Invasive Macrophyte Research Articles

Phytoremediation of battery industry effluent through aquatic macrophytes

Research was conducted to quantify the level of copper (Cu), chromium (Cr), cadmium (Cd) and lead (Pb) contamination in battery industry effluent and to assess the remediation potential of three invasive aquatic macrophytes Eichhornia crassipes, Pistia stratiotes and Hydrocotyle umbellata by growing on industrial effluent collected from Lead acid Battery industry.The effluent was heavily contaminated with Pb (10mg/l) and sulphuric acid (pH 2- 2.1). Due to high Pb concentrations and low pH (2-2.2) the plants were unable to survive. Mortality rate of E. crassipes was 96 % while P. stratiotes and H. umbellata were 100% rotten. The experiment was repeated after adjusting the effluent pH to 7-7.5 to increase the plant life.Plant parts and wastewater samples were analyzed after every 3 days interval uptil 21st day. The amount of Cr, Cd and Cu in the effluent was 0.076 mg /L, 0.036 mg /L and 0.097 mg /L, which was in permissible limits of NEQs (1.0 mg/l, 0.1 mg/l and 1.0 mg/l) respectively. Pb was found 10 times higher i.e. 10 mg/l than the permissible limit 0.5 mg/l. E. crassipes removed Pb>Cr>Cu>Cd while P. stratiotes and H. umbellata reduced Cd, Cr, Cu more than Pb from the effluent. E. crassipes was most efficient Pb removing plant in 21 days of experiment. Â

Native and Invasive Macrophytes Differ in Their Effectiveness as Nurseries for Juvenile Endangered Salmon

For marine biogenic habitats, such as kelp and seagrass, declines and local extinction events cause concern because of the loss of ecosystem services they provide. Many of these habitats function as valuable nurseries, but this function may be eroded when invasive species alter the structure of the habitats. For anadromous salmonids along the northeast Pacific, there is little known about the nursery role of coastal habitats, which presents a challenge for scientists to fully understand their complex life histories necessary for informing resource managers in decision-making processes regarding habitat protection and restoration. To address these issues, we ran a 3-week experiment testing the nursery functions of seagrass (Zostera marina), the invasive alga Sargassum muticum, mixed seagrass-Sargassum, and bare sand plots on the growth, survival, and prey availability for endangered Chinook salmon (Oncorhynchus tshawytscha) smolts. We found mixed effects of each habitat type when compared with each other. Chinook salmon smolts grew less in seagrass when compared with the three other habitats (bare sand, Sargassum, mixed seagrass-Sargassum). However, fish survival was lower in Sargassum habitat compared with seagrass and bare sand. Prey availability was greatest in mixed seagrass-Sargassum habitat compared with bare sand, Sargassum, or seagrass. We used a principal components analysis (PCA) to develop a nursery index using the smolts’ growth rate, percent survival, prey availability, and density of prey in gut contents. The nursery index showed that mixed seagrass-Sargassum habitat had the most positive effects on nursery performance. These results suggest that invasive species can serve positive habitat functions, but only when in the presence of a habitat-forming native species. Our study supports the theory that habitat diversity leads to greater nursery function of coastal ecosystems.

Broad-scale detection of environmental DNA for an invasive macrophyte and the relationship between DNA concentration and coverage in rivers

Environmental DNA (eDNA) techniques have the potential to become useful tools for investigating the distribution and biomass of aquatic organisms. Additionally, Unmanned Aerial Vehicle (UAV) photos have recently been applied to evaluate vegetation cover. We tested the ability of eDNA techniques to evaluate the distribution and biomass of an invasive macrophyte, Egeria densa (Brazilian waterweed). We conducted field surveys in two Japanese rivers to determine the abundance of eDNA from E. densa and compared it with macrophyte coverage by evaluating UAV photographs taken in the summer and winter. We found eDNA of E. densa in all sampled sites, including various sites with no macrophyte coverage, indicating that there was a broad-scale distribution of E. densa eDNA. In summer, we detected a slightly positive relationship between E. densa eDNA and macrophyte coverage. We did not find a clear relationship between E. densa eDNA and macrophyte coverage, probably because of their widespread and dense distribution and the flow of their materials in the rivers. The seasonal differences in the regression may have been caused by the seasonal growing period of E. densa in the summer, with a decline in their biomass in late autumn and winter. We confirmed the ability of eDNA techniques to survey this invasive macrophyte in rivers by comparing results with coverage measurements from UAV photographs.

The invasive macrophyte Hydrilla verticillata causes taxonomic and functional homogenization of associated Chironomidae community

Exotic species have invaded freshwater ecosystems, causing biodiversity loss of associated communities. We investigated the influence of the invasive macrophyte Hydrilla verticillata on taxonomic and functional richness, and on taxonomic and functional beta diversity of associated Chironomidae community, comparing this macrophyte with the structurally similar native macrophyte, Egeria najas. We conducted a field experiment where the native and invasive plants were kept side-by-side and colonized by invertebrates. We used accumulation curves to test if richness differed between macrophytes. We used multivariate dispersion to investigate whether taxonomic and functional composition differed between both macrophytes and to test if beta diversity was higher among individuals of the native than among individuals of the invasive macrophytes. We measured beta diversity values as an average distance of the compositions to the centroid in a multidimensional space (taxonomic and functional) given by a Principal Coordinates Analysis. We found similar taxonomic richness and similar taxonomic and functional Chironomidae composition between macrophytes. However, functional richness as well as taxonomic and functional beta diversity of Chironomidae were higher among the native than among the invasive macrophytes. Thus, although H. verticillata did not cause changes neither in Chironomidae taxonomic richness nor on taxonomic and functional composition, its spread may drive the simplification of species and functional traits of associated Chironomidae communities.

Root anatomy and nutrient uptake of the cattail Typha domingensis Pers. (Typhaceae) grown under drought condition

Typha domingensis is an invasive macrophyte which can be found even under low water levels. The objective of this study was to evaluate the root growth and anatomy as related to nutrient uptake and distribution of cattail under different water availabilities. Typha domingensis individuals were subjected to five water conditions: waterlogged, field capacity (FC), 75%FC and 50%FC. Nutrient contents of shoots and roots as well as the root growth and anatomy were evaluated. Lower water levels reduced root length (30%) and dry mass (90%) of cattail. Moderate drought increased aerenchyma development in root cortex but reduced the number and the diameter of xylem vessels in the vascular cylinder. Drought reduced the uptake of most nutrients; however, cattail promoted a higher translocation of macronutrients to shoot. Typha domingensis showed drought tolerance with modifications in root anatomy and higher nutrient translocation to shoots allowing its survival under mild water limitation.

Gimme Shelter: differential utilisation and propagule creation of invasive macrophytes by native caddisfly larvae

In aquatic systems, invasive submerged macrophytes considerably alter the structure and functioning of communities, thus potentially compromising ecosystem services. The prolific spread of invasive macrophytes is often aided by vegetative fragment propagation, yet the contributions of various commonly occurring invertebrates to such fragmentation are often unquantified. In the present study, we examine fragmentary spread of invasive macrophytes by a group of shredder-herbivores, larval caddisflies. Through novel application of the comparative functional response (FR; resource use as a function of density) approach to the native case-building species Limnephilus lunatus, we compared utilisation of non-native waterweeds Elodea canadensis and E. nuttallii in mono- and polycultures. Furthermore, we quantified de-cased and cased caddisfly-induced fragment production and length changes among non-native E. canadensis, E. nuttallii, Crassula helmsii and Lagarosiphon major under two different plant orientations: horizontal (floating) versus vertical (upright) growth forms. Larval caddisflies exhibited Type II (hyperbolic) FRs towards both Elodea species, and utilised each plant at similar rates when plants were provided separately. When plant species were presented in combination horizontally, E. canadensis was significantly less utilised compared to E. nuttallii, corroborating observations in the field. De-cased larvae produced new plant fragments for all four aquatic macrophytes, whereas cased larvae fragmented plants significantly less. Elodea nuttalii and C. helmsii were fragmented the most overall. Crassula helmsii was utilised to the greatest extent when plants were horizontally orientated, and Elodea species when vertically orientated. This study identifies and quantifies a mechanism from a novel species group that may contribute to the spread of invasive macrophytes in aquatic systems. Whilst exploititative interactions are thought to impede invasion success, here we demonstrate how resource utilisation by a resident species may exacerbate propagule pressure from an invasive species.

Environmental variables and macrophytes of lakes of the Chitwan National Park, Central Nepal

Abstract Wetlands are areas where water is the primary factor controlling the environment, associated plant and animal life. The present study has been conducted to investigate the environmental variables of water and to make a quantitative analysis of aquatic macrophytes. Five lakes, i.e. Tamor, Beeshazar, Kingfisher, Athaieshazar and Chepang of the Chitwan National Park were studied during the post-monsoon season. Four different sites were studied for each lake. 12 replica of water samples were collected from each site of the lakes and environmental variables of water i.e. pH, temperature, dissolved oxygen, total alkalinity, conductivity, total hardness, nitrate, inorganic phosphorus, total solid matter and free CO2 were analyzed. Macrophyte floras were collected during field sampling with the help of a 1m×1m light wooden quadrat and herbaria were prepared following the standard technique. Altogether 10 quadrats (five paired quadrats) were plotted in each site of the study area. Data obtained from water analysis and macrophytes were analyzed by SPSS statistics 20 and CANACO version 4.5. Higher values of nitrate and inorganic phosphorus were found in Beeshazar Lake and Tamor Lake, i.e. 4.41 ±0.52 mg dm–3 and 2.93 ±0.29 mg dm–3, respectively. In most of the lakes, macrophyte species, mostly Eichhornia crassipes was found to be dominant in terms of the importance value index (IVI), whereas in Tamor Lake, Spirodela polyrhiza was dominant. All the studied lakes were in the hypereutrophic category on the basis of nitrate and phosphorus concentration. Runoff of polluted water with agricultural fertilizers, pesticides and untreated industrial discharge as well as domestic wastes from the Khageri canal and excessive growth of invasive macrophytes are major threats to the studied lakes. The luxuriant growth of invasive macrophytes like Eichhornia crassipes also revealed the productive nature of the lakes and they can be taken as ecological indicators of organic pollution.

Biological control of water lettuce, Pistia stratiotes L., facilitates macroinvertebrate biodiversity recovery: a mesocosm study

Floating aquatic weed infestations have negative socio-economic and environmental consequences to the ecosystems they invade. Despite the long history of invasion by macrophytes, only a few studies focus on their impacts on biodiversity, while the ecological benefits of biological control programmes against these species have been poorly quantified. We investigated the process of biotic homogenization following invasion by Pistia stratiotes on aquatic biodiversity, and recovery provided by biological control of this weed. Biotic homogenization is the increased similarity of biota as a result of introductions of non-native species. The study quantified the effect of P. stratiotes, and its biological control through the introduction of the weevil, Neohydronomus affinis on recruitment of benthic macroinvertebrates to artificial substrates. Mats of P. stratiotes altered the community composition and reduced diversity of benthic macroinvertebrates in comparison to an uninvaded control. However, reduction in percentage cover of the weed through biological control resulted in a significant increase in dissolved oxygen, and recovery of the benthic macroinvertebrate community that was comparable to the uninvaded state. This highlights the process of homogenization by an invasive macrophyte, providing a justification for sustained ecological and restoration efforts in the biological control of P. stratiotes where this plant is problematic.

Invasive macrophytes induce context‐specific effects on oxygen, pH, and temperature in a hydropeaking reservoir

AbstractDense macrophyte beds are known to produce extreme diurnal oxygen and temperature conditions in shallow lakes. However their influences in managed hydropeaking reservoirs has received limited attention. We measured dissolved oxygen, pH and water temperature in the Lake Karāpiro hydroreservoir, northern New Zealand, across a gradient of proportional water‐column height occupied by the invasive macrophytes Egeria densa and Ceratophyllum demersum, which dominated in the upper‐riverine (variable water inflow) and lower‐lacustrine (variable water level) sections, respectively. Hypoxia and anoxia events that occurred inside invasive macrophyte beds during their summer peak biomass accumulation period were more pronounced for C. demersum than for E. densa, and within the bottom 20% of the water column. In contrast, pH and temperature changed little in relation to proportional macrophyte height. Macrophyte species differences in the production of hypoxia and anoxia events increased when site‐specific hydropeaking management covariates (depth, inflows, water level) were accounted for. This association with hydropeaking likely resulted from contrasting hydrodynamics in the lower‐lacustrine and upper‐riverine lake sections, where oxygen can decrease with higher water levels and lower water inflow rates, respectively. During the course of our study, some macrophyte beds were treated with herbicide, enabling us to document prolonged and sustained hypoxic/anoxic conditions near the bottom following spraying. These results underscore the adverse effects of invasive macrophytes on water physicochemical attributes that sustain aquatic biota, and highlight the context‐dependent nature of these effects moderated by reservoir management for hydropeaking and macrophyte control.

Nutrient-mediated silica uptake from agricultural runoff in invasive floating macrophytes: implications for biological control

Silica (Si) plays a significant role in alleviating the effects of biotic and abiotic stressors in many plants, especially in an agricultural context. With increased use of Si-based fertilisers, understanding plant responses to the addition of Si to their environment, particularly aquatic environments, is important. We investigated how two invasive macrophytes, Eichhornia crassipes and Pistia stratiotes, responded to different nutrient and Si concentrations, in the presence and absence of herbivory. Both species incorporated Si into their foliage, but uptake of Si did not increase under high nutrient availability but rather decreased, especially in P. stratiotes. Plant quality (i.e. C:N) for both weed species was affected more by nutrient concentrations than Si content, and the addition of Si had a negative effect on plant growth. Eichhornia crassipes increased daughter plant production under high Si conditions, while P. stratiotes plants showed no reproductive response to increased Si except in low nutrient conditions where reproduction was reduced. The addition of Si resulted in increased biomass of E. crassipes, while P. stratiotes was unaffected. These results highlight that runoff of Si from fertiliser alter aquatic plant–insect interactions, which has consequences for biological control.

Perspectives of using the water hyacinth (Eichhornia heterosperma) for self-purification in a Colombian water reservoir

Eutrophication and heavy metal contamination of freshwater reservoirs cause serious problems world- wide. With increasing nutrient levels in lakes and reservoirs, invasive macrophytes like the perennial water hyacinth Eichhornia spp. can intensify the degradation process, but the plants can also be supporting because of their high capacity for heavy metal and nutrient accumulation. In this study, we assessed the potential of E. heterosperma for nutrient removal. Therefore, we measured nutrient and heavy metal concentrations in the water and the plant tissue of E. heterosperma plants harvested in a hypereutrophic reservoir (Porce II, Antioquia, Colombia). We found mean nitrogen concentrations between 21–45 g and phosphorus between 2.1–3.0 g kg –1 dry weight in the different plant parts (leaves, stems, roots). Regarding metals, we measured 3.1–2;37 mg chrome, 62 mg–7.4 g aluminium, 22–70 mg zinc, 12–95 mg copper, and 0.4–1.3 g manganese per kg of dry weight. This exceptional high ability for nutrient and heavy metal uptake makes Eichhornia heterospermaan appropriate candidate for bioremediation in reservoirs. Therefore, we assessed the potential of the plants as fertilizer for forests and agriculture regarding the heavy metal accumulations. We found that the harvest of 1.0 km² of plant cover in Porce II would result in a removal of 4.3 % phosphorus and 4.0 % nitrogen of the nutrients in the water column. This indicates that for hypereutrophic lakes with an annual input of about 43443 t N and 2490 t P, the remediation capacity of this plant is limited.

New records of the invasive macrophyte, Urochloa arrecta extend its range to eastern Brazilian Amazon altered freshwater ecosystems

ABSTRACT Invasive species influence the structure and functioning of ecosystems, as they affect native species, significantly decreasing their diversity. Aquatic ecosystems harbor a great biodiversity, and invasive macrophytes significantly affect the native plant communities, causing a cascade effect on other trophic levels. Among invasive macrophytes, Urochloa arrecta is cause for concern in the Neotropics and is found in several regions of Brazil, specially in the southeastern and southern regions. So far the species had been recorded only in the northern state of Amazonas. We report the first record of the species in the state of Pará, in the eastern Brazilian Amazon. We emphasize that identifying sites where this species is invasive is the best strategy to prevent its spread, aiming at the protection and conservation of Amazonian freshwater ecosystems.

Seed source regions drive fitness differences in invasive macrophytes.

PremiseWorldwide, ecosystems are threatened by global changes, including biological invasions. Invasive species arriving in novel environments experience new climatic conditions that can affect their successful establishment. Determining the response of functional traits and fitness components of invasive populations from contrasting environments can provide a useful framework to assess species responses to climate change and the variability of these responses among source populations. Much research on macrophytes has focused on establishment from clonal fragments; however, colonization from sexual propagules has rarely been studied. Our objective was to compare trait responses of plants generated from sexual propagules sourced from three climatic regions but grown under common environmental conditions, using L. peploides subsp. montevidensis as a model taxon.MethodsWe grew seedlings to reproductive stage in experimental mesocosms under a mediterranean California (MCA) climate from seeds collected in oceanic France (OFR), mediterranean France (MFR), and MCA.ResultsSeed source region was a major factor influencing differences among invasive plants recruiting from sexual propagules of L. peploides subsp. montevidensis. Trait responses of young individual recruits from MCA and OFR, sourced from geographically distant and climatically distinct source regions, were the most different. The MCA individuals accumulated more biomass, flowered earlier, and had higher leaf N concentrations than the OFR plants. Those from MFR had intermediate profiles.ConclusionsBy showing that the closer a seedling is from its parental climate, the better it performs, this study provides new insights to the understanding of colonization of invasive plant species and informs its management under novel and changing environmental conditions.

Evaluation of Habitat Preferences of Invasive Macrophyte Egeria densa in Different Channel Slopes Using Hydrogen Peroxide as an Indicator.

Egeria densa is an often-found invasive species in Japan, which has spread widely in the past two decades in rivers where no macrophytes had previously been found. As a result, these ecosystems have now become dominated by E. densa. The habitat preference for E. densa colony formation was investigated using the tissue concentrations of hydrogen peroxide (H2O2: a reactive oxygen species) under varying conditions in rivers and laboratory conditions. The empirical equations that can describe the macrophyte tissue H2O2 formation under various velocity and light conditions were produced. The H2O2 concentrations of dark-adapted plants are proportional to the flow velocity, and the surplus H2O2 concentration in the light-exposed condition corresponded to the photosystems produced H2O2. When the H2O2 concentration exceeds 16 μmol/gFW, plant tissue starts to deteriorate, and biomass declines, indicating the critical values required for long-term survival of the plant. The empirically obtained relationships between flow velocity or light intensity and the analysis of H2O2 concentration for different slopes and depths of channels found that the H2O2 value exceeds the critical H2O2 concentration in channels with above 1/100 at around 0.6 m depth. This agrees with the observed results where colonies were not found in channels with slopes exceeding 1/100, and biomass concentration was the largest at depths of 0.6 to 0.8 m. H2O2 concentration is quite applicable to understanding the macrophyte condition in various kinds of macrophyte management.

Friends of mine: An invasive freshwater mussel facilitates growth of invasive macrophytes and mediates their competitive interactions

Abstract Increasing rates of invasions in ecosystems worldwide necessitate experiments to determine the role of biotic interactions in the success and impact of multiple alien species. Here, we examined competitive and facilitative interactions among various combinations of three widespread and often co‐occurring invaders: the zebra mussel Dreissena polymorpha, and the macrophytes Elodea canadensis and Elodea nuttallii. Using a mesocosm‐based, factorial experimental design, we assessed the effect of interspecific competition on macrophyte growth rates in the absence and presence at varying biomass of D. polymorpha. Growth rates (wet g/day) of E. canadensis and E. nuttallii were similar when grown in isolation. When grown together, in the absence of D. polymorpha, E. canadensis growth was not significantly reduced in the presence of E. nuttallii and vice versa. In the presence of D. polymorpha (26.0 ± 1 mm), monocultural growth of E. canadensis was largely unaffected, while E. nuttallii growth was strongly enhanced. Low (2.64 g) and medium (3.96 g) mussel biomass led to negative interspecific effects between E. canadensis and E. nuttallii; at high (5.28 g) mussel biomass, the effect of interspecific competition was negated. Overall, D. polymorpha alleviated competitive interactions between the two invasive macrophytes when all three species co‐occurred, and substantially enhanced growth of E. nuttallii with increasing mussel biomass, thereby suggesting a possible influence on the relative dominance of these macrophytes in the field. Our study demonstrates how facilitations can cause shifts in dominance among closely related invaders. The consequences of such facilitations for the structure and function of communities remain to be explored generally.

Feeding of fish inhabiting native and non-native macrophyte stands in a Neotropical reservoir

Owning to dissimilarity with native macrophytes, invasive macrophytes may negatively affect the diet and foraging efficiency of fishes. We evaluated the invertebrate availability, diet composition, and foraging efficiency of four fish species that use macrophytes as habitat in a native and a highly invasive macrophyte. The samples were taken in a reservoir in Brazil (22° 33′ S, 52°54′ W). We collected invertebrates and fishes simultaneously in macrophyte stands dominated by the invasive Poaceae Urochloa arrecta and the native Eichhornia azurea. We evaluated the foraging efficiency by the total number of prey consumed and by the degree of stomach fullness. We used an approach based on resampling procedures to compare differences in composition of invertebrates, composition of fish diet, and the similarity between invertebrates and fish diet. The abundance of invertebrates and the diet composition differed significantly between plants. On the other hand, fish foraging efficiency did not differ between macrophytes. Despite this lack of difference of foraging efficiency, the lower abundance of food items in the invasive macrophyte and the significant changes in fish diet suggest that U. arrecta is not a favorable feeding habitat for fishes, compared to the native E. azurea.

Influence of Macrophyte and Gut Microbiota on Mercury Contamination in Fish: A Microcosms Study

The freshwater lakes of southwestern France are subject to the development of invasive macrophytes which are associated with mercury (Hg) contamination of the food web. The aim of this study was to determine the bioavailability of methylmercury (MeHg) produced by plant roots in aquatic ecosystems. A microcosm experiment was performed using isotopically enriched inorganic Hg at environmental concentrations (1 µg 199IHg·L−1). For all conditions, total Hg in fish as well as Hg species associated with different compartments (water, sediments, plant roots, fish) were analyzed by gas chromatography-inductively coupled plasma-mass spectrometry (GC-ICP-MS). In addition, sediment, plants, and fish gut microbiota were studied by MiSEQ sequencing. Some strains were isolated and tested for their ability to methylate Hg. The results revealed 199MeHg production in plant roots and the presence of this form in fish (tissues and gut), highlighting a MeHg trophic transfer. Moreover, methylator bacteria were identified from the gut contents of the fish when they were in the presence of plants. Some of them were related to bacteria found in the plant roots. On the basis of these results, the transfer of MeHg and bacteria from plants to fish is highlighted; in addition, Hg methylation is strongly suspected in the fish gut, potentially increasing the Hg bioaccumulation.

Dead and gone: Steam exposure kills layered clumps of invasive curly waterweed Lagarosiphon major

Population suppression and eradication of invasive, alien macrophytes can be complex, costly and labour intensive, therefore prevention of further spread is an essential aspect of management. However, following the physical removal of entangled clumps of plant material adhering to anthropogenic vectors including outboard engines, guidelines for appropriate disposal are often unclear, inadequate, or non-existent. Here, we explore use of direct steam exposure to cause complete degradation of layered clumps of invasive curly waterweed Lagarosiphon major (Ridley) Moss. Clumps were arranged as three, stacked 15 × 15 cm layers, with 40 ± 0.1 g of entangled stems per layer, to which steam was directly applied downwards onto the top layer. The top surface area was divided into nine subsections to ensure an even application of steam per 5 × 5 cm for durations of 5, 10, 30, 60, or 120-sec, equivalent to 0.75, 1.5, 4.5, 9, or 18-min steam applications. Ten seconds of exposure caused total degradation of top and middle layers, while up to 30-sec was required for the bottom layer. For shorter exposures, new growth - if it occurred - was evidenced by a single new shoot of < 5 mm in length following 28-days of recovery. Conversely, control specimens displayed excellent survival and production of new growth. We suggest that the simple, yet highly efficacious technique of steam exposure can be used to improve prevent spread of invasive macrophytes.

Tomorrow Never Dies: biodegradation and subsequent viability of invasive macrophytes following exposure to aquatic disinfectants

Aquatic invasive alien species (IAS) negatively impact freshwater ecosystems worldwide. As suppression and eradication of established invader populations are often complex, costly and resource-intensive, the prevention of further invader spread is considered a key aspect of proactive management measures. Although broad-spectrum aquatic disinfectants have been suggested as a suitable decontamination mechanism to enhance invader spread-prevention strategies, inconsistencies concerning their effectiveness are reported within the literature. Here, we examine the use of two aquatic disinfectants, which were developed to kill damaging microbes, to induce substantial degradation of the apical fragmentary propagules of five invasive macrophytes: Crassula helmsii (Kirk) Cockayne; Egeria densa Planchon; Elodea canadensis Michx; Hydrocotyle ranunculoides Linnaeus; Lagarosiphon major (Ridley) Moss. Apical fragments were exposed to 0% (0 g L-1), 2% (20 g L-1) or 4% (40 g L-1) solutions of Virkon® Aquatic and Virasure® Aquatic, for submergence treatments of five, fifteen, thirty or sixty minutes. After 28 days, degradation of treated fragments was significantly greater than that of control groups, particularly for 4% solutions and longer exposure times. Despite this, sustained viability in relation to shoot and/or root regrowth was exhibited by almost all plant species. However, new shoot growth rates were significantly reduced following exposure to all treatments. At matched concentrations, there was no significant difference between the two disinfectants. Overall, it appears that the examined aquatic disinfectants will not curtail the spread of these invasive macrophytes. Yet, longer submergence times, multiple applications and synergistic effects of different biosecurity treatments may enhance preventative measures against further spread and this requires investigation.

First Report on the Occurrence of Invasive Macrophyte Elodea canadensis Michx. in Sapanca Lake

Objective: Elodea canadensis Michx. is a common invasive aquatic macrophyte that has successfully spread along European, Asian and Australian inland waters. The aim of this study is to evaluate the presence and distribution of an alien and invasive species, E. canadensis, in Sapanca Lake (Turkey) for the first time. Materials and Methods: Sampling for macrophytes and main environmental parameters was carried out seasonally between the years 2016 and 2017 along the coasts of Sapanca Lake. Macrophytes samples were taken from bounded areas. Morphological observations were made on both unfixed-living and dried materials, and morphological details were observed under a light microscope. Results: Elodea canadensis Michx. was reported for the first time in Sapanca Lake during the spring period of 2016 with water temperatures of 20.9 ±0.9°C. A total of six submerged macrophytes species were recorded together with E. canadensis. Conclusion: The first record of this species in Sapanca Lake is important for contributing to the changing biodiversity dynamics of the lake and also contributes to the assessment of the possible ecological and economic risks of the region in terms of lake management.