Comparative study of periphyton colonisation on common reed (Phragmites australis) and artificial substrate in a shallow lake,Manyas, Turkey

Hydrobiologia - Colonisation of epiphytic algae on the common reed (Phragmites australis) and on glass slides were studied during a twenty-four week exposure period in a shallow, turbid lake,...     

Assessment of aquatic and terrestrial reed (Phragmites australis) stands

A survey of recent publications shows that research on Phragmites australishas oftenapplied character because of the considerableecological and economic significance of the species.The main applications are water treatment, agriculture(food production or weed control) and natureconservation. In Europe, most research on natural reedstands has been motivated by reed die-back and effortstowards protection or restoration. Reed progressionand reed control have been the main concerns in otherparts of the world, and reed progression has alsoreceived increasing attention in Europe. While reeddie-back generally affects aquatic stands, progressioncan occur at both terrestrial and aquatic sites, andit can be desired (e.g. lake shore restoration)or unwanted (e.g. in species-rich fens ormarshes). Therefore, reed stands need to be assessedindividually to decide on management aims andappropriate methods. The varying status of Phragmites australisformed the background of the`European Reed Conference' held in Zürich/Switzerlandin October 1998. The seven contributions published inthis special issue are introduced with particularreference to differences between aquatic andterrestrial reed stands and to approaches used in theirassessment.     

Sulphide utilization and injuries in hypoxic roots and rhizomes of common reed (Phragmites australis)

The presented investigations have been carried out in order to estimate toxic sulphide levels and to examine detoxification capabilities in roots and rhizomes of the common reed (Phragmites australis). Underground organs of common reed are sensitive towards sulphide above 1 mM applied exogenously under hypoxia. However, certain tolerance may be achieved by sulphide detoxification. Accumulated sulphide is partially used for the synthesis of non-toxic thiols, mainly glutathione. But the detoxification capacity of the underground organs is limited. Maximum concentrations of thiols are about 60 nmol/g^?1 fw in roots and 300 nmol/g^?1 fw in rhizomes. Energy metabolism is considerably affected by low sulphide concentrations of 1 mM for 4 days, and immediately disturbed by increased concentrations up to 6 mM sulphide. Adenylate energy charge, total adenylates, posthypoxic respiration, and fermentation capacity decrease significantly. Roots are more sensitive than rhizomes.     

Effects of seasonal temperature on shoot growth dynamics and shoot morphology of common reed (Phragmites australis)

The shoot growth during the vegetation period andshoot morphology at the end of the season wereinvestigated in four monoclonal aquatic reed stands(Phragmites australis) with differentproductivity in Berlin and Brandenburg. Investigationswere conducted over a period of six years (1991–96) toascertain the effects of differences in temperatures.All clones showed significant year-to-year variationin shoot morphology. The mean final shoot length ofthe two clones with highest variation ranged from252 cm (1991) to 388 cm (1993; Templiner See), andfrom 170 cm (1993) to 229 cm (1994; Parsteiner See).In spite of this considerable variation, morphologicalparameters measured at the end of the growing seasonshowed only a slight relation to the average airtemperature either during the main growth phase (Aprilto June) or during the period of bud formation (Augustto October of the previous year). Contrary to meanshoot length at the end of the growing season, shootelongation during the main growth phase (from April toJune) was clearly related to the sum of daily averagetemperatures. Thus, taking into account temperaturemay enhance the accuracy of studies on reed growthwhenever these studies are carried out at localitiesdiffering in temperature or in different years.     

The consortium of the sponge Ephydatia fluviatilis (L.) living on the common reed Phragmites australis in Lake Piediluco (central Italy)

Lake Piediluco (Central Italy) displays a discontinuous reed-belt along its shore, the dominant macrophyte being Phragmites australis (Cav.) Trin ex Steud., the reeds of which support the growth of the spongeEphydatia fluviatilis (L.). Samplings were carried out at ten stations located along the reed-belt with the aim of investigating the ‘consortium’, which is the result of the association between the edificatory E. fluviatilis and the related organisms. These last were considered at three different levels: (a) spatial localisation (epibionts, endobionts); (b) kind of association (occasional, strictly linked); (c) model of organisation (unicellular, multicellular). The associated fauna was investigated by considering both sponge biomass and life-cycle. The faunal composition of associated organisms and their quantitative rates were determined, and statistical differences among stations were tested by using 1-way ANOVA (p<0.05). It emerged that there were significant differences among stations and that the dipteran Chironomus sp. was the most common taxon, its presence being independent of the spatial gradient. By contrast, the mean density (total number of hosted macroinvertebrates/sponge wet-weight) did not vary significantly from station to station. A positive relationship between sponge biomass (wet-weight) and the total number of taxa was found, but a sponge weight of 2000 g seemed to provide a better habitat for macroinvertebrates than higher values. This finding emerged from the non-linear relationship between sponge biomass and the number of hosted organisms. Histological analysis of the gut content of some associated organisms enhanced knowledge of their ability to utilize sponge tissues as food.     

Common reed (Phragmites australis) invasion and amphibian distribution in freshwater wetlands

Invasive plants can substantially modify wetland structure and animal distribution patterns. In eastern North America, a Eurasian haplotype of the common reed (Phragmites australis, haplotype M) is invading wetlands. We studied the invasion of common reed in freshwater wetlands of an urbanized landscape and its effects on the distribution of amphibians at different life stages. Specifically, we hypothesized that the probability of reed invasion would be greatest in wetlands near anthropic disturbances. We predicted that the probability of desiccation at sampling stations increases with reed cover. Furthermore, we expected that wetlands invaded by common reed would have lower amphibian abundances, apparent survival, and rates of recruitment. We conducted trapping surveys to compare anuran assemblages of tadpoles, juveniles, and adults in 50 wetlands during two field seasons. The probability of reed invasion in wetlands increased with the cover of heavily-managed areas within 1,000 m and the distance to the nearest forest, but decreased with the length of roads within 1,000 m. The probability of station desiccation increased with reed cover. We found no evidence of a negative effect of reed presence on anuran population parameters, at any life stage. Landscape variables, such as the percent cover of forest or heavily-managed areas within a given radius from each wetland, influenced the abundance or the apparent survival of juvenile frogs and the abundance of ranid tadpoles. Our results show that amphibian patterns depend more strongly on the structure of the landscape surrounding wetlands than on exotic reed invasion in wetlands.     

Heavy metal bioaccumulation by the organs of Phragmites australis (common reed) and their potential use as contamination indicators

The concentrations of heavy metals in the roots, rhizomes, stems and leaves of the aquatic macrophyte Phragmites australis (common reed), and in the corresponding water and sediment samples from the mouth area of the Imera Meridionale River (Sicily, Italy), were investigated to ascertain whether plant organs are characterized by differential accumulation, and to test the suitability of the various organs for heavy metal biomonitoring of water and soil. Heavy metals considered were Cd, Cr, Cu, Hg, Mn, Ni, Pb, Zn. Results showed that belowground organs were the primary areas of metal accumulation. In particular, metal concentrations in plant organs decreased in the order of root > rhizome ≥ leaf > stem. All four organs showed significant differences in concentration for Cr, Hg, Mn, Zn, thus suggesting low mobility from roots to rhizomes and to aboveground organs. Although the organs followed different decreasing trends of metal concentration, the trend Mn > Zn > Pb > Cu was found in each plant organ. Mn showed the highest concentrations in all organs whereas the lowest concentrations regarded Cd and Cr in the belowground and aboveground organs, respectively. The toxic threshold was exceeded by Cr in roots, rhizomes and leaves, Mn in roots and leaves, Ni in roots. The highest average concentrations were found as follows: Cd, Hg, Pb, Zn in root, Cr, Mn, Ni in sediment, Cu in water. Positive linear relationships were found between heavy metal concentrations in all plant organs and those in water and sediment, thus indicating the potential use of such organs for pollution monitoring of water and sediment. Advantages of using plant species as biomonitors, especially Phragmites australis, were also discussed.     

Patterns of variation in the acoustic calling signals of Chloriona planthoppers (Homoptera: Delphacidae) coexisting on the common reed Phragmites australis

Populations of the Tour species of Chloriona commonly found in the Netherlands C dorsata, C. glaucescens, C. smaragdula and C. vasconica –were cultured in the laboratory on Phragmites australis, their exclusive host plant in the field. The low frequency substrate-transmitted signals produced during the calling phase of mating behaviour were digitally analysed for the males and females of each species. Variables selected to cover most aspects of the call were measured, and variation was quantified within species and statistically tested among species using univariate and multivariate techniques. The calls of the males were more complex in structure than those of the females, with two different phase patterns recognized, and were species-specific. C. glaucescens and C vasconica were also separated on variables of the female call, but C dorsata and C. smaragdula completely overlapped. No significant differences were found between the calls of the long-winged and.short-winged female morphs of C. smaragdula. A possible role for variation in calling signals, and responses to them, in the evolution and maintenance of reproductive isolation in Chlonona is discussed.     

Microbial decomposition of reed (Phragmites communis) leaves in a saline lake

Microbial colonization and its relation to the decomposition of reed (Phragmites communis) leaf litter were studied in the littoral area of a saline lake from autumn to summer using litter bag method. There was considerable fungal population on the leaves at the beginning of submergence. These fungi were probably terrestrial in origin. The fungal population rapidly disappeared few days after submergence, when bacteria, including cellulolytic and xylanolytic types, proliferated. Associated with this rapid colonization of bacteria, decomposition rates of cellulose and xylan increased. The rates declined from day 39 to day 100 with decreasing water temperature, though cellulolytic and xylanolytic bacteria maintained a sizeable population until day 150. A community of cellulolytic and xylanolytic fungi increased steeply after day 150. It coincided with a second increase in decomposition rate. These results suggest that the principal decomposers of reed leaf litter were bacteria in the initial phase and fungi in the later phase of the experiment.     

Increasing the efficiency of reed plantations on stressed lake and river shores by using special clones of Phragmites australis

In an investigation aimed at comparing the variationin growth and expansion of different reed clones, 10reed clones were planted in spring of 1995 on sixexperimental fields on the River Dahme and the RiverHavel in Berlin. Their sites of origin differed innutrient supply, substrate quality and shoreexposition. The main aim of this large-scaleexperiment was to search for reed clones that would beable to colonize lake shores rapidly and to expandinto deeper water. Two years after planting thedeveloping reed stands differed significantly inmorphology and stand structure, both among clones andamong sites. This indicates that the development ofreed stands depended on the environment as well as onthe genotype. The differences in development impliedthat some of the clones would be more suited thanothers for restoration purposes, so that successfulrestoration of a degraded river or lake shores mightdepend on the selection of the best suited clones.The nitrogen contents in the aboveground biomass oftwo clones differing in nitrogen dynamics at theiroriginal sites (described as `assimilation' and`translocation' types in the literature) did notdiffer in this experiment, even though the two clonesdid differ in some morphological traits. These resultsmight be influenced by the fact that stands were stilldeveloping and that possibly clones had reached adifferent degree of maturity. Nevertheless, theysuggest that nitrogen content depends more on siteconditions, with only little genetically determineddifference, and that morphological variation isdetermined by factors other than variation in nitrogenuptake.     

Effects of Phragmites australis removal on marsh nutrient cycling

In the northeast US removal of exotic and invasive plant species is a common wetland restoration activity and the invasive common reed (Phragmites australis) is often the target of control efforts. We examined effects of reed removal on sediment nutrient pools and denitrification potential in a tidal freshwater marsh on the Connecticut River. In the first year after herbicide application and cutting of a reed stand, porewater ammonium concentrations in the removal area were about 4× higher relative to extant reed or cattail. Denitrification potentials were 50% lower than in a reference stand of reed. Denitrification activity had recovered by the second growing season after reed removal but porewater ammonium continued to accumulate. By the third growing season following reed removal, plant regrowth had occurred over approximately half the experimental plot and porewater ammonium had declined to pre-manipulation levels. Sediment organic content, moisture and porewater phosphate showed no significant response to reed removal over the four-year course of this study. Reed removal allowed regrowth of a more diverse plant community thereby achieving one of the goals of this restoration effort but patterns in ammonium accumulation and denitrification suggest a reduction in the capacity of this site to act as a sink for nitrogen.     

Seasonal dynamics of aufwuchs Naididae (Oligochaeta) on Phragmites australis in a eutrophic lake

The Oligochaeta and Aphanoneura in the aufwuchs on Phragmites australis in a eutrophic hardwater lake were studied at two sites over a period of one year, in order to elucidate the structure and dynamics of this assemblage. The naidids Chaetogaster diastrophus, Nais spp., and Stylaria lacustris dominated the assemblage at any season. At both sites these taxa showed the same distinct pattern of successive population maxima in spring and summer: Chaetogaster diastrophus reached its peak density first, followed by Nais species, and eventually by Stylaria lacustris. Differences in temporal dynamics between sites were small apart from a second Stylaria maximum which was only observed at one site. Total naidid densities reached peak values of 3.8 individuals per cm² reed stem surface area. With mean individual biomass of 2.2 µg dry mass for Chaetogaster diastrophus, 13.3 µg for Nais, and 86 µg for Stylaria lacustris, respectively, maximum total naidid biomass on reed stems was 44 µg dry mass per cm². The biomass peak occurred later than that of total naidid density because in summer larger naidids dominated the assemblage. The observed succession appears to be consistent with seasonal changes in periphytic algal communities on the reed stems.     

Effects of winter harvest on water and sediment chemistry in a stand of reed (Phragmites australis)

An investigation of the effects of repeated winter harvest and removal of dry reed culms on water and sediment chemistry was made in a shallow lake dominated by closed, monospecific reed stands. The oxygen concentration and redox potential in the water, as well as temperature, showed regular diurnal fluctuations inside the reed stands. Ammonium and nitrate + nitrite did not exhibit diurnal fluctuations and differences between a harvested and an unharvested reed area were small. Molybdate reactive phosphorus (MRP) concentration was higher in the unharvested area.Because the winter harvest caused an almost doubling of shoot production compared to the unharvested area, net addition of reed litter (leaves, stubble and culms) to the sediment of the harvested area was similar to that of the unharvested area. It is concluded that removal of reed culms in winter has the largest effect on microclimate in spring, and that the rate of mineralization and reducing intensity in the substrate are not immediately affected. Significantly higher summer standing crop of reed after harvest may have caused lower phosphate concentration in the water column and sediment interstitial water.     

Diversity of reed (Phragmites australis) stem biofilm bacterial communities in two Hungarian soda lakes

From reed biofilm samples of Kelemen-szék (Kiskunság National Park, KNP) and Nagy-Vadas (Hortobágy National Park, HNP) altogether 260 bacterial isolates were gained after serial dilutions and plating onto different media. Following a primary selection 164 strains were investigated by "traditional" phenotypic tests and clustered by numerical analysis. Fifty-six representative strains were selected to ARDRA and 16S rDNA sequence analysis for identification. Strains were identified as members of genera Agrobacterium, Paracoccus, Halomonas, Pseudomonas, Bacillus, Planococcus and Nesterenkonia. The species diversity was also investigated by a cultivation independent method. A clone library was constructed using the community DNA isolated from the biofilm sample of Kelemen-szék. Screening of the 140 bacterial clones resulted in 45 different ARDRA groups. Sequence analysis of the representatives revealed a great phylogenetic diversity. A considerable majority of the clones was affiliated with uncultured bacterial clones (with sequence similarity between 93 and 99%) originating from diverse environmental samples (for example salt marshes, compost or wastewater treatment plants). The DNA sequences of other clones showed the presence of genera Flavobacterium, Sphingobacterium, Pseudomonas and Agrobacterium.     

Factors affecting metal concentrations in reed plants (Phragmites australis) of intertidal marshes in the Scheldt estuary

We aimed to identify the environmental factors which significantly affect metal uptake by reed plants in the intertidal marshes along the river Scheldt. Transfer coefficients, defined as the ratio of metal concentrations in reed stems to the metal contents in specific sediment fractions (i.e. the exchangeable Cd and Zn fraction and total Cr, Cu, Ni and Pb content), were calculated for each sampling site. They were inversely related to the sediment clay and/or organic matter content. Metal mobility and thus plant availability is higher in sediments with a lower clay or organic matter content. Moreover, the plants might actively accumulate in particular essential elements when concentrations in the sediments are rather low, which is the case in sediments low in clay and organic matter contents. Finally, more sandy sediments are expected to be susceptible to occasional oxidation of sulphides, which leads to an increased metal availability. A higher salinity promoted the uptake of Cu, Cr and Zn.     

The endophytic fungal communities associated with the leaves and roots of the common reed (Phragmites australis) in Lake Trasimeno (Perugia,Italy) in declining and healthy stands

We surveyed the fungal endophytes in the leaves and roots of Phragmites australis plants along a gradient of reed decline at Lake Trasimeno (central Italy) in Oct. 2010. An integrated approach consisting of cultivation and molecular identification was used. Endophytes were recovered from 61.59 % of the samples, with a total of 1 541 isolates. On the basis of a molecular analysis of the rDNA Internal Transcribed Spacer (ITS) region, 25 operational taxonomic units (OTUs) were identified. Fusarium sp. (OTU 21) and Gibberella moniliformis (OTU 1) were the most frequently isolated fungi. Comparisons of the leaf and root samples demonstrated spatial heterogeneity in the endophyte assemblages among the plant parts and sites. In this study, we have shown that reed plants in different states of decline harbour different endophytic communities. This finding may help to understand the very complex scenario of reed die-back.     

Effects of the freshwater gastropod Planorbis carinatus on reed (Phragmites australis) litter microbial activity in an experimental system

SUMMARY. The freshwater gastropod Planorbis carinatus can enhance the aerobic respiration of micro-organisms on reed ( Phragmites australis ) litter in laboratory systems. This effect is contributed to by both direct and indirect mechanisms and, at least in the latter case, increased microbial respiration entails accelerated decomposition. Enhanced turnover of dissolved inorganic phosphate in the presence of the snail may play a role in these interactions.