Spatial and temporal distributions of dominant epiphytes on the stipes of Laminaria hyperborea (Gunn.) Fosl. (Phaeophyta:Laminariales) in S.E. Scotland

The epiphytic flora of the stipes of Laminaria hyperborea (Gunn.) Fosl. at St. Abbs Head, Berwickshire, Scotland has been examined. Four species Palmaria palmata (L.) O. Kuntze, Ptilota plumosa, (C. Ag.) Huds., Membranoptera alata (Huds.) Stackh., and Phycodrys rubens (L.) Batt. make up > 95% of the epiphyte biomass. The species show two distinct patterns of zonation, one with depth the other with respect to position on the host stipe. Palmaria is found on the upper parts of the stipes at 1 and 2 m depth, with the three other species found lower on the stipe. At 6 m depth Ptilota occupies the position on the stipe where Palmaria had occurred in the shallower water. In the deepest samples (12m) Ptilota was absent and its position on the stipe was occupied by Phycodrys and Membranoptera. This zonation is reflected in the biomass of the epiphyte species, Palmaria is restricted to the shallow waters, Ptilota reaches its greatest biomass at intermediate depths while Membranoptera and Phycodrys are most abundant at 6 m and below. Palmaria, Membranoptera, and Phycodrys show similar patterns of seasonal changes in epiphyte biomass with a peak in September and a decline in winter. Ptilota, which in the British Isles is considered to be a species of northern distribution, shows an earlier peak biomass and a correspondingly earlier decline in abundance.     

Cystocarps and tetrasporangia on the same thallus in Membranoptera alata and Polysiphonia urceolata

Numerous plants of Membranoptera alata (Huds.) Stackh, and a single specimen of Polysiphonia urceolata (Dillw.) Grev. were found bearing both cystocarps and tetrasporangia.     

LATITUDINAL TRENDS IN THE GROWTH AND REPRODUCTIVE SEASONALITY OF DELESSERIA SANGUINEA,MEMBRANOPTERA ALATA,AND PHYCODRYS RUBENS (RHODOPHYTA)1

The seasonality of Delesseria sanguinea, Membranoptera alata, and Phycodrys rubens (Rhodophyta) was studied at Helgoland (North Sea, Germany) and Roscoff (Brittany, France). Plants were collected at bimonthly intervals, and growth and reproduction were monitored. Growth of blades was observed mainly in spring, although small blades were found on plants of M. alata and P. rubens all year round. In summer, plants started to degenerate and in autumn they became fertile. The reproductive season of D. sanguinea lasted from October to February/April at both locations, whereas reproductive plants of M. alata and P. rubens were found until April at Helgoland and until June and August, respectively, in Roscoff_: Lower winter temperatures at Helgoland than at Rascoff may have caused these differences in the duration of the reproductive season. Using published data, the seasonal patterns at Helgoland and Roscoff were compared to those found at other locations (e.g. Barents Sea; Maine, USA; Isle of Man, UK) and local temperature/daylength conditions. Blade growth was synchronized across all populations and occurred in spring, when temperatures were usually still suboptimal for growth. Maximum reproduction was generally found in the colder half of the year but started earlier in autumn in the Barents Sea. Adaptive strategies in the seasonal control of growth and reproduction are discussed. Adequate timing of the history events (e.g. appearance of juveniles in spring) appears more important than maximal growth and reproduction of adults during the season with the most favorable temperatures.     

The reproductive phenology of nine species of Rhodophyta in the subtidal region of the Isle of Man

Monthly samples of about 40 separate plants of each species were collected from 1 to 3 m below lowest astronomical tide on Port Erin breakwater, Isle of Man, Irish Sea. In three species growing on rock, Plocamium cartilagineum, Cryptopleura ramosa and Callophyllis laciniata, about 90% of the plants were fertile in late summer but less than 10% in spring although some fertile plants were always present. Delesseria sanguinea and Odonthalia dentata, also epilithic, had a winter sporing season, Odonthalia extending into late spring, and all plants were sterile in summer. Three species growing epiphytically, Palmaria palmata, Membranoptera alata and Phycodrys rubens, reproduced maximally in the first half of the year at the time when the stipes of the host species, Laminaria hyperborea, grow fastest. Only Palmaria had a sterile season, late summer. The encrusting Cruoria pellita showed little seasonality. The first three species, which reproduce mainly when the sea temperature is above average, are in the northern part of their geographical range. The remaining species (apart from Cruoria) reproduce mainly at low temperatures and are in the southern half of their ranges. Male plants appear to be in a minority in all species, presumably because they were manifest for a shorter period than carposporic plants. They appeared first after sterile periods and were absent as sporing declined. Plocamium and to a lesser extent Cryptopleura show an extremely high preponderance of tetrasporophytes in the population. This is attributed to perennation and some factor disallowing the survival of most of the tetraspores.     

Photosynthetic performance of Arctic macroalgae after transplantation from deep to shallow waters

Transplantation experiments conducted in the Arctic Kongsfjord (Spitsbergen) in summer 1997 investigated the effects of various types of filtered natural radiation (solar, solar without UV-B, solar without UV-A/B) on photosynthesis of various macroalgae. Two brown algal species (Laminaria solidungula, Saccorhiza dermatodea) and four red algal species (Palmaria palmata, Phycodrys rubens, Phyllophora truncata, Ptilota plumosa) were collected from deeper waters, kept in UV-transparent plexiglass tubes wrapped with different spectral cut-off filter foils and positioned at fixed depths in shallow waters for 7-9 days. At regular intervals, chlorophyll fluorescence of photosystem II (optimum quantum yield, F_v/F_m) was determined, as an indicator of photosynthetic performance. The data demonstrate that shallow-water species such as P. palmata are much less affected by natural photosynthetically active radiation (PAR) and UV radiation near the surface than extremely sensitive deep-water species such as Phyc. rubens which exhibited strong decreases in photosynthetic performance, as well as photobleaching of part of the thallus. The other species showed intermediate response patterns. In most species investigated inhibition of photosynthesis was mainly caused by the UV-B wavelengths. Interpretation of the data clearly indicates species-specific tolerances of photosynthesis to ambient solar radiation which can be explained by broad physiological acclimation potentials and/or genetic adaptation to certain (low or high) irradiances. The species-specific photosynthetic performance under radiation stress is in good accordance with the vertical distribution of the macroalgae on the shore.     

Depth-dependent reproductive output of the green sea urchin, Strongylocentrotus droebachiensis (O.F. Müller), in relation to the nature and availability of food

Reproductive output of green sea urchins (Strongylocentrotus droebachiensis O.F. Müller) in the field was highest at depths where preferred macro-algae were abundant, and lowest at depths where preferred macro-algae were overgrazed or replaced by non-preferred species (Agarum and Ptilota). Feeding rate and gonad indices of sea urchins in the laboratory were highest on a diet of preferred algae (Fucusdistichus L. subsp. edentatus (Pyl.) Powell, Laminaria longicruris Pyl., Desmarestia spp. and Saccorhizadermatodea (Pyl.) J. Ag.), and lowest on the less preferred Agarum cribrosum (Mert.) Bory, Ptilota serrata Kütz., and crustose corallines. Gamete production/unit area in overgrazed habitats was as great or greater than in kelp beds because of the higher biomass of urchins in overgrazed areas. Gonad weight and reproductive output of urchins from habitats poor in food can be increased by providing preferred foods.     

Distribution of histamine in the thallus ofFurcellaria lumbricalis

Histamine occurs in all regions of the thallus of male, female and tetrasporophyte plants ofFurcellaria lumbricalis (Huds.) Lamour. The mean values varied from 60 μg to 500 μg (g fresh weight)^?1. There were few consistent differences either between the same region of different types of plant or different regions of the thallus of one type of plant. Fluorescence staining of sections of the thalli ofF. lumbricalis, with o-phthalaldehyde, revealed that cells of the cortex and medulla have histamine associated with them. The histamine appears to be intracellular since only intact cells exhibit fluorescence. Cells in sections of female plants ofPolyides rotundus (Huds.) Grev., which do not contain histamine, do not exhibit fluorescence dependent upon o-phthalaldehyde.     

A taxonomic appraisal of Callophyllis and Euthora (Rhodophyta)

Critical examination of the literature and specimens of the three described species of Euthora indicates that the acceptance of the northern species E. cristata (C. Ag.) J. Ag. and E. fruticulosa (Rupr.) J. Ag. has been based on lack of familiarity with the degree of variation normal within one species, and these two species should be united. The carpogonial branch system of this combined species is typical of that found in the genus Callophyllis within which it should therefore be included as Callophyllis cristata (C. Ag.) Kütz. The taxonomic position of the only other species of Euthora, E. tristanensis Baardseth, cannot be determined until information on the carpogonial structure is available.     

The algal flora of a subtidal Zostera bed in ventry bay,Southwest Ireland

Ventry Bay in County Kerry, southwest Ireland, was surveyed in June 1977 to a depth of 17 m using SCUBA and a grid of stations which were 400 m apart. The principal substrate was sand. Zostera marina L. was dominant and widespread from 0.5 to 13 m below Chart Datum and is the deepest-growing Zostera in Northwest Europe. Sixty species of algae were found and their occurrence and that of Zostera marina was subjected to cluster analysis resulting in one distinct cluster of Zostera marina, Ulva lactuca L., Gracilaria verrucosa (Huds.) Papenf., Polysiphonia elongata (Huds.) Spreng., Ectocarpus sp., Ceramium rubrum (Huds.) C. Ag. and Brongniartella byssoides (Good. et Woodw.) Schmitz. These algae are so common and widespread in the subtidal zone that their co-occurrence with Zostera is not considered to be significant. Zostera occurs virtually as monospecific stands in sand and the co-occurrence of any macroalgae is largely fortuitous and dependent on the heterogeneity of the substrate.     

Strain selection and cell isolation of Ulvaria oxysperma (Kuetz.) Bliding (Chlorophyta) for net cultivation

North Carolina and Bermuda isolates of the green seaweed Ulvaria oxysperma (Kuetz.) Bliding were grown in cross-gradient light-temperature culture to determine the effects of varied photon fluence rates, temperature and photoperiod on their growth and reproduction. Results indicated significant genetic-based variation between the two populations. Spheroplast were obtained from the vegetative thallus of the North Carolina isolate following enzymatic digestion with abalone gut extract and maceration. Single cell isolates developed new cell walls in 2–3 days and attached to nylon net substrate. Cultured isolates regenerated into juvenile plants with normal development and morphology. Results are discussed in terms of the suitability of this economically important species for land-based mariculture.     

THE WOOL-LIKE COVERING OF THE ROOTS OF LANNEA ALATA I. THE ORIGIN AND MORPHOLOGY OF THE WOOLY COAT

Lannea alata (Engl.) Engl., Anacardiaceae, a tree or shrub of East Africa, has roots covered with dense wool-like hair. Cork cambium of the root produces a closely appressed cork from which the hairs (modified cork cells) arise. Cork cells and wooly hair are rich in sterol and carotin-oid-like compounds and have thick walls. It is suggested that the root wool plays a role in the soil-air, soil-water relations of Lannea alata and other plants.     

Allelopathic influence of algae on the growth of Eichhornia crassipes (Mart.) Solms

The growth of Eichhornia crassipes (Mart.) Solms was inhibited when grown in water containing algae such as Scenedesmus bijugatis (Turp.) Kuetz, Chlorella pyrenoidosa Chick and species of Aphanothece, Euglena, Merismopedia and Coelastrum. The size of plants, their dry weight and chlorophyll a and b contents and their rate of vegetative propagation were very much reduced compared with control plants grown in algae-free water. The hyacinth plants ultimately died after 90–100 days of growth with algae.     

Flora Algale Dell'Isola Lachea (Golfo di Catania)

Abstract

Observations on the seaweeds on the Island of Lachea. — Within the frame of the research on seaweeds in the Eastern part of Sicily which is being carried out at the Botanical Department of Catania University, the AA. have undertaken a study on the seaweeds to be found on the Island of Lachea. The material has been collected from the supralittoral to the infralittoral. One hundred and thirty-five species have been identified and data about the local distribution and habitat have been given. The following species are new to Sicily: Spatoglossum solierii (Chauv.) Kuetz., Bonnemaisonia asparagoides (Woodw.) Ag., Gelidiella ramellosa (Kuetz.) Feld. et Ham., Antithamnion cruciatum (C. Ag.) Naeg. var. profundum G. Feld., Antithamnion plumula var. bebbii (Reinsch) J. Feld., Ceramium bertholdi Funk, Ceramium codii (Richards) G. Maz., Spermothamnion repens (Dillw.) K. Ros. var. flagelliferum (De Not.) Feld., Griffithsia barbata (Smith) C. Ag., Polysiphonia biformis Zan., Lophocladia lallemandi (Mont.) Schmitz; and the following species are new to Eastern Sicily: Codium difforme Kuetz., Bryopsis penicillata Kuetz., Liebmannia leveillei J. Ag., Thuretella schousboei (Thur.) Schmitz, Dudresnaya verticillata Le Jol., Amphiroa cryptharthrodia Zan., Corallina squamata Ell. et Sol., Pseudolithophyllum expansum (Phil.) Lem., Ceramium rubrum var. implexo-contortum Solier, Ptilothamnion pluma (Dillw.) Thuret, Aglaothamnion neglectum G. Feld.     

EFFECTS OF UV-B-INDUCED DNA DAMAGE AND PHOTOINHIBITION ON GROWTH OF TEMPERATE MARINE RED MACROPHYTES: HABITAT-RELATED DIFFERENCES IN UV-B TOLERANCE

The sensitivity to UV-B radiation (UVBR: 280–315 nm) was tested for littoral (Palmaria palmata[L.] O. Kuntze, Chondrus crispus Stackhouse) and sublittoral (Phyllophora pseudoceranoides S. G. Gmelin, Rhodymenia pseudopalmata[Lamouroux] Silva, Phycodrys rubens[L.] Batt, Polyneura hilliae[Greville] Kylin) red macrophytes from Brittany, France. Algal fragments were subjected to daily repeated exposures of artificial UVBR that were realistic for springtime solar UVBR at the water surface in Brittany. Growth, DNA damage, photoinhibition, and UV-absorbing compounds were monitored during 2 weeks of PAR + UV-A radiation (UVAR) + UVBR, whereas PAR + UVAR and PAR treatments were used as controls. The littoral species showed a higher UV tolerance than the sublittoral species. After 2 weeks, growth of P. palmata and C. crispus was not significantly affected by UVBR, and DNA damage, measured as the number of cyclobutane-pyrimidine dimers per 10⁶ nucleotides, was negligible. Photoinhibition, determined as the decline in optimal quantum yield, was low and decreased during the course of the experiment, coinciding with the production of UV-absorbing compounds in these species. In contrast, no UV-absorbing compounds were induced in the sublittoral species. Growth rates of P. pseudoceranoides and R. pseudopalmata were reduced by 40% compared with the PAR treatment. Additionally, constant levels of DNA damage and pronounced photoinhibition were observed after the UVBR treatments. Growth was completely halted for Phycodrys rubens and Polyneura hilliae, whereas DNA damage accumulated in the course of the experiment. Because Phycodrys rubens and Polyneura hilliae showed the same degree of photoinhibition as the other sublittoral species, it appears that the accumulation of DNA damage may have been responsible for the complete inhibition of growth. The results suggest an important role of DNA repair pathways in determining the UV sensitivity in red macrophytes.     

Growth studies of macroalgae in a microcomputer-assisted spray cultivation system

Apical growth rates of Furcellaria lumbricalis (Huds.) Lamour. and Ahnfeltia plicata (Huds.) Fries (Gigartinales: Rhodophyceae), and Ascophyllum nodosum (L.) Le Jol. (Fucales: Phaeophyceae), were studied in spray culture, applying independent microcomputer systems for control, data-logging, and apical growth measurements. The system functioned with a minimum of maintenance. Sea-water temperature and light seemed to be more important for growth than nutrient supply under the prevailing conditions. Basal shoots (young, undivided parts of the plants close to the holdfast) of Furcellaria lumbricalis had growth rates three times higher than the apices (apical meristem on the distal end of mature plants) from the older parts of the thallus. For Ascophyllum nodosum apical growth rates of basal shoots, divided and undivided apices were similar. Whereas apical growth rate of A. nodosum was normal, the biomass yield was low. A. nodosum cultivated simultaneously in tanks and in continuous spray had similar growth rates. The spray cultivation technique facilitated control of the experimental conditions, and handling of the plants during the experimental work while excluding epiphytes.     

Ecological and genecological distinctions of a high intertidal dwarf form of Fucus distichus (L.) Powell in New England

Morphological, ecological, and genetic distinctions of a high intertidal, dwarf, non-tide pool member of the Fucus distichus (L.) Powell complex were assessed at an exposed site in southern Maine, U.S.A. Variation in plant stature from typical F. distichus ssp. edentatus (De la Pylaie) Powell to the dwarf form is continuous. On the other hand, measurements of reproductively mature plants collected throughout the eulittoral zone showed a bimodal pattern, i.e., there was a high frequency of dwarf forms (4–8 cm) and F. distichus ssp. edentatus (13–28 cm). The two forms have distinct reproductive phenologies: the dwarf plant exhibiting a unimodal reproductive maximum (fall), while F. distichus ssp. edentatus has pronounced bimodal reproductive maxima (spring and fall). Differences in stature and reproduction between the dwarf form and F. distichus ssp. edentatus were maintained when their respective progeny were grown under common environmental conditions. Thus, the differences are heritable rather than environmentally induced.     

Mass culture experiments with Brachionus Rubens

In order to develop the optimum conditions for a mass culture of Brachionus rubens, eight strains of phytoplankton were tested as food for the rotifers. The optimum food concentration as well as the concentration of algal medium tolerated by R. rubens, and the influence of nitrite, sodium chloride, extreme pH-values and low oxygen concentrations on the reproduction of B. rubens were determined.     

Geographic patterns of genetic variation in nuclear and chloroplast genomes of two related oaks (<Emphasis Type="Italic">Quercus aliena</Emphasis> and <Emphasis Type="Italic">Q. serrata</Emphasis>) in Japan: implications for seed and seedling transfer

In this study, we assessed geographic patterns of genetic variations in nuclear and chloroplast genomes of two related native oaks in Japan, Quercus aliena and Q. serrata, in order to facilitate development of genetic guidelines for transfer of planting stocks for each species. A total of 12 populations of Q. aliena and 44 populations of Q. serrata were analyzed in this study. Genotyping of nuclear microsatellites in Q. aliena was done with only nine populations (n = 212) due to limited numbers of individuals in two populations, while all 12 populations (n = 89) were used in sequencing chloroplast DNA (cpDNA). In Q. serrata, 43 populations (n = 1032) were genotyped by nuclear microsatellite markers, while cpDNA of 44 populations (n = 350) was sequenced. As anticipated, geographic patterns detected in the variations of Q. aliena’s nuclear genome and its chloroplast haplotype distribution clearly distinguished northern and southern groups of populations. However, those of Q. serrata were inconsistent. The geographic distribution of its chloroplast haplotypes tends to show the predicted differentiation between northern and southern lineages, but geographic signals in the genetic structure of its nuclear microsatellites are weak. Therefore, treating northern and southern regions of Japan as genetically distinct transferrable zones for planting stocks is highly warranted for Q. aliena. For Q. serrata, the strong NE-SW geographic structure of cpDNA should be considered.     

蛇足石杉生态适应性研究Ⅰ茎叶解剖特征的比较

利用解剖学方法对湘西地区蛇足石杉5个野生居群个体(S1,S2,S3,S4,S5)的茎叶进行了解剖学比较和分析,结果表明:不同居群蛇足石杉解剖结构的性状存在明显的差异性,其中维管柱厚度、皮层厚度、海绵组织厚度、叶片厚度这4个性状是造成居群间蛇足石杉解剖学性状差异的主要因子;茎叶解剖结构也表现出对阴湿环境适应的的形态特征,但是,S1居群的蛇足石杉具有适应旱生生境的趋势。这些解剖学性状除受遗传因子控制外,环境因子(主要为光照和水分)起着重要的作用,因此,蛇足石杉形态解剖学上的差异性或可塑性是其赖以适应环境和生存的基础。