Production of reproductive shoots, vegetative shoots, and seeds in populations ofRuppia maritima L. from the Chesapeake Bay, Virginia

Abstract

The production of reproductive shoots, vegetative shoots, and seeds was characterized for Ruppia maritima populations in the Virginia portion of Chesapeake Bay in 1988 and 1989. The study locations included two previously unvegetated sites recently colonized by R. maritima in the Rappahannock River and an established site and an in'egularly flooded marsh panue site, both in the York River. A corer was used to collect plant material, which was then separated into reproductive shoots, vegetalive shoots, and seeds. Sampling took place at approximately 2-week intervals from the time of first observation of flowering shoots until reproductive senescence. Reproductive shoot and seed production were high for all sites, particularly the previously unvegetated sites. The percent of reproductive shoots ranged from less than one percent to 52 percent. One previously unvegetated site produced 23,390 seeds m--" in 1988, the highest level of seed production measured during this study. Dramatic decreases in production from 1988 to 1989 at two of the study locations, the salt pannc and one previously unvegetated site, are attributable to the effects of drought and cownose ray (Rhinoptera bonasus) activity, respectively. High levels of seed production, frequently above 20,000 seeds m ~' , and their eventual dispersal may account for the rapid colonization in cerlain areas of Chesapeake Bay by R. mar#ima.

Flowering and biomass allocation in U.S. Atlantic coast Spartina alterniflora

“…Spartina alterniflora can produce >2000 seeds/m 2 (Callaway and Josselyn, 1992), though many of the seeds produced are not viable (Fang, 2002). Large reproductive output is similarly observed in other aquatic plants, such as seagrass (Silberhorn et al, 1996) and mangroves (Clarke, 1992). Ocean‐dispersal‐based life history strategies such as these tend to favor the production of large numbers of offspring to compensate for losses during transport (Gaines and Bertness, 1992; Pechenik, 1999; Hedgecock and Pudovkin, 2011).…”

Spatial Distribution and Long-term Movement Patterns of Cownose Rays Rhinoptera bonasus Within an Estuarine River

“…This species feeds extensively within estuarine systems (Orth 1975;Smith and Merriner 1985;Blaylock 1992;Collins et al 2007a) and, as an apex predator of benthic fauna, occupies an important role in the estuarine food chain (Smith and Merriner 1985;Blaylock 1993;Collins et al 2007a;Myers et al 2007). A mobile and pelagic batoid, cownose rays complete large-scale oceanic migrations (Rogers et al 1990;Schwartz 1990;Grusha 2005), but they are also regularly observed within estuaries and are known to frequent the lower reaches of coastal rivers (Clark 1963;Schwartz 1965;Snelson and Williams 1981;Smith and Merriner 1987;Blaylock 1993;Silberhorn et al 1996). As euryhaline elasmobranchs, cownose rays can tolerate salinities as low as 5-7 ( Thompson and Verret 1980;Smith and Merriner 1987).…”

Estuarine Restoration of Submersed Aquatic Vegetation: The Nursery Bed Effect

“…Stevenson et al (1993) suggest that the “r‐selected” nature of R. maritima was responsible for its ability to re‐colonize unvegetated habitat in the lower Choptank River during the mid‐1980s. Silberhorn et al (1996) quantified the growth potential of R. maritima in a study of two previously unvegetated sites in another Chesapeake Bay tributary, the Rappahannock River, and suggested that the abundant seed production of R. maritima may account for its rapid colonization of previously unvegetated areas.…”