Derbesia.     

ASSOCIATION OF PLEUROCAPSA AND CALOTHRIX (CYANOPHYTA) IN A THERMAL STREAM1,2

A crustose, nodular mat, primarily composed of Calothrix sp. and Pleurocapsa sp., occurs in some alkaline hot springs of the western United States. Together, these species constituted ca. 71% of the mat biomass; the remainder was partitioned between other cyanophytes and bacteria. Their temperature growth ranges in culture were 24–50 C (Calothrix) and 30–55 C (Pleurocapsa). Both clonal cultures had maximal growth rates at 45 C (Pleurocapsa, 1.28 doublings/24 h; Calothrix 2.30). Calothrix grew at approximately twice the rate of Pleurocapsa throughout their coincidental temperature range. The relative proportions of Calothrix (42%) and Pleurocapsa (27%) were constant in a thick mat (ca. 1 mm) regardless of season; however, a thin mat (ca. 0.5 mm) contained significantly more Pleurocapsa (71%) and less Calothrix (5%). Analysis of 10 μm thick microtome sections showed that Pleurocapsa dominated the innermost region (substrate side) of the nodule mat while Calothrix abundance increased from ca. 3% in this region to 80–96% at the surface of thick mat samples (ca. 0.8–2.3 mm). Our proposed that the grazing pressure exerted by an ostracod population accounts for the continued coexistence of and the observed spatial relationships between these species appears most consistent with the observations.     

DISTRIBUTION OF BLUEGREEN ALGAE IN A MISSISSIPPI GULF COAST SALT MARSH1

Edaphic bluegreen algal communities were sampled from five menotypic angiosperm zones in Grvelline Bay Marsh near Ocean Spring. Mississippi. Samples and environmental data were taken on a quarterly basis from October 1976 to June 1977 beneath the following marsh angiosperms: Distichlis spicata (L.) Green, Scirpus olneyi gray, SPartina patens (Aiton) Muhl., Sp. alterniflora Loisel., and Juncus roemerianus Scheele. Communities in all five zones were dominated by Schizothrix calcicola (Ag.) Gom. (sensu Drauet) throughout the study, while the subdominant bluegreens varied according to season. The number of individuals in all zones was greatest in the summer and lowest in the winter. An examination of the structure of the five edaphic communities indicated a single, nearly homogeneous community exists over the entire surface of the marsh shaded by a angiosperm canopy. Light intensity appears to be the major factor affecting the distribution of bluegreen algae in this salt marsh.     

LONG-TERM EFFECTS OF MANIPULATING LIGHT INTENSITY AND NUTRIENT ENRICHMENT ON THE STRUCTURE OF A SALT MARSH DIATOM COMMUNITY1,2

The long-term effects of manipulating light intensity and nutrient enrichment on the structural characteristics of a diatom community inhabiting the sediments beneath a pure stand of dwarf Spartina alterniflora Loisel. were investigated over a yearly cycle. Clipping or shading the cord grass cover, or phosphorus enrichment caused significant decreases in both species diversity (H') and the number of diatom species, whereas nitrogen enrichment only significantly decreased the latter parameter. Of the 105 diatom taxa identified, only 10 were restricted to certain of the 12 study areas; and of these, 8 occurred exclusively in the clipped habitats. An analysis of variance (light × nutrient × collection date) involving 19 of the most abundant taxa revealed that certain experimental treatments had significant effects on the relative abundances of each and every taxon. However, attempts to group taxa with similar response patterns proved unsuccessful because of the frequent significance of the 3-way interaction term. Synthesis of these results with earlier work by the author showed that differences in structure of diatom communities inhabiting the sediments beneath the 3 dominant marsh grasses were not primarily caused by differences in reduction of light intensity by their grass canopies, and that clipping of the cord grass produced a shift in community structure towards that characteristic of a salt panne algal mat.     

PORPHYRA REDIVIVA SP. NOV. (RHODOPHYTA): A NEW SPECIES FROM NORTHEAST PACIFIC SALT MARSHES1

A new species, Porphyra rediviva (Bangiales, Rhodophyta), is described from the northeast Pacific based on morphological, cytological, reproductive, ecological, and molecular characters. This species occurs at high intertidal levels in salt marshes along the coasts of Washington, Oregon, and northern California and exhibits a growth optimum at reduced salinity. It is further distinguished by a distinct demarcation between male and female sectors of the gametophytic thalli of epilithic specimens. The species is found most commonly in the drift or trapped in Salicornia beds, but these detached blades never have been found with sporangia or gametangia. Molecular analyses using restriction fragment length polymorphism patterns of polymerase chain reaction–amplified ribosomal DNA (rDNA) show that this salt marsh Porphyra is conspecific throughout its range and is distinct from other Pacific Porphyra species with similar reproductive patterns. Based on molecular data, P. rediviva is related most closely to P. purpurea from the North Atlantic. Fixed rDNA polymorphisms between the two taxa, however, support ecological and cytological evidence that they should be considered different species.     

BEHAVIOR AND ECOLOGY OF THE ATLANTIC WHITE-SIDED DOLPHIN (LAGENORHYNCHUS ACUTUS) IN COASTAL NEW ENGLAND WATERS

Atlantic white-sided dolphins ( Lagenorhynchus acutus ) are among the most abundant, and least studied, cetaceans in coastal New England. Between April and October 1984 through 1997 we sighted 1,231 groups of Atlantic white-sided dolphins, primarily on Stellwagen Bank and Jeffreys Ledge (two shallow glacial deposits along the coasts of Massachusetts, New Hampshire, and Maine). Mean group size was 52 (≥90.9), and was significantly larger from August through October (71.9 ± 111.4) than April through June (35.0 ± 45.4). Calf sightings were uncommon until June and July, after which they were present in over 50% of groups. Combined with observations of apparent newborn calves, this confirms that early summer is an important calving period. The presence of calves did not, however, solely account for the increase in group size. Boat interaction (bow- and stern-wake riding) was the most commonly recorded behavior (47.4% of sightings), followed by traveling (31.4%), interactions with other cetacean species (27.6%), social interaction (15.5%), and feeding (9.5%). While feeding was uncommon, one observation of apparently coordinated "ball" feeding was seen with sand lance ( Ammodytes spp.) as the visible prey. Aerial behavior showed a positive correlation with group size, although it was often impossible to tell whether the same dolphins were leaping repeatedly. Eighty-eight dolphins were photo-identified using either unusual body pigment or a distinctive dorsal fin. While several individuals were reidentified between years and between areas, no reidentifications were made within a year in the same area. Unusually pigmented individuals were much more likely to be reidentified than those with distinctive dorsal fins, most likely due to higher visibility. We suggest that Atlantic white-sided dolphins are generally using the study area as transients in what appears to be a large home range.     

小黑螨科一新属新种（蜱螨亚纲：辐螨亚目）

建立了小黑螨科一新属：华颚螨属Ｓｉｎｏｇｎａｔｈｕｓ ｇｅｎ．ｎｏｖ．;描述了模式种：王氏华颚螨Ｓ．ｗａｎｇａｅ ｓｐ．ｎｏｖ．,并列出了该科分属检索表。     

DISTRIBUTION AND SYSTEMATICS OF BATRACHOSPERMUM(BATRACHOSPERMALES,RHODOPHYTA) IN NORTH AMERICA. 6. SECTION TURFOSA1

Twenty-one populations of Batrachospermum section Turfosa from North America were compared to nine type and two historically important specimens using multivariate morphometrics and image analysis. The protologues of six other infrageneric taxa were also compared. From this analysis, six species are recognized worldwide: B, de-sikacharyi Sankaran, B. gombakense Kumano et Ratnasabapathy, B. keratophytum Bory de Saint-Vincent [syn. B. vagum var. keratophytum (Bory de Saint-Vincent) Sirodot, B. gulbenkianum Reis, and B. suevorum Kützing nom. Meg.], B. sinense Jao, B. turfosum Bory de Saint-Vincent [syn. B. vagum (Roth) C. Agardh and B. vagum var. undulato-pedicellatum Kumano et Watanabe], and B. vogesiacum F. G. Schultz ex Skuja [syn. B. vagum var. flagelliforme Sirodot, B. flagelliforme (Sirodot) Necchi], These species are distinguished on the basis of carposporophyte-bearing branch cortication, secondary fascicle development, monoecy or dioecy, presence of spermatangia on involucral filaments and monosporangia, and dimensions of trichogynes and carposporangia. Peripheral cortication has been previously used to separate species in this section, but we observed that this feature is quite widespread in the section. Presence of indeterminate gonimoblast filaments has been reported for some taxa in section Turfosa, but no such structures were seen in any of the specimens examined. Only B. keratophytum has been collected in North America, ranging from southwestern Greenland (64°N) to Louisiana (30° N).     

A NEW LARVAL FISH BIOASSAY FOR TESTING THE PATHOGENICITY OF PFIESTERIA SPP. (DINOPHYCEAE)1

Water quality, microbial contamination, prior fish health, and variable results have been major impediments to identifying the cause and mechanism of fish mortality in standard aquarium‐format Pfiesteria bioassays. Therefore, we developed a sensitive 96‐h larval fish bioassay for assessing Pfiesteria spp. pathogenicity using six‐well tissue culture plates and 7‐day‐old larval cyprinodontid fish. We used the assay to test pathogenicity of several clonal lines of Pfiesteria piscicida Steidinger and Burkholder and P. shumwayae Glasgow and Burkholder that had been cultured with algal prey for 2 to 36 months. The P. shumwayae cultures exhibited 80%–100% cumulative mortality in less than 96 h at initial zoospore densities of approximately 1000 cells·mL^?1. No fish mortalities occurred with P. piscicida at identical densities or in controls. In a dose‐response assay, we demonstrated a strong positive correlation between dinospore density and fish mortality in a highly pathogenic culture of P. shumwayae, generating a 96‐h LD₅₀ of 108 zoospores·mL^?1. Additionally, we applied the assay to evaluate a 38‐L P. shumwayae bioassay that was actively killing fish and compared results with those from exposures of juvenile tilapia (Oreochromis niloticus) in a 500‐mL assay system. Water from the fish‐killing 38‐L assay was filtered and centrifuged to produce fractions dominated by dinoflagellates, bacteria, or presumed ichthyotoxin (cell‐free fraction). After 96 h, the larval fish assay exhibited 50%–100% cumulative mortality only in fractions containing dinoflagellates, with no mortalities occurring in the other fractions. The 500‐mL bioassay with tilapia produced inconsistent results and demonstrated no clear correlation between mortality and treatment. The new larval fish bioassay was demonstrated as a highly effective method to verify and evaluate dinoflagellate pathogenicity.     

PROPERTIES OF MICROCYSTIS AERUGINOSA AND M. FLOS-AQUAE (CYANOPHYTA) IN CULTURE: TAXONOMIC IMPLICATIONS1

Cultures were cloned from a sample containing Microcystis aeruginosa, M. flos-aquae and a few morphological intermediates. The M. aeruginosa cultures remained distinct from the M. flos-aquae cultures in (a) cell size, (b) cell aggregation pattern, (c) width of the mucilage surrounding the multicellular colonies, (d) sharpness of the mucilage boundary, (e) efect of 0.1–1.0 μM calcium chloride on the disaggregation of multicellular colonies, (f) frequency of mucilage mutants and (g) colony morphology on agar media. No M. flos-aquae culture produced morphs resembling M. aeruginosa, inconsistent with proposals that M. flos-aquae is a developmental stage or environmentally-induced variant of M. aeruginosa. After longterm cultivation, but not soon after origanal isolation, several M. aeruginosa cultures contained mutants with diminished mucilage production and an altered colony shape.     

Studies on mixed mass cultivation of Anabaena spp. (nitrogen-fixing blue-green algae, cyanobacteria) on a large scale

Studies on mixed mass cultivation of Anabaena spp. on a large scale (5170m²) were conducted continuously for 3 years. Under the continental monsoon climate in northern subtropics (30°N, 115°E), 7–11 g dry weight m⁻² day⁻¹ of microalgal biomass on average was harvested in simple plastic greenhouses in the effective growth days during the warmer seasons. The maximum productivity was 22 g m⁻² day⁻¹ in the middle of summer. Observations on the productive properties of strains of Anabaena spp. indicated that they were different from and could compensate for each other in their productivities and adaptations to the seasonal changes. With different lining materials (PVC sheets, concrete, sand and soil) in the culture ponds, no significant variation of productivity was found, but bubbling with biogas in the middle of the day and the application of some growth regulating substances (2,4-D, NaHSO₃ and extracts of oyster mushroom spawn) was able to improve the production. The cost of microalgal biomass in this way was around 0·75–1·0 US dollar(s) per kilogram.     

EFFECTS OF TEMPERATURE AND IRRADIANCE ON THE SEASONAL VARIATION OF A SPIROGYRA (CHLOROPHYTA) POPULATION IN A MIDWESTERN LAKE (U.S.A.)

Although Spirogyra Link (1820) is a common mat‐forming filamentous alga in fresh waters, little is known of its ecology. A 2‐year field study in Surrey Lake, Indiana, showed that it grew primarily in the spring of each year. The population consisted of four morphologically distinct filamentous forms, each exhibiting its own seasonal distribution. A 45‐μm‐wide filament was present from February to late April or early May, a 70‐μm‐wide form was present from late April to mid‐June, a 100‐μm‐wide form was present from February to mid‐June, and a 130‐μm‐wide form appeared only in February of 1 of 2 study years. The 70‐ and 100‐μm‐wide forms contributed to the peak amount of biomass observed in late May and early June. Multiple regression analysis indicated that the presence of the 45‐, 70‐, and 100‐μm‐wide forms was negatively correlated with temperature. Presence of the 130‐μm‐wide form was negatively correlated with irradiance. Isolates of these filament forms were exposed to temperature (15, 25, and 35° C)/irradiance (0, 60, 200, 400, 900, and 1500 μmol·m^?2·s^?1) combinations in the laboratory. Growth rates of the 45‐μm‐wide form were negative at all irradiances at 35° C, suggesting that this form is susceptible to high water temperatures. However, growth rates of the other forms did not vary at the different temperatures or at irradiances of 60 μmol·m^?2·s^?1 or above. Net photosynthesis was negative at 35° C and 1500 μmol·m^?2·s^?1 for the 100‐ and 130‐μm‐wide forms but positive for the 70‐μm‐wide form. All forms lost mat cohesiveness in the dark, and the 100‐ and 130‐μm‐wide forms lost mat cohesiveness under high irradiances and temperature. Thus, the morphological forms differed in their responses to irradiance and temperature. We hypothesize that the rapid disappearance of Spirogyra populations in the field is due to loss of mat cohesiveness under conditions of reduced net photosynthesis, for example, at no to low light for all forms or at high light and high temperatures for the 100‐ and 130‐μm‐wide forms. Low light conditions can occur in the interior of mats as they grow and thicken or under shade produced by other algae.     

MORPHOLOGICAL VARIATION WITHIN AND BETWEEN NATURAL POPULATIONS OF NON-TIDE POOL FUCUS DISTICHUS (PHAEOPHYTA) IN NEW ENGLAND1,2

The sources of morphological variation in natural populations of Fucus distichus L. ssp. edentatus (De la Pyiaie) Powell and F. distichus L. ssp, evanescens (C. Agardh) Powell from New England were evaluated. Individuals from different populations were morphologically distinct as judged by population means and analysis of variance. A correlation between the plant's form and its habitat was established by field observation. The broadest material grows in calm estuarine habitats, while the narrowest plants occur in exposed, open coastal areas. Major differences in morphology also appear seasonally. In addition, microhabitat factors such as exposure to wave action and elevation explain some morphological variation. Cultured germlings from distinct populations of “evanescens” and “edentatus” type plants were outplanted to an experimental garden in order to ascertain whether the variation was heritable or environmentally induced. The latter experiments indicate that major differences in morphology are genetically determined.     

Effect of oxygen availability and salinity on EARLY LIFE HISTORY STAGES OF SALT MARSH PLANTS. I. Different germination strategies of Spartina alterniflora and Phragmites australis (Poaceae)

Gradients in oxygen availability and salinity are among the most important environmental parameters influencing zonation in salt marsh communities. The combined effects of oxygen and salinity on the germination of two salt marsh grasses, Spartina alterniflora and Phragmites australis, were studied in growth chamber experiments. Germination of both species was initiated by emergence of the shoot and completed by root emergence. Percentage S. alterniflora germination was reduced at high salinity (40 g NaCl/L) and in decreased oxygen (5 and 2.5%). In 0% oxygen shoots emerged, but roots did not. P. australis germination was reduced at a lower salinity (25 g NaCl/L) than S. alterniflora, and inhibited at 40 g NaCl/L and in anoxia. However, a combination of hypoxia (10 and 5% O2) and moderate salinity (5 and 10 g NaCl/L) increased P. australis germination. When bare areas in the salt marsh are colonized, the different germination responses of these two species to combinations of oxygen and salt concentrations are important in establishing their initial zonation. In high salinity wetlands S. alterniflora populates the lower marsh and P. australis occupies the high marsh at the upland boundary.     

DETERMINING THE AFFINITIES OF SALT MARSH FUCOIDS USING MICROSATELLITE MARKERS: EVIDENCE OF HYBRIDIZATION AND INTROGRESSION BETWEEN TWO SPECIES OF FUCUS (PHAEOPHYTA) IN A MAINE ESTUARY1

The high degree of morphological plasticity displayed by species of the brown algal genus Fucus L. is well documented. Such variation is especially pronounced for those estuarine taxa lacking holdfasts (termed ecads) that often bear little resemblance to the attached species from which they are derived. To better understand the systematics of salt marsh fucoids, we developed a suite of four microsatellite‐containing loci capable of distinguishing between F. vesiculosus L. and F. spiralis L. The genetic markers were used to determine the relationships of the fucoid ecads F. vesiculosus ecad volubilis (Hudson) Turner and a muscoides‐like Fucus in the Brave Boat Harbor (ME, USA) estuary. Ecad populations had 2‐ to 3‐fold higher levels of heterozygosity than attached populations of F. vesiculosus and F. spiralis. Further, ecads were “intermediate” between F. vesiculosus and F. spiralis in their allele frequencies and genotype composition. Our data indicate that populations of muscoides‐like Fucus in Brave Boat Harbor mainly consist of F₁ hybrids between F. vesiculosus and F. spiralis, whereas F. vesiculosus ecad volubilis may arise through backcrosses between F. vesiculosus and other fertile hybrids. Finally, our data support the hypothesis that introgression has occurred between attached populations of F. vesiculosus and F. spiralis.     

中国霍克小蜂属—新种及—新记录（膜翅目：小蜂科）

1.木蛾霍克小蜂Hockeria epimactis新种 雌:体长5.0毫米。前翅基部1/3透明,端部稍褐,其余烟褐色,具暗褐色毛;近痣脉端部有1具白毛的圆斑,圆斑中有1褐色的钭纹;近臀角处另有1略呈三角形的大浅色斑(图1)。前、中足跗节及胫节端部暗黄褐色。胸部背面具白毛,其余毛黄白色。     

DISTRIBUTION AND SYSTEMATICS OF BATRACHOSPERMUM (BATRACHOSPERMALES,RHODOPHYTA) IN NORTH AMERICA. 3. SECTION SETACEA1

Six populations of Batirachospermum section Setacea from North America were compared to eight type specimens using multivariate morphometrics and image analysis. From this analysis, four species in this section were distinguished worldwide: B. atrum (Hudson) Hartley [syn. B. gallaei Sirodot]; B. orrthostichum Skuja, B. sertularina (Bory) Bory]; B. diatyches Entwisle; B. androinvolucrum sp. nov.; and B. puiggarianum Grunow in Wittrock et Nordstedt (syn. B. angolense Welwitsch ex West et West, B. nigrescens Welwitsch ex West et West). Two of these species were found in North America: B. atrum in California and Texas and B. androinvolucrum in British Columbia, Washington State, and Alabama. The new species, B. androinvolucrum, is distinguished by having spermatangia restricted to one-celled involucral bracts of the carpogonial branch.