Sunday, July 27, 2014

American Wildcelery (Vallisneria americana)

American Wildcelery (Vallisneria americana)

GIF -- Intro picture (fig. 1)


Roots, rhizomes, and stolons of most aquatic plants help to reduce erosion and facilitate colonization by benthic algae and invertebrates; their foliage offers shelter, support and, at least during daylight, a locally enriched oxygen supply . Macrophytes also provide a direct or indirect source of food for an immense variety of aquatic invertebrates and fishes, and for birds and mammals that frequent aquatic habitats
Wildlife Food

All parts of V. americana are important food items for many species of waterbirds  reported that V. americana was eaten by 19 species of wild ducks. Martin and Uhler (1939) examined 7,998 stomachs of 18 species of ducks; V. americana accounted for about 2% of the food eaten, making it the seventh most popular plant food. The plant was the most important food used by ducks in the Minnesota . Vallisneria americana and Potamogeton spp. were the most important plant foods as measured by percent volume and the collection of 47 greater scaup (Aythya marila), 44 lesser scaup (A. affinis), and 39 common goldeneye (Bucephala clangula) 

Foods consumed by canvasbacks and food availability were studied on Navigation Pool 7 of the Upper Mississippi River in 1978, 1979, and 1980 . Canvasbacks fed primarily on winter buds of V. americana and consumed 40% of the standing crop of 380,000 (+,-) 44,350 SD kg (dry weight) in Woman lake . Traditionally, canvasbacks have been primarily obligated to two foods during fall migration -- sago pondweed (Potamogeton pectinatus) and V. americana . The proliferation of V. americana in Navigation Pools 7, 8, and 9 of the Upper Mississippi River (C. E. Korschgen, unpublished data) occurred at the same time that historically important migrational habitats deteriorated elsewhere. During the 1960's and 1970's, canvasbacks shifted their migration routes to respond to the food supplies produced by V. americana on the Upper Mississippi River. An estimated 75% of the canvasback population in the three eastern flyways use this food resource each fall .

Nutritive Value
Shoot Material

The nutritive value of aquatic macrophytes is dependent on the fertility of their water medium. Protein content is usually considered the most valuable constituent of foodstuffs. Crude protein (dry weight) has been measured for V. americana from several locations. Proximate analysis of entire shoots collected , revealed a crude protein range of 17.6-27.0% of dry weight (Boyd and Blackburn 1970). Plants collected from Women Lake MN, had 12.4-24.1% crude protein  plants from Baby lake , had 18.1-19.8% .  determined the crude protein content of various parts of V. americana over the growing season . Levels of various amino acids showed a similar pattern in 12 species of aquatic macrophytes collected  of the essential amino acids, V. americana had moderate amounts of leucine, arginine, and valine, but was relatively low in lysine .

Mineral and nutrient content of V. americana leaves is similar to that of land forages in the United States  Although the nutritive value of dried V. americana was similar to alfalfa hay according to  fed dried pelleted V. americana leaves to tame roosters and ducks and determined that it had a true metabolizable energy value of about half that of dehydrated alfalfa. However, the V. americana in was not washed before it was dried and surface contamination may have caused excessive amounts of surface ash, therefore a lower true metabolizable energy value. If V. americana is grown in soft water and washed, ash might decrease; V. americana should then have metabolizable energy values comparable to alfalfa and other forage plants .

Winter Buds

Winter buds are high in dry matter and low in ash and fiber content, consequently giving them high nutritional potential  Winter buds harvested from September 1980 through April 1981 from Navigation Pool 9 of the Upper Mississippi River contained 10.4% crude protein and averaged 3,978 cal/g dry weight . Vallisneria americana winter buds collected in 1980 from  of the Upper Mississippi River had mean caloric contents of 4,075 cal/g dry weight . Winter buds collected from in fall 1980 had a mean crude protein value of 11.0%; ash, 4.6%; crude fiber, 2.8%; crude fat, 0.8%; and nitrogen-free extract, 80.8% 

Invertebrate Cover

A mixed stand of Chara and V. americana in Lantern Bay of Women Lake Mn, contained high numbers of amphipods, midge larvae, and other important yellow perch (Perca flavescens) food items  When comparing introduced Myriophyllum spicatum beds and mixed native Potamogeton-V. americana communities as habitat for fish and their invertebrate prey in Women Lake mn, five major zoobenthos taxa were found to be 3 to 7 times more abundant in the mixed native communities than in the introduced M. spicatumbeds  significantly more Isopoda, Chironomidae larvae, Ephemeroptera nymphs, Trichoptera larvae, and small gastropods were found in the Potamogeton-V. americana communities in May and July. Densities of foliage invertebrates in May were 4 times as great on combined samples of Potamogeton robbinsii and V. americana than on M. spicatum foliage, twice as great in June, 3 times as great in July, and twice as great in August . Vallisneria americana had a greater quantity of benthic organisms beneath it than didElodea canadensis and Najas flexilis; V. americana, with its more extensive root system, may have provided a more stable substrate for the benthos .
Fish Cover

Eight times as many bluegills (Lepomis macrochirus) and twice as many pumpkinseeds (Lepomis gibbosus) were netted by day in Potamogeton-V. americana mixed communities than in M. spicatum beds . For bluegills, the ratio was maintained in night collections. Numbers of yellow perch were also higher at night in the mixed native plant communities. In July, 3 to 6 times as many bluegills, pumpkinseeds, and yellow perch were netted, day or night, in the mixed communities. In several Minnesota  lakes, 35 species of juvenile fish inhabited dense aquatic plant communities that included V. americana 

Submersed aquatic macrophytes serve as important primary producers, using CO2 and inorganic nutrients as raw materials for carbohydrate and protein production. Submerged macrophytes, including V. americana, act as nutrient buffers by using dissolved nitrogen and phosphorus for growth . When these nutrients are removed from the water, they become unavailable for use by algae. Submerged macrophytes also act as nutrient cyclers. Most shoot nutrients are obtained from the sediments through the roots; the nutrients and organic matter leak into the water from living shoots and are liberated during decomposition of dead plant material. Dissolved nutrients and organic matter released to the water may then be transported by currents throughout the water body. In this way, littoral vegetation is a potential source of materials for pelagic production 

The success of vegetation management programs for waterfowl is dependent on knowing the physical and physiological requirements of the target species. Lakes and riverine impoundments that contain an abundance of the American wild celery plant (Vallisneria americana) have traditionally been favored by canvasback ducks (Aythya valisineria) and other waterfowl species as feeding areas during migration. Information on the ecology of V. americana is summarized to serve as a guide for potential wetland restoration projects. Because of the geographic diversity and wetland conditions in which V. americana is found, we have avoided making hard-and-fast conclusions about the requirements of the plant. Rather, we present as much general information as possible and provide the sources of more specific information. Vallisneria americana is a submersed aquatic plant that has management potential.