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The article provides an analysis of the dynamics of the constancy indicators of representatives of higher aquatic vegetation (VBR) in the upper reaches of the Belaya River (Republic of Bashkortostan) from 2005 to 2019. Constancy indicators of 11 species of BBP ( Butomus umbellatus L., 1753; Elodea canadensis Michx., 1803; Najas marina L., 1753; Potamogeton natans L., 1753; Potamogeton perfoliatus L., 1753; Potamogeton crispus L., 1753; Stuckenia pectinata L., 1753; Myriophyllum spicatum L., 1753; Lemna minor L., 1753; Spirodela polyrhiza Schleid., 1839 and Ceratophyllum demersum L., 1753) were registered in the areas of 2 state water posts – the Shushpa railway station and the Arsky Kamen recreation house. In the course of research, for the first time, lists of permanent, additional and random species of BBP were compiled, correlation-regression models of the relationships between the constancy indicators of representatives of higher aquatic vegetation with the content of chemicals were calculated, the pollutants most strongly affecting the constancy indicators of representatives of BBP were identified, determined in the water of the upper course of the Belaya River.

Introduction. The population using waste man-made water reservoirs for recreation and providing household needs can be at potential health risk. Such pollutants as heavy metals do not undergo decomposition processes. They accumulate in the biotic and abiotic components of the reservoir. Subsequently, hazardous toxicants can enter the human body through food chains. An ecological and hygienic assessment of the state of the waste reverse reservoir of the Semyonov gold recovery plant has been carried out. Material and methods. The object of the study is located in the Zauralye of the Republic of Bashkortostan at the geographical coordinates 52° 30’20″ N, 58° 19′48″ E. The content of heavy metals (Zn, Cu, Pb, and Cd) in water, bottom sediments and biomass of aquatic macrophyte (Potamogeton perfoliatus L.) was studied. In the bottom sediments, mobile forms of metals have been detected. They are extracted by an acetate-ammonium buffer with pH = 4.8 Results. It has been revealed that in water the concentration of heavy metals is higher than the maximum permissible concentrations for fishery reservoirs: 19–27 times for copper, 10–24 times for zinc, 2.7–5.8 times for lead, 1–1.4 times for cadmium. Exceeding the standards for water bodies for drinking, domestic and cultural water use is recorded for cadmium (6 times) and lead (2.5 times). In bottom sediments, the zinc content of mobile forms is 372.00 ± 28.51 mg/kg, copper - 144.37 ± 4.08 mg/kg, lead - 14.09 ± 1.48 mg/kg, cadmium - 0.036 ± 0.002 mg/kg. The total index (Z C ), reflecting the additive excess of the background, is 1686, which corresponds to an extremely high level of man-made pollution of bottom sediments. The concentrations of heavy metals in the aboveground and underground organs of Potamogeton perfoliatus L. are much higher than the background levels. Conclusion. The waste reverse reservoir of the Semenov gold extraction factory is potentially dangerous to the local population health when it is used for breeding poultry, watering cattle, and fishing. The activities aimed at improving the environmental and hygiene situation in the territory of the locality are imperative.

This paper provided an ecological and phytochemical evaluation of the aquatic macrophytes at El-Rayah El-Nasery and El-Noubaria Canal of the Nile River, Egypt. Throughout the study period from spring 2015 to winter 2016, 12 macrophyte species related to 6 families and 8 genera were recorded, one floating species, three submerged and eight emergent. Myriophyllum spicatum L., Echinochloa stagnina (Retz.) P. Beauv, Potamogeton perfoliatus L. and Cyperus articulatus L. were found as the most frequent species. In comparison, autumn, spring and the sites (N7, N8) at the end of El-Noubaria Canal were recorded as the richest seasons and sites in species numbers. The analysis of the macrophyte biochemical composition revealed the presence of species specificity as well as temporal and spatial variations. In the two studied areas, nitrogen-free extracts constitute the major part of the macrophyte organic matter content, while total lipid constitutes the minor one. Among all the analyzed macrophyte samples, the highest values of protein, digestible crude protein and nitrogen were found in autumn samples of P. perfoliatus from site N5 (after the confluence of El-Rayah with El-Noubaria Canal), while the highest energy value and metabolized energy were obtained from the winter samples of M. spicatum from site N4 (the beginning of El-Noubaria Canal). There were different relationships between the different macrophyte species, their chemical composition and the ambient water variables. Therefore, it is difficult to detect a main single factor affecting their pattern of variation. However, in general, the analyzed macrophytes could be considered a good economic natural food resource for animals and fishes.

Natural antioxidants, especially those of plant origins, have shown a plethora of biological activities with substantial economic value, as they can be extracted from agro-wastes and/or under exploited plant species. The perennial hydrophyte, Potamogeton perfoliatus, has been used traditionally to treat several health disorders, however, little is known about its biological and its medicinal effects. Here, we used an integrated in vitro and in vivo framework to examine the potential effect of P. perfoliatus on oxidative stress, nociception, inflammatory models, and brewer’s yeast-induced pyrexia in mice. Our results suggested a consistent in vitro inhibition of three enzymes, namely 5-lipoxygenase, cyclooxygenases 1 and 2 (COX-1 and COX-2), as well as a potent antioxidant effect. These results were confirmed in vivo where the studied extract attenuated carrageenan-induced paw edema, carrageenan-induced leukocyte migration into the peritoneal cavity by 25, 44 and 64% at 200, 400 and 600 mg/kg, p.o., respectively. Moreover, the extract decreased acetic acid-induced vascular permeability by 45% at 600 mg/kg, p.o., and chemical hyperalgesia in mice by 86% by 400 mg/kg, p.o., in acetic acid-induced writhing assay. The extract (400 mg/kg) showed a longer response latency at the 3 h time point (2.5 fold of the control) similar to the nalbuphine, the standard opioid analgesic. Additionally, pronounced antipyretic effects were observed at 600 mg/kg, comparable to paracetamol. Using LC-MS/MS, we identified 15 secondary metabolites that most likely contributed to the obtained biological activities. Altogether, our findings indicate that P. perfoliatus has anti-inflammatory, antioxidant, analgesic and antipyretic effects, thus supporting its traditional use and promoting its valorization as a potential candidate in treating oxidative stress-associated diseases.

Stratiotes aloides (Hydrocharitaceae) is a member of hydromacrophyte communities, which are widespread in the waterbodies of Eurasia. In the course of our study, which covered both fieldwork across a large part of the species range as analysis of published sources, we determined that S. aloides is a Pliocene relic showing a boreal-sublatitudinal sub-Eurasian range with a small North American enclave. Its populations are generally quite stable across much of their current range. However, in Western, Central and southern Europe and in the South of European Russia, both local population sizes and area of occupancy of S. aloides populations decline significantly, mainly due to habitat degradation. Regeneration via seed is of particular importance to the plant in extreme conditions, and also for maintaining or increasing the genetic diversity of its populations. Seeds are usually more easily dispersed, across a wider area, than vegetative propagules produced by the plant. Yet, in some populations sexual reproduction is hindered by spatial isolation of the plants of different sexual types and prevalence of gynomonoecious populations. On the other hand, vegetative (clonal) propagation of S. aloides can result in locally-high biological productivity, and extensive occupation of water area by the plant at individual sites. Populations of S. aloides have been found to co-occur with at least 134 other macrophyte species variously present. Highly constant species (present in more than 50% of communities containing S. aloides) include Ceratophyllum demersum, Hydrocharis morsus-ranae, Lemna trisulca, Potamogeton perfoliatus, Spirodela polyrhiza, and Utricularia vulgaris. This species prefers mesotrophic, β-mesosaprobic freshwaters, and detrital, muddy-clayey bottom soils.

Clasping-leaved Potamogeton L. species growing in Turkey are P. praelongus Wulfen and P. perfoliatus L. There exists no detailed study about distribution, habitat requirements, and anatomical properties of the Turkish populations of the two species. Potamogeton perfoliatus is widespread throughout the country but P. praelongus was recorded only from a single locality. Therefore, P. praelongus is rare and endangered in Turkey. In this study, we recorded presence of P. perfoliatus in 54 wetlands based on examination of 86 herbarium specimens. Physical and chemical parameters of the water bodies where the two species occur were measured from 24 sites for P. perfoliatus and from one site for P. praelongus. According to our findings, P. praelongus grows in an alpine lake with oligotrophic, calcareous and alkaline water. Potamogeton perfoliatus occupies diverse habitats but prefers deep lentic water bodies with high pH and low salinity levels. Stem anatomy of the species were studied based on three individuals for P. praelongus and 35 individuals for P. perfoliatus. Morphological features of the species were also investigated and descriptions based on Turkish material were prepared. We provided the distinguishing anatomical and morphological characters between the species. Our anatomical findings showed that P. praelongus specimens have eight vascular bundles in contrast to previous reports on the species. Our results can be used for future monitoring of the two submerged Potamogeton species as we provide detailed information about their current distribution pattern and habitat features., Türkiye’de yetişen gövdeyi saran yapraklı Potamogeton L. türleri P. praelongus Wulfen ve P. perfoliatus L.’tur. Bugüne kadar bu türlerin dağılımı, habitat tercihleri ve anatomik özellikleriyle ilgili detaylı çalışmalar yoktur. Potamogeton perfoliatus ülke çapında yaygın bir türdür ancak P. praelongus sadece bir lokaliteden kaydedilmiştir. Bu nedenle P. praelongus Türkiye’de nadir ve tehdit altındadır. Bu çalışmada 86 herbaryum örneğine dayanarak P. perfoliatus’u 54 sulak alandan kaydettik. Türlerin yetiştiği suların fiziksel ve kimyasal parametreleri P. perfoliatus için 24 noktadan, P. praelongus için bir noktadan ölçülmüştür. Bulgularımıza göre, P. praelongus oligotrofik, kalkerli ve alkali alpin bir gölde yetişmektedir. Potamogeton perfoliatus çok farklı habitatlarda bulunmakla birlikte, yüksek pH, düşük tuzluluk değerlerine sahip, derin ve durgun suları tercih etmektedir. Türlerin gövde anatomileri P. praelongus için 3 birey, P. perfoliatus için ise 35 bireyden örnek alınarak incelenmiştir. Türlerin morfolojik özellikleri de araştırılmış ve Türkiye’den toplanan materyallere dayalı olarak betimler hazırlanmıştır. Türler arasındaki ayırt edici anatomik ve morfolojik karakterler verilmiştir. Anatomi bulgularımız P. praelongus’un önceki bazı çalışmalara aykırı olarak sekiz iletim demetine sahip olduğunu göstermektedir. Bu çalışmada türlerin güncel dağılım ve habitat tercihleriyle ilgili sunduğumuz kapsamlı bulgular iki batık Potamogeton türünün gelecekte izlenmesinde faydalı olacaktır.

Summary: The objective of the research conducted in the years 2011–2014 in the near-shore zone of the Vistula Lagoon was the verification of the hypothesis that in the coastal lagoon, similarly as in inland waters, habitat conditions can be substantially modified by macrophytic vegetation, depending on the represented life form and its abundance. The research was conducted in the zone of emergent plants (reed rush composed of Phragmites australis) and in the zone of submerged plants occurring as scattered patches of Potamogeton perfoliatus and Stuckenia pectinata. The hypothesis was supported only in the case of the reed rush which substantially modified water insolation, temperature, and oxygenation, as well as the grain size composition of sediments, and concentration of organic matter contained in the sediments. Patches of submerged vegetation had insufficient surface area and were too scarcely overgrown by plants to considerably affect the habitat conditions and weaken the strong mechanical effect of waves and rate of water exchange between the littoral and open water zone. Keywords: Submerged and emergent vegetation, Oxygenation, Temperature, Insulation, Sediments

Interactions between plants will shift between competition and facilitation along environmental stresses, which has already been widely demonstrated in terrestrial ecosystems. Reestablishment of submerged macrophytes in eutrophic aquatic ecosystems has been recognized as a pivotal measure in the process of ecological restoration. However, little is known about the interactions between neighbor species and target species of submerged macrophytes along a nutrient gradient in freshwater ecosystems. Here, we carried out a mesocosm factorial experiment to investigate the responses of three target species (Potamogeton perfoliatus, Myriophyllum spicatum and Vallisneria natans) to the presence/absence of neighbor species (Potamogeton malaianus) under five nutrient levels. Results showed that the neighbor species has a strong negative effect on the performance of P. perfoliatus, whereas has weak effects on the performances of M. spicatum and V. natans (negative and neutral, respectively). Along the experimental nutrient gradient, the neighborhood effects shifted from facilitation to competition, whereas no significant facilitative effects were found in the study. Strong negative neighborhood effects were found in high nutrient levels due to the higher periphyton biomass. Multiple regression analysis suggested that the neighborhood effects are significantly affected and largely explained by the periphyton attached on target species. Overall, our results suggested that periphyton may be a potential factor mediating the neighborhood effects on restoration of submerged macrophytes in eutrophic freshwater ecosystems.

Zostera marina a kind of seagrass with high wildlife value, is threatened by human activities in the coastal area of China and Indonesia. In this study, we obtained the complete chloroplast genome sequence of Zostera marina, of which the length is 143,877 bp. It contained a pair of IR regions (25,915 bp) separated by a small single copy region (8823 bp) and a large single copy region (83,224 bp). The overall GC contents of the chloroplast genome were 35.5%. This circular genome contains 116 annotated genes, including 78 protein-coding genes, 30 tRNAs and 8 rRNA. By phylogenetic analysis using maximum likelihood (ML) and neighbor-joining (NJ) method, Z. marina showed the closest relationship with Elodea canadensis and Potamogeton perfoliatus. This complete chloroplast genomes can be subsequently used for population genomic studies of Z. marina and provide valuable insight into in situ and ex situ conservation for this valuable species.

The accumulation of heavy metals (Cu, Ni, Zn, Mn, and Fe), parameters of the photosynthetic apparatus, and flavonoid content in leaves of two widespread species of submerged hydrophytes (Elodea canadensis Michx. and Potamogeton perfoliatus L.) from habitats with different levels of pollutions have been studied. The investigations are carried out in the surroundings of the metallurgical plant in the town of Revda, Sverdlovsk oblast, Russia (Revda River, upstream and downstream the confluence of the sewage). It is shown that hydrophytes from polluted habitats (impact site) differ from the plants of a less polluted zone (background site) by a higher accumulation of heavy metals (HMs), greater leaf thickness, and larger cells and chloroplasts. Plants from the polluted site are characterized by a high content of photosynthetic pigments, while flavonoid content in the leaves is lower. The identified trends indicate a high adaptive potential of these species of plants and their ability to inhabit in an aquatic environment polluted with metals and other pollutants.

Content of some heavy metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) and macroelements (Ca, Mg, Na, and K) were determined in samples of water, sediment, macrophytes (Potamogeton crispus, Potamogeton perfoliatus, Myriophyllum spicatum, and Chara vulgaris), and leech (Hirudo sulukii n. sp.) collected from Kara Lake Adiyaman, Turkey at four distinct seasons using inductively coupled plasma optical emission spectrometer (ICP-OES). It was found that the studied heavy metals were completely below the detection limit of ICP-OES for water samples. The results showed that most heavy metals (Ni, Cr, Zn, Fe, and Pb) and macroelements (Mg and Na) had their highest values in sediment samples in August. Increases of heavy metals and macroelements may be due to evaporation because of summer stagnation at this period. The average content of studied elements was in the order of Mn>Ni>Cr>Zn>Fe>Pb>Cu in sediment samples. As a non-essential heavy metal, Cr was the most accumulated in all the macrophytes studied. The average Cr concentration was in the order of P. crispus > P. perfoliatus > M. spicatum > C. vulgaris. In C. vulgaris, the accumulation of Ca was the highest compared with other macrophytes. The accumulation of heavy metal was in the order of Fe>Zn>Cu>Pb>Mn>Cr>Ni>Cd in H. sulukii n. sp. The obtained results showed that the heavy metal and macroelement (Na, Ca, Mg, and K) concentrations in water, sediment, macrophytes, and leech are below the risk values according to the aquatic life pollutant data provided by the U.S. Environmental Protection Agency. Overall, the element contents can be attributable to the geological sources because of the general absence of serious pollution in Kara Lake, Adiyaman, Turkey.

This study is devoted to the analysis of the distribution of heavy metals in the aquatic system of the Barguzin River. This is one of the largest rivers of the Baikal lake system. The element composition of the aerial scion of Potamogeton pectinatus L. (syn. Stukenia pectinata (L.) Borner), Potamogeton perfoliatus L., Hippuris vulgaris L. and Nymphoides peltata (S.G. Gmelin) O. Kuntze of the Barguzin River is studied in this research. One of the main results of the study is the establishment of the following sequence of the accumulation of metals in aquatic plants: Mn > Fe > Сu (Zn) > Сr > Ni > Сo > Pb > Cd > Hg. Hippuris vulgaris L. contains the highest concentration of the studied metals. Thus, this research provides one of the important steps for the development of regional environmental standards and environmental risk assessments.

The genus Ditylenchus consists of more than 60 species, some of which are plant parasites. In this paper we report on Ditylenchus laurae sp. n. from Poland, a new species associated with the aquatic plant, Potamogeton perfoliatus L. Ditylenchus laurae sp. n. is characterised by a long and slender body with L = 1881 (1523-2095) μm and 1875 (1690-2089) μm, a = 88.8 (72.5-102.5) and 89.7 (71.9-97.9), stylet length = 10.8 (9.6-12.1) μm and 8.3 (7.7-9.0) μm, tail length = 117.2 (103.5-126.7) μm and 102.4 (98.3-113.6) μm in females and males, respectively; four incisures, rounded stylet knobs, long basal bulb (about ten times as long as wide), post-vulval uterine sac from 4.3-5.6 vulval body diam. long, and mucronate tail. Characterisation using the ITS rRNA, COI and hsp90 gene sequences was conducted and a phylogenetic analyses revealed that D. laurae sp. n. belongs to the D. dipsaci complex.

Life-history traits like dominance of certain reproductive modes (e.g. vegetative, specialized, unspecialized or sexual propagules) and overwintering strategies (evergreen or re-sprouting) determine the success and timing of the ability of aquatic plants to colonize new areas. In the present experiment the distribution of these reproductive modes was examined in-situ, where new gaps were experimentally formed and establishment of new vegetation observed on a monthly bases in ten plots. During a period of 126 days, altogether 73% of all established plants (n = 1822) colonized by rhizomatic growth and 11% by rooting of vegetative fragments. Myriophyllum spicatum was observed to use mostly fragment rooting (81%), while Potamogeton perfoliatus followed a more mixed strategy combining re-rooting fragments and rhizomatic growth (31% and 41%, respectively). Stuckenia pectinata also preferred colonisation by rhizomes (84%). No colonisation by specialized vegetative units (tubers or turions) was observed during the study period The importance of surrounding vegetation was shown by comparing colonisation on inner and marginal sections of the plots (30% vs.70%). Three different patterns of timing of peak colonisation intensities were observed, related to species’ life-history traits. While several experimental works have been done on the regeneration and colonisation abilities of different species under laboratory conditions, information on the in-situ application of the different strategies is scarce. Insights on the modes by which plants succeed in colonising gaps helps us understand how (re)establishment of aquatic vegetation might function in lake ecosystems recovering after eutrophication.

The evaporation ( E p ) of a US Class A pan ( C ) with submerged, freshwater aquatic macrophytes ( Potamogeton perfoliatus , Myriophyllum spicatum and Najas marina ), hereafter macrophytes ( P s ) and a sediment-covered bottom ( S ) was measured in Hungary during 2014–2015 using reference E of Shuttleworth ( E o ) and Penman-Monteith crop reference evapotranspiration (crop ET o ). There were two main climatic controls affecting variation in E : direct (air and water temperature) and indirect (wind-mediated change affecting the penetration of sunlight; precipitation inflow, impacting plant emergence). Lower seasonal mean E p rates of 2.75 ± 0.89, 2.83 ± 0.91 and 3.06 ± 1.14 mm day −1 were observed in C , S and P s , respectively, during the wet 2014. In the 2015 season, higher overall daily mean E p rates for C , S and P s were 3.76 ± 1.3, 4.19 ± 1.34 and 4.65 ± 1.52 mm day −1 , respectively. A comparison of US Class A pan E p containing macrophytes/sediments with that of a standard US Class A pan showed that pan coefficients ( K ap and K as ) might allow for more accurate on-site lake E estimates. In 2014, seasonal mean K as and K ap were 1.04 ± 0.14 and 1.09 ± 0.18, respectively. Slightly higher K a values were observed during the warm and dry 2015 ( K as : 1.15 ± 0.22; K ap : 1.26 ± 0.23). A K a value greater than 1 indicates that the E p of a US Class A pan containing macrophytes and sediment is always higher than that of C . The calculated E o overestimated measured E p of P s during the course of this study. During the warm-dry growing season, crop ET o was closest to E p of P s . Empirical coefficients can be useful for estimating E of lakes with submerged macrophytes more precisely. The accuracy of the estimate of Keszthely Bay’s E improved by 9.85% when K a was determined on site.

Interactions between plants and aquatic insects are poorly documented, especially for turbid freshwater ecosystems. Many Swiss lakes offer such habitats, several of which are inhabited by the leaf beetle Macroplea appendiculata (Panzer 1794). This donaciid beetle is the only coleopteran species known to complete its life cycle entirely under water, where it lives primarily on perfoliate pondweed (Potamogeton perfoliatus L.), with Eurasian watermilfoil (Myriophyllum spicatum L.) as an alternative host plant. Direct observations during diving trips, aquatic olfactometer bioassays, and stir bar sorptive extractions (SBSE) coupled with GC–MS analysis were used to understand how these beetles locate their patchily distributed host plants and congeners in a harsh, often swirling environment. In olfactometer assays we observed that the aquatic beetle is strongly attracted to water extracts of pondweed, whereas neither mature males nor females beetles seem to produce attractive cues. The chemical analyses revealed that perfoliate pondweed releases one dominating compound, eucalyptol. Olfactometer assays confirmed that this is a potent attractant for the beetle. We also observed attraction to phytol, which is released by the main, as well as the alternative host plant. These finding are somewhat surprising as eucalyptol has never been reported for aquatic plants and phytol is poorly soluble in water. In addition, both are frequently described as insect repellents in terrestrial ecosystems. We suggest that these terpenoids normally have a defensive function against herbivores and pathogens, but that the highly specialized leaf beetle has evolved to exploit its host’s defence chemistry for optimal foraging.

Primary, the author places special emphasis on the study of traditional technologies for processing of geophytes. Modern development trends in biotechnology demand of expansion of the raw material base. The increase in needs medicine, food and feed industries in biologically active substances pay attention to new unconventional sources of renewable raw materials. From this perspective, higher aquatic plants Zostera noltii and Potamogeton perfoliatus L. can be considered as a perspective object due to its high content of unique biologically active substances with different properties. Rationale of choosing of plant material and identifications of optimum performance and operational conditions for the production of biologically active substances: alcohol extraction in the mixer at room temperature limited to 7-10 days. Studied the organoleptic, physicochemical and microbial properties of end products – aqueous-alcoholic extracts of hydrophytes. Experimentations (UV spectrophotometric analysis, thin layer chromatography, mass spectrometry) indicate that the composition of plants and extracts contains different biologically active substances. The high content of quercetin and pigments in the extracts of Z. noltii and Potamogeton perfoliatus L. shows the future use of hydrophytes in the Volga river and the Northern Caspian sea as an additional natural source of flavonoids and antioxidants. Therefore, plant preparations (aqueousalcoholic extracts of zostera and pondweed) are combinations of various compounds, which have a high biological activity with different properties: adsorptive capacity, antioxidant and antimicrobial activity. Products of studied plants after extraction with water-alcohol can be used in the food industry as a source-native with minerals, carbohydrates, protein, vitamins, flavonoids, terpenoids, alcohols, aliphatic acids and etc. Find an opportunity of use of biologically active substances from eelgrass and pondweed and herbal precipitate after extraction.

This study is devoted to the analysis of the distribution of heavy metals in the aquatic system of the Barguzin River. This is one of the largest rivers of the Baikal basin. The element composition of surface water, bottom sediments, water plants ( L., Potamogeton perfoliatus L., Hippuris vulgaris L., Nymphoides peltata (S.G. Gmelin) O. Kuntze) and fish (Abramis brama, Cyprinus rubrofuscus, Perca fluviatilis, Rutilus rutilus lacustris) of the Barguzin River is studied. The following sequence of the accumulation of metals in aquatic plants: Mn > Fe > u (Zn) > r > Ni > o > Pb > Cd > Hg is established. Hippuris vulgaris L. contains the highest concentration of the studied metals. In the distribution of metals over the body of the studied fish species the following sequence Zn Fe> Cu Mn Cr > Pb> Ni Cd> Hg is observed. There is an accumulation of zinc, manganese and chromium in fish scales, and iron, lead in the liver. The obtained data of the distribution of heavy metals broadens and clarify the understanding of the biochemical characteristics of aquatic system components. This research provides one of the important steps for the development of environmental standards and environmental risk assessments.

Aquatic plants play an important role in maintaining the health of water environment in nature. Studies have shown that linear alkylbenzene sulfonate (LAS), a type of omnipresent pollutant, can cause toxic damage to aquatic plants. In the present research, we studied the physiological and growth response of submerged plant Potamogeton perfoliatus L. to different concentrations of LAS (0.1, 1.0, 10.0, 20.0, and 50.0 mg l−1). The results showed that LAS is toxic to P. perfoliatus, and the toxicity is dose-dependent. Only slightly reversible oxidative damages were observed in the physiological parameters of P. perfoliatus when P. perfoliatus was exposed to lower LAS doses (

Aquatic plant communities are frequently subjected to water level fluctuation. While many experimental studies have examined effects of water level fluctuation on the growth of individual aquatic plant species, very few have tested those on aquatic plant communities. We constructed aquatic communities consisting of four submerged macrophytes ( Potamogeton perfoliatus , Myriophyllum spicatum , Chara fragilis and Ceratophyllum demersum ), and subjected them to three static water depths (30, 90 and 150 cm) and three water level fluctuations with low, medium and high frequency (two, four and eight cycles of water depth change between 30 cm to 150 cm). Water depth in each of the three fluctuation treatments was on average 90 cm, which was comparable to the static water depth of 90 cm. Increasing water depth significantly decreased the growth of the communities in terms of biomass, number of shoot nodes and shoot length because it decreased the growth of most species ( P. perfoliatus , M. spicatum and C. fragilis ). Compared to the static water depth of 90 cm, water level fluctuation increased number of shoot nodes and shoot length of the communities, whereas fluctuation frequency had little impact. We conclude that water level fluctuation may potentially increase the vegetative spread of submerged macrophyte communities and managing water level fluctuation may be helpful for the restoration of submerged macrophyte communities in degraded wetlands.

Phragmites australis, Potamogeton pectinatus, Potamogeton perfoliatus and Ceratophyllum demersum were selected to study concentrations of PAHs in lotic ecosystems. Six sampling sites were selected along Al-Hilla River and sampling was conducted in 2010 and 2011. Sixteen PAHs listed as priority pollutants were detected in the samples collected, including Naphthalene (Nap), Acenaphthylene (Acpy), Acenaphthene (Acp), Fluorene (Flu), Phenanthrene (Phen), Anthracene (Ant), Fluoranthene (Flur), Pyrene (Py), Benzo (a) Anthracene (B(a)A), Chrysene (Chry), Benzo (b) Fluoranthene (B(b)F), Benzo (k) Fluoranthene (B(k)F), Benzo (a) Pyrene (B(a)P), Dibenzo (a, h) Anthracene (D(b)A), Benzo (ghi) Perylene (B(ghi)P) and Indeno (1,2,3-cd) Pyrene (Ind). The results of the study illustrate that the PAH concentration in macrophytes varies among their species. These variances were as follows: P. australis 0.425 to 299.424 μg/g dry weight (Dw) for B(ghi)P and B(b)F, respectively; P. perfoliatus 0.354 to 235.84 μg/g Dw for B(b)F and B(ghi)P, respectively; C. demersum 0.996 to 162.942 μg/g Dw for Ant and B(ghi)P, respectively; and P. pectinatus 0.383 to 99.87 μg/g Dw for Ant and Nap, respectively. The accumulation potential of PAHs was also investigated by calculating the Bioconcentration Factor (BCF) and Bio-sediment Accumulation Factor (BSAF). The ranges of BCF ratios were 0.05 to 5334.5, 0.08 to 1602.5, 0.01 to 536.6, 0.16 to 1882 in P. australis, P. perfoliatus, P. pectinatus and C. demersum, respectively. The range of BSAF ratios were 3.14 to 1041.6 and 1.5 to 2920.8 in P. australis and P. perfoliatus, respectively.

The biomass and composition of autotrophic communities in the littoral zone are mainly affected by light availability. In a field study, the spectral attenuation of periphyton was assessed. Periphyton absorbed more light in the red than in the infrared spectral range, resulting in a lower red to infrared ratio (~0.3 during the most active period of periphyton accumulation, compared with 0.9–1 otherwise). The lowest red to infrared ratio was detected in the upper 20–40 cm of the water column. Epiphytic algae are therefore found to affect not only the quantity but also the quality of light passing through periphyton. Acclimation of Potamogeton perfoliatus L. plantlets to such infrared-enriched light was also studied in the laboratory. During leaf morphogenesis, lower red to infrared ratio light was associated with increased leaf area via the growth of existing (+85%) and the production of new leaves. Intensified internode length growth (+130%) was also observed. Post morphogenesis, no leaf or internode growth was observed and new shoot production was also intensive. Leaf photochemical activity did not significantly differ between groups or treatments. Results suggest that periphyton could trigger shade-tolerance (leaf growth), shade-avoidance (internode growth), and morphogenetic (branch production from axillary buds) adaptations in macrophytes.

Submerged aquatic plants have attracted increasing attention as an advanced component for wastewater treatment. This study performed a laboratory-scale investigation using three submerged plants, namely Myriophyllum verticillatum, Potamogeton perfoliatus, and Najas minor to determine the response of submerged plants to seasonal changes and intermittent reclaimed water amendment. The three plants were pre-selected from seven commonly used submerged plants. Reclaimed water from a wastewater reclamation plant was used as raw water. The total phosphorus (TP), total nitrogen (TN), ammonium, chemical oxygen demand, and dissolved oxygen were monitored during the experiments to investigate their resistance to changes in water conditions. With seasonal changes from April to June, the water temperature ranged between 19 and 23°C, and the TN and TP removal efficiencies were negatively affected. The highest TN and TP concentrations in the tanks with M. verticillatum and P. perfoliatus were reached on day 14. ...

The ability to select appropriate substratum in a patchy environment is crucial for food availability, reproductive success, anti-predator defence and resistance to other environmental dangers. Therefore, even euryecious invasive species may exhibit clear substratum preferences, contributing to their success in novel areas. We used 24-h pairwise-choice experiments to study substratum preferences of the highly invasive freshwater Ponto-Caspian gammarid Dikerogammarus villosus (Amphipoda, Crustacea). We tested its preferences for stony substrata of various grain diameters (2–124 mm), macrophytes differing in structural complexity (Myriophyllum spicatum, Ceratophyllum demersum, Potamogeton perfoliatus, Potamogeton nodosus, Stuckenia pectinata) and zebra mussels. We hypothesized that: (1) gammarids would select substrata adjusted to their body size and offering maximum protection; (2) mussels would be the most preferred substratum except in high densities, which lead to deterioration of water quality; (3) large gammarids would displace smaller conspecifics to worse substratum. Our results showed that large (>9 mm) and small ( 6 cm and between 6 and 8 cm, respectively, with relatively large empty spaces among particles (4–9 cm). Small gammarids selected complex plants, particularly M. spicatum, whereas large individuals also preferred less complex forms with large leaves (Pot. nodosus, Pot. perfoliatus). Small gammarids exhibited higher affinity for natural macrophytes than large individuals. All gammarids preferred stones over plants. Contrary to most of the published data, gammarids selected stones more often than dense zebra mussel colonies and did not discriminate between low density mussel and stone habitats. Oxygen depletion seems to be the factor distracting gammarids from mussel habitats. Thus, they seem to select mussel colonies only when alternative hard substrata are missing. Differences in substratum preferences between size classes were not pronounced, but small individuals switched to the less preferred habitat in the presence of adults, probably avoiding cannibalism and competition.

Harmful algal blooms are considered to be one of the biggest threats to benthic vegetation. The amount of annual algal mats has increased due to eutrophication but their effects on perennial vegetation have rarely been tested in field experiments. In regions where eelgrass ( Zostera marina ) grows in mixed meadows, plant species richness may ameliorate algal-induced stress through facilitative mechanisms and improve eelgrass growth and survival. To test this, we conducted a 3 mo. field experiment at 3.5 m depth in the Baltic Sea, where we applied filamentous brown algae (300 g ww) to eelgrass monocultures and polycultures ( Z. marina , Ruppia cirrhosa , Stuckenia pectinata and Potamogeton perfoliatus ). The algal stress period lasted for 13 d and plots were sampled after a 5 wk recovery period. In both algal-stressed mono- and polycultures, the presence of algal mats significantly reduced eelgrass shoot and root biomass production and affected the leaf growth negatively. Plant richness did not have strong effects on eelgrass growth and eelgrass in both algal-stressed mono- and polycultures showed significantly reduced productivity. Our results clearly demonstrate that loose-lying algal mats pose a serious threat to seagrass meadows and that plant diversity cannot alone ameliorate negative effects by macroalgal mats.

Recent field works in the central and southern regions of Saudi Arabia including agricultural centers have managed to collect four vascular plants new to terrestrial and wetland flora of the country. These new additions include one new genus Malvastrum A. Gray (M. coromandelianum) subsp. capitato-spicatum (O. Kuntze) S.R. Hill, Potamogeton perfoliatus L. (Potamogetonaceae), Euphorbia tirucalli L. (Euphorbiaceae) and Sesuvium portulacastrum (L.) L. (Aizoaceae). Detailed morphological description, distribution and habitat of each of these species are provided along with illustrations and photographs. The report of new additions to the flora of Saudi Arabia indicated that the country needs thorough botanical explorations.

Light within the littoral zone affects the productivity and interaction between periphyton and its macrophyte substrate. The effect of periphyton on macrophyte photosynthesis, seasonal variation and vertical distribution of periphyton on artificial substrates (plastic strips), and the effect of periphyton on the light environment was studied in Lake Balaton. Data showed that an average of 4.1 ± 0.4 mg (dry weight) cm−2 of periphyton had accumulated on the plastic strips after 8.8 ± 0.4 days. This biomass corresponded to 294 ± 30 μg m−2 chl-a of epiphytic algae and blocked 92.3 ± 0.8 % of the depth specific radiation. Seasonal variation and specific vertical distribution of periphyton were observed. The most active time of periphyton accumulation corresponded to spring up until mid-June. Later in the year, the amount of periphyton significantly decreased. The optimal conditions for periphyton accumulation were at 30–40 cm depth. Most of the light reaching the adaxial leaf surface was attenuated by periphyton, decreasing the production of Potamogeton perfoliatus by 60–80 %. This increased the importance of backscattered light that corresponded to 10–15 % of the macrophyte production. A smaller part of the periphyton consisted of precipitated inorganic material, while epiphytic algae, making up the majority of the periphyton, were connected to both benthic (dominantly benthic penales) and pelagic (very close seasonal dynamics of pelagic and epiphytic biomass) algae. Periphyton affects macrophyte production especially in spring and in the upper water layers even in a mesotrophic water body. This increases the importance of the light absorbed through the abaxial side of the leaf and confirm the role of periphyton in transition from clear to turbid water states.

The transport of dissolved inorganic nitrogen in wetlands was investigated in the Yeyahu National Preserve of Beijing, China, from July to December 2011. Stable isotope of nitrogen ( 15 N) as NH 4 + was added to experimental mesocosms vegetated by seven common wetland plants. The 15 N abundance in soil and various plant parts were measured at prescribed time intervals during the 49-day experimental period. Rapid 15 N enrichments were found in soil and aquatic plants during the first sampling event at day 3 and typically increased linearly during the experimental period. Highest 15 N enrichment was found in submerged plants, followed by emergent plants and soil. No differences in δ 15 N values were found among leaves and stems of all submerged plants ( Potamogeton pusillus , Potamogeton perfoliatus , Najas marina , Ceratophyllum demersum ), suggesting that these plant structures are equally effective in nitrogen assimilation. The roots of P. perfoliatus displayed the lowest enrichment compared to the stems and leaves. Such results indicate that submerged plant roots may have a relatively weak role in nitrogen assimilation. The two emergent plants ( Phragmites australis and Typha orientalis ) showed no differences in δ 15 N values among all plant parts, suggesting rapid translocation of nitrogen from roots to other portions. This experiment demonstrates that wetland soil and plant stems and leaves are major sinks for dissolved nitrogen from the surface water and provides valuable insight into nitrogen retention and transport pathways in various wetland plants.

Submerged macrophyte plays an important role in lake ecosystems.It is not only a primary producer in the food chain,but also plays a major role in lake nutrient accumulation and circulation,thus,having a great influence on the eutrophication process of lakes.This study reports the seed dormancy and germination of three submerged macrophytes(Potamogeton pectinatus,Potamogeton perfoliatus and Myriophyllum verticillatum) in the Yellow River,located in the Hetao irrigation area of the Inner Mongolia.The result shows:Myriophyllum verticillatum seed has a high dormancy rate,but its dormancy is easy to be broken.Various treatments including seed coat scarification,low temperature stratification,applications of KNO3 and gibberellin can significantly increase the germination percentages.Potamogeton pectinatus seed has a deep dormancy.Low temperature stratification and application of GA can effectively break the seed dormancy,but other treatments had no effect on.Potamogeton perfoliatus seed has a deep dormancy.None of the above mentioned treatments can significantly break its dormancy.

Plastic effect of environmental factors acting on an aquatic submerged plant, Potamogeton perfoliatus L. at the plant-level (nutrient availability) and the leaf-level (light intensity) at different sites in Lake Balaton was studied. Light-dependent morphological traits (foliar morphology and internode length) of P. perfoliatus were measured and analysed across the environmental gradients of the lake. The size of leaves was influenced by both trophic state and light environment: nutrient surplus increased the size of leaves by y 29%, whereas a more heterogeneous light environment resulted in 15% larger leaves. The light environment influenced shoot morphology (internode length) to a greater extent than nutrient surplus (38% vs. 19%). Contrary to this, within-plant morphological variability was significantly higher (41%) at the nutrient limiting sites as a result of diversification effect of the leaf-level environmental factor, light. Foliar parameters and within-plant variability showed correlation only with the total N content of the sediment. Appearance of P. perfoliatus is shaped by counteracting effects: within-plant differentiation, promoted by leaf-level environmental sensitivity and within-plant homogenization triggered by perception of the surroundings at plant-level. Both light attenuation, stimulating an increase of morphological variability, and nutrient surplus, initiating the stabilization of morphological parameters, could have adaptive advantages. The variability of leaf size leads to diversification of foliar parameters, thus increasing the efficiency of light harvest at low-nutrient sites and making responses to changes in the light environment more dynamic. These results suggest that leaf-level-induced diversification is counteracted by the standardization effect triggered by plant- level environmental factors.

When parental taxa are adapted to different habitats, hybrid genotypes are often highly heterogeneous, such that habitat or ecological factors influence hybrid fate and ecological performance. Trait expression in hybrids is not always intermediate between the parents, but may instead be either parental-like or extreme (transgressive) depending on genetic control of the phenotypes. Maternal effects arising from interspecific interaction between cytoplasmic and nuclear genomes are widely recognized as playing a role in character expression of natural hybrids. Such interaction often leads to hybrid sterility or inviability. When hybrids are viable, however, cytonuclear interaction may contribute to hybrid persistence through its influence on trait expression. To date, maternal influence on hybrid performance has been examined primarily in experimentally produced hybrids, or in natural hybrids without identification of the cross direction owing to difficulty in obtaining species-specific molecular markers. In aquatic plants, many hybrids persist by extensive clonal growth and are important components of aquatic communities. Many such hybrids are known in Potamogeton (pondweeds), the largest aquatic genus. Because Potamogeton species are ecologically highly diverse and maternal lineages are readily distinguished using molecular markers, natural hybrids of Potamogeton are well-suited for studies of maternal effects, especially those affecting vegetative performance. As a case study, we have focused on maternal effects on drought tolerance and depth distribution in the natural hybrid P. ¥ anguillanus derived from the closely related species P. perfoliatus and P. wrightii.

Phosphate (Pi) uptake kinetics were determined in shoot and root tissues for four freshwater macrophyte species, Littorella uniflora, Potamogeton perfoliatus, Myriophyllum alterniflorum and Elodea canadensis, using a radioactive 33P phosphate technique. Collection of plant material in the oligotrophic softwater lake, Lake Hampen, Denmark, where Pi limits macrophyte growth, enabled us to characterize and compare the Pi uptake kinetics and competitive characteristics of the four species in a low level Pi environment. The maximum Pi uptake rates (Vmax), the half saturation constants (Km) together with the affinity at low Pi concentrations (Vmax/Km) were determined by fitting data to the Michaelis-Menten kinetics.L. uniflora showed the highest Vmax/Km in the root tissue and the lowest Km. M. alterniflorum showed the highest and E. canadensis and P. perfoliatus the lowest Vmax/Km in leaf tissue. M. alterniflorum had the highest Vmax and, as the only species, a higher Vmax in leaves than in roots. Surface area explained about half of Vmax in M. alterniflorum leaves. Roots were the dominant organ for Pi assimilation for all species at the Lake Hampen Pi concentrations. Km showed positive correlation to%P content in root tissue.The results indicate that at low lake water Pi concentrations L. uniflora is able to survive on the Pi pools in the sediment porewater. M. alterniflorum showed high affinity for Pi at both low and high Pi concentrations by both roots and shoots, and suggests that M. alterniflorum is a strong competitor at both low and high Pi concentrations.

The present study examined certain physical and chemical parameters in epiphytic and epipsammic diatoms identified on Potamogeton perfoliatus and Chara sp. collected from an area of one square kilometers in Gölbaşı Lake located within the borders of Adıyaman city from March to October 2014.Over the course of the study, 14 taxa belonging to epiphytic diatoms and 24 taxa of epipsammic diatoms were identified. Among the epiphytic diatoms, Amphora ovalis, Diatoma vulgaris and Ulnaria ulna were the most significant ones in terms of abundance and individual occurrences, while among the epipsammic diatoms the most remarkable ones were Navicula salinarum, Navicula radiosa, Nitzschia linearis and Cyclotella comta with regard to abundance and individual occurrences. According to Sorensen Index the highest similarity (78%) was found between diatoms on Potamageton perfoliatus and Chara sp. The similarity between epiphytic and epipsammic diatoms was only as high as 26% and 30%. Accordingly, the macrophyte preference of diatoms as a substratum was to a large extent similar. Diatoms displayed the highest level of development in late spring and summer, when there is more light and temperatures are higher.Keywords: Epiphitic diatoms, Epipsammic diatoms, Sorensen Similarity Index, Gölbaşı Lake, East Anatolia, Turkey, Bu çalışmada Adıyaman il sınırları içinde bulunan Gölbaşı Gölü’ nden Mart- Ekim 2014 tarihleri arasında bir kilomerekarelik alandan toplanan Potamogeton perfoliatus ve Chara spp.’ nin epifitik ve epipsammik diyatomeleri bazı fiziksel ve kimyasal parametreler ile birlikte araştırılmıştır. Araştırma süresince epifitik diyatomelere ait toplam 14 takson, epipsammik diyatomelere ait toplam 24 takson kaydedilmiştir. Epifitik diyatomeler içerisinde ortaya çıkış sıklıkları ve birey sayıları ile en dikkat çeken türler Amphora ovalis, Diatoma vulgaris ve Ulnaria ulna olurken; epipsammik diyatomeler içerisinde ise ortaya çıkış sıklığı ve birey sayıları itibariyle en dikkat çeken türler Navicula salinarum, Navicula radiosa, Nitzschia linearis ve Cyclotella comta olmuştur. Potamogeton perfoliatus ve Chara sp üzerindeki diatomeler arasında Sorensen benzerlik indeksi %78 çıkmıştır. Epifitik ve epipsammik diyatomeler arasındaki benzerlikler ise %26 ve % 30 gibi değerlerde çıkmıştır. Substrat olarak diatomelerin makrofitleri tercihinde büyük bir benzerlik görüldü. Diyatomeler en iyi gelişimlerini ışığın ve sıcaklığın arttığı ilkbahar sonları ile yaz aylarında göstermişlerdir

We carried out a first study of Lake Baikal epiphyton on six species of submerged macrophytes: Myriophyllum spicatum L., Potamogeton perfoliatus L., Potamogeton sp., Sparganium gramineum Georgi, Ceratophyllum demersum L., and Elodea сanadensis Michaux. We identified 70 epiphyton species and intraspecific taxa belonging to 3 phyla, viz. Ochrophyta, Cyanobacteria, and Chlorophyta. Nine species of Cyanobacteria were new records for Lake Baikal. Epiphyton communities differing in species composition and quantitative characteristics grew on diverse species of submerged macrophytes. High levels of species richness were recorded on Sparganiumgramineum and Potamogeton sp., whereas low diversity of epiphyton was observed on Myriophyllum spicatum and Elodea canadensis. A monodominant community was revealed on the invasive Elodea canadensis represented by Cocconeis placentula var. placentula. Specific characteristics of morphology of submerged macrophytes influenced the structural organization and quantitative development of epiphyton. Epiphyton abundance and biomass were higher on upper sections of most plants than on lower sections, probably because of canopy shading of macrophyte lower portions.

Damming could alter hydrological cycle in a region rapidly and produce profound influences on ecosystem structures and functions of wetlands.Plants are the essential composition of the wetland ecosystem and the alteration of hydrological conditions caused by damming can directly affect spatial distribution,ecosystem structures and functions of wetlands.The impacts of impoundment by damming on wetland ecosystems have become a worldwide concern. Lashihai,a typical closed and semi-closed wetland in the northwestern Yunnan Plateau,belongs to the Jinsha River catchment and is also one of the 12 wetlands of international importance in the plateau region.Since 1994,Lashihai has changed from a seasonal flooding wetland to a lake with relatively stable water level after a dam establishment.To study the distribution patterns and changes of aquatic communities in Lashihai after impoundment by damming can provide a sound basis for scientific assessment of impacts of dam establishment on wetland ecosystems. By using the RS and GIS technologies combined with field surveys,the plant communities,species composition and their distribution patterns in the plateau wetlands of Lashihai were studied over 13 years following impoundment by damming.The results of a comparative analysis of changes in plant communities from 1994a to 2006a showed that 13 years after dam establishment,there were two emergent communities(Scirpus tabernaemontani and Polygonum amphibium),two floating-leaved communities(Potamogeton tepperi and Trapa bispinosa),five submerged communities(Myriophyllum spicatum,Potamogeton pectinatus,Potamogeton crispus,Potamogeton perfoliatus and Potamogeton pusillns) and lakeside meadow community in Lashihai.The number of species was 61,belonging to 25 families and 48 genera.Plant species richness was the lowest in the submerged communities and increased gradually in the floating-leaved communities and emergent communities,and reached the highest in the lakeside meadows.The current distribution area of the submerged communities amounted to 615.08 hm2,the meadows and floating-leaved communities covered 214.60 hm2 and 140.01 hm2,respectively,and the emergent communities was only 9.34 hm2.In the past 13 years after impoundment,the plant communities in Lashihai changed from a simple submerged community to a diverse system of submerged,floating-leaved and emergent communities,where the submerged plant communities of Myriophyllum spicatum,Potamogeton pectinatus and Potamogeton pusillns remained,and Butrachium bungei,Potamogeton malaianus and Chara spp.communities had disappeared.Damming altered the natural hydrological conditions and changed greatly species composition,community structure and spatial patterns of wetland vegetation in Lashiha.The key driving force for the changes in wetland vegetation was dam construction,as the wetland plants with different strategies of renewal and spreading responded to hydrologic changes by damming.Lashihai wetland has been designated to a wetland of international importance,with a main conservation object of Ciconia nigra and other wintering waterfowl,as well as their habitats.The diverse plant communities and regular spatial distribution of wetlands in Lashihai could provide crucial habitat,shelter and food for waterfowl.The number of winter waterfowl increased significantly as compared to that before dam construction.The present stable relationships among hydrology-vegetation-waterfowl provided a foundation to maintain the wetland ecosystem structures and functions.A scientific assessment of dam establishment on wetland ecosystems could provide sound information for plateau wetland conservation,management and wise use.

†Background and Aims Molecular-based studies of thermotolerance have rarely been performed on wild plants, although this trait is critical for summer survival. Here, we focused on thermotolerance and expression of heat shock transcription factor A2 (HSFA2) and its putative target gene (chloroplast-localized small heat shock protein, CP-sHSP) in two allied aquatic species of the genus Potamogeton (pondweeds) that differ in survival on land. †Methods The degree of thermotolerance was examined using a chlorophyll bioassay to assess heat injury in plants cultivated under non- and heat-acclimation conditions. Potamogeton HSFA2 and CP-sHSP genes were identified and their heat-induction was quantified by real-time PCR. †Key Results The inhibition of chlorophyll accumulation after heat stress showed that Potamogeton malaianus had a higher basal thermotolerance and developed acquired thermotolerance, whereas Potamogeton perfoliatus was heat sensitive and unable to acquire thermotolerance. We found two duplicated HSFA2 and CP-sHSP genes in each species. These genes were induced by heat shock in P. malaianus, while one HSFA2a gene was not induced in P. perfoliatus. In non-heat-acclimated plants, transcript levels of HSFA2 and CP-sHSP were transiently elevated after heat shock. In heat-acclimated plants, transcripts were continuously induced during sublethal heat shock in P. malaianus, but not in P. perfoliatus. Instead, the minimum threshold temperature for heat induction of the CP-sHSP genes was elevated in P. perfoliatus. †Conclusions Our comparative study of thermotolerance showed that heat acclimation leads to species-specific changes in heat response. The development of acquired thermotolerance is beneficial for survival at extreme temperatures. However, the loss of acquired thermotolerance and plasticity in the minimum threshold temperature of heat response may be favourable for plants growing in moderate habitats with limited daily and seasonal temperature fluctuations.

With 4 figures Abstract: Patterns of distribution vary greatly among species in the Modern Yellow River Delta, the largest es- tuarine wetland in China. Although salinity has been considered as the key factor determining plant distribution patterns in this delta, the intrinsic mechanisms accounting for distribution patterns are far from clear. To this end, three submerged macrophytes (Ceratophyllum demersum L., Potamogeton perfoliatus L. and Myriophyllum spica- tum L.) were grown in 0.2 (control), 1.2, 2.4 and 3.6 psu salinity waters. The relative growth rate (RGR), content of MDA (malondialdehyde) and activities of the enzymes (SOD - superoxide; POD - peroxidase; CAT - catalase; APX - ascorbate peroxidase) in leaves were investigated. The RGR of M. spicatum decreased only in the 3.6 psu treatment, while those of C. demersum and P. perfoliatus declined significantly with increasing salinity. Compared to the control, RGR of M. spicatum, C. demersum and P. perfoliatus decreased by 31.8 %, 78.5 % and 71.0 % while the MDA content increased by 12.0 %, 35.9 % and 28.3 % in the 3.6 psu treatment, respectively, indicating that M. spicatum had a higher salinity tolerance ability than the other two species. The activities of four antioxidative enzymes increased with increasing salinity in M. spicatum. However, for C. demersum and P. perfoliatus, the four antioxidative enzymes increased in the 0.2 to 2.4 psu treatments, but decreased subsequently in the 3.6 psu treat- ment except for the activities of SOD and APX in C. demersum. It is concluded that antioxidative enzymes can protect M. spicatum from oxidative stress under higher salinity, but that this mechanism is absent in C. demersum and P. perfoliatus.

Comparative significance and synchronicity of morphological and photosynthetic adjustments of Potamogeton perfoliatus to shore-specific environments were examined on plants growing at the maximum depth of colonisation of the northern and southern shores of Lake Balaton. The shore-specific environments did not affect photophysiological parameters: the photosynthesis of plants on both shores was high, coupled with low respiration and compensation irradiances. In contrast, morphological and habitual differences between the shores were significant: plants of the shady, northern shore had lighter, but larger leaves, and longer internodes concentrated in the apex of the plants. Thus, photophysiological variability of Potamogeton does not follow its morphological differentiation.

The habitats of 356 phytocoenoses dominated by 15 species of aquatic plants were investigated. Among the properties of water, Na + , pH, total Fe, Ca 2+ ,N O 3 x ,S O 4 2x , hardness and COD-KMnO4 were the most important in differentiating the habitats of the phytocoenoses studied. Considerable physicochemical differences were found between the waters of the phytocoenoses of Ranunculus circinatus (hard waters rich in Na + ), Nuphar pumila (soft waters with high levels of total Fe), Elodea canadensis, Ceratophyllum demersum (alkaline waters) and Stratiotes aloides (waters containing high concentrations of Ca 2+ and SO4 2x ). The sub- strate properties that best differentiated the habitats compared were PO4 3x , hydration, organic matter con- tent, total N, dissolved SiO2 ,C a 2+ ,N a + and pH. Patches of R. circinatus inhabited substrates containing the highest levels of PO4 3x . Those of S. aloides were associated with substrates poor in PO4 3x . Patches of C. demersum were confined to substrates rich in total N. Phytocoenoses of R. circinatus were associated with large lakes, whereas those of N. pumila were restricted mostly to smaller lakes. The deepest parts of lakes were inhabited by Potamogeton lucens. Phytocoenoses of S. aloides occurred mostly in shallow waters, on thick sediments. The investigated phytocoenoses also represent different stages of succession. The phytocoenoses of Potamogeton perfoliatus, R. circinatus, Myriophyllum spicatum and Polygonum amphibium, which develop on mineral substrates, initiate the process of succession, whereas those of Myriophyllum verticillatum, Nymphaea candida, Nymphaea alba, N. pumila and S. aloides, which inhabit highly hydrated organic substrates, are characteristic of the late stages of succession.

Abiotic heterogeneity of the littoral zone of Lake Balaton influences both horizontal and vertical distribution of macrophytes, but biotic differences could shape the nature of a community. Vertical and tem- poral (small timescale) biomass distributions of Potamogeton perfoliatus and Myriophyllum spicatum were analysed in relation to their photosynthetic capacities to understand their coexistence, general presence over the northern shore of the lake seasonal shift of dominance within the community. Our results indicated the adaptation of these macrophytes to the rapidly changing and mostly low irradiance of the Lake Balaton originated from its high turbidity: both P. perfoliatus and M. spicatum had high photosynthetic activity (20 to 50 mg O2.g drw x1 .h x1 ), low dark respiration (around 12-14% of maximal photosynthetic capacity) and high shade tolerance (Ic of plants were 29 i 18 and 26 i 18 mmol.m x2 .s x1 , re- spectively). The majority of photosynthetic parameters had no (or little) seasonal changes. On the other hand, in Lake Balaton P. perfoliatus and M. spicatum differed in vertical distribution of biomass: Myriophyllum concentrated its biomass in the upper, well-lit region of the water more strongly than the Potamogeton. Results suggest that the autogenic shift of dominance from Potamogeton to Myriophyllum in Lake Balaton can't be explained only by seasonal patterns of photophysiological changes, but supported by constitutive differences in plants architecture could led to the described phenomena.

Stable isotope and fatty acid analyses were used to study carbon sources for animals in a submerged plant bed. Epiphytes growing on Potamogeton perfoliatus, sand microflora, and alder leaves were the most important carbon sources. The most abundant macrophyte, P. perfoliatus was unimportant as a food source. Modelling (IsoSource) showed that epiphytes were the most important food source for the most abundant benthic invertebrates, the isopod Asellus aquaticus (annual mean contribution 64%), the amphipod Gammarus pulex (66%), and the gastropod Potamopyrgus antipodarum (83%). The mean annual contributions of sand microflora were, respectively, 21, 19, and 9%; and of alder leaves, 15, 15, and 8% for these three species. The relative importance of carbon sources varied seasonally. The relative contribution of epiphytes was lowest for all three grazer species in July: A. aquaticus 38%, G. pulex 43%, and P. antipodarum 42%. A decline in epiphyte biomass in summer may have caused this switch to less attractive food sources. P. perfoliatus provided habitat and shelter for consumers, but food was mainly supplied indirectly by providing space for attached epiphytes, which are fast-growing and provide a highly nutritious food source.

Water currents are among the strongest environmental variables determining the occurrence and/or abundance of aquatic plants and the European Water Framework Directive (WFD) considers river morphology and current conditions important aspects of reference conditions. We used the database of the Joint Danube Survey JDS-2, organised by the International Commission for the Protection of the Danube River (ICPDR, Vienna), to assess the relationship between water flow velocity and the occurrence and abundance of aquatic macrophyte to be species along the navigable reach of the Danube River. Species abundance was assessed in accordance with European Standard EN 14184-2003. Flow velocities were assessed close to the plant stands and estimated in 4 classes, worked out in earlier studies in combination with flow meter measurements, which is appropriate for the conditions in this large river. Statistical analysis revealed that only survey units with either no visible flow or those with fast flow were characterised by indicator species with high significance. Still water conditions or barely visible flow (flow class 1) were indicated by Potamogeton friesii , Nitellopsis obtusa and Trapa natans , and by Potamogeton perfoliatus , Potamogeton nodosus and Stuckenia pectinata . Lemna minor , indicative for flow class 1 as well, was detected in all the other flow classes, too: in all these cases it established its stands closely intermingled with other aquatic species. For survey units with slow (flow class 2) or intermediate flow (flow class 3). No statistically significant indicator species could be determined. The highest flow velocities (flow class 4) were significantly indicated by Fissidens rufulus , Cinclidotus fontinaloides and Cinclidotus riparius . Occurrence of aquatic mosses was also highly related to the Berger–Parker dominance index in NMDS analysis. In the same analysis, but towards the smallest flow velocities, the majority of vascular species and the Simpson diversity index were closely related. The spectrum of life forms was considerably reduced under medium and high flow velocity conditions. With regard to Simpson species diversity, our analysis indicates an agglomeration of diversity in the Middle Danube reach that includes the Iron Gates impoundment. Our results offer a first look at the macrophyte/water flow relationship of a very large river in Europe, the Danube.

We studied preferences of invasive Ponto-Caspian amphipod P. robustoides for various macrophyte species (Myriophyllum spicatum, Ceratophyllum demersum, Potamogeton perfoliatus, Elodea canadensis) and artificial plant-like objects (artificial Christmas tree branches) in laboratory pairwise-choice tests. Juvenile (

Habitat structure influences organism communities by mediating interactions between individuals and species, affecting abundance and species richness. We examined whether variations in the morphology of soft-bottom plants affect their function as habitat and whether complex structured plants support higher macroinvertebrate abundance and species richness. Three Baltic Sea plant species were studied, together with artificial plants resembling each species. In a field collection, we found higher invertebrate abundance on the morphologically more complex plants Myriophyllum spicatum and Chara baltica than on the structurally simpler plant Potamogeton perfoliatus. In a colonization experiment, we found the highest invertebrate abundance on artificial M. spicatum but found no difference between natural plants. Invertebrate taxon richness displayed no consistent relationship with plant structural complexity. The results imply that plant morphology influences small-scale invertebrate distribution, partly supporting the hypothesis that structurally complex plants harbour higher invertebrate abundance.

The historic decline of submersed aquatic vegetation (SAV) in mesohaline regions of Chesapeake Bay, United States involved a diversity of plant species. The recent modest recovery is mostly, however, associated with a single, prolific but ephemeral species, Ruppia maritima. Two previously abundant and more stable species, Potamogeton perfoliatus and Stuckenia pectinata, have shown virtually no evidence of recovery. Based on previous studies that demonstrated the ability of R. maritima stands to enhance water clarity and nutrient conditions for SAV growth, we hypothesized that these beds would serve as effective “nursery” areas to incite transplant success for other SAV. We conducted experiments in a two-phase study at small and large spatial scales designed to explore this “nursery effect” as a restoration approach to increase plant species diversity. The first phase was conducted at small spatial scales to test effects of patch density by planting P. perfoliatus and S. pectinata into bare, sparse, and densely vegetated areas within three similar R. maritima beds in a tributary of Chesapeake Bay. Mean seasonal percent survivorship and shoot density were significantly higher in bare patches compared to vegetated patches. In the second phase of the study, P. perfoliatus was transplanted into separate R. maritima beds of different densities to test the effect of bed scale plant density on P. perfoliatus survival and growth. Transplant success of P. perfoliatus was positively correlated with the density of R. maritima among all sites.

Potamogeton perfoliatus readily adopts different morphological forms, and is therefore especially suitable for investigating variations of aquatic plants' morphology according to different environmental con- ditions. This paper discusses the morphological diversity of P. perfoliatus at different sites in Lake Balaton, where it occurs as one of the dominant species. We measured 11 morphological variables which were analyzed statistically within the environmental gradients present in the Lake (gradients in trophic condition, water depth and in wave exposure). We found morphological differences between the plants growing on the south- ern shallow shore which is more exposed to waves and those growing on the northern, deeper and sheltered shore as well as differences along the trophic and the water depth gradient. On the northern shore plants were significantly longer, their internodes were longer and their leaves were relatively thinner (greater Standard Leaf Area). Plants were larger in the more nutrient rich western basins of the Lake and also showed morpho- logical changes along the water depth gradient. The different degrees of wave exposure probably interact partly with trophic differences due to lake morphology. However, we proved that modifications in plant mor- phology, of which some might be adaptive and therefore of importance in a changing environment, do occur in the common, submerged macrophyte P. perfoliatus in Lake Balaton.

Summary 1. The perfoliate pondweed Potamogeton perfoliatus L. constitutes large monospecific macrophyte patches in many Central European lakes. Correlative evidence from the field suggests that P. perfoliatus is under an increasing grazing pressure during its short vegetation period from May to September due to seasonal outbreaks of the aquatic moth Acentria ephemerella Denis & Schiffermuller. We used a mesocosm experiment to determine the influence of A. ephemerella herbivory on P. perfoliatus shoot development and resting bud production and to study the defence strategies of this macrophyte. 2. Herbivory resulted in a reduction of the P. perfoliatus vegetation period by more than 2 months thereby reducing the average resting bud size and the overall resting bud biomass sevenfold. This suggests that besides its severe immediate effects, herbivory affects P. perfoliatus growth and dynamics also during the subsequent season. 3. As a response to herbivory P. perfoliatus translocated nutrients (phosphorus (P) and nitrogen (N)) from leaves towards buds. Acentria ephemerella larvae had a high P content, implying P limita- tion of larval growth especially within the herbivory treatment. This suggests that at least the P translocation from leaves towards resting buds may be viewed as an anti-predator strategy rather than as a nutrient conservation strategy. 4. Acentria ephemerella herbivory changed the allocation strategy of P. perfoliatus in the size versus number of resting buds: only the number, but not the size of resting buds was reduced under shoot grazing by Acentria ephemerella. This change in the number versus size trade-off might allow the plant to produce a minimum resting bud size necessary for successful sprouting in the next spring. 5. Synthesis. Overall, our results suggest an escape syndrome (after Agrawal & Fishbein, Ecology, 87 (2006) S132) as a defence strategy against herbivory for P. perfoliatus, consisting of a shortening of the growth period, a translocation of nutrients and a change in allocation strategy. The increased plant senescence that was accompanied by the shortening of the growth period has further implica- tions for the usage of macrophyte patches as a habitat for invertebrates and fishes and for the struc- ture of littoral food webs.

We present an overview of long-term changes in the floristic composition and growth areas in L. Peipsi (3555 km 2 , unregulated water level) that have occurred since the 1960s and a list of plant taxa containing 140 species of higher plants and 4 charophytes. A significant correlation was found between the relative abundance and frequency per stations (Fs) (Rs = 0.93). Data on five inhabitants of the eulittoral revealed significant ( p p p Potamogeton perfoliatus , belong still among the top 33 in the list. A significant ( χ 2 = 11.8; p

Studies conducted in terrestrial ecosystems have shown that increasing plant diversity enhances ecosystem processes such as primary production. In marine systems, knowledge of how plant diversity influences ecosystem processes and higher trophic levels is still limited. To examine how plant richness and composition influence recruitment and colonization processes, defaunated eelgrass ( Zostera marina ), sago pondweed ( Potamogeton pectinatus ) and perfoliate pondweed ( Potamogeton perfoliatus ) were planted on an unvegetated, sandy bottom in all possible combinations in July and August. Both field experiments lasted 1 week. Our results showed that in these plant assemblages plant richness had a negative effect on faunal diversity ( H′ ) and evenness ( J′ ), while total abundance showed strong temporal variation with weak, positive relationships with plant species richness in both August and July. Plant species composition had strong effects on amphipods ( Gammarus spp.), thus both the abundance and biomass were higher in treatments containing P. perfoliatus . The colonization process was significantly influenced by the numerical dominance of a few faunal species, e.g. the settlement of lagoon cockles ( Cerastoderma glaucum ), and by the timing of the experiments. The results indicate that faunal colonization in these communities is rapid and significantly influenced by the traits of particular plant species.