Potamogeton Pectinatus Research Articles

Diaspore bank analysis of Baltic coastal waters

The coastal waters are important transition zones for terrestrial nutrient and pollutant runoff and the open Sea. During the last decades, eutrophication has negatively influenced macrophyte communities of the coastal ecosystems, making restoration activities inevitable. This study analysed recent macrophyte vegetation and the reproductive potential through the sediment diaspore reservoir along the German Baltic Sea coastline. Salinity was identified to be the responsible factor for shifts in the macrophyte community with most commonly found species like Stuckenia pectinata or Myriophyllum spicatum. In contrast, the oospores of small charophytes (e.g. Tolypella nidifica) clearly dominated the sediment diaspore bank. The germination rates differed in the recent vegetation composition and the diaspore bank composition with Zannichellia palustris as the dominant species. However, several species not visually detected at the respective sites were represented in the diaspore bank and germinated at a low rate (e.g. Chara contraria and Lamprothamnium papulosum). The maximal germination frequency corresponded to the sediment layer in which diaspore density was the highest (5–15 cm). In conclusion, the germinable diaspores were observed at all sites. Considering the differences between the diaspore composition, recent vegetation and germination success, we have illustrated the potential of the diaspore banks for the restoration of the macrophyte communities after at least mid-term periods of disturbance.

Biomonitoring of nutrient and toxic element concentrations in the Sarno River through aquatic plants

The Sarno River is considered the most polluted river in Europe and one of the ten most polluted rivers in the world. So far, its quality has been usually evaluated by water and sediment analyses of either inorganic or organic pollutants. However, a biomonitoring approach would be of paramount importance in the evaluation of river quality, since it integrates pollutant temporal fluctuations, as in the case of discontinuous inputs from urban, industrial and agricultural activities. To this end, a passive biomonitoring study of the Sarno River was carried out, using two native aquatic plants accumulators of inorganic pollutants. The spring area was monitored analysing the roots of the semi-submerged Apium nodiflorum, whereas the whole river course was monitored analysing the shoots of the submerged Potamogeton pectinatus. The information on the four macronutrient (Ca, K, Mg, P), the six micronutrient (Cu, Fe, Mn, Na, Ni, Zn) and the four toxic element (Cd, Cr, Pb, V) concentrations were separately combined in the Nemerow Pollution Index. Results evidenced a severe pollution degree of the Sarno River, attributable to toxic elements > micronutrients > macronutrients. In particular, the spring area showed high K concentrations, as well as high concentrations of several micronutrients and toxic elements. A generalized Zn contamination and a progressive macronutrient (above all Ca and P), micronutrient (above all Ni, Cu and Fe) and toxic element (above all Cr and Pb) accumulation toward the mouth was related to pollution from agricultural and urban activities. Industrial sources, especially tanneries along the Solofrana tributary, accounted for high Mn concentrations, whereas the volcanic origin of the substrate accounted for a generalized V contamination.

Molecular characterization of macrophyte-derived dissolved organic matters and their implications for lakes

Chemical properties of whole organic matter (OM) and its dissolved organic matter (DOM) extracted from three types of dominant macrophytes in Lake Dianchi were comparatively characterized using elemental analysis, UV, 3D-EEM and 13C NMR spectroscopy and their implications for lakes were discussed. Ratios of C/N and C/P were least in the floating water hyacinth and submerged sago pondweed, while total dissolved nitrogen (TDN) and phosphorus (TDP), dissolved organic nitrogen (DON) and phosphorus (DOP) were greatest in those species. In emergent species, C/N, C/P, DON and DON/TDN were less in leaves than in their corresponding shoots. The specific UV absorbance at 254nm (SUVA254) and 280nm (SUVA280) of extracts were in the range of 0.50–1.96L/mgC·m and 0.40–1.48L/mgC·m. Both SUVA values were greater in leaves than those in shoots. 3D-EEM spectra showed only a single fulvic-like fluorescence in leaves of emergent macrophytes. In contrast, protein-like peak were observed in spectra of floating and submerged species, as well as the shoot DOM of emergent species. Solid-state 13C NMR demonstrated that leaves had greater percentage of recalcitrant alkyl C and aromatic C, while shoots were rich in labile carbohydrates. The overall characterization works suggested that macrophyte-derived DOM has less aromatic constituents than do DOM in natural waters and soil leachates. Also OM and DOM derived from shoots had greater contents of protein-like and carbohydrate materials, while leaves were rich in aromatics. Floating and submerged plants possessed potential to not only accumulate excess N and P, but also for returning them to the lake. Shoots of riparian and emergent species were also an important source of nutrients. Thus, macrophyte biomass should be a great concern in nutrient regulation in Lake Dianchi.

Genetic diversity of Potamogeton pectinatus L. in Iran as revealed by ISSR markers

AbstractPotamogeton pectinatusL. is a widespread aquatic species distributed widely in aquatic ecosystems of Iran. In this study, inter simple sequence repeat (ISSR) markers were used to assess the genetic diversity of 35 accessions and 175 individuals ofP. pectinatuscollected from different regions of Iran. In total, 123 polymorphic DNA fragments were amplified from five combinations of ISSR primers. The ISSR based principle coordinate analyses (PCoA) demonstrated four different groups mostly corresponding with their geographic origins (North, Kerman/Fars, Centre and Southwest). The most variable populations were found in the central region of Iran possibly as a consequence of the larger number of samples from that region. The result of molecular variance (AMOVA) attributed 11% of the total genetic variation among and 89% within population variation. The results showed high levels of intra-regional and low inter-regional gene flow between clones, although the Northern accessions were clearly differentiated from the others. There was a low correlation between genetic distance and geographic distance of accessions. The results of STRUCTURE analysis suggested the presence of three genetic groups of this species in Iran, mostly adapted to different ecological conditions. Our results cover one of the gaps of different studies worldwide. In addition, our results confirm high levels of genetic diversity ofP. pectinatusin Iran.

Sitting ducks: diet of wintering wildfowl in Lake Tonga, northeast Algeria

Dietary studies of five species of Anatidae (Gadwall Anas strepera, Shoveler Anas clypeata, Pochard Aythya ferina, Ferruginous Duck Aythya nyroca, and White-headed Duck Oxyura leucocephala) were carried out at Lake Tonga, northeast Algeria, from December 2011 to March 2012. Diet analysis of all five wintering species indicated a heavy reliance on seeds, which included a wide variety of aquatic plants, such as Myriophyllum spicatum, Ceratophyllum demersum, Sparganium erectum, Scirpus lacustris and Potamogeton pectinatus. Noteworthy is the paucity of ingested macroinvertebrates. Despite dietary overlap, the type, abundance and frequency of food consumed clearly indicated differences in resource use among the ducks. Incidentally, the study also highlighted the high vulnerability of threatened ducks to poaching (harvesting and disturbance) in a protected area. We discuss the implications of these findings for the management and conservation of wintering wildfowl and their North African habitats.

Biosynthetic hydrogen isotopic fractionation factors during lipid synthesis in submerged aquatic macrophytes: Effect of groundwater discharge and salinity

Sedimentary lipid biomarkers have become widely used tools for reconstructing past climatic and ecological changes due to their ubiquitous occurrence in lake sediments. In particular, the hydrogen isotopic composition (expressed as δD values) of leaf wax lipids derived from terrestrial plants has been a focus of research during the last two decades and the understanding of competing environmental and plant physiological factors influencing the δD values has greatly improved. Comparatively less attention has been paid to lipid biomarkers derived from aquatic plants, although these compounds are abundant in many lacustrine sediments. We therefore conducted a field and laboratory experiment to study the effect of salinity and groundwater discharge on the isotopic composition of aquatic plant biomarkers. We analyzed samples of the common submerged plant species, Potamogeton pectinatus (sago pondweed), which has a wide geographic distribution and can tolerate high salinity. We tested the effect of groundwater discharge (characterized by more negative δD values relative to lake water) and salinity on the δD values of n-alkanes from P. pectinatus by comparing plants (i) collected from the oligotrophic freshwater Lake Stechlin (Germany) at shallow littoral depth from locations with and without groundwater discharge, and (ii) plants grown from tubers collected from the eutrophic Lake Müggelsee in nutrient solution at four salinity levels. Isotopically depleted groundwater did not have a significant influence on the δD values of n-alkanes in Lake Stechlin P. pectinatus and calculated isotopic fractionation factors εl/w between lake water and n-alkanes averaged −137±9‰ (n-C23), −136±7‰ (n-C25) and −131±6‰ (n-C27), respectively. Similar ε values were calculated for plants from Lake Müggelsee grown in freshwater nutrient solution (−134±11‰ for n-C23), while greater fractionation was observed at increased salinity values of 10 (163±12‰) and 15 (−172±15‰). We therefore suggest an average ε value of −136±9‰ between source water and the major n-alkanes in P. pectinatus grown under freshwater conditions. Our results demonstrate that isotopic fractionation can increase by 30–40‰ at salinity values 10 and 15. These results could be explained either by inhibited plant growth at higher salinity, or by metabolic adaptation to salt stress that remain to be elucidated. A potential salinity effect on δD values of aquatic lipids requires further examination, since this would impact on the interpretation of downcore isotopic data in paleohydrologic studies.

Biodegradation of Potamogeton pectinatus biomass by hydrogen and methane coproduction: Effect of different pretreatments and parallel factor analysis

To enhance the hydrogen and methane coproduction potential, three pretreatments (i.e., acid, alkali and cellulase) were investigated during a two-stage anaerobic fermentation using Potamogeton pectinatus biomass. The fluorescence spectral characteristics of the dissolved organic matter (DOM) from the two-stage effluents, coupled with parallel factor analysis, were studied. The maximum hydrogen proportions (42.65%) and production rate (4.1 mL h−1) were obtained under the 0.5 mol L−1 HCl pretreatment. The highest methane proportions (52.82%) and production rate (14.2 mL h−1) were observed under the 0.5 mol L−1 HCl and 10 mg g−1 cellulase pretreatments, respectively. Combined with fluorescence spectra and parallel factor analysis, three fluorescent components were identified, and the protein-like substances were determined to be dominant. Using the acid pretreatment, the change of the maximum fluorescence intensities in the DOM was the most significant among the three pretreatments, followed by that of the cellulose pretreatment. The result indicated that the macromolecular substances in P. pectinatus can be decomposed by effective pretreatment and thereby enhances the hydrogen and methane coproduction potential. This technique represents a promising method for improving cellulosic biomass biodegradation and green energy coproduction.

Bioremediation of paper and pulp mill effluent with the help of phragmites karka and potamogeton pectinatus

Bioremediation of paper and pulp mill effluent with the help of phragmites karka and potamogeton pectinatus

Water parameters and species composition of macrophytes in reclamation lakes in the area of a former sulphur borehole mine (SE Poland)

Macrophytes and selected physical-chemical water properties were studied in 17 post-mining lakes of Jeziórko Sulphur Mine – one of the largest borehole sulphur mines in the world. Artificial lakes were constructed in subsidence depressions during the reclamation process of mining fields. They were characterized by high mineralization – conductivity ranged from 723 to 2295 μS/cm. The reaction was near neutral, or more frequently, slightly alkaline. Concentrations of phosphorus and organic matter were low. In the group of hydrophytes, Ceratophyllum demersum, Myriophyllum spicatum, Najas marina, Utricularia vulgaris, Eleocharis acicularis, Potamogeton pectinatus, Potamogeton natans and Potamogeton pusillus were frequently dominant. In several lakes, large macroscopic algae dominated – charophytes forming large, dense Chara meadows. In marsh communities, Phragmites australis was the most expansive. Reclamation process had a positive effect on diversity, some of the species found in the study area are regionally rare, including one species which is threatened in Poland (Najas minor). No alien species were recorded.

Spatiotemporal dynamics of submerged macrophyte status and watershed exploitation in a Mediterranean coastal lagoon: Understanding critical factors in ecosystem degradation and restoration

Increases in the intensity of disturbances in coastal lagoons can lead to shifts in vegetation from aquatic angiosperms to macroalgal or phytoplankton communities. Such abrupt and discontinuous responses are facilitated by instability in the equilibrium controlling the trajectory of the community response. We hypothesized that the shift in macrophyte populations is reversible, and that this reversibility is dependent on changes in the pressures exerted on the watershed and lagoon functioning. Biguglia lagoon (Mediterranean Sea, Corsica) is an interesting case study for the evaluation of long-term coastal lagoon ecosystem functioning and the trajectory of submerged macrophyte responses to disturbances, to facilitate the appropriate restoration of ecosystems. We used historical data for a two hundred-year period to assess changes in human activities on the watershed of the Biguglia lagoon. Macrophyte mapping (from 1970) and monitoring data for dynamics (from 1999) were used to investigate the trajectory of the community response. The changes observed in this watershed included a large number of hydrological developments affecting salinity and resulting in changes in macrophyte distribution. Nutrient inputs over the last 40 years have led to a shift in the aquatic vegetation from predominantly aquatic angiosperm community to macroalgae and phytoplankton in 2007 (dystrophic crisis). Changes in hydrological management and improvements in sewage treatment after 2007 led to a significant increase of aquatic angiosperms over a relatively short period of time (4–5 years), particularly for Ruppia cirrhosa and Stuckenia pectinata. There has been a significant resurgence of Najas marina, due to changes in salinity. The observed community shift suggests that Biguglia lagoon is resilient and that the transition may be reversible. The restored communities closely resemble those present before disturbance. These findings demonstrate the need to understand watershed exploitation and ecosystem variability in lagoon restoration.

Stoichiometric characteristics of four submersed macrophytes in three plateau lakes with contrasting trophic statuses

Plant nutrient concentrations and their stoichiometric characteristics are often used to predict nutrient availability and nutrient limitation. However, there is still debate because plants, especially submersed macrophytes, can store excess nutrients and exhibit different survival strategies. To determine the extent to which the trophic status of lakes affect nutrient concentrations of submersed macrophytes and to estimate the relative contribution of lake and interspecific differences to variation of plant nutrient concentrations, we investigated four common submersed macrophytes, Potamogeton maackianus, Potamogeton pectinatus, Potamogeton malaianus and Myriophyllum spicatum, in three plateau lakes with contrasting trophic statuses (i.e. oligotrophic: Fuxian Lake; mesotrophic: Erhai Lake; eutrophic: Dianchi Lake) in Yungui Plateau in southwest China. The results indicated that the average C: N ratios were not different among the three lakes. However, the C: P and N: P ratios in Erhai Lake and Dianchi Lake were significantly lower than those in Fuxian Lake. The N: P ratios of P. maackianus and P. pectinatus did not significantly differ among the lakes. By contrast, the N: P ratios of P. malaianus and M. spicatum indicated different levels of interspecific stoichiometric homeostasis. The C and N concentrations and C: N ratios were mainly determined by the species, while the P concentrations and C: P ratios were mainly determined by the trophic status of lakes. Our study suggested that the C: N: P stoichiometric characteristics of submersed macrophytes exhibit high interspecific differences but substantial homoeostasis in response to different trophic conditions in plateau lakes.

Strong Genetic Differentiation of Submerged Plant Populations across Mountain Ranges: Evidence from Potamogeton pectinatus in Iran.

Biogeographic barriers for freshwater biota can be effective at various spatial scales. At the largest spatial scale, freshwater organisms can become genetically isolated by their high mountain ranges, vast deserts, and inability to cross oceans. Isolation by distance of aquatic plants is expected to be stronger across than alongside mountain ridges whereas the heterogeneity of habitats among populations and temporary droughts may influence connectivity and hamper dispersal. Suitable aquatic plant habitats became reduced, even for the widespread submerged Potamogeton pectinatus L. (also named Stuckenia pectinata) giving structure to various aquatic habitats. We compared the level of genetic diversity in a heterogeneous series of aquatic habitats across Iran and tested their differentiation over distances and across mountain ranges (Alborz and Zagros) and desert zones (Kavir), with values obtained from temperate region populations. The diversity of aquatic ecosystems across and along large geographic barriers provided a unique ecological situation within Iran. P. pectinatus were considered from thirty-six sites across Iran at direct flight distances ranging from 20 to 1,200 km. Nine microsatellite loci revealed a very high number of alleles over all sites. A PCoA, NJT clustering and STRUCTURE analysis revealed a separate grouping of individuals of southeastern Iranian sites and was confirmed by their different nuclear ITS and cpDNA haplotypes thereby indicating an evolutionary significant unit (ESU). At the level of populations, a positive correlation between allelic differentiation Dest with geographic distance was found. Individual-based STRUCTURE analysis over 36 sites showed 7 genetic clusters. FST and RST values for ten populations reached 0.343 and 0.521, respectively thereby indicating that allele length differences are more important and contain evolutionary information. Overall, higher levels of diversity and a stronger differentiation was revealed among Iranian P. pectinatus than previously observed for temperate European regions, due to regional differences across mountain ranges over long distances.

Assessment of biodiversity and environmental quality using macrozoobenthos communities in the seagrass meadow (Gulf of Gdańsk, southern Baltic)

Abstract This study shows the macrozoobenthic biodiversity and the quality status of the Zostera marina meadow in the Gulf of Gdansk. To our knowledge, this is the first study focused on the assessment of environmental quality based on macrofauna occurring on such a small and specific habitat as a seagrass meadow. The meadow is dominated by Zostera marina, but also Zanichellia palustris and Potamogeton pectinatus are present. Compared to the soft bottom macrofauna in the southern Baltic, the biodiversity of macrozoobenthos is very high, which is reflected in 33 taxa observed during the whole research, while the mean number of taxa was 12. There were also some taxa found only on the bottom overgrown with vegetation, e.g. Idotea balthica or even taxa that are currently rarely observed in the Gulf of Gdansk, e.g. Gammarus locusta or Gammarus ineaquicauda. Nineteen percent of the stations were classified into the very good quality status and 50% into the good quality status, so the environmental status of this meadow based on the BQI index is assessed as good. Given these results, this is probably one of the best preserved meadows in the southern Baltic.

Effects of sediment and salinity on the growth and competitive abilities of three submersed macrophytes

Submersed macrophytes are generally found in multispecies beds, with the dominance of individual species varying in both space and time. In estuarine environments, these plants can grow across a range of environmental conditions which may alter species interactions. Three species common to the Chesapeake Bay region, Vallisneria americana (wild celery), Heteranthera dubia (water stargrass), and Stuckenia pectinata (sago pondweed), were planted in a microcosm designed to test their growth and interactions (relative yielding) under a range of conditions of salinity (0, 5, or 10), sediment type (mud or sand), and species combinations. H. dubia was most sensitive to elevated salinity, while sediment type impacted only V. americana, performing better in mud compared with sand. V. americana and H. dubia were strong competitors, overyielding in many treatments when grown in mixture, while S. pectinata never overyielded and frequently underyielded. Interspecific competition was only strong between H. dubia and S. pectinata under 0 salinity, regardless of sediment type. V. americana on the other hand, showed strong interspecific competition with S. pectinata across multiple salinity and sediment types, indicating that this species is able to compete well across a wider range of environmental conditions. Our results suggest that H. dubia and V. americana are strong candidates for multi-species restoration, as positive interactions were observed when grown together. This measure of complementarity provides evidence for increased mixed bed plant performance under environmental conditions that would typically be more stressful to each growing alone.

Long-term and interannual changes of submerged macrophytes and their associated diaspore reservoir in a shallow southern Baltic Sea bay: influence of eutrophication and climate

Long-term and interannual changes in composition of submerged vegetation, diaspore reservoir and germination were investigated in the lagoon system Westrugensche Boddenkette, Baltic Sea, north-east Germany. Comparison with a survey from 1932, showed vegetation cover is similar to the past, maintaining high cover to depths of 2.8 m despite a period of eutrophication between about 1960 and 1990. Species dominance shifted, however, from small charophytes to larger species like Potamogeton pectinatus. We explain interannual vegetation changes by weather conditions. Such changes were observed in several species, most notably in Chara canescens. This annual species seems to be favoured by extensive winter ice cover. The diaspore reservoir and the germination success of submerged macrophytes do not mirror their frequency in the vegetation, but rather reflect life form strategies. Small oospores, mainly of annual charophytes, represented >97% of all diaspores but very few Chara oospores germinated. The numerous Tolypella oospores probably originated from a discrete period with high abundance during the 1950s and have completely failed to germinate. Angiosperm seeds are larger and less frequent but have higher germination success, especially Ruppia seeds. In conclusion, charophytes are outcompeted by larger angiosperms due to the combined effect of moderate eutrophication and climate change.

Alien aquatic plants do not have higher fragmentation rates than native species: a field study from the River Erft

Aquatic plants mostly disperse via vegetative means, and plant fragments are the most important vegetative dispersal units. Here we studied the fragment drift in the medium sized River Erft, in which the macrophyte community is dominated by alien aquatic plants. The plant fragments were sampled at six different sites in the drift of the river. We analyzed the drifting biomass, the number of fragments and the number of propagation units (based on the known minimum size of fragments needed for regeneration of each species) as potential propagation units. Overall, we sampled >13,000 drift units of various sizes, from short stem fragments 400 connected plants (Vallisneria spiralis), resulting in >500,000 propagation units. The total number of sampled drift units and propagation units were significantly higher for native than for alien plant species. The number of sampled drift units and biomass was correlated with the total plant mass (TPM, calculated from species abundances per river section and section lengths) of the species in the river. However, the highest numbers of drift and propagation units per unit TPM were found for the four natives Ceratophyllum demersum, Potamogeton pectinatus, Potamogeton crispus and Myriophyllum spicatum, contributing to more than 75 % of the total number of fragments sampled. Conversely, lowest numbers of drift units were found for alien plants Hygrophila polysperma and Hydrocotyle ranunculoides, and no drift units were collected for four aquatic plant species in the river (alien Myriophyllum aquaticum and natives Nuphar lutea, Potamogeton nodosus and Sparganium emersum).

Polycyclic Aromatic Hydrocarbon (PAHs) Concentrations in Some Aquatic Macrophytes in Hilla River, Iraq

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.

Phosphorus Partitioning in a Storm Water Pond

Abstract Storm water ponds are commonly employed to trap sediments, nutrients and other pollutants in non-point runoff. Aquatic macrophytes are thought to offer enhanced nutrient control via nutrient uptake and other processes. This study sampled and compared the phosphorus contents of water, sediment, and a dominant macrophyte, Stuckenia pectinata (Sago Pond Weed), in a storm water detention pond in the fall of 2013 and 2014. Phosphorus concentrations [ug P (g material)−1] were much higher in macrophyte tissues than in sediment and water, but the areal amounts of phosphorus (mg P m−2) bound in these three forms were ranked differently: sediment>>water>macrophyte, with macrophyte-bound P accounting for only <1–2% of total P in this pond. Macrophyte management may, therefore, have only marginal effectiveness in nutrient control by storm water detention ponds, although macrophytes support a variety of other ecosystem services.

Associations of Epiphytic Macroinvertebrates within Four Assemblages of Submerged Aquatic Vegetation in a Recovering Urban Lake

Abstract Onondaga Lake in Syracuse, NY, is recovering from a century of industrial and municipal pollution. The distribution and diversity of aquatic macrophytes have increased significantly in the past decade, and the plants currently cover 80% of the littoral area. To assess the effects of aquatic vegetation on aquatic biota, we employed quantitative sampling to examine associations of epiphytic macroinvertebrates in 4 assemblages of submerged aquatic vegetation in Onondaga Lake in 2010 and 2011. Two assemblages were predominantly monocultures—one of Stuckenia pectinata (Sago Pondweed) and the other of Chara sp. (stonewort). The third was dominated by Potamogeton foliosus (Leafy Pondweed) and Potamogeton pusillus (Small Pondweed), and the fourth was a heterogeneous community that included Ceratophyllum demersum (Coon's Tail), Myriophyllum spicatum (Eurasian Watermilfoil), and Elodea canadensis (Canadian Waterweed). Measures of invertebrate community composition—which included taxa richness, ETO richness...

Salinity Tolerance and Competition Drive Distributions of Native and Invasive Submerged Aquatic Vegetation in the Upper San Francisco Estuary

Both abiotic and biotic factors govern distributions of estuarine vegetation, and experiments can reveal effects of these drivers under current and future conditions. In upper San Francisco Estuary (SFE), increased salinity could result from sea level rise, levee failure, or water management. We used mesocosms to test salinity effects on, as well as competition between, the native Stuckenia pectinata (sago pondweed) and invasive Egeria densa (Brazilian waterweed), species with overlapping distributions at the freshwater transition in SFE. Grown alone at a salinity of 5, E. densa decreased fivefold in biomass relative to the freshwater treatment and decomposed within 3 weeks at higher salinities. In contrast, S. pectinata biomass accumulated greatly (~4× initial) at salinities of 0 and 5, doubled at 10, and was unchanged at 15. When grown together in freshwater, S. pectinata produced 75 % less biomass than in monoculture and significantly more nodal roots (suggesting increased nutrient foraging). At a salinity of 5, a decline in E. densa performance coincided with a doubling of S. pectinata shoot density. Additional experiments on E. densa showed elevated temperature (26 and 30 °C) suppressed growth especially at higher salinities (≥5). We conclude that salinity strongly influences distributions of both species and that competition from E. densa may impose limits on S. pectinata abundance in the fresher reaches of SFE. With a salinity increase of 5, S. pectinata is likely to maintain its current distribution while spreading up-estuary at the expense of E. densa, especially if increased temperature also reduces E. densa biomass.