Curly Pondweed Research Articles

Removal of Agricultural Non-Point Source Pollutants by Ditch Wetlands of the Maixi River, Guizhou Province, China

A natural ditch wetland grown with nature annual bluegrass (Poa annua L.), alligator weed (Alternanthera philoxeroides (Mart.) Griseb.), common duckweed (Lemna minor L.) and curly pondweed (Potamogeton crispus L.) etc. were selected to study the removal capacity of agricultural non-point source pollutants in the Maixi River in Guiyang City, the capital of Guizhou Province, China. The removal characteristics and seasonal variation of chemical oxygen demand (COD), total phosphorus (TP), ammonia-nitrogen (NH+4-N), and suspended solids (SS) in the ditch water was studied. The results showed that there existed a certain seasonal diversity in the removal characteristics of nitrogen, phosphorus and organic pollutants by the ditch. The removal efficiency of TP, COD and SS demonstrated an increasing tendency with their increasing concentration at the ditch inlet, whereas that of the NH4+-N displayed contrary tendency as the concentration of NH4+-N increased.

Monitoring the dynamics of an invasive emergent macrophyte community using operational remote sensing data

Potamogeton crispus L. (curly pondweed) is a cosmopolitan aquatic macrophyte considered invasive in North America and elsewhere. Its range is expanding and, on individual water bodies, its coverage can be dynamic both within and among years. In this study, we evaluate the use of free and low-cost satellite remote sensing data to monitor a problematic emergent macrophyte community dominated by P. crispus. Between 2000 and 2006, we acquired eight satellite images of 24,000-ha Lake Sharpe, South Dakota (USA). During one of the dates for which satellite imagery was acquired, we sampled the lake for P. crispus and other emergent macrophytes using GPS and photography for documentation. We used cluster analysis to assist in classification of the satellite imagery and independently validated results using the field data. Resulting estimates of emergent macrophyte coverage ranged from less than 20 ha in 2002 to 245 ha in 2004. Accuracy assessment indicated 82% of image pixels were correctly classified, with errors being primarily due to failure to identify emergent macrophytes. These results emphasize the dynamic nature of P. crispus-dominated macrophyte communities and show how they can be effectively monitored over large areas using low-cost remote sensing imagery. While results may vary in other systems depending on water quality and local flora, such an approach could be applied elsewhere and for a variety of macrophyte communities.

Distribution of egg strands of perch (Perca fluviatilis L.) with respect to depth and spawning substrate

The distribution of egg strands of perch Perca fluviatilis was studied in relation to water depth and spawning substrate during late April and early May 2007 in Chabařovice Lake, Czech Republic, using SCUBA divers and parallel transects. The depth distribution of egg strands differed significantly between the two sampling dates, being much deeper in early May compared to late April. Perch used at least seven different spawning substrates of which the most important were curly pondweed Potamogeton crispus, worm weed Artemisia sp. and common reed Phragmites communis. However, while living submerged vegetation, although more abundant, was generally avoided, dead submerged vegetation was strongly preferred. It appears that dead vegetation is an ideal spawning substrate for perch since placement of the egg strands over those hard, complex three-dimensional structures ensures that the eggs remain well oxygenated 24 hours a day. Factors with significant influence on the distribution of egg strands were as follows (in order of decreasing influence): depth of deposition, type of spawning substrate, date of spawning and temperature at the depth of deposition.

Exotic and Invasive Aquatic Plants in Great Lakes Coastal Wetlands: Distribution and Relation to Watershed Land Use and Plant Richness and Cover

We use data from inundated-area surveys of 58 coastal wetlands spanning a gradient of anthropogenic impacts across all five Laurentian Great Lakes to describe the distribution of nine exotic and invasive taxa of aquatic plants. We found plants that were exotic or have invasive strains to be substantially more prevalent in wetlands in Lakes Erie and Ontario than in Lakes Superior and Huron, with Lake Michigan wetlands intermediate. Najas minor (slender naiad), Butomus umbellatus (flowering rush), and Hydrocharis morsus-ranae (European frogbit) were restricted to the lower lakes and rarely dominant. Myriophyllum spicatum (Eurasian milfoil), Potamogeton crispus (curly pondweed), Lythrum salicaria (purple loosestrife), Phalaris arundinacea (reed canary grass), Phragmites australis (common reed), and Typha sp. (cattail) were more widespread and except for P. crispus, often among the dominant taxa. None of the submerged or floating-leaf exotic taxa were associated with altered total plant cover or richness, although M. spicatum, P. crispus, and native Stuckenia pectinatus (sago pondweed) were positively associated with agricultural intensity in the watershed (a surrogate for nutrient loading). Emergent P. australis, L. salicaria, and Typha were more likely to be present and dominant as agricultural intensity increased, and were associated with elevated emergent cover and decreased emergent genera richness. Effects of dominant taxa on plant cover and richness were readily detected using ordinal data from 100 m inundated segments but were harder to discern with data aggregated to the wetland scale. The sum of shoreline-wide abundance scores for four easily identified taxa ( S. pectinata, P. australis, Typha, and L. salicaria) is proposed as a rapidly-measured indicator of anthropogenic disturbance across the Great Lakes.

Submersed Plant Invasions and Declines in New York

ABSTRACT Control of nuisance species appears to be the primary goal of aquatic plant management in New York State. The three principal species of concern are Myriophyllum spicatum L. (Eurasian watermilfoil), Potamogeton crispus L. (curly pondweed), and Trapa natans L. (water chestnut). A wide range of lake types are apparently colonized by nuisance macrophyte species; these range from acidic, disturbed, oligotrophic lakes to alkaline, eutrophic lakes. Hand harvesting, mechanical harvesting, drawdown, and herbicides have been used for aquatic plant control in the state. Populations of native aquatic plants are stable to declining. There is no clear relationship between invasion of exotics and decline of native species.

THE BIOLOGY OF CANADIAN WEEDS.: 69. Potamogeton crispus L.

A review is provided of information on the biology of curly-leaved pondweed (Potamogeton cripsus L.). This submersed aquatic behaves as a winter annual through the production of summer-dormant apices. These germinate in the fall giving rise to an overwintering plant with narrow, acute, flat-margined leaves. In spring, the winter foliage disintegrates and larger leaves with serrulate, undulate margins and round tips begin to develop. Fruit is produced and the development of dormant apices is completed mostly by late June, after which the plants begin to die and dormant apices sink to the bottom. An introduced species, curly-leaved pondweed had spread through much of the U.S. by 1950. It is now well established in southern Ontario and is one of the province’s major nuisance aquatics. It is also well established in Quebec, but is not a nuisance there and is not spreading (C. Hamel, pers. commun.). In contrast it is spreading rapidly in western Canada where it was first noticed only 20 yr ago. Curly pondweed has potential uses in waterfowl management and compositing. It thrives in alkaline, calcareous and polluted waters. The dormant apices are the most important mode of reproduction with up to 900 being produced by a single plant in 1 year. Where the plant is a problem in Ontario, mechanical harvesting techniques of control have been used effectively. Dominance of curly-leaved pondweed in some areas is probably a consequence of its unusual vegetative life cycle allowing competition avoidance, and its tolerance of polluted water.Key words: Potamogeton crispus, weed biology, Canada, distribution

Turion formation, dormancy and germination of curly pondweed, Potamogeton crispus L.

Turion formation, dormancy, and germination in curly pondweed ( Potamogeton crispus L.) was investigated under natural condition as well as in growth chambers. In Lake Ojagaike, Chiba, turions started to germinate and develop in late autumm, reaching maximum development during May. Flowering took place in late spring (May) and fruits could be collected during May-June. Turions were formed during May-June, turion development taking about two weeks. Non-dormant turions collected from the lake were of two different colours, brown and green. The rate of germination of brown turions was lower than that of green turions. The germination of non-dormant green turions was affected by water temperature but not by light intensity. Dormancy was fully broken by a cold treatment (5°C) for 1 week, a warm treatment (30°C) for two weeks or a heat treatment (35°C) for two weeks, but not by an almost freezing temperature (−1 to 2°C). There was significant interaction between the length of heat treatment and light or dark conditions. IAA and GA 3 (10 −5 and 10 −6 M) broke dormancy of warm-treated turions, however in high concentrations (10 −3 and 10 −4 M) the dormancy was fully broken even in non warm-treated turions. With higher concentrations GA 3 promoted shoot elongation in light, whereas in the dark, shoot elongation was inhibited.

Environmental control of turion formation in curly pondweed (Potamogeton crispus)

AbstractThe turions of Potamogeton crispus L. develop in early summer and function in propagation and dispersal. Under natural conditions during longday periods, an average minimum air temperature of more than 12°C was found to be important for turion formation. Experiments with controlled environments indicate that both temperature and photoperiod regulate turion formation. Turions can be induced at 13°C or above but not at 8 or 10°C. At a temperature range of 13–24°C turions form in both 12‐ and 16‐h days, but not in 8‐h days. By increasing temperature from 24 to 30 or 35°C turions can be induced under 8‐h days. Light intensity was found to be important in the formation of turions.