American Pondweed Research Articles

Using in situ hyperspectral reflectance data to distinguish nine aquatic plant species

In situ hyperspectral reflectance data were studied at 50 bands (10 nm bandwidth) over the 400–900 nm spectral range to determine their potential for distinguishing among nine aquatic plant species: American lotus [Nelumbo lutea (Willd.) Pers.], American pondweed (Potamogeton nodusus Poir.), giant duckweed [Spirodela polyrrhiza (L.) Schleid.], Mexican waterlily (Nymphaea mexicana Zucc.), white waterlily (Nymphaea odorata Aiton), spatterdock [Nuphar lutea (L.) Sm.], giant salvinia (Salvinia molesta Mitchell), waterhyacinth [Eichhornia crassipes (Mart.) Solms] and waterlettuce (Pistia stratiotes L.). The species were studied on three dates: 30 May, 1 July and 3 August 2009. All nine species were studied in July and August, while only eight species were studied in May; giant duckweed was not studied in May due to insufficient availability. Two procedures were used to determine the optimum bands for discriminating among species: multiple comparison range tests and stepwise discriminant analysis. Multiple comparison range tests results for May showed that most separations among species occurred at bands 795–865 nm in the near-infrared (NIR) spectral region where up to six species could be distinguished. For July, few species could be distinguished amongthe 50 bands; most separations occurred at the 715 nm red-NIR edge band where four species could be differentiated. The optimum bands in August occurred in the green (525–595 nm), red (605–635 nm) and red-NIR edge (695–705 nm) spectral regions where up to six species could be distinguished. Stepwise discriminant analysis identified 11 bands in the blue, green, red-NIR edge and NIR spectral regions to be significant to discriminate among the eight species in May. For July and August, stepwise discriminant analysis identified 15bands and 13 bands, respectively, from the blue to NIR regions to be significant for discriminating among the nine species.

Abundance and habitat use of juvenile sunfish among different macrophyte stands

Collingsworth, PD and Kohler, CC. 2010. Abundance and habitat use of juvenile sunfish among different macrophyte stands. Lake Reserv. Manage. 26:35-42. Juvenile Lepomis sunfish (< 75 mm total length, TL) density, plant stem density and invertebrate density were compared in the 3 most common habitats in the littoral zone of Cedar Lake, a Midwestern North American reservoir: nonvegetated areas, stands of the exotic macrophyte Eurasian watermilfoil (Myriophyllum spicatum) and stands of American pondweed (Potomogeton nodosus). Eurasian watermilfoil stands consistently had significantly higher stem density and invertebrate density than American pondweed stands. Juvenile sunfish densities were significantly higher in vegetated habitats than nonvegetated areas, but no significant differences were observed between the 2 vegetated habitats. Juvenile sunfish densities were initially higher in American pondweed stands than Eurasian watermilfoil stands, but fish density in American pondweed stands declined dramatically as water levels fell in autumn. Juvenile sunfish size structure was related to habitat type, with the smallest fish associated with Eurasian watermilfoil (38.2 mm TL), intermediate fish associated with American pondweed (43.1 mm TL), and the largest fish associated with nonvegetated habitats (51.2 mm TL). We suggest resource agencies should focus vegetation management efforts on eradicating Eurasian watermilfoil stands to provide foraging access for largemouth bass to improve their growth rate and reduce stunting of sunfish. However, management agencies must recognize that a healthy plant community below the depth of water level fluctuation may be the only source of cover for juvenile centrarchids during late summer in reservoirs prone to fluctuating water levels.

New Hybrid Combinations Revealed by Molecular Analysis: The Unknown Side of North American Pondweed Diversity (Potamogeton)

Abstract The occurrence and diversity of Potamogeton hybrids was investigated in eastern North America, the region of the highest diversity of Potamogeton species in the world. For various reasons, however, the existence of hybrids in this area has been largely overlooked. ITS direct sequencing and RFLPs revealed four previously unknown hybrids, which are described as Potamogeton ×aemulans (P. bicupulatus × P. epihydrus), P. ×mirabilis (P. gramineus × P. oakesianus), P. ×versicolor (P. epihydrus × P. perfoliatus), and P. ×absconditus (P. perfoliatus × P. richardsonii). These are the first confirmed hybrids involving P. bicupulatus, P. epihydrus, P. oakesianus, and P. richardsonii. Another hybrid, P. ×nitens (P. gramineus × P. perfoliatus), is for the first time confirmed for North America with molecular markers. The hybrids' maternal parents were revealed by cpDNA sequencing. Phenotypically, two of the hybrids more closely resemble other taxa than their parents. Hybrid diversity and recognition in North A...

First report of Potamogeton × undulatus (P. crispus × P. praelongus, Potamogetonaceae) in North America, with notes on morphology and stem anatomy

Abstract Despite the frequent occurrence of hybridization events between broad-leaved members of the genus Potamogeton, few documented reports and descriptions of these taxa are found in North American pondweed literature. Potamogeton crispus and P. praelongus are common broad-leaved pondweed species with overlapping distributions in North America, yet no confirmed report of their hybrid, P. × undulatus, has been previously documented from this continent. We provide the first confirmed report of P. × undulatus in North America, where it was collected from a northeastern Indiana lake. Because most descriptions of P. × undulatus are found in somewhat less accessible nineteenth century European pondweed literature, morphological characters that are diagnostically valuable in distinguishing the hybrid from its parents are discussed and illustrated. A vegetative key to this hybrid and its parental species is also provided.

The Effect of Temperature and Daylength on the Germination ofPotamogeton nodosusTubers

ABSTRACT The effects of temperature and daylength were studied in the germination of American pondweed (Potamogeton nodosus Poir.) tubers. Germination was examined at temperatures ranging from 5 to 30°C in conjunction with light treatments of short and long daylength and continuous darkness. Greatest percentage of tuber germination occurred between 15 and 20°C. Within this temperature range, daylength did not significantly affect germination. Outside this temperature range, however, the absence of light inhibited germination. From these results, we conclude that temperature was the most important factor controlling germination, with an optimal range of 15 to 20°C. Daylength (14:10 versus 10:14) had no effect on germination, but the absence of light suppressed germination at 10, 25, and 30°C. The results were further supported by similar data obtained from a pond study of P. nodosus.

Consumption and apparent dry matter digestibility of aquatic macrophytes by male and female crayfish ( Orconectes virilis)

Crayfish are generally thought to be omnivores; however, the relative nutritional importance of various foods is poorly understood. In this study, we fed adult (mean weight 18.3 g) male and female crayfish ( Orconectes virilis) 14 aquatic macrophytes and quantified consumption and apparent dry matter digestibility (ADMD). Specifically, we fed cattail ( Typha sp.), horsetail ( Equisetum sp.), bulrush ( Scirpus sp.), arrowhead ( Sagittaria sp.), horned pondweed ( Zannechellia palustris), musk-grass ( Chara sp.), curlyleaf pondweed ( Potamogeton crispus), sago pondweed ( P. pectinatus), American pondweed ( P. nodosus), eel grass ( Vallisneria sp.), water buttercup ( Ranunculus longirostris), water stargrass ( Heteranthera dubia), American lotus ( Nelumbo lutea) and dried, pelleted duckweed ( Lemna sp.). Except for consumption of horned pondweed, there were no significant differences in consumption or ADMD between males and females. Based on the low consumption estimates (ranging from 0.01 to 0.87% body weight/day; overall mean of palatable macrophytes 0.19% body weight/day), it appears that macrophytes do not comprise a major source of nutrients for this size and species. Further, ADMD coefficients were significantly different between macrophytes of similar nutritional composition and may indicate the presence of antinutritional factors. Thus, growth of certain macrophytes in aquaculture ponds should be discouraged, while others may be beneficial as a minor food source or as a source of selected nutrients. Methods for future digestion studies were evaluated and discussed.

Effects of Static versus Flowing Water on Aquatic Plant Preferences of Triploid Grass Carp

Triploid grass carp Ctenopharyngodon idella were presented with three aquatic plant species (sago pondweed Potamogeton pectinatus, Eurasian watermilfoil Myriophyllum spicatum, and American pondweed P. nodosus) in outdoor canals with static and flowing water in winter, spring, and summer. Plant consumption by triploid grass carp in winter was low but increased dramatically in spring and summer. Based on plant shoot lengths, triploid grass carp preferences in spring for static water were sago pondweed = American pondweed, American pondweed = Eurasian watermilfoil, sago pondweed > Eurasian watermilfoil; for flowing water, sago pondweed = Eurasian watermilfoil > American pondweed. Summer preferences for static water were sago pondweed = Eurasian watermilfoil = American pondweed; for flowing water, sago pondweed = Eurasian watermilfoil = American pondweed. Plants of all three species produced longer shoots in canals with flowing water than with static water. The differences in shoot length may have altered the triploid grass carpˈs consumption rate and preference. Flowing conditions also had varying effects on nutritional content of plants, as shown in proximate analyses of dry matter and percent of fat, ash, protein, crude fiber, nitrogen free extract, and acid detergent fiber. Ash content was consistently higher in plants of all three species from canals with flowing water. This may reflect a morphological response to flow by the plants. None of the variables of the proximate analysis of plants correlated statistically with preference. This suggests that accessibility and ease of mastication were more important in determining preference than nutritional quality of the plants. Algae consumption by triploid grass carp, however, made it difficult to discern correlations between nutritional factors and vascular plant consumption.

Effects of abscisic acid on growth and leaf development in American pondweed ( Potamogeton nodosus poir.)

Synthetic abscisic acid (ABA) or natural ABA from avocado ( Persea americana Mill.) induces formation of “floating-type” leaves in American pondweed ( Potamogeton nodosus Poir.) at low concentrations (5 × 10 −7 M). Benzyladenine, gibberellic acid or kinetin counteract this effect. Winterbuds exposed to high levels of ABA (> 2 × 10 −5 M) do not germinate and 10 −5 M ABA reduces germinability, growth, inhibits protein synthesis, but allows some chlorophyll synthesis. Very short exposure to 5 × 10 −6 M ABA (2–4 h) is sufficient to cause formation of stomata (floating-type leaves). Cordycepin and actinomycin-D counteracted induction of “floating” leaves by ABA, which suggests that new RNA synthesis is required for this ABA effect.

Effect of Light on the Phytotoxicity of Fluridone in American Pondweed (Potamogeton nodosus) and Sago Pondweed (P. pectinatus)

The effect of 1.0 ppmw fluridone {1-methyl-3-phenyl-5-[3-trifluoromethyl)phenyl]-4(1H)-pyridinone} on growth of American pondweed (Potamogeton nodosusPoir.) and sago pondweed (Potamogeton pectinatusL.) was examined in plants kept in darkness or under various numbers of 12-h photoperiods. When plants were exposed to 1.0 ppmw fluridone for 1 to 10 12-h days, no stunting of American pondweed occurred until 21 days after treatment. Thirtythree days after treatment, plants that had received 4 to 10 days' exposure were most stunted. Sago pondweed was slightly more susceptible than American pondweed (87% and 50% reduction in length, respectively) 37 days after a 10-day exposure. Chlorophyllsaandbwere significantly lower in both species 14 days after all fluridone treatments. American pondweed plants exposed to fluridone continuously (1.0 ppmw) for 15 days, but given 0, 3, 6, 9, 12, or 15 12-h days were stunted only after having received at least six photoperiods. Stunting in sago pondweed was only slightly light-dependent. Neither species absorbed significantly more14C-labeled fluridone after 2, 4, or 14 photoperiods compared to plants kept in darkness for the same time.

Allelopathy in Dwarf Spikerush (Eleocharis coloradoensis)

The production of new shoots of American pondweed (Potamogeton nodosusPoir.) and sago pondweed (P. pectinatusL.) was reduced significantly when winterbuds and tubers of these species were planted in dwarf spikerush [Eleocharis coloradoensis(Britt.) Gilly] sod. In most instances, the number of shoots produced was several times greater when winterbuds and tubers were planted in bare soil than when planted in spikerush sod. Similar results were obtained when the pondweeds were grown in separate aquaria, each aquarium being exposed to 500 ml of leachate per day from spikerush sod. The differences in reproduction of pondweeds could not be attributed to altered water quality nor to reduced levels of nutrients. No appreciable allelopathic response was elicited by the pondweed plants originating from planted tubers or winterbuds. The principal response appeared to be reduction in numbers of new shoots produced from the original propagules, although the reduction in biomass of the pondweeds exposed to the effects of spikerush was obvious. Of the two pondweeds investigated, sago pondweed was most sensitive to the influence of spikerush.

Movements of Herbicides through Isolated American Pondweed (Potamogeton nodosus) Epidermal Tissues

Enzymatically isolated American pondweed (Potamogeton nodosusPoir.) epidermal tissues were exposed to14C-labeled dichlobenil (2,6-dichlorobenzonitrile), diquat (6,7-dihydrodipyrido[1,2-α: 2′, 1′-c] pyrazinediium ion), silvex [2-(2,4,5-trichlorophenoxy) propionic acid] or 2,4-D [(2,4-dichlorophenoxy)acetic acid] at concentrations of 5 × 10−4, 5 × 10−5, and 5 × 10−610M, and the amount of herbicide crossing the tissue layer was measured. Rates of herbicide movement were compared to those found when copper sulfate pentahydrate was added as a potential synergist at concentrations of 5 × 10−5M (12.5 ppm), 5 × 10−6M (1.25 ppm), and 5 × 10−7M (0.125 ppm). Copper sulfate at 5 × 10−6M increased the rate of movement of all herbicides. However, diquat and dichlobenil exhibited the most enhanced movement in the presence of copper sulfate. Without copper sulfate, 0.1 nmoles of 5 × 10−6M14C diquat penetrated the tissue within 24 h, compared to 1.3 nmoles following the addition of 5 × 10−7M of copper sulfate.

Dormancy in Winter Buds of American Pondweed,Potamogeton nodosusPoir

Winter buds of American pondweed (Potamogeton nodosus Poir.) were found to be strongly dormant at maturity. Under normal conditions the dormancy lasted for several months. Cold treatment decreased the period required for after-ripening, and exposure of dormant buds to 32° C for three days caused most of the buds to grow in two weeks. Removal of bud scales in light was very effective in promoting growth. Soaking of dormant buds in solutions of gibberellic acid, sucrose, combinations of gibberellic acid and sucrose, α-naphthylacetic acid and fenac (2,3,6-trichlorophenylacetic acid) partially relieved the growth suppression. Treatments with indole-3-acetic acid at 1,000 ppm for 18 hours broke dormancy completely in all buds, indicating that low levels of this substance may be the primary cause of dormancy in this species.

Occurrence of the American Pondweed, Potamogeton epihydrus Raf., in the Hebrides

IN August 1943, when I was dragging the lochs in the vicinity of Loch Eynort in the Isle of South Uist, Outer Hebrides, for pondweeds, there occurred in a backwater of Loch Ceann a'Bagh a very puzzling Potamogeton which, in its apparently sterile inflorescence, the paucity of its floating leaves and, in some plants, their total absence, strongly recalled × Potamogeton billupsii (= P. coloratus × P. gramineus), which I had discovered previously in Loch na Liane Moire in the neighbouring Isle of Benbecula. Nevertheless, the submersed leaves, in their general texture, lengths, breadths and parallel sides, were definitely against such an interpretation of the South Uist plant. Instead, they seemed to point clearly to a relationship with P. polygonifolius Pourr., or one of its hybrids. However, these ideas were in turn dispelled in 1944, when new and fruiting material was procured by Dr. W. A. Clark from a deep, peaty lochan draining into Loch Ceann a'Bagh. This enabled me to determine, with certainty, that both sets of plants belonged to the common American species Potamogeton epihydrus Raf. In this manner, not only was an important member added to the list of the American element in the British flora, but also a new species of pondweed placed on record for Europe.