A risk assessment on Zostera chilensis, the last relict of marine angiosperms in the South-East Pacific Ocean, due to the development of the desalination industry in Chile.

Seagrasses, which are considered among the most ecologically valuable and endangered coastal ecosystems, have a narrowly limited distribution in the south-east Pacific, where Zostera chilensis is the only remaining relict. Due to water scarcity, desalination industry has grown in the last decades in the central-north coasts of Chile, which may be relevant to address in terms of potential impacts on benthic communities due to their associated high-salinity brine discharges to subtidal ecosystems. In this work, we assessed ecophysiological and cellular responses to desalination-extrapolable hypersalinity conditions on Z. chilensis. Mesocosms experiments were performed for 10 days, where plants were exposed to 3 different salinity treatments: 34 psu (control), 37 psu and 40 psu. Photosynthetic performance, H2O2 accumulation, and ascorbate content (reduced and oxidized) were measured, as well as relative gene expression of enzymes related to osmotic regulation and oxidative stress; these, at 1, 3, 6 and 10 days. Z. chilensis showed a decrease in photosynthetic parameters such as electron transport rate (ETRmax) and saturation irradiance (EkETR) under hypersalinity treatments, while non-photochemical quenching (NPQmax) presented an initial increment and a subsequent decline at 40 psu. H2O2 levels increased with hypersalinity, while ascorbate and dehydroascorbate only increased under 37 psu, although decreased along the experimental period. Increased salinities also triggered the expression of genes related to ion transport and osmolyte syntheses, but salinity-dependent up-regulated genes were mostly those related to the reactive oxygen species metabolism. The relict seagrass Z. chilensis has shown to withstand increased salinities that may be extrapolable to desalination effects in the short-term. As the latter is not fully clear in the long-term, and considering the restricted distribution and ecological importance, direct brine discharges to Z. chilensis meadows may not be recommended.

The assessment of cadmium, chromium, copper, and nickel tolerance and bioaccumulation by shrub plant Tetraena qataranse.

Heavy metals constitute some of the most significant environmental contaminants today. The abundance of naturally growing Tetraena qataranse around Ras Laffan oil and gas facilities in the state of Qatar reflects its toxitolerant character. This study examined the desert plant's tolerance to Ba, Cd, Cr, Cu, Ni and Pb relative to soil concentration. Analysis by inductively coupled plasma - optical emission spectroscopy (ICP-OES) showed that the plant biomass accumulates higher Cd, Cr, Cu and Ni concentration than the soil, particularly in the root. The bioconcentration factor (BCF) of all metals in the root and shoot indicates the plant's capacity to accumulate these metals. Cd had a translocation factor (TF) greater than one; however, it is less than one for all other metals, suggesting that the plant remediate Cd by phytoextraction, where it accumulates in the shoot and Cr, Cu and Ni through phytostabilization, concentrating the metals in the root. Metals phytostabilization restrict transport, shield animals from toxic species ingestion, and consequently prevent transmission across the food chain. Fourier Transform Infrared Spectroscopy (FTIR) analysis further corroborates ICP-OES quantitative data. Our results suggest that T. qataranse is tolerant of Cd, Cr, Cu, and Ni. Potentially, these metals can accumulate at higher concentration than shown here; hence, T. qataranse is a suitable candidate for toxic metals phytostabilization.

Assessment of Cadmium Scavenging Potential of Canna indica L.

The aquatic plant, Canna indica L. (Indian shoot) of Cannaceae family was investigated to assess cadmium scavenging potential at 5, 10, 25, 50, 100 and 150 mg Cd L-1 exposers. The results showed that Canna has considerable potential of cadmium accumulation, which was up to 58.69 and 10.13 mg Cd kg-1 dry weight in root and shoot of Canna, respectively. The effects of different cadmium levels on biomass production of plant tissues were significantly (p = 0.05) showed negative relation due to cadmium toxicity. The root concentration factor was higher than the bioconcentration factor which indicated the lower translocation factor of Canna. Considering the high root concentration factor, average bioconcentration factor, rapid growth and optimum adaptive properties up to 100 mg Cd L-1 level, the Canna could be employed as an eco-friendly and efficient aquatic plant for cadmium scavenging. This study plays a potential role in remediation of cadmium contaminated wastewater.

Radionuclide uptake and dose assessment of 14 herbaceous species from the east-Ural radioactive trace area using the ERICA Tool.

The evaluation of radiation exposure in 14 species of herbaceous plants from the East-Ural Radioactive Trace (EURT) zone was performed, using the ERICA Tool, v. 1.2. Recent (up to 2015) levels of radionuclide activity concentration were measured in soil and vegetative plant mass. 239,240Pu content was used for the first time to estimate external dose rates for herbaceous plant species along the pollution gradient. In addition, a new approach to assessing the geometry of objects was adopted, including not only aboveground but also underground plant organs. This improved approach to the evaluation of radiation exposure confirms previous findings that herbaceous plant populations currently exist under low-level chronic exposure in the EURT area. This reassessment based on new data suggests a 48-977-fold increase in the total dose rate per plant organism at the most polluted site compared to background areas. The highest capacity for the transfer of 90Sr and 137Cs was observed in Taraxacum officinale and Plantago major. In these species, the total dose rate per plant exceeded 150 µGy h-1 due to 90Sr + 137Cs + 239,240Pu radionuclide anthropogenic pollution in the EURT zone. All estimated total dose rates per plant were below the dose rate screening value of 400 µGy h-1.

Direct uptake of HCO3- in the marine angiosperm Posidonia oceanica (L.) Delile driven by a plasma membrane H+ economy.

Seagrasses access HCO3- for photosynthesis by 2 mechanisms, apoplastic carbonic anhydrase-mediated dehydration of HCO3- to CO2 and direct HCO3- uptake. Here, we have studied plasma membrane energization and the mechanism for HCO3- import in Posidonia oceanica. Classical electrophysiology and ion-selective microelectrodes were used to measure the membrane potential, cytosolic pH, and the cytosolic concentrations of Na+ and Cl- upon the addition of HCO3- . The photosynthetic response to HCO3- and to inhibitors was also measured. Results indicate that the primary pump of P. oceanica plasma membrane is a fusicoccin-sensitive H+ -ATPase. Bicarbonate depolarizes the plasma membrane voltage and transiently acidifies the cytosol, indicating that HCO3- is transported into the cells by an H+ -symport. Initial cytosolic acidification is followed by an alkalinization, suggesting an internal dehydration of HCO3- . The lack of cytosolic Na+ and Cl- responses rules out the contribution of these ions to HCO3- transport. The energetics of nH+ /HCO3- symport allows, for n = 1, an estimate of cytosolic accumulation of 0.22 mM HCO3- . Because this transporter could permit accumulation of HCO3- up to 100 times above the equilibrium concentration, it would be a significant component of a carbon-concentrating mechanism in this species.

Direct assessment of the metabolic origin of carbon atoms in glutamate from illuminated leaves using 13 C-NMR.

Glutamate (Glu) is the cornerstone of nitrogen assimilation and photorespiration in illuminated leaves. Despite this crucial role, our knowledge of the flux to Glu de novo synthesis is rather limited. Here, we used isotopic labelling with 13 CO2 and 13 C-NMR analyses to examine the labelling pattern and the appearance of multi-labelled species of Glu molecules to trace the origin of C-atoms found in Glu. We also compared this with 13 C-labelling patterns in Ala and Asp, which reflect citrate (and thus Glu) precursors, that is, pyruvate and oxaloacetate. Glu appeared to be less 13 C-labelled than Asp and Ala, showing that the Glu pool was mostly formed by 'old' carbon atoms. There were modest differences in intramolecular 13 C-13 C couplings between Glu C-2 and Asp C-3, showing that oxaloacetate metabolism to Glu biosynthesis did not involve C-atom redistribution by the Krebs cycle. The apparent carbon allocation increased with carbon net photosynthesis. However, when expressed relative to CO2 fixation, it was clearly higher at low CO2 while it did not change in 2% O2 , as compared to standard conditions. We conclude that Glu production from current photosynthetic carbon represents a small flux that is controlled by the gaseous environment, typically upregulated at low CO2 .

Effect of heavy metals and organic matter on root exudates (low molecular weight organic acids) of herbaceous species: An assessment in sand and soil conditions under different levels of contamination.

Bioavailability of heavy metals can be modified by different root exudates. Among them, low molecular weight organic acids (LMWOAs) play an important role in this process. Three plant species (Poa annua, Medicago polymorpha and Malva sylvestris), potentially used for phytoremediation, have been assessed for both metal uptake and LMWOAs excretion in contaminated environments with different concentrations of Cd, Cu and Zn. The experiments have been carried out in washed sand and in three contaminated soils where two organic amendments were added (biosolid compost and alperujo compost). The most abundant LMWOAs excreted by all studied plants were oxalic and malic acids, although citric and fumaric acids were also detected. The general tendency was that plants responded to an increase of heavy metal stress releasing higher amounts of LMWOAs. This is an efficient exclusion mechanism reducing the metal uptake and allowing the plant growth at high levels of contamination. In the experiment using wash sand as substrate, the organic acids composition and quantity depended mainly on plant species and metal contamination. M. polymorpha was the species that released the highest concentrations of LMWOAs, both in sand and in soils with no amendment addition, whereas a decrease of these acids was observed with the addition of amendments. Our results established a clear effect of organic matter on the composition and total amount of LMWOAs released. The increase of organic matter and nutrients, through amendments, improved the soil quality reducing phytotoxicity. As a result, organic acids exudates decreased and were solely composed of oxalic acid (except for M. polymorpha). The release of LMWOAs has proved to be an important mechanism against heavy metal stress, unique to each species and modifiable by means of organic amendment addition.

A microcosm study to support aquatic risk assessment of nickel: Community-level effects and comparison with bioavailability-normalized species sensitivity distributions.

The aquatic risk assessment for nickel (Ni) in the European Union is based on chronic species sensitivity distributions and the use of bioavailability models. To test whether a bioavailability-based safe threshold of Ni (the hazardous concentration for 5% of species [HC5]) is protective for aquatic communities, microcosms were exposed to 5 stable Ni treatments (6-96 µg/L) and a control for 4 mo to assess bioaccumulation and effects on phytoplankton, periphyton, zooplankton, and snails. Concentrations of Ni in the periphyton, macrophytes, and snails measured at the end of the exposure period increased in a dose-dependent manner but did not indicate biomagnification. Abundance of phytoplankton and snails decreased in 48 µg Ni/L and 96 µg Ni/L treatments, which may have indirectly affected the abundance of zooplankton and periphyton. Exposure up to 24 µg Ni/L had no adverse effects on algae and zooplankton, whereas the rate of population decline of the snails at 24 µg Ni/L was significantly higher than in the controls. Therefore, the study-specific overall no-observed-adverse-effect concentration (NOAEC) is 12 µg Ni/L. This NOAEC is approximately twice the HC5 derived from a chronic species sensitivity distribution considering the specific water chemistry of the microcosm by means of bioavailability models. Thus, the present study provides support to the protectiveness of the bioavailability-normalized HC5 for freshwater communities.

Metabolic Effect Level Index Links Multivariate Metabolic Fingerprints to Ecotoxicological Effect Assessment.

A major goal of ecotoxicology is the prediction of adverse outcomes for populations from sensitive and early physiological responses. A snapshot of the physiological state of an organism can be provided by metabolic fingerprints. However, to inform chemical risk assessment, multivariate metabolic fingerprints need to be converted to readable end points suitable for effect estimation and comparison. The concentration- and time-dependent responsiveness of metabolic fingerprints to the PS-II inhibitor isoproturon was investigated by use of a Myriophyllum spicatum bioassay. Hydrophilic and lipophilic leaf extracts were analyzed with gas chromatography-mass spectrometry (GC-MS) and preprocessed with XCMS. Metabolic changes were aggregated in the quantitative metabolic effect level index (MELI), allowing effect estimation from Hill-based concentration-response models. Hereby, the most sensitive response on the concentration scale was revealed by the hydrophilic MELI, followed by photosynthetic efficiency and, 1 order of magnitude higher, by the lipophilic MELI and shoot length change. In the hydrophilic MELI, 50% change compares to 30% inhibition of photosynthetic efficiency and 10% inhibition of dry weight change, indicating effect development on different response levels. In conclusion, aggregated metabolic fingerprints provide quantitative estimates and span a broad response spectrum, potentially valuable for establishing adverse outcome pathways of chemicals in environmental risk assessment.

An Abandoned Copper Mining Site in Cyprus and Assessment of Metal Concentrations in Plants and Soil.

Mining is an important source of metal pollution in the environment and abandoned mines are extremely restricted habitats for plants. Some plant species growing on metalliferous soils around mine tailings and spoil-heaps are metal-tolerant and accumulate high concentrations of metals. In this investigation, we aimed to perform a research in the CMC-abandoned copper mining area in Lefke-North Cyprus to assess the recent metal pollution in soil and plant systems. We collected 16 soil samples and 25 plant species from 8 localities around the vicinity of tailing ponds. Some concentrations of metals in soil samples varied from 185 to 1023 mg kg(-1) Cu, 15.2 to 59.2 mg kg(-1) Ni, 2.3 to 73.6 mg kg(-1) Cd and metals for plants ranged from 0.135 to 283 mg kg(-1) Cu, 0.26 to 31.2 mg kg(-1) Ni, 0.143 to 277 mg kg(-1) Cd. Atriplex semibaccata, Acacia cyanophylla, Erodium spp., Inula viscosa, Juncus sp., Oxalis pes-caprea, Pistacia lentiscus, Senecio vulgaris and Tragopogon sinuatus accumulated higher concentrations. BCF for Atriplex semibaccata was found very high, for this reason this plant can tentatively be considered as a hyperaccumulator of Cu and Cd, but it needs further investigation for its potential in phytoremediation.

Juncus maritimus root biochemical assessment for its mercury stabilization potential in Ria de Aveiro coastal lagoon (Portugal).

Major endogenous biochemical properties can make plants ideal agents for metal/metalloid-contaminated site cleanup. This study investigates the biochemistry of Juncus maritimus (Lam) roots for its high mercury (Hg) stabilization potential in the sediments of the Ria de Aveiro coastal lagoon (Portugal), which received Hg-rich effluents from a chlor-alkali industry between 1950 and 1994. J. maritimus plants were collected at a reference (R) site and three sites with the highest (L1), moderate (L2), and the lowest (L3) Hg contamination levels. The highest Hg-harboring/stabilizing J. maritimus roots at L1, exhibited significantly elevated damage endpoints (H2O2; lipid peroxidation, LPO; electrolyte leakage, EL; protein oxidation, PO; proline) which were accompanied by differential changes in H2O2-metabolizing defense system components (ascorbate peroxidase, catalase, glutathione peroxidase, glutathione S-transferase), glutathione reductase and the contents of both reduced and oxidized glutathione. Trends in measured endpoints reached maximum levels at L1 followed by L2 and L3. Cross-talks on root-Hg status and the studied biochemical traits revealed (a) high Hg-accrued elevations in oxidative stress as an obvious response; (b) Hg-stabilization potential of J. maritimus roots as a result of a successful mitigation of elevated high Hg-induced H2O2, and its anomalies such as LPO, EL, and PO; and (c) the induction of and a fine synchronization between non-glutathione and glutathione-based systems. Overall, the study unveiled biochemical mechanisms underlying root tolerance to Hg burden-accrued anomalies which, in turn, helped J. maritimus during Hg-stabilization.

Resource-use strategies of native and invasive plants in Eastern North American forests.

Studies in disturbed, resource-rich environments often show that invasive plants are more productive than co-occurring natives, but with similar physiological tradeoffs. However, in resource-limited habitats, it is unclear whether native and invasive plants have similar metabolic constraints or if invasive plants are more productive per unit resource cost - that is, use resources more efficiently. Using a common garden to control for environment, we compared leaf physiological traits relating to resource investments, carbon returns, and resource-use efficiencies in 14 native and 18 nonnative invasive species of common genera found in Eastern North American (ENA) deciduous forest understories, where growth is constrained by light and nutrient limitation. Despite greater leaf construction and nitrogen costs, invaders exhibited greater instantaneous photosynthetic energy-use efficiency (PEUE) and marginally greater photosynthetic nitrogen-use efficiency (PNUE). When integrated over leaf lifespan (LL), these differences were magnified. Differences in efficiency were driven by greater productivity per unit leaf investment, as invaders exhibited both greater photosynthetic abilities and longer LL. Our results indicate that woody understory invaders in ENA forests are not constrained to the same degree by leaf-based metabolic tradeoffs as the native understory flora. These strategy differences could be attributable to pre-adaptation in the native range, although other explanations are possible.

Gold phytomining. A review of the relevance of this technology to mineral extraction in the 21st century.

The precious metal gold can be found at high concentration in tailings dumps and waste rock piles at many mining locations around the world. Conventional technology is generally unable to economically recover this residual gold, and, as a result, the potential resource is wasted, presenting environmental risk to the wider ecosystem through particulate and dissolved metal leaching and erosion. For the past 14 years, the idea of gold phytomining to recover this gold resource has been researched by various scientific groups worldwide. A number of plant species have been tested under laboratory, greenhouse, and field conditions to determine their potential for use in the phytoextraction of gold. This paper presents a review of reported gold phytomining trials developed in the laboratory, the greenhouse under soil and hydroponic conditions, as well as in the field, between 1998 and 2011. A summary economic assessment for gold phytomining in Mexico is also presented. Mexico is an example of a developing country with a long history of gold mining that has a large resource of sites that might be suitable to gold phytomining. The technology remains limited by certain environmental and plant physiology factors. However, the increase in the market price for gold during the first decade of the 21st century and into 2011, and advances recorded for the gold concentration and biomass yield of a range of plant species, suggest that gold phytomining might be an economically viable technology.

Sewage treatment in integrated system of UASB reactor and duckweed pond and reuse for aquaculture.

The performance of a laboratory-scale upflow anaerobic sludge blanket (UASB) reactor and a duckweed pond containing Lemna gibba was investigated for suitability for treating effluent for use in aquaculture. While treating low-strength sewage having a chemical oxygen demand (COD) of typically less than 200 mg/L, with an increase in hydraulic retention time (HRT) from 10.04 to 33.49 h, COD removal efficiency of the UASB reactor decreased owing to a decrease in organic loading rate (OLR) causing poor mixing in the reactor. However, even at the lower OLR (0.475 kg COD/(m3 x d)), the UASB reactor gave a removal efficiency of 68% for COD and 74% for biochemical oxygen demand (BOD). The maximum COD, BOD, ammonia-nitrogen and phosphate removal efficiencies of the duckweed pond were 40.77%, 38.01%, 61.87% and 88.57%, respectively. Decreasing the OLR by increasing the HRT resulted in an increase in efficiency of the duckweed pond for removal of ammonia-nitrogen and phosphate. The OLR of 0.005 kg COD/(m2 x d) and HRT of 108 h in the duckweed pond satisfied aquaculture quality requirements. A specific growth rate of 0.23% was observed for tilapia fish fed with duckweed harvested from the duckweed pond. The economic analysis proved that it was beneficial to use the integrated system of a UASB reactor and a duckweed pond for treatment of sewage.

Differences in leaf construction cost between alien and native mangrove species in Futian, Shenzhen, China: implications for invasiveness of alien species.

Construction cost (CC) is a quantifiable measure of energy demand for biomass production, and low CC is hypothesized to give an alien plant growth advantages and increase its potential to be an invader. Comparison of leaf CC and growth traits between alien and native mangroves in Shenzhen Futian Nature Reserve showed CC per unit mass (CC(mass)), carbon concentration and gross and ash-free caloric values of alien mangroves were significantly lower than those of native species, while the height and chest circumference were just the opposite. Alien species Sonneratia apetala had the lowest CC(mass) while Sonneratia caseolaris had the lowest CC(area), and were 8.99% and 32.17% lower than those of native species, respectively. Conversely, specific leaf area (SLA) of these two Sonneratia species was significantly higher than native species. Lower CC and higher SLA make the two Sonneratia species grow and spread faster than other mangroves and enhance their invasive potential.

Comparative assessment of Azolla pinnata and Vallisneria spiralis in Hg removal from G.B. Pant Sagar of Singrauli Industrial region, India.

The aim of the present work was to monitor the Hg pollution in water and sediments of G.B. Pant Sagar located in Singrauli Industrial Region, India and to suggest the efficient aquatic plants for its phytoremediation. The study assessed the comparative potential of a free floating water fern Azolla pinnata and submerged aquatic macrophyte Vallisneria spiralis to purify waters polluted by Hg. Six days laboratory experiments have been conducted to mark the percentage removal of Hg at initial concentration of 0.1, 0.5, 1.0 and 3.0 mg L(-1). The percentage removal of Hg was higher for A. pinnata (80-94%) than V. spiralis (70-84%). Likewise, the Hg accumulated in dry mass was much higher for A. pinnata and a high correlation (R(2) = 0.91 for A. pinnata and 0.99 for V. spiralis) was obtained between applied Hg doses and accumulated amounts in biomass. A concentration dependent decrease in chlorophyll a, protein, RNA, DNA and nutrients (NO(3-) and PO(4)(3-)) uptake was detected in A. pinnata and V. spiralis due to Hg toxicity. The decrease was more prominent in Azolla than Vallisneria. The results recommended the use of A. pinnata and V. spiralis to ameliorate the industrial effluents (thermal power, chlor-alkali and coal mine effluent) contaminated with Hg.

Do we underestimate the importance of leaf size in plant economics? Disproportional scaling of support costs within the spectrum of leaf physiognomy.

BACKGROUND: Broad scaling relationships between leaf size and function do not take into account that leaves of different size may contain different fractions of support in petiole and mid-rib. METHODS: The fractions of leaf biomass in petiole, mid-rib and lamina, and the differences in chemistry and structure among mid-ribs, petioles and laminas were investigated in 122 species of contrasting leaf size, life form and climatic distribution to determine the extent to which differences in support modify whole-lamina and whole-leaf structural and chemical characteristics, and the extent to which size-dependent support investments are affected by plant life form and site climate. KEY RESULTS: For the entire data set, leaf fresh mass varied over five orders of magnitude. The percentage of dry mass in mid-rib increased strongly with lamina size, reaching more than 40 % in the largest laminas. The whole-leaf percentage of mid-rib and petiole increased with leaf size, and the overall support investment was more than 60 % in the largest leaves. Fractional support investments were generally larger in herbaceous than in woody species and tended to be lower in Mediterranean than in cool temperate and tropical plants. Mid-ribs and petioles had lower N and C percentages, and lower dry to fresh mass ratio, but greater density (mass per unit volume) than laminas. N percentage of lamina without mid-rib was up to 40 % higher in the largest leaves than the total-lamina (lamina and mid-rib) N percentage, and up to 60 % higher than whole-leaf N percentage, while lamina density calculated without mid-rib was up to 80 % less than that with the mid-rib. For all leaf compartments, N percentage was negatively associated with density and dry to fresh mass ratio, while C percentage was positively linked to these characteristics, reflecting the overall inverse scaling between structural and physiological characteristics. However, the correlations between N and C percentages and structural characteristics differed among mid-ribs, petioles and laminas, implying that the mass-weighted average leaf N and C percentage, density, and dry to fresh mass ratio can have different functional values depending on the importance of within-leaf support investments. CONCLUSIONS: These data demonstrate that variation in leaf size is associated with major changes in within-leaf support investments and in large modifications in integrated leaf chemical and structural characteristics. These size-dependent alterations can importantly affect general leaf structure vs. function scaling relationships. These data further demonstrate important life-form effects on and climatic differentiation in foliage support costs.

Desiccation tolerance of five tropical seedlings in panama. Relationship to a field assessment of drought performance.

Studies of the desiccation tolerance of the seedlings of five tropical trees were made on potted plants growing in a greenhouse. Pots were watered to field capacity and then dehydrated for 3 to 9 weeks to reach various visual wilting stages, from slightly wilted to dead. Saturated root hydraulic conductance was measured with a high-pressure flowmeter, and whole-stem hydraulic conductance was measured by a vacuum chamber method. Leaf punches (5.6-mm diameter) were harvested for measurement of leaf water potential by a thermocouple psychrometer method and for measurement of fresh and dry weight. In a parallel study, the same five species were studied in a field experiment in the understory of a tropical forest, where these species frequently germinate. Control seedlings were maintained in irrigated plots during a dry season, and experimental plants were grown in similar plots with rain exclusion shelters. Every 2 to 4 weeks, the seedlings were scored for wilt state and survivorship. After a 22-week drought, the dry plots were irrigated for several weeks to verify visual symptoms of death. The field trials were used to rank drought performance of species, and the greenhouse desiccation studies were used to determine the conditions of moribund plants. Our conclusion is that the desiccation tolerance of moribund plants correlated with field assessment of drought-performance for the five species (r(2) > 0.94).

Herbicide risk assessment for non-target aquatic plants: sulfosulfuron--a case study.

Herbicides entering the aquatic environment by spray drift, run-off and leaching to field drains may cause adverse effects on non-target aquatic vegetation. The potential for such effects has typically been evaluated from tests with floating, monocotyledonous Lemna sp. However, concern has been expressed as to whether this species could be used to indicate potential effects on other vegetation types, particularly rooted, submerged, emergent or dicotyledonous species. In 1997, the Centre for Aquatic Plant Management undertook development of new tests based on the additional species, Glyceria maxima (Hartm) Holmb, Lagarosiphon major (Ridl) Moss and Myriophyllum spicatum L. The resulting methodology was used to assess the effects of the sulfonylurea herbicide, sulfosulfuron on these species. Data presented here demonstrate that exposure to initial sulfosulfuron concentrations of 3.33 microg litre(-1) for up to 21 days was tolerated by these species and that adverse effects were observed only when plants were exposed to initial concentrations of 3.33 and 10 microg litre(-1) for 70 days. As the occurrence of such high initial concentrations for long periods is unlikely in the aquatic environment, sulfosulfuron is not expected to have adverse effects on the growth of these species. This study has also demonstrated that G maxima, L major and M spicatum grown in small outdoor tanks can be used successfully to assess the effects of crop-protection products on non-target aquatic flora.