Didymosphenia geminata in two Alberta headwater rivers: an emerging invasive species that challenges conventional views on algal bloom development

2007 ◽  
Vol 64 (12) ◽  
pp. 1703-1709 ◽  
Author(s):  
Andrea E Kirkwood ◽  
Troina Shea ◽  
Leland J Jackson ◽  
Edward McCauley
Keyword(s):  
Invasive Species ◽  
Environmental Factors ◽  
Flow Regime ◽  
Negative Relationship ◽  
Invasion Biology ◽  
Water Clarity ◽  
Supporting Evidence ◽  
Mean Flow ◽  
Didymosphenia Geminata ◽  
New Variant

The diatom Didymosphenia geminata (Bacillariophyceae) has garnered increased attention as a nuisance and invasive species in freshwater systems. Historically described as rare yet cosmopolitan, a suspected new variant of D. geminata has the capacity to inundate kilometres of river bottom during a bloom. Unlike most other bloom-forming algae, D. geminata proliferates under high water quality (i.e., low turbidity and low nutrient) conditions. To inform management strategies, the environmental factors and conditions that promote bloom events must be ascertained. Our study of the Bow and Red Deer rivers in southern Alberta, Canada, provides supporting evidence that the mean flow regime is associated with bloom development, based on a significant negative relationship detected between D. geminata biomass and mean discharge (r2 = 0.30). While flow regulation by dams can create the stable flow environment preferred by D. geminata, our results indicate that flow regime (rather than just proximity to dam outflows) is the likely mechanism, in addition to other environmental factors, such as water clarity, temperature, pH, conductivity, and total phosphorus. We discuss the formidable challenges to D. geminata management, particularly along unregulated river reaches, yet also recognize the unique research opportunities that this organism poses for the growing field of invasion biology.

scholarly journals Variation in hip and sepal parameters of invasive Rosa rugosa between sites and years

Botanica ◽  
2021 ◽  
pp. 1-12
Author(s):  
Zigmantas Gudžinskas ◽  
Mindaugas Rasimavičius
Keyword(s):  
Invasive Species ◽  
Environmental Factors ◽  
Sunshine Duration ◽  
Negative Relationship ◽  
Cumulative Effect ◽  
Field Studies ◽  
Width Ratio ◽  
Coastal Habitat ◽  
Rosa Rugosa ◽  
Sepal Length

Rosa rugosa is among the most invasive species in Europe, and it is considered a severe threat to the diversity and stability of coastal habitats. In Lithuania, it is a widespread invasive species occurring in coastal and inland areas. This research aimed to estimate the variation in R. rugosa hip and sepal parameters within and among sites from coastal and inland areas, and investigate the effects of environmental factors on the hip and sepal sizes. Field studies were performed at four coastal and three inland sites in 2008, and the studies were repeated in 2016. We collected 100 mature hips at each site and measured the hip width, hip length and sepal length. We analysed variation in hip and sepal parameters between the study years, and the effect of meteorological factors and agrochemical properties of the soil on hip and sepal sizes. This study revealed significant variation in R. rugosa hip width, hip length and sepal length among the studied sites. The largest hips and sepals were found in the coastal habitat at the Smeltė site, whereas the smallest hips and sepals were recorded in inland habitat at the Staviškės site, where R. rugosa occurred in woodland. The comparison of hip and sepal sizes at the same sites during two study years revealed irregular variation. Mean hip width and mean length of sepals in 2008 were significantly more prominent than in 2016, whereas no significant differences in hip length were found between the study years. The content of phosphorus in the soil negatively correlated, whereas the content of carbonates positively correlated with the sepal length. A strong negative relationship was found between the sunshine duration and hip length and width ratio. However, the revealed relationships of the hip and sepal parameters with the environmental factors could be a coincidence or a result of the cumulative effect of the multiple factors’ interaction and should be investigated separately.

scholarly journals Diseases and Pests of Ash-Leaved Maple (Acer negundo L.) in Moscow region

2018 ◽  
pp. 79-87
Author(s):  
O.I. Yasinskaya
Keyword(s):  
Invasive Species ◽  
Environmental Factors ◽  
Woody Plants ◽  
Moscow Region ◽  
Acer Negundo ◽  
Adventitious Species ◽  
Resistance To Diseases

In the megapolis, native and adventitious species of woody plants are exposed to the most powerful adverse environmental factors that reduce resistance to diseases and pests. The investigation objective was to identify diseases and pests of a dangerous invasive species Acer negundo L. and to estimate their effect on invasion activity of this species. A. negundo leaves are affected by Рhyllosticta negundinis (Sacc. et Speg.), Sawadaia bicornis (Wallr. ex. Fr.) Miyabe and are occasionally damaged by a timber pest such as Rhopalopus clavipes F. A set of unfavorable environmental factors cause noninfectious toxicosis of A. negundo leaves. Meanwhile, all these diseases and pests do not cause considerable harm to A negundo and do not substantially reduce its invasion activity.

Relating initial paraquat injury to final efficacy in selected weed species influenced by environmental conditions

2020 ◽  
pp. 1-10
Author(s):  
Nick T. Harre ◽  
Garth W. Duncan ◽  
Julie M. Young ◽  
Bryan G. Young
Keyword(s):  
Environmental Factors ◽  
Negative Relationship ◽  
Injury Rate ◽  
Time Of Day ◽  
Palmer Amaranth ◽  
Shoot Biomass ◽  
Lag Phase ◽  
Progression Rate ◽  
Weed Species ◽  
Time Of Application

Abstract Weed control of paraquat can be erratic and may be attributable to differing species sensitivity and/or environmental factors for which minor guidance is available on commercial labels. Therefore, the objectives of this research were to quantify selectivity of paraquat across select weed species and the influence of environmental factors. Experiments were performed under controlled conditions in the greenhouse and growth chamber. Compared with purple deadnettle (dose necessary to reduce shoot biomass by 50% = 39 g ai ha−1), waterhemp, Palmer amaranth, giant ragweed, and horseweed were 4.9, 3.3, 1.9, and 1.3 times more sensitive to paraquat, respectively. The injury progression rate over 3 d after treatment (DAT) was a more accurate predictor of final efficacy at 14 DAT than the lag phase until symptoms first appeared. For example, at the 17.5 g ha−1 dose, the injury rate of waterhemp and Palmer amaranth was, on average, 3.6 times greater than that of horseweed and purple deadnettle. The influence of various environmental factors on paraquat efficacy was weed specific. Applications made at sunrise improved control of purple deadnettle over applications at solar noon or sunset. Lower light intensities (200 or 600 μmol m−2 s−1) surrounding the time of application improved control of waterhemp and horseweed more than 1,000 μmol m−2 s−1. Day/night temperatures of 27/16 C improved horseweed and purple deadnettle control compared with day/night temperatures of 18/13 C. Though control was positively associated with injury rates in the application time of day and temperature experiments, a negative relationship was observed for waterhemp in the light-intensity experiment. Thus, although there are conditions that enhance paraquat efficacy, the specific target species must also be considered. These results advocate paraquat dose recommendations, currently based on weed height, be expanded to address sensitivity differences among weeds. Moreover, these findings contrast with paraquat labels stating temperatures of 13 C or lower do not reduce paraquat efficacy.

Species richness of both native and invasive aquatic plants influenced by environmental conditions and human activity

Botany ◽  
2009 ◽  
Vol 87 (3) ◽  
pp. 306-314 ◽  
Author(s):  
Robert S. Capers ◽  
Roslyn Selsky ◽  
Gregory J. Bugbee ◽  
Jason C. White
Keyword(s):  
Invasive Species ◽  
Species Richness ◽  
Human Activity ◽  
Environmental Conditions ◽  
Native Plants ◽  
Water Clarity ◽  
Phosphorus Concentration ◽  
Lake Area ◽  
Species Dominance ◽  
High Productivity

Invasive plants alter community structure, threatening ecosystem function and biodiversity, but little information is available on whether invasive species richness responds to environmental conditions in the same way that richness of native plants does. We surveyed submerged and floating-leaved plants in 99 Connecticut (northeast USA) lakes and ponds, collecting quantitative data on abundance and frequency. We used multiple linear and logistic regression to determine which environmental conditions were correlated with species richness of invasive and native plants. Independent variables included lake area, maximum depth, pH, alkalinity, conductivity, phosphorus concentration, productivity, and dominance (the proportional abundance of the most abundant and frequently found species), plus two estimates of human activity. Species richness of both native and invasive richness was correlated with alkalinity and human activity. Native richness also increased with water clarity, lake area, and productivity; invasive species richness also rose with pH. We found no evidence that richness of one group affected richness of the other. We also investigated patterns of dominance and found that native plants were as likely to become dominant as invasive species. Dominance occurred overwhelmingly in shallow lakes with high productivity.

Female preference and male nuptial colouration in the freshwater fish Gobiomorphus breviceps: geographic variation among populations

1999 ◽  
Vol 77 (3) ◽  
pp. 463-469 ◽  
Author(s):  
William J Hamilton ◽  
Robert Poulin
Keyword(s):  
Environmental Factors ◽  
Freshwater Fish ◽  
Geographic Variation ◽  
Parasite Load ◽  
Water Clarity ◽  
Female Mate Choice ◽  
Local Conditions ◽  
Sexually Selected Traits ◽  
Different Populations ◽  
Selected Traits

Geographic variation in the strength or direction of sexual selection acting on different populations has been documented before but has not been the subject of intense study. We examine covariation among sexually selected traits and environmental factors for five stream populations of a small New Zealand freshwater fish, the upland bully, Gobiomorphus breviceps (Eleotridae). Levels of infection by a trematode parasite and some aspects of female behaviour and male colouration varied significantly among populations. Among individual fish we found that female mate choice behaviours and male colouration did not correlate similarly with other traits, or with parasite load, in the different populations studied. We also determined whether average population values correlated among the different stream populations. Whereas environmental factors such as water clarity and substrate colouration appeared to be unimportant, average parasite load correlated with some components of male colouration, and female preferences appeared to be correlated with male colouration. These results illustrate both the variability among populations that prevents results obtained from one population from being generalized to the entire species, and the plasticity of sexually selected traits in relation to local conditions.

scholarly journals Invasion biology: critique of a pseudoscience

2004 ◽  
Vol 10 (1) ◽  
pp. 70
Author(s):  
Michael Calver
Keyword(s):  
Invasive Species ◽  
Invasion Biology ◽  
Rigorous Evaluation ◽  
Empirical Tests

Science is both highly competitive and highly cooperative, so a rigorous evaluation of an idea comes not from one's close colleagues, but from one's opponents (Hull 1988). While robust disagreement may not lead to consensus, at its best it should lead to clarification of areas of agreement and areas of dispute, as well as dialogue on the empirical tests necessary to solve the disagreements. In this context, David Theodoropoulos' new book on invasion biology attempts a rigorous, sceptical critique of the belief that invasive species are a significant threat to biodiversity.

scholarly journals Seasonal variation of phycoerythrin chromophores of Synechococcus spp. in the East Sea/Japan Sea

2019 ◽  
Vol 1 (1) ◽  
pp. 6
Author(s):  
Defri Yona ◽  
Mi Ok Park
Keyword(s):  
Seasonal Variation ◽  
Environmental Factors ◽  
High Salinity ◽  
Japan Sea ◽  
Water Clarity ◽  
High Light Intensity ◽  
East Sea ◽  
Seasonal Patterns ◽  
Distributional Pattern ◽  
The One

The very small size of Synechococcus spp. as one important contributor of ocean primary productivity can be identified using its phycoerythrin pigment chromophores, phycourobilin (PUB) and phycoerythrobilin (PEB). Seasonal variation of the excitation (EX) ratio of PUB and PEB in the surface water of East Sea/Japan Sea was observed. This study aimed to describe the effects of environmental factors during different season to the excitation ratio of PUB and PEB contained Synechococcus spp.  Summer and winter showed slightly similar distributional pattern with PUBEX:PEBEX ratio > 1, while PUBEX:PEBEX ratio < 1 could be found in autumn and spring. The results of this study showed seasonal patterns of phycoerythrin pigment from Synechococcus were highly related with variability of environmental factors. High light intensity during summer and high salinity during winter were the reasons of high PUB:PEB ratio of Synechococcus spp. Moreover, high PUB type of Synechococcus spp. was also dominated the offshore study areas as the result of higher water clarity compared to the one in the coastal areas.

scholarly journals Application of quantile regression in environmental epidemiology

2019 ◽  
Vol 129 (3) ◽  
pp. 72-74
Author(s):  
Mieczysław Szyszkowicz
Keyword(s):  
Air Pollution ◽  
Environmental Factors ◽  
Quantile Regression ◽  
Negative Relationship ◽  
Environmental Epidemiology ◽  
Ambient Air ◽  
Emergency Department Visits ◽  
Ambient Air Pollution ◽  
Mortality Data ◽  
Weather Factors

Abstract Introduction. Among many problems present in studies evaluating associations between health conditions and exposure to ambient air pollution, there is the correlation between environmental factors. These issues are usually resolved by providing a correlation matrix for the parameters of interest. Aim. To explore correlations between environmental factors. Material and methods. As sample data we use environmental factors presented in Milan mortality data (Italy, 1980-1989) and emergency department visits for asthma in Windsor (Canada, 2004-2010). Here, we propose to use a series of quantile regression evaluations to emphasize and identify dependency among environmental factors. Results. This presentation outlines an important role to investigate the potential correlations among ambient air pollutants, weather factors, and the values of the Canadian Air Quality Health Index (AQHI). In environmental epidemiology studies, these components are usually used in a common statistical model. Their correlations affect the values of the estimated relative risks, odds ratios or other estimated health effects. The presented approach examines associations among the factors as well as changes in correlations along quantiles. The examples used in this study explain various environmental phenomena; for example, the negative relationship between ambient ozone and nitrogen dioxide. Conclusions. By a consequence, this work can aid in further developing policies aimed at reducing the health impacts of air pollution as it allows to identify highly correlated factors in the constructed models.

scholarly journals Environmental Factors Affecting Spatial Dinoflagellate Cyst Distribution in Surface Sediments Off Aveiro-Figueira da Foz (Atlantic Iberian Margin)

2021 ◽  
Vol 8 ◽  
Author(s):  
Iria García-Moreiras ◽  
Anabela Oliveira ◽  
Ana I. Santos ◽  
Paulo B. Oliveira ◽  
Ana Amorim
Keyword(s):  
Environmental Factors ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Latitudinal Gradients ◽  
Supporting Evidence ◽  
Dinoflagellate Cysts ◽  
Surface Salinity ◽  
Good Correspondence ◽  
Dinoflagellate Cyst ◽  
Iberian Margin

Resting cysts of planktonic dinoflagellates, once produced, sink to the seabed where they can remain viable for a long time. These cysts have important ecological roles, such as acting as the inoculum for the development of planktonic populations. Moreover, dinoflagellate cyst records from depth sediment cores are broadly used as a proxy to infer past environmental conditions. In this study, the main objective was to obtain information on the relationships between the spatial distribution of modern dinoflagellate cysts and present-day hydrography in the NW Iberian shelf. Cyst assemblages were analyzed in 51 surface sediment samples with varying grain sizes, collected at different water depths, following nine transects perpendicular to the coast, between Aveiro and Figueira da Foz (Atlantic Iberian margin). Multivariate statistical analyses revealed marked land-sea and latitudinal gradients in the distribution of cysts, and helped investigate how environmental factors [water depth, grain size, sea-surface temperature (SST), sea-surface salinity (SSS), bottom temperature (BTT) and surface chlorophyll-a concentration (CHL)] influence modern dinoflagellate cyst composition and abundances. Three main ecological signals were identified in the modern dinoflagellate cyst assemblages: (1) the heterotroph signal as the main upwelling signal; (2) the dominance of P. reticulatum and L. polyedra signal, indicative of warm stratified conditions, possibly reflecting transitional environments between more active inshore upwelling and warmer offshore waters; and (3) the G. catenatum signal for the presence of mid-shelf upwelling fronts. The almost absence of viable cysts of the toxic and potentially toxic species G. catenatum L. polyedra and P. reticulatum suggests that in the study area, for these species, there is no build-up of significant cyst beds and thus planktonic populations must depend on other seeding processes. These results are the first detailed modern distribution of dinoflagellate cysts in the NW Iberian Atlantic margin (off Portugal), and show a good correspondence with hydrographic features of summer upwelling season in the study area, meaning that they are reflecting water column characteristics and therefore may be used as supporting evidence for the interpretation of stratigraphic cyst records and reconstruction of past marine ecosystems in W Iberia.

scholarly journals Phenotypic polymorphism Harmonia axiridis Pall. of invasive species on the territory of the cultivation of the Greater Chernykhychyan of the Sumy district of Sumsky area

2018 ◽  
Vol 22 ◽  
pp. 74-79
Author(s):  
V. M. Toryanik ◽  
L. P. Mironets
Keyword(s):  
Invasive Species ◽  
Environmental Factors ◽  
Harmonia Axyridis ◽  
Phenotypic Variability ◽  
Survey Method ◽  
Phenotypic Polymorphism ◽  
The Village

Aim. The features of phenotypic polymorphism Harmonia axyridis Pall. were studied. in the form of a pronotum and an imago elder as an invasive species on the territory of the village of Velyka Chernecha Sumy region of the Sumy region. Methods. The collection of the imago for two years was carried out manually using the route survey method in three directions (southern, southwest, and southeast) from the village center. Phenotypes were allocated according to the classification A.V. Blekhman. Distribution and analysis of phenomorphs on the drawing of the pronotum and the elite of the imago were carried out according to the classification of O.Yu. Kruglova. Results. The presence of 3 phenotypes Harmonia axyridis Pall. in the village is established: succinea, spectabilis, conspicua. According to the projitum and the elite of the imago, 14 and 22 phenoforms were detected, respectively. Conclusions. In the territory of the village of Velyka Chernecchina, there is a pronounced phenotypic variability of Harmonia axyridis Pall. according to the sketches of the pronotum and the imago elite, indicating the presence in the population of microevolutionary processes with a tendency to survive the phenophores with adaptations to stressful environmental factors, probably, it is possible to forecast forming of stable populyaciy of Harmonia axyridis Pall. on territory of the Sumy district.Keywords: Harmonia axyridis Pall., pronotum, elites, phenotypic variability.

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