Rare charophytes in Scotland's coastal saline lagoons

Summary

Recently collected data comparing the distribution and performance of the rare lagoonal charophyte Lamprothamnium papulosum across a number of UK coastal lagoon sites, including nine sites in the Western Isles, is presented. The surveys revealed that the species occurred over a wide range of salinities but was absent from sites with high phosphorus concentrations. The sites in the Western Isles held the most extensive populations and were least threatened by nutrient pollution. The discovery of two other endangered and vulnerable charophytes of brackish water, Tolypella nidifica and Chara baltica, at two of the Western Isles sites further highlights the importance of Scotland's saline lagoon resource. The use of the autoecological data on salinity and nutrient conditions for supporting Biodiversity Action Plan implementation for Lamprothamnium papulosum and for saline lagoon conservation in general is considered. Status summaries for all the charophyte species of brackish water recorded in Scotland are also provided.     

Numerical taxonomy of some charophytes in Iran

Morphological characters of 10 species of Chara from different localities in northern, western and central Iran have been analyzed, with Nitella hyalina and Tolypella glomerata as outgroups. Phenetic and cladistics analyses of populations belonging to the 10 Chara species were undertaken to reveal their inter‐population morphological variation and inter‐specific relationships. Clustering was based on 54 characters (41 qualitative and 13 quantitative). This produced two major clusters, grouping Chara crassicauliss, C. vulgaris var. longibracteata, C. vulgaris var. vulgaris and C. contraria separate from C. grovesii, C. gymnophylla var. gymnophylla, C. gymnophylla var. rohlenae, C. kirghisorum and C. tomentosa. A smaller cluster of C. socotrensioides, C. fibrosa and Chara sp. was separate from these two clusters. A factor analysis identified the most variable morphological characters as type of cortification, prescence and length of the spine cells, stipulode length, type of branchlet cortication, bract cells length, placement of the gametangia, character of end segment, length of branchlet and internode, development of posterior bract cells, oogonia length and width, oospore length, width and length/width ratio, fossa breath, and number of striae.     

Gradualistic characean lineages in the Upper Cretaceous–Palaeocene of southern Europe

Two charophyte lineages from the Upper Cretaceous–Palaeocene of southern Europe are described here, constituting a useful biostratigraphic tool for correlating non-marine stratigraphic sequences. The Peckichara pectinata lineage, ranging from the middle Campanian to the middle–upper Maastrichtian, consists of four successive gyrogonite morphotypes that displayed progressively more complex gyrogonite ornamentation and increasingly smaller gyrogonites with time. The Peckichara sertulata lineage, ranging from the middle Campanian to the Danian, consists of three morphotypes that followed a more common evolutionary trend, developing progressively larger gyrogonites without any changes in ornamentation. Intermediate forms between the successive morphotypes suggest that they corresponded to anagenetic varieties of the same evolutionary species rather than to separate species. The different trends observed appear to be palaeoenvironmentally controlled. The grades of the P. pectinata lineage first occurred in permanent lakes that later shifted to fluvial influenced floodplain ponds, this shift accounting for the reduction in gyrogonite size. By contrast, the P. sertulata lineage mainly occurred in permanent lakes, where stable palaeoenvironmental conditions enabled a steady rise in gyrogonite size to increase the space available for the zygote.     

Oospores of <Emphasis Type="Italic">Chara tomentosa</Emphasis> from Holocene sediments of Lake Zeribar (Iran)

Biometric measurements were performed on oospores of Chara tomentosa from Core 63-J from Lake Zeribar in Iran. The partially fossilized oospores examined did not differ significantly in dimensional measurements, number of ridges, or colour from oospores of modern specimens of C. tomentosa.     

Dynamic aspects of spermiogenic chromatin condensation patterning by phase separation during the histone-to-protamine transition in charalean algae and relation to bryophytes

During early-to-middle spermiogenesis in multicellular, internally fertilizing charalean green algae (Chara fibrosa, Chara vulgaris, Chara tomentosa, Nitella missouriensis), patterning of chromatin/nucleoplasm in developing spermatid nuclei changes from granules → fibers → contorted lamellae → condensed chromatin. Cytochemical, immunocytochemical, electrophoretic studies on C. vulgaris and C. tomentosa spermatids (Kwiatkowska, Poplonska) and amino acid analysis of protamines in Chara corallina sperm (Reynolds, Wolfe), indicate that more positively charged protamines replace histones directly during spermiogenesis, not indirectly through other intermediate transitional proteins as in internally fertilizing neogastropods and sharks with more ordered spermatid lamellae. We hypothesize that such lamellar-mediated patterning is due to liquid–liquid phase separation by spinodal decomposition. This is a spontaneous thermodynamic process that involves diffusive instability of a lamellar chromatin network, a dominant pattern repeat distance and bicontinuity of chromatin/nucleoplasm phases. C. vulgaris sperm show contorted lamellae in the posterior region, whereas C. corallina sperm display contorted peripheral lamellae and interior fibrils. Among internally fertilizing liverworts, which may have evolved from Zygnematales, mid-spermatid nuclei lack lamellae. Instead they display self-coiled chromatin rods in Blasia pusilla, contain short chromatin tubules in Haplomitrium hookeri resembling those in internally fertilizing mosses and a hornwort and indirectly replace histones with protamines in Marchantia polymorpha.     

The seasonal effects on the encrustation of charophytes in two hard‐water lakes

Encrustation and element content of six charophyte species from two hard‐water lakes were investigated monthly for a period of 1 year. Seasonal patterns were analyzed for the interaction of water chemistry. Encrustation followed a seasonal pattern for Chara contraria, Chara subspinosa, and Nitellopsis obtusa in Lake Krüselin and for Chara globularis and Chara tomentosa in Lake Lützlow. However, no seasonality in the precipitated CaCO₃ was observed for C. subspinosa in Lake Lützlow and for C. tomentosa in Lake Krüselin, indicating a lake‐specific dependency. Species‐specific encrustation was found. Chara contraria and N. obtusa encrusted the most in June and August, whereas C. subspinosa and Nitella flexilis/opaca exhibited lowest encrustation in March and April. The precipitated CaCO₃ of charophytes correlated negatively to the concentration of total inorganic carbon in both lakes. Element content of plant dry weight was species‐specific for Ca and K, and lake‐specific for Mg. No specific pattern was found for the TP and Fe contents. The results showed seasonal, species, and lake‐specific influences on the encrustation of charophytes.     

New charophyte assemblage from middle Miocene lacustrine deposits of Moneva (Ebro Basin,Spain)

Two new fossil charophyte species from middle Miocene lacustrine deposits of Moneva (Ebro Basin, NE Spain) are described and illustrated. Sphaerochara miocenica nov. sp. is represented by medium sized gyrogonites with a characteristic spheroidal shape and ornamented with numerous small and regularly spaced tubercles arranged along the spiral cells. Several specimens show an unusual carbonate encrusted layer that covers completely or partially the gyrogonite. Psilochara monevaensis nov. sp. is characterized by large gyrogonites, with typical prolate shape and protruding apical poles. A second population of S. miocenica nov. sp. from a distant early upper Miocene lacustrine basin located in the Middle East (Bekaa Valley, Lebanon), identified in a previous study as Sphaerochara sp., is described and illustrated here, allowing the comparison of these distant populations. Ecologically, the associated fauna and facies from both localities suggest that these taxa grew in very shallow athalassic lakes. Interestingly, S. miocenica nov. sp. having a wide geographic distribution in peri-Mediterranean lakes with variable salinity, may become a fossil guide for the Miocene, providing at the same time important palaeoecological information.     

Germination of Chara vulgaris and Nitella flexilis oospores: What are the relevant factors triggering germination?

Factors governing the germination of Chara vulgaris L. and Nitella flexilis L. were investigated in a series of three experiments. Temperature, light regimes, drying, and changes in oxidation–reduction potential are postulated to be possible triggers working in isolation or in combination on dormant oospores originating in sediments with different physical/chemical characteristics.In Experiment 1, none of the N. flexilis oospores inoculated into Petri plates and culture tubes containing either agar or water and then exposed to ‘normal’ 12 h daylight 12 h dark germinated when the redox of the media remained relatively constant over the 20-day observation period, while all of the oospores in a tube in which the redox of the agar declined to below 200 mV, germinated. Similarly no germination occurred in the dark without a decrease in redox. When redox fell to below 200 mV, 11% of the inoculated oospores germinated.In Experiment 2, N. flexilis and C. vulgaris oospores were subjected to cold pre-treatments and inoculated into either water or agar in both plates and tubes. Of the N. flexilis oospores 53% germinated in the dark, and 31% under normal lighting. Of the C. vulgaris, 3% germinated in the dark and 53% under normal lighting. The stimulation of germination with the decrease in redox in the media did not re-occur.Experiment 3 compared the germination of C. vulgaris oospores from four ponds contaminated by mining wastes and from a comparatively clean wetland. The oospores were again subjected (or not) to cold pre-treatments, and were drawn from both freshly concentrated sediments and air-dried sediments that had been held in storage for either 97 or 376 days. Notably, a consistent reduction in oospore viability occurred in oospores from a particular mine pond, contaminated by nickel tailings.     

西藏台错晚第四纪轮藻类的新类型

本文的研究材料来自西藏羌塘高原西部台错古湖一个3.69 m的天然剖面,其地层测年为32.6-4.5ka.从其156个样品中获取大量的轮藻类、介形类和腹足类及少量有孔虫等微体化石.据轮藻类藏卵器外形,顶部结构、螺旋细胞钙化式样等特征,该剖面的轮藻类应归属于轮藻科Characeae之轮藻属Chara.经研究得知,台错古湖在...     

New finds of charophytes in Iceland with an update on the distribution of the charophyte flora

Charophyte species new to the flora of Iceland are reported and an update on the distribution of the previously known species is given. Four species are new to Iceland; Chara aspera Willdenow, Chara contraria Braun ex Kützing, Tolypella canadensis Sawa and Tolypella glomerata (Desvaux) Leonhardi, while four species were previously known: Chara globularis Thuiller, Chara virgata Kützing, Nitella flexilis (L.) Agardh and Nitella opaca (Agardh ex Bruzelius) Agardh. The finding of the species new to Iceland add to the hitherto known worldwide distribution of those species, including a significant extension to the north.     

Long-term changes in macrophyte vegetation after reduction of fish stock in a shallow lake

Starting in the middle of the 1970s, submerged macrophytes began to disappear from shallow Lake Warniak due to feeding pressure by grass carp (Ctenopharyngodon idella). In the middle of the 1980s, the lake was stocked with seston-feeding silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis). By 1993, the biomass of silverhead carp and bighead carp had declined. This allowed charophytes to recolonize the bottom of the lake. The main charophyte species at this time were Chara globularis and Chara rudis. Since then, five other stonewort species have been found: Chara contraria, C. filiformis, C. tomentosa, C. aspera and Nitellopsis obtusa. Seventeen species of aquatic angiosperms have also been found. There were distinct changes in the relative abundance and spatial distribution of particular species. C. rudis developed most intensely in the shallow parts of the lake near the southern and western shores. C. globularis gradually took over the deeper central part of the lake. In 2001, C. rudis began to retreat again. The relative abundance and spatial distribution of charophytes was correlated to water clarity (r = 0.87, p < 0.05), total phosphorus level (r = −0.78; p < 0.05), and chlorophyll a content (r = −0.79; p < 0.05).     

Analysis of morphological characters of Chara baltica, C. hispida, C. horrida, and C. rudis from Europe

Morphological characters of Chara baltica, C. hispida, C. horrida, and C. rudis from different localities in Central Europe and Scandinavia were analyzed. The plants were preliminarily classified using specific qualitative features into four species: C. baltica, C. hispida, C. horrida, and C. rudis. Of the 14 characters, all were used in principal-component and cluster analyses, and 12 were applied in a discriminant analysis. In the discriminant analysis, the most useful characters for distinguishing particular species were selected. The methods (canonical discriminant and canonical analyses) used herein offered good differentiation between brackish water species C. horrida and C. baltica and fresh water species C. hispida and C. rudis. The analysis showed that the two morphologically very similar species C. hispida and C. rudis are only partially distinguished.     

Culturing of stoneworts and submersed angiosperms with phosphate uptake exclusively from an artificial sediment

1. We aimed to demonstrate reproducible nutrition and growth of macrophytes in non‐axenic laboratory cultures preventing growth of phytoplankton and epiphytes. 2. Macrophyte shoot segments were planted in a mixture of commercial acid‐washed silica sand with crystalline tricalcium phosphate, and this artificial sediment was covered with a layer of pure silica sand. The liquid mineral media used did not contain phosphorus but were rich in all other nutrient elements. A CO₂ reservoir provided sustainable CO₂ supply to macrophyte cultures by gas diffusion through a polyethylene membrane. 3. Chara hispida, Chara tomentosa, Chara baltica, Elodea canadensis, Potamogeton pectinatus and Zanichellia palustris could be cultivated for long term without medium exchange and aeration. Microalgae growth was prevented by the absence of phosphate in the water column. Mobilisation of tricalcium phosphate and phosphate uptake by the rhizoids of C. hispida enabled sustainable rapid shoot growth and increased the concentration of inorganic phosphate in the shoot dry weight by five to six times in comparison with plants cultivated on pure silica sand. A significant growth support from tricalcium phosphate was also observed for E. canadensis, but the rate of phosphate uptake by the roots was not sufficient to maintain a storage pool of inorganic phosphate (P_i) in the growing shoots of this plant. 4. Membrane‐controlled CO₂ supply from a reservoir and artificial sediments like the one described provide attractive options for the laboratory culture of macrophytes.     

Structure and development of the sex organs in Tolypella nidifica (O. Müll.) A.Br. (Characeae)

The occurrence of Tolypella (Characeae) in Libya is recorded for the first time. Also for the first time, the structural development of the male and female fructifications (the globule (antheridium) and the nucule (oogonium) respectively) in Tolypella nidifca (O. Müll.) A.Br. is described. Both the globule and the nucule show the same course of development as is seen in Chara. In the final structure of the globule, however, there are two stalk cells in Tolypella , while only a single cell is present in Chava and Nitella. The corona has ten cells in two tiers of five each, as in Nitella , but in Chara there is only a single tier of five cells forming the corona.     

The interactive effects of irradiance and photoperiod on Chara vulgaris L.: concerted responses in morphology, physiology, and reproduction

Both the single and interactive effects of irradiance and photoperiod on a worldwide charophyte species, Chara vulgaris L., were investigated in a greenhouse experiment. Under high light intensity, plants exhibited shortened shoot, compact canopy and low Chl a/Caro. In contrast, elongated shoot, expanded canopy and low Chl a/Chl b corresponded to low light intensity. In addition, both ash mass ratio and relative growth rate (RGR) were positively related to light intensity. The effect of photoperiod on plants was relatively complex. Although photoperiod did not affect morphological characters, an increased photoperiod significantly decreased Chl a/Chl b and Chl a/Caro ratios. Two-way analysis of variance (ANOVA) analysis indicated that significant interaction of irradiance and photoperiod was present on ash mass ratio, RGR, Chl a/Chl b, Chl a/Caro and Chl (a + b)/Caro ratios. The high RGR found for 50% sunlight, L:D 16:8 (50/16) conditions along with the significant interaction of irradiance and photoperiod on RGR indicated that the effect of irradiance was more important than photoperiod for plant growth. And finally, both irradiance and photoperiod had positive effects on the emergence of sex organs (♂♀) and the maturation of oospores, except that increased photoperiod did not accelerate the maturation of oospores. In summary, for both plant growth and reproduction, C. vulgaris was able to acclimate morphologically and physiologically to different irradiance levels and photoperiods. This study can partly explain the broad geographic distribution of C. vulgaris. Handling editor: S. M. Thomaz     

New insights into Paleozoic charophyte morphology and phylogeny

Examination of Paleozoic charophyte fructifications using microscopy and high-resolution x-ray synchrotron microtomography has revealed that most of them have a utricle that forms a supplementary calcified cover around the gyrogonite. All Paleozoic families with utricles have been assigned to the Sycidiales. We consider the Moellerinaceae to occupy a central position in the phylogeny of the Charophyta. From these, one group of descendants constitutes the gyrogonites inside the utricles of the Sycidiales; a second descendant goup is thought to be the utricle-free ancestors of the Charales prior to inversion of spiralization and reduction in cell number. The Sycidiales have a multilayered wall and an internal vesicle, but their families are distinguished by diversity in orientation of external cells, complexity of the utricle wall, and in presence or absence of antheridia. The solidly packed structure of the utricle is believed to be an organ protecting the zygote against dessication. We interpret the morphological similarities between Paleozoic Sycidiales and Mesozoic Clavatoraceae, both with a utricle, as homoplasous rather than expressing a true phylogenetic relationship. We confirm that some umbellids might correspond to utricles of charophytes.     

Charophytes, indicateurs de paléobathymétrie du lac Tigalmamine (Moyen Atlas, Maroc)

A paleolimnological study can be particularly accurate in situations where the species found in the sediments have persisted in the same lake and can provide a direct modern analogue for interpretation. Lake Tigalmamine, thus, represents an exceptionally favourable context, compared to most paleolakes in North Africa, as this site allows comparing the fossil remains of the Characeae to those produced by the living plants. Tigalmamine is a hydrosystem composed of three karstic lakes located at 1626 m above sea level in the Middle Atlas of Morocco. The site had been the subject of a 16 m long core taken in the center of the central lake under 16 m of water (core C 86 in Lamb and Kaars, 1995 [The Holocene 5 (1995) 400-408]). The section represents the total of the Holocene from 10,200 BP to Present (El Hamouti et al., 1991 [Comptes Rendus de l’Académie des Sciences de Paris 2 (1991) 259-265]; Lamb et al., 1995 [Nature 373 (1995) 134-137]). The latter published a synthesis of the pluridisciplinary studies conducted on this core. Also, the numerous gyrogonites isolated from that core had been determined as Chara hispida (Soulié-Märsche in Benkaddour, 1993 [Changements hydrologiques et climatiques dans le Moyen-Atlas marocain : chronologie, minéralogie, géochimie isotopique et élémentaire des sédiments lacustres de Tigalmamine. PhD thesis, Université Paris-Sud, Orsay (inédit)]). Further fieldwork at Tigalmamine by the authors of the present paper in year 2000 showed that Chara hispida is still present in the lake where it forms a belt of submerged vegetation restricted to the range of 2 to 9 m water depth. This paper describes the morphological and ecological characteristics of the extant Chara hispida as a reference for the interpretation of the fossil remains. Based on these data, the frequency changes of the gyrogonites in the core sediments become significant in terms of bathymetry. The detailed analysis of the charophytes from the core, as a complement to the previous studies, confirms the existence of four Holocene phases with lake level low stand at Tigalmamine. The aim of the present study is to enhance the value of the charophytes as a useful complementary tool for paleolimnological reconstruction.     

Chara zeylanica Wildenow（现生轮藻）藏卵器几个特征的统计分析

本文对采自广西涠洲岛的现生轮藻Ｃｈａｒａ ｚｅｙｌａｎｉｃａ藏卵器的几个特征作了统计分析,结果表明,藏卵器的最大长度,最大宽度和螺旋环数等性状的变异有一定范围,服从统计规律,单变量的变化呈正态分布,具一明显峰值;ＬＰＡ是ＬＥＤ的线性函数,呈正相关。藏卵器乌黑细胞的钙化程度与成熟度有关。未成熟藏卵器的顶部构造为典型的轮藻型,成熟藏卵的顶部构造与有盖轮藻型接近。因此认为,Ｃｒａｍｂａｓｔｉｃｈａｒａ     

The composition and density of epiphyton on several species of submerged macrophytes — the neutral substrate hypothesis tested

Epiphyton samples same taken from different macrophyte species (three chararaceans Potamogeton pectinatus L.). While some epiphyton taxa were evenly distributed, the density of others differed according to plant part, site or macrophyte species. Diatoms were classified according to host plant species by cluster analysis. Thus, the neutral substrate hypothesis is revised.Differences in epiphyton composition were larger between the closely related species Chara tomentosa L. and C. globularis Thuill. than between Chara tomentosa and Nitellopsis obtusa (Desv.) J. Groves. The latter two species were heavily marl-encrusted. Potamogeton pectinatus was separated from the other macrophyte species by its lower total density of epiphyton and the high abundance of Cocconeis placentula Ehr.