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Algae

Stands of Scirpus maritimus frequently contain the macroalgae Chara spp. and Enteromorpha spp. (Metcalf 1931; Jensen 1940; Nelson 1954; Klavestad 1957; Stewart and Kantrud 1971; Daborn 1975; Britton and Podlejski 1981; Lieffers 1981; Grillas and Duncan 1986). A carpet of Vaucheria frequently covers the bottom in Swedish stands (Tyler 1969). Marvan and Komarek (1978) described stands of S. maritimus as poor in epiphytes but rich in planktonic and filamentous algae. Marvan et al. (1978) suggested that greater light penetration increases the frequency of planktonic algae more in the shorter, more open stands of S. maritimus than in stands of taller emergents such as Phragmites australis, Schoenoplectus (Scirpus) lacustris, and Typha latifolia. The alga Vaucheria sometimes helps stabilize soft silts between S. maritimus shoots (Gillham 1957). Cladophora spp. may be abundant algae during the first year South Carolina impoundments are flooded but may disappear as populations of S. robustus and Ruppia maritima expand (Wilkinson 1970). DeVoe and Baughman (1986) quantified algal taxa in planktivorous fishes from South Carolina impoundments that support S. robustus. Zingmark (1986) measured productivity of microbenthic algae from those impoundments. Komarkova and Marvan (1978) estimated annual and gross productions of planktonic and periphytic (including filamentous) algae in a Czechoslovakian S. maritimus stand. Algal associates of this bulrush in wetlands in Russia (Gladyshev and Kogan 1977) and the Netherlands (Verhoeven and Van Vierssen 1978) are listed.

Diseases and Parasites

Little is known about pathogens or parasites of the two bulrushes. Clevering et al. (1995) noted mortality of Scirpus maritimus caused by Pseudomonas bacteria in the greenhouse but not of infected plants in the field. The fungus Uromyces lineolatus parasitizes S. maritimus in England (Ellis 1960, cited in Beeftink 1977). Two recently described nematodes form root galls on California populations of S. robustus (Abdel-Rahman and Maggenti 1981a,b; 1987a,b).

Invertebrates

Primary invertebrate groups found in the digestive tracts of waterfowl collected in stands of Scirpus maritimus in coastal Oregon are Cladocera, Copepoda, Ostracoda, Odonata, Chironomidae, and Molluska (Pederson and Pederson 1983). Stands in extremely saline lakes in interior Canada may support few benthic invertebrates, although certain crustaceans often are abundant (White and Hartland-Rowe 1969; Daborn 1975; Hammer et al. 1975). In Galveston Bay, Texas, Rozas and Zimmerman (1994) recorded higher densities of several decapod crustaceans in stands of S. maritimus than in other habitat types. In New Jersey, S. maritimus is a major species used by a dipteran (Hybomitra daeckei) for ovipositing (Sofield and Hansens 1982).

Consumption of S. maritimus by invertebrates seems common. Lepidopteran caterpillars may remove 46% of the standing crop in Utah wetlands (Foote et al. 1988). At least eight specialized endophagous invertebrates are known from stands in western Europe (Dijkema et al. 1984). Syrphid flies feed on S. maritimus pollen in the Netherlands and may aid in pollination (Leereveld et al. 1981; Leereveld 1984). Invertebrates have been described from wetlands that support this bulrush in California (Schuler 1987), Korea (Kikuchi et al. 1989), and the Netherlands (Verhoeven and Van Vierssen 1978; Smit et al. 1981, cited in Adam 1990; Dijkema et al. 1984). Powell et al. (1987) identified substances in S. maritimus that are toxic to brine shrimp.

Of various sampling sites in natural wetlands and impoundments in South Carolina, sites in impoundments dominated by S. robustus have the highest densities of macrobenthic invertebrates, especially Oligochaeta, Molluska, Polychaeta, and Insecta (Wenner and Beatty 1988). Coull (1986), DeVoe and Baughman (1986), Olmi (1986), Taniguchi (1986), and Wenner (1986a,b) documented the species compositions and abundances of planktonic, benthic, and nektonic organisms in these wetlands. These impoundments can be used for the commercial culture of various crustaceans (Wenner and Beatty 1988). Fiddler crabs (Uca minax) attain high populations in coastal Virginia wetlands dominated by S. robustus (Kerwin 1971). Ditching portions of Delaware wetlands dominated by S. robustus for mosquito control eliminates shallow water and reduces populations of macroinvertebrates important as foods of waterbirds (Bourn and Cottam 1939, 1950; Cottam et al. 1938; Daiber 1974).

Amphibians, Reptiles, and Fishes

Little information is available on the use of the two bulrushes by amphibians, reptiles, or fishes. Alligators (Alligator mississippiensis) regularly use South Carolina impoundments containing stands of Scirpus robustus (Epstein and Joyner 1986). These wetlands can support commercial fisheries (Wenner et al. 1986; Wenner and Beatty 1988). Seeds of S. maritimus are consumed by common carp (Cyprinus carpio) in France (Crivelli 1981).

Birds

Plants in the genus Scirpus provide food and cover for many aquatic birds (Martin et al. 1951; Haslam 1973). Stands of S. maritimus and S. robustus on managed and unmanaged wetlands rate especially high as sources of plant and animal food and as cover for moulting, migrating, and wintering waterfowl (Wetmore 1921; Chamberlain 1959; Yocom and Keller 1961; Wilkinson 1970; Palmisano 1972; Morgan et al. 1976; Sandifer et al. 1980; Gordon et al. 1987; Gray et al. 1987; Strange 1987; Thorn and Zwank 1993).

Certain groups of waterfowl eat the two bulrushes; dabbling ducks especially consume the achenes (Table 11). Addy (1946) considered S. maritimus superior to S. robustus for migrant American black ducks (Anas rubripes) in Massachusetts because S. maritimus is shorter and its heads shatter achenes earlier. Mallards (A. platyrhynchos) may prefer wetlands where managers increase the availability of S. robustus achenes through winter burning (Loesch et al. 1989). Hurricanes probably have minor effects on the availability of achenes for ducks (Kimble 1958; Kimble and Ensminger 1959).

Although ducks frequently consume them, the importance of achenes as food remains obscure because they may also serve as grit (Mall 1969; Pederson and Pederson 1983). Also, S. robustus achenes rank low in preference when offered to various ducks, geese, and American coots (Fulica americana) ad libidum with six other domestic and wild seeds and commercial chicken feed (McFarland et al. 1963). Large numbers of achenes pass through the digestive systems of some waterbirds with increased viability and can be transported long distances (DeVlaming and Proctor 1968; Ogle 1981).

Shoots, rhizomes, and corms of both bulrushes are readily eaten by geese (Table 11). Their grubbings sometimes heavily damage large stands of S. maritimus, but such stands have great regenerative capacity and may benefit from the openings created (Nagel 1969; Zwarts [1972] and Loosjes [1974], cited in Reed 1989; Ondok and Kvet 1978). Goose grubbing can greatly reduce belowground net production of both S. robustus and S. maritimus (Smith and Odum 1981). Nevertheless, grubbed stands sometimes increase their canopy covers because of increased achene production and seedling growth when environmental conditions are favorable (e.g., high rainfall that reduces bottom substrate salinity, and lack of high tides that can damage stands; Smith, L. 1983). Where geese are excluded from such sites, S. robustus can decrease under competition from other rhizomatous emergents such as Spartina patens (Smith, T. 1983). Wintering geese can have drastic effects on stands of Scirpus robustus. Intense feeding by large numbers of geese sometimes deepens wetlands, causing their abandonment as livestock pasturage (McAtee 1910; Lynch et al. 1947). If storm tides follow and remaining vegetation is washed away, open-water lakes are created that can persist for decades (McAtee 1910; Lynch et al. 1947). McIlhenny (1932) provided a detailed historical description on how snow geese (Chen caerulescens) and whooping cranes (Grus americana) extract S. robustus rhizomes.

Tundra swans (Cygnus columbianus) eat S. robustus achenes (Stewart and Manning 1958). Gillham (1956) stated that S. maritimus is seldom eaten by mute swans (C. olor), although the birds may severely damage stands by trampling.

Other waterbirds use S. maritimus, especially American coots, which eat the achenes and leaves and build their nests with the aboveground parts (Jones 1940; Reznicek 1973; Smith and Kadlec 1985c). Scirpus maritimus is eaten by long-billed dowitchers (Limnodromus scolopaceus; Sperry 1940). Coots and soras (Porzana carolina) also feed on S. robustus achenes (Webster 1964; Prevost et al. 1978). Passerine species such as long-billed marsh wrens (Cistothorus palustris), common yellowthroats (Geothlypis trichas), red-winged blackbirds (Agelaius phoeniceus), and boat-tailed grackles (Quiscalus major) may forage extensively in tidal wetlands where S. robustus is a dominant or co-dominant plant (Peterson et al. 1995). Epstein and Joyner (1986) and DeVoe and Baughman (1986) list many other birds that use impoundments containing S. robustus.

Mammals

Plants in the genus Scirpus are important to mammals (Martin et al. 1951). Scirpus maritimus and S. robustus are used for food and cover by furbearers, including muskrats and nutria (Myocastor coypus; Arthur 1931; Lynch et al. 1947; O'Neil 1949; Harris and Webert 1962; Gaevskaya 1966; Palmisano 1972; Podlejski 1981). Simulated grazing experiments by Taylor (1992) in Louisiana suggested that extreme herbivory by nutria may lower the abundance of S. robustus. This bulrush, in mixed stands with Salicornia virginica, Atriplex patula, and Frankenia grandifolia, provides good habitat for the endangered saltmarsh harvest mouse (Reithrodontomys raviventris; Shellhammer et al. 1982). Domestic animals including cattle, horses, sheep, and swine also eat these bulrushes (Mall 1969; Zafar 1976; Brehm 1979; George 1980; Podlejski 1981). Although Scirpus maritimus harvested in North Dakota seems distinctly unpalatable to sheep (Christensen et al. 1947), Ranwell (1961) noted an increase in this bulrush in the absence of sheep grazing in Spartina-dominated marshes in England. Blankenship (1905, cited in Yanovsky 1936) stated that Scirpus maritimus rootstocks are eaten by Amerindians.