The Aquatic Vegetation of the Old Woman Creek National Estuarine Research Reserve (Huron, Ohio): A Lake Erie Coastal Wetland

Page  63 ï~~2003 THE MICHIGAN BOTANIST 63 THE AQUATIC VEGETATION OF THE OLD WOMAN CREEK NATIONAL ESTUARINE RESEARCH RESERVE (HURON, OHIO): A LAKE ERIE COASTAL WETLAND Robert S. Whytel, David A. Francko2 and David M. Klarer3 1Glen Helen Ecology Institute Antioch College 795 Livermore Street Yellow Springs, OH 45387 [email protected] 937. 767. 7376 2Botany Department, Pearson Hall Miami University Oxford, Ohio 45056 513. 529. 4200 301d Woman Creek State Nature Preserve & National Estuarine Research Reserve Ohio Department of Natural Resources 2514 Cleveland Road, East Huron, Ohio 44839 419. 433. 4601 ABSTRACT A floristic survey and macrophyte study of the Old Woman Creek National Estuarine Research Reserve (OWC), a 56-hectare coastal wetland located in the western basin of Lake Erie, was conducted between 1993 and 1995 with limited follow-up surveys in 1996 and 1997. The survey was done to document the relatively unstudied vegetation of OWC as well as provide a review of historical change in species composition. During the multi-year survey, 143 aquatic and wetland plant species were recorded. This represents an increase of 39 documented species since the prior 1974 floristic survey. Notable changes since 1974 include the decline of the submerged species Potamogeton pectinatus and the emergent Peltandra virginica. Areas previously occupied by P. pectinatus and other submerged species, and the emergents Typha spp., Scirpus fluviatilis, and P. virginica have been replaced by extensive monotypic beds of Nelumbo lutea and Phragmites australis. Additional changes include the growth and distribution of Ceratophyllum demersum throughout the estuary and a first record of the exotic and highly invasive submersed species Myriophyllum spicatum. Change in species composition and abundance appear to be driven by water level fluctuations and the ability of certain invasive species to expand in this highly disturbed environment. INTRODUCTION The Old Woman Creek National Estuarine Research Reserve (OWC-NERR) and State Nature Preserve (SNP) represents one of the few remaining undeveloped coastal wetland systems along the southern shore of Lake Erie. Coastal wetlands once prevalent in Lake Erie's Western Basin have disappeared through the combined effects of natural shoreline disturbance and cultural impacts. Old Woman Creek is often referred to as a freshwater estuary as first described by Leverett and Taylor (1915) and more recently by Brant and Herden

Page  64 ï~~64 THE MICHIGAN BOTANIST Vol. 42 dorf (1972). Bates and Jackson (1980) defined freshwater estuaries of the Great Lakes as the lower portion of a tributary or drowned river mouth, exhibiting an area of mixing between stream and lake water, and directly influenced by meteorological events. Whether Great Lakes estuaries are analogous to "true" estuaries-typified by the mixing of saltwater and freshwater, as categorized by Schubel and Pritchard (1971), is questioned by some (Dyer 1990; Odum 1990; Schubel and Pritchard 1990). Herdendorf (1990) suggested that freshwater estuaries such as OWC are similar in many aspects to marine estuaries, including constriction at the mouth and continuous exchange and mixing of water between two distinct systems. When the mouth of OWC is open, periodic seiche events allow upstream movement of water and subsequent mixing, giving OWC the appearance of many tidal marsh creeks along the Atlantic coast (Dyer 1990). Great Lakes estuarine wetlands are functionally equivalent to marine counterparts as a transition zone between terrestrial and wetland habitats and the open water of the lakes. Great Lakes and marine estuaries are both highly productive systems (Reeder 1990; Mitsch and Gosselink 1986), providing refuges and spawning areas for many fish, invertebrates, and other organisms. Both support extensive growth of wetland vegetation adapted to continuous fluctuations in water levels and daily variations in water quality. Great Lakes coastal wetlands exhibit relatively diverse populations of emergent, floating and submersed plants. Annual fluctuations in water levels are thought to maintain species diversity, limiting the long-term establishment of extensive monotypic plant stands (Keddy & Reznicek 1985). However, both natural and anthropogenic disturbance to many of these systems has resulted in the elimination of many submersed species and facilitated the invasion of exotic and aggressive plant species (Stuckey 1989). Numerous historical descriptive studies of the aquatic and wetland flora of Great Lakes coastal wetlands have appeared in the literature (e.g., Keough 1987; Lowden 1969; Marshall 1977; Moore 1973; Reznicek & Catling 1989; Stuckey 1975, 1976). The majority of these studies were reviewed in Stuckey's monograph (1989) on the aquatic and wetland flora of western Lake Erie. However, to our knowledge recent studies do not exist, and therefore our recent study provides the only comprehensive update of the flora in the 1990s. OWC is an ideal site to study vegetation response to environmental influences and to examine long-term vegetation change in the aquatic and wetland habitats. Since OWC was designated as an NERR and SNP in 1981 there has been no complete floristic inventory of the estuary. Contributing factors to this apparent lack of botanical interest in the OWC flora may be a belief that the site is species-poor or that the relative botanical importance of wetland sites is based on the presence of rare species and not the quality of the coastal wetland ecosystem. Similarly, Reznicek and Catling (1989) in their botanical investigation of Long Point, Ontario wetlands attribute, in part, the previous lack of floristic studies to an assumption by researchers that the work had already been done. In addition, the dynamic aspects of the estuary are also not appreciated fully with respect to vegetation change. Seasonal and long-term vegetation changes are continuous, and continuity in species composition or diversity cannot be assumed.

Page  65 ï~~2003 THE MICHIGAN BOTANIST 65 Floristic inventories provide essential baseline information on the vegetation of OWC, and facilitate future studies of the site and other coastal wetlands along the south shore of Lake Erie. The data presented here are particularly relevant as Lake Erie water levels return to their long-term mean from an extended period of high water levels and OWC macrophyte species composition shifts in response to lower lake levels (Trexel & Francko 2001). These data could also be used to test the idea that major coastal wetland types along the south shore of Lake Erie are floristically similar to OWC, and that continued documentation of species composition and change in response to changes in environmental and biotic variables could provide a theoretical, field-based model for coastal wetland management strategies. This study documents aquatic and wetland vegetation distribution for the period 1993-1995 with supplemental data extending to 1997. We also review historical change in community structure and species composition in OWC. SITE DESCRIPTION The present day Old Woman Creek estuary encompasses approximately 56 hectares and drains a watershed of 69 km2. Its drowned river mouth and sand barrier-beach separating the wetland from Lake Erie characterize this shallow wetland. Water depths in OWC average less than 50 cm but can increase to more than 1 m in response to storm events from the watershed and Lake Erie storm surges. The wetland lies directly east of Sandusky Bay and the mouth of the Huron River, near the southernmost point in the Great Lakes, 410 22'N, 820 3 1'W (Figure 1). Its geographic location is reflected in the floristic composition of the aquatic and wetland plant communities, which contain species with a broad geographical affinity, including a distinct southern component (Stuckey 1989). The southern species Nelumbo lutea (American water lotus) is the dominant aquatic macrophyte in OWC, and is widely distributed in the coastal wetlands of Lake Erie's western basin. The presence of N. lutea and other southern species is due in part to an area climate moderated by Lake Erie: from the lakeshore to a few kilometers inland, summer and winter temperatures are dampened. The growing season is approximately 200 days, about 30-35 days longer than observed farther inland (Herdendorf 1989). The physico-chemical environment, wetland hydrology, and selected biological aspects of OWC have been the focus of numerous investigations. The physical environment including the geology, sediment transport and deposition, and biogeochemistry have been studied by Buchanan (1982), Frizado et al. (1986), and Reeder and Eisner (1994); the morphometry and hydrology by Herdendorf and Hume (1991), Herdendorf and Krieger (1989), and Reeder (1990). Biological investigations include wetland fish populations and recruitment (Hoffman 1985; and Rotenberry et al. 1988), macroinvertebrate communities (Krieger & Klarer 1992), and phytoplankton dynamics (Havens 1991; Klarer & Millie 1992). Klarer (1988) and Reeder (1990) have investigated and reported on water quality and nutrient cycling. Krieger (1989) summarizes Lake Erie estuarine sys

Page  66 ï~~66 THE MICHIGAN BOTANIST Vol. 42 66 THE MICHIGAN BOTANIST Vol. 42 LAKE ERIE wary KILOMETERS 0 0.36 Upper Estuary Creek FIGURE 1. Location of the Old Woman Creek estuary on the south shore of Lake Erie. tems, with an emphasis on the OWC environment. While these studies do not directly assess the vegetation of the estuary, their findings are important for a better understanding of vegetation dynamics and overall wetland function. VEGETATION HISTORY Mosley (1899) and Pieters (1901) were the first to document and describe the vegetation of Lake Erie's western basin and the Sandusky Bay area. Stuckey (1989) and Gordon (1969) provided historical reviews of the aquatic vegetation

Page  67 ï~~2003 THE MICHIGAN BOTANIST 67 and documented changes in species composition and abundance. Marshall (1977) was the first to conduct a comprehensive floristic survey of OWC, including the surrounding upland. Klarer and Millie (1992), using aerial photographs for the periods of 1984-1985 and 1988-1989, documented change in the distribution of Nelumbo lutea throughout the estuary. The Cleveland Museum of Natural History maintains a partial plant list compiled from periodic surveys of the estuary in 1988 (Jim Bissell, pers. comm.). Aerial photographs of OWC from as early as 1937 through the present provide an accurate record of aquatic plant coverage and community types, although species identification from these photographs is speculative at best. Analysis of sediment cores provides a glimpse of postglacial vegetation, indicating an extensive wetland environment dominated by Typha, Cyperaceae, Nymphaeaceae, and graminoids (Reeder 1994). OWC's designation as a SNP and NERR has greatly enhanced on-site research efforts, and facilitated the documentation of the dominant vegetation in the estuary (Klarer & Millie 1992). Earlier literature and herbarium records suggest that the present-day floristic structure of OWC has changed markedly (Marshall & Stuckey 1974; Marshall 1977; Klarer & Millie 1992). Since the early 1970s, the estuary has shifted from a predominantly emergent community dominated by Peltandra virginica and Polygonum amphibium to an open water community dominated by Nelumbo lutea (Klarer & Millie 1992). Nelumbo lutea has expanded from a few beds covering less than 10 percent of the estuary, as found in the 1970s, to extensive beds with an areal cover of about 35 to 36 percent in 1993, 1994, and 1995 (Whyte 1996; Whyte et al. 1997). Also significant is the appearance of the submerged macrophytes Ceratophyllum demersum and Myriophyllum spicatum, and the presence of Phragmites australis. Potamogeton pectinatus has periodically appeared and disappeared since 1974; the dense beds found in the northwest embayment in 1974 disappeared during the high water years of the mid-1980s, and subsequently returned in 1989. Overall, species richness has increased, although the number of species considered rare or occasional has increased, and the number of species common and abundant has decreased (Figure 2). The latter may be due in part to the extensive monotypic beds of N. lutea and P australis presently found in the estuary. METHODS Floristic Survey The aquatic and wetland vegetation of OWC was surveyed in the spring and summer of 1993, 1994 and 1995, with less extensive surveys in 1996 and 1997. Ground surveys were complemented with aerial photography in late July or early August for each of the first three years. Areas surveyed included wetland plant communities in areas of open water, the immediate shoreline, and the sand barrier-beach. Voucher specimens were collected for all reported species, and were deposited in the Willard Sherman Turrell Herbarium of Miami University, Oxford, Ohio (MU). To facilitate the examination of recorded species by other investigators, duplicate specimens were collected for many of the reported species for deposit at the OWC-NERR, Huron, Ohio. Quantitative sampling of aquatic vegetation in the northwest embayment (of the lower estuary) was done in August of each year of the study period ('93-'95 and '97) utilizing standard transect sampling procedures for aquatic and wetland vegetation (as described by Titus 1993). Nine transects

Page  68 ï~~68 THE MICHIGAN BOTANIST Vol. 42 68 THE MICHIGAN BOTANIST Vol. 42 1973 1995 Abundant Common Occasional Rare 50 40 30 20 10 0 10 20 30 40 50 Percent FIGURE 2. Change in species abundance between the initial floristic survey completed in 1974, and the survey completed in 1995. spaced 60 meters apart were placed perpendicular to the shore extending into the open water. The initial transect position was randomly determined within a 50 meter segment of shoreline of the northeast corner of the embayment. Species presence was recorded in 0.25 m2 quadrats placed every three meters along each transect. This method was used in order to map the existing vegetation and to document change in species distribution during the study period. Peak biomass data (grams dry-weight/m2) were obtained in August of 1995 for submerged species, the emergent species Phragmites australis and Scirpus fluviatilis (River bulrush), and the floating-leaved plant Nelumbo lutea. Biomass was determined for submerged species by randomly tossing a circular 0.5m2 quadrat within the nearshore and open water of the northwest embayment of the lower estuary. Within each circular quadrat, a 0.25m2 sample of submerged vegetation was harvested. Fifteen samples were obtained in the nearshore zone and 10 samples in the open water. Quadrats of 0.5m2 were randomly placed in selected stands of P. australis and S. fluviatilis, and 1m2 quadrats in a single large bed of N. lutea. All plant material was washed of debris and oven-dried at 105Â~C.

Page  69 ï~~2003 THE MICHIGAN BOTANIST 69 FLORA OF OLD WOMAN CREEK Overview of the Flora For the period 1993-1995, 143 aquatic and wetland species were documented. Most species were widespread, but the number of abundant species was limited (Table 1). The list of species includes 50 families and 101 genera. The Cyperaceae and Poaceae were the largest families, represented by 16 and 15 species respectively. Two species are listed as endangered (Ohio), and one as potentially threatened. Overall the number of documented species represents an increase of 39 species from Marshall's initial survey completed in 1976; 64 represent new species not documented by Marshall, and 25 previously documented species were not found in the most recent study. The flora of OWC exists within a highly disturbed environment. Fluctuating Lake Erie water levels as well as human disturbances including agriculture, rail and road construction, and development in the watershed have likely altered the species composition. Of the 143 identified species, 15 or about 10% are considered aliens. The aquatic and wetland vegetation of OWC consists of submerged, floatingleaved, and free-floating communities in open water areas of a depth generally less than 1 meter, and predominantly sedges, grasses and emergents along the shoreline on exposed mudflats or shallow water of less than 10 centimeters. For the period of study, open water habitat dominated the estuary and includes the creek and surrounding floodplain. The entire lower portion of the creek was flooded, extending from Lake Erie to south of the railway. Herdendorf (1989) refers to remnant embayment marshes, which are all that remain of the once extensive marsh habitat that existed prior to the current period of high water. Shoreline areas, including the remnant marsh areas represented the most diverse habitat in the estuary and exhibited the greatest seasonal and annual change in species composition. Vegetation within each of the shoreline communities consisted predominantly of emergents, grasses and sedges, and pioneer annuals able to survive seasonal disturbances. Within each of the described habitats there exists some overlap of plant species, generally resulting from short-term fluctuations in water level. Additional plant communities found on the periphery of OWC include areas of wet woods drained by seasonally flowing streams along the east shore, and a more extensive wet lowland (swamp) forest bordering the estuary to the south. Common woody species in these areas are Cephalanthus occidentalis (Buttonbush), Fraxinus americana (White Ash), Quercus rubra (Red Oak), Crataegus mollis (Downy Hawthorn), and Viburnum acerifolium (Arrowwood). Numerous herbaceous species appear on the forest floor early in the growing season and include Boehmeria cylindrica (False nettle), Caltha palustris (Marsh marigold), Cardamine bulbosa (Bitter cress), Cardamine douglassii (Purple bitter cress), Laportea canadensis (Wood nettle), Floerkea proserpinacoides (False mermaid), Senecio aureus (Golden ragwort), Anemonella thalictroides (Rue anemone), Viola sororia (Common blue violet), Arisaema triphyllum (Jack-inthe-pulpit), and several species of Ranunculus (Buttercup), the most common

Page  70 ï~~70 THE MICHIGAN BOTANIST Vol. 42 TABLE 1. Comparison of species composition and abundance of aquatic and wetland plants reported for Old Women Creek in 1974-1976 and 1993-1995. Years in which a species was not reported are indicated by a blank space. Family Species* Aceraceae Acoraceae Alismataceae Alismataceae Apiaceae Apiaceae Araceae Araceae Asclepiadaceae Aspleniaceae Aspleniaceae Asteraceae Asteraceae Asteraceae Asteraceae Asteraceae Asteraceae Asteraceae Asteraceae Asteraceae Asteraceae Balsaminaceae Balsaminaceae Brassicaceae Brassicaceae Brassicaceae Brassicaceae Brassicaceae Brassicaceae Butomaceae Campanulaceae Campanulaeae Caprifoliaceae Ceratophyllaceae Convolvulaceae Cornaceae Cornaceae Cornaceae Cucurbitaceae Cyperaceae Cyperaceae Cyperaceae Cyperaceae Cyperaceae Cyperaceae Cyperaceae Cyperaceae Cyperaceae Cyperaceae Cyperaceae Acer saccharinum Acorus americanus Alisma subcordatum Sagittaria latifolia Cicuta maculata Sium suave Arisaema triphyllum Peltandra virginica Asclepias incarnata Athyrium filix-femina Dryopteris carthusiana Aster lanceolatus Bidens cernua Bidens connata Bidens frondosa Bidens laevis Eclipta prostrata Eupatorium perfoliatum Rudbeckia laciniata Senecio aureus Vernonia gigantea Impatiens capensis Impatiens pallida Alliaria petiolata Barbarea vulgaris Cardamine bulbosa Cardamine douglassii Cardamine pensylvanica Rorippa palustris Butomus umbellatus Lobelia cardinalis Lobelia siphilitica Sambucus canadensis Ceratophyllum demersur Calystegia sepium Cornus amomum Cornus drummondii Cornus stolonifera Echinocystis lobata Carex comosa Carex complanata Carex crinita Carex crus-corvi Carex frankii Carex grayi Cyperus erythrorhizos Cyperus esculentus Cyperus odoratus Cyperis rivularis Cyperus strigosus Presence/Abundance* 1974-1976** occasional rare occasional rare abundant common common occasional common occasional rare occasional occasional abundant rare common common rare occasional occasional n rare common common common rare occasional common rare occasional 1993-1995 occasional rare rare common rare occasional occasional occasional occasional rare rare rare common occasional occasional occasional rare rare common rare occasional common occasional rare common common rare occasional common occasional rare common rare occasional occasional rare rare rare rare occasional common common occasional Origin N N N N N N N N N N N N N N N N N N N N N N N A A N N N N A N N N N N N N N N N N N N(E) N N N N N N N

Page  71 ï~~2003 THE MICHIGAN BOTANIST 71 2003 THE MICHIGAN BOTANIST 71 TABLE 1. Continued Presence/Abundance*** Family Species* 1974-1976** 1993-1995 Cyperaceae Cyperaceae Cyperaceae Cyperaceae Cyperaceae Fabaceae Haloragaceae Hydrocharitaceae Iridaceae Iridaceae Juncaceae Juncaceae Juncaceae Lamiaceae Lamiaceae Lamiaceae Lamiaceae Lamiaceae Lamiaceae Lamiaceae Lamiaceae Lamiaceae Lamiaceae Lamiaceae Lamiaceae Lemnaceae Lemnacea Limnanthaceae Lythraceae Lythraceae Malvaceae Nelumbonaceae Nymphaeaceae Nymphaeaceae Onocleaceae Onagraceae Onagraceae Onagraceae Onagraceae Osmundaceae Platanaceae Poaceae Poaceae Poaceae Poaceae Poaceae Poaceae Poaceae Poaceae Poaceae Poaceae Poaceae Poaceae Eleocharis ovata Scirpus americanus rare Scirpus atrovirens occasional Scirpus fluviatilis common Scirpus validus occasional Amorpha fruticosa Myriophyllum spicatum Elodea canadensis Iris pseudacorus Iris versicolor common Juncus acuminatus Juncus effusus rare Juncus tenuis rare Lycopus americanus rare Lycopus europaeus rare Lycopus uniflorus occasional Lycopus virginicus rare Mentha arvensis common Mentha xgentilis rare Prunella vulgaris common Scutellaria epilobiifolia common Scutellaria lateriflora common Stachys hispida occasional Stachys tenuifolia Teucrium canadense occasional Lemna minor abundant Spirodela polyrhiza abundant Floerkea proserpinacoides Decodon verticillatus occasional Lythrum salicaria Hibiscus moscheutos common Nelumbo lutea abundant Nuphar advena occasional Nymphaea tuberosa common Onoclea sensibilis occasional Circaea quadrisculata Epilobium ciliatum Epilobium glandulosum occasional Ludwigia palustris rare Osmunda cinnamomea occasional Platanus occidentalis Agrostis stolonifera occasional Calamagrostis canadensis occasional Calamagrostis canadensis occasional Calamagrostis canadensis occasional Cinna arundinacea rare Echinochloa crusgalli rare Echinochloa muricata occasional Echinochloa walteri rare Elymus virginicus occasional Glyceria striata rare Leersia oryzoides common Leersia virginica rare rare occasional common occasional rare occasional rare rare common rare occasional rare occasional occasional occasional common occasional occasional common occasional rare abundant occasional rare occasional rare common abundant rare common rare rare rare occasional rare occasional occasional common rare common occasional Origin N(E) N N N N N A N A N N N N N A N N N N A N N N N N N A N N A N N N N N N N N N N N N N N N N A N N N N N N (Continued)

Page  72 ï~~72 THE MICHIGAN BOTANIST Vol. 42 TABLE 1. Continued Presence/Abundance*** Family Species* 1974-1976** 1993-1995 Origin Poaceae Poaceae Poaceae Polygonaceae Polygonaceae Polygonaceae Polygonaceae Polygonaceae Polygonaceae Polygonaceae Polygonaceae Polygonaceae Polygonaceae Pontederiaceae Potamogetonaceae Potamogetonaceae Potamogetonaceae Potamogetonaceae Primulaceae Primulaceae Primulaceae Ranunculaceae Ranunculaceae Ranunculaceae Ranunculaceae Ranunculaceae Ranunculaceae Ranunculaceae Ranunculaceae Ricciaceae Ricciaceae Rosaceae Rosaceae Rosaceae Rubiaceae Rubiaceae Salicaceae Salicaceae Salicaceae Salicaceae Salicaceae Saururaceae Scrophulariaceae Scrophulariaceae Scrophulariaceae Scrophulariaceae Scrophulariaceae Saxifragaceae Sparganiaceae Typhaceae Typhaceae Typhaceae Urticaceae Panicum lanuginosum Phalaris arundinacea abundant Phragmites australis Polygonum amphibium common Polygonum hydropiperoides Polygonum lapathifolium common Polygonum pensylvanicum common Polygonum persicaria occasional Polygonum punctatum occasional Polygonum sagittatum rare Polygonum virginianum Rumex orbiculatus rare Rumex verticillatus common Pontederia cordata Potamogeton crispus Potamogeton foliosus Potamogeton nodosus rare Potamogeton pectinatus common Lysimachia ciliata occasional Lysimachia nummularia abundant Lysimachia quadriflora common Caltha palustris occasional Ranunculus abortivus Ranunculus fascicularis common Ranunculus hispidus Ranunculus recurvatus Ranunculus repens common Ranunculus sceleratus common Thalictrum dioicum Riccia fluitans Ricciocarpus natans Rosa palustris common Rubus odoratus Spiraea alba rare Galium aparine Galium tinctorium common Populus deltoides Salix amygdaloides Salix babylonica Salix exigua Salix nigra Saururus cernuus rare Chelone glabra Lindernia dubia rare Mimulus alatus Mimulus ringens occasional Veronica serpyllifolia Penthorum sedoides rare Sparganium eurycarpum occasional Typha angustifolia rare Typha xglauca Typha latifolia occasional Boehmeria cylindrica common rare abundant abundant common occasional occasional common common occasional occasional common rare rare rare rare occasional rare abundant rare occasional occasional occasional occasional occasional rare rare rare rare rare occasional rare rare occasional rare rare occasional occasional rare occasional occasional occasional abundant rare rare common N Z Z N N N N A N N N N N N A N N N N A N N N N(P) N N A N N N N N N N N N N N A N N N N N N N A N N Z N N N

Page  73 ï~~2003 THE MICHIGAN BOTANIST 73 TABLE 1. Continued Presence/Abundance*** Family Species* 1974-1976** 1993-1995 Origin Urticaceae Laportea canadensis common common N Urticaceae Pilea fontana occasional N Uritcaceae Pilea pumila common common N Urticaceae Urtica dioica rare N Verbenaceae Verbena hastata common common N Vitaceae Vitis riparia rare rare N Violaceae Viola sororia common common N Violaceae Viola cucullata common N Violaceae Viola striata occasional N Total 171 106 143 Nomenclature follows Gleason and Cronquist (1991), for the most part. *Species status as an aquatic and wetland plant is based upon national wetland status (Reeder 1988), and known occurrence in moist or wet habitat. **From Marshall (1977). ***Abundance follows Marshall (1977): abundant = several to many individuals in nearly all sites; common = several to many individuals in many sites; occasional = several individuals in more than one site; rare = individuals found in only a single site. Origin as given in Herdendorf et al. (2001). A = alien species, N =native species, Z =native to North America, naturalized to OWC Ohio Plant Status (Ohio Division of Natural Areas and Preserves). E = endangered, P = potentially threatened. taxa being R. hispidus (Hispid buttercup) and R. sceleratus (Cursed crowfoot). Woody species of the wet woods were not completely surveyed, and surveying of the swamp forest was limited to the backwater channel. A species list of the OWC swamp forest vegetation is available from the Ohio Department of Natural Resources, which monitors this area on an ongoing basis (Jennifer Windus, pers. comm.). FLOATING-LEAVED MACROPHYTES Dense, monotypic beds of Nelumbo lutea characterize the open water zones of the estuary. Nelumbo lutea beds are found in all areas of the estuary, extending from the south basin to north of State Route 6. Nelumbo lutea coverage was relatively stable from 1993 to 1995, covering approximately 36% of the estuary surface area, although individual beds were observed to expand or contract. Whyte and Francko (1997) provide a complete description of its distribution in OWC. Beds of Nelumbo lutea were generally monotypic, but were occasionally associated with Nymphaea tuberosa (White water-lily), Ceratophyllum demersum, Potamogeton pectinatus, and Lemna minor (Smaller duckweed). Late in the growing season, L. minor formed thick mats completely covering the water

Page  74 ï~~74 THE MICHIGAN BOTANIST Vol. 42 surface in the quiet water of the N. lutea beds. Conversely, P pectinatus appeared to be shade intolerant, unable to survive in areas where it was encroached upon by N. lutea later in the growing season. Nymphaea tuberosa also occurred throughout the estuary in small patches along protected areas of shoreline. The largest population of N. tuberosa was located in the northwest embayment where it occupied numerous beds of about 1-3 m in diameter. These beds were often encroached upon by the larger Nelumbo lutea beds, but were not displaced. Observational data and aerial photography in 1995 indicated an expansion of Nymphaea tuberosa from 1994 to 1995. This contrasts with a 90 percent decline-from 1994 to 1995-in the number of quadrats observed to contain Nelumbo lutea in the northwest embayment. The observed decline resulted from the disappearance of two of the three major beds, 2,929 m2 and 601 m2 in area, located in the northwest embayment (Whyte & Francko 1997). Other floating-leaved and floating species include Nuphar advena (Yellow water-lily), Spirodela polyrhiza (Giant duckweed), and two species of floating liverworts, Riccia fluitans (Slender riccia) and Ricciocarpus natans (Purplefringed riccia). Nuphar advena occurred at the entrance to the backwater channel in the southeast corner of the south basin. The floating liverworts were found in the south basin and the backwaters of the swamp forest, and represented the first reported occurrence of these species in the estuary. The increased appearance of Ricciaceae may be related to seasonal flooding or high rainfall. SUBMERGED MACROPHYTES Seven species of submerged macrophytes were found in open water areas of the estuary (Table 2). Only Ceratophyllum demersum and Potamogeton pectinatus have established populations, and only C. demersum occurred south of Star Island. This free-floating plant, found throughout the estuary, formed dense monotypic beds in quiet shallow areas along the shoreline, particularly in the northwest embayment of the main basin and throughout the backwater channel extending into the swamp forest. Ceratophyllum demersum was also frequently found scattered throughout the dense beds of Nelumbo lutea. Away from the shore and into the open water of the northwest embayment, C. demersum was replaced by scattered patches of P pectinatus. Potamogeton pectinatus was also present in the nearshore of the north basin. A few scattered patches of P. pectinatus, P foliosus (Leafy pondweed), and Myriophyllum spicatum were discovered immediately north of Star Island on the perimeter of the N. lutea beds and along the main channel of the creek in 1995. An isolated population of Myriophyllum spicatum, believed to be the first documented occurrence within the estuary, was discovered in 1992 but failed to reappear in 1993 or 1994 (Whyte & Francko 2002). A second population was discovered north of State Route 6 in 1993, but also failed to return in 1994. Numerous fragments of this species were found floating in the northwest embayment and north of State Route 6 in 1993 and 1994. In 1995, multiple sites within

Page  75 ï~~2003 THE MICHIGAN BOTANIST 75 TABLE 2. Species of aquatic plants observed (X) in areas of open water in the Old Woman Creek estuary from 1993 through 1997. Species 1993 1994 1995 1996 1997 Submersed Ceratophyllum demersum X X X X X Elodea canadensis X Myriophyllum spicatum X F* X X Potamogeton crispus X X Potamogeton foliosus X Potamogeton nodosus X Potamogeton pectinatus X X X X X Floating-Leaved Nelumbo lutea X X X X X Nuphar advena X X X X X Nymphaea tuberosa X X X X X Floating Lemna minor X X X X X Riccia fluitans X X Ricciocarpus natans X X Spirodella polyrhiza X X X X X Total 10 10 12 8 7 F* Floating fragments observed the northwest embayment and just north of State Route 6 were found containing several rooted plants. Although growing within the vicinity of the sampled transect lines, M. spicatum was not found in any of the sample plots. Species diversity and frequency of occurrence were highly variable from 1993 to 1997 (Table 3). Potamogeton pectinatus, the dominant submersed macrophyte in 1993, all but disappeared in 1994, although a few scattered patches were found. It reappeared in 1995, although was less abundant than in 1993. All submersed aquatic plant species were relatively scarce in 1994. Macrophytes were recorded in only 17 percent of the sampled quadrats. In 1995, submerged plants were more abundant and the submerged aquatic community was slightly more diverse. Potamogetonfoliosus and Elodea canadensis, species previously unreported in the estuary, and P nodosus (Longleaf pondweed) and P crispus (Curlyleaf pondweed), species not reported in over 15 years, were found in the northwest embayment. The submersed macrophyte community had not previously been well studied, and therefore it is possible that these and other species may have been missed in previous surveys. EMERGENT AQUATIC MACROPHYTES Steep banks and occasional low-lying areas supporting a dense growth of woody riparian vegetation characterize the OWC shoreline. The common species Quercus alba (White oak), Q. palustris (Pin oak), Salix exigua (Sandbar

Page  76 ï~~76 THE MICHIGAN BOTANIST Vol. 42 TABLE 3. Percent occurrence of aquatic plants found in all sample plots (in the Northwest Embayment) for the period 1993-1995, 1997. Species 1993 1994 1995 1997 Ceratophyllum demersum 19.7 1.3 48.2 0 Potamogeton pectinatus 21.3 0 5 0 Lemna minor 23.8 NA 48.2 <1 Nelumbo lutea 23 8.9 2.1 2.7 Nymphaea tuberosa 3.3 4.5 2.1 1.8 Polygonum amphibium <1 1.3 <1 0 Typha glauca <1 0 0 0 Sagittaria latifolia 1.6 1.3 2.1 0 Spirodella polyrhiza 1.6 NA 0 <1 Phragmites australis 1.6 1.3 1.4 2.7 Phalaris arundinacea <1 0 0 0 Sparganium eurycarpum <1 <1 <1 0 Potamogeton foliosus 0 0 <1 0 Leersia orzyoides 0 0 <1 0 Total Species Present 12 7 11 5 Present/Absent (Total %) 68/54 (55.7) 27/130 (17.2) 100/41 (70.9) 10/98 (9.3) willow), Cornus florida (Flowering dogwood), C. drummondii (Rough-leaved dogwood), Cephalanthus occidentalis, Populus deltoides (Cottonwood), and Vitis riparia (River-bank grape) formed a closed canopy, limiting available light to understory and shoreline emergent vegetation. The combination of a closed canopy and steep bluffs reduced available habitat for the growth of emergent vegetation. Common species characteristic of this environment were Impatiens capensis (Jewel-weed), Iris versicolor (Blue-flag), Leersia orzyoides (Rice cutgrass), Phalaris arundinacea (Reed canary-grass), Pilea pumila (Clearweed), Lobelia inflata (Indian tobacco), Ranunculus hispidus, Scutellaria lateriflora (Skullcap), Solanum nigrum (Black nightshade), and Carex spp. Adjacent to the shoreline and extending into the open water, fallen trees and discarded railroad ties formed a micro-habitat providing a suitable substrate for a number of weedy herbaceous species (e.g., Setaria faberi (Foxtail-grass), Carex comosa, Eclipta prostrata (Yerba-de-tajo), Polygonum persicaria (Lady's thumb), and Rorippa palustris (Common yellow-cress). Along certain reaches of shore, steep bluffs give way to open areas of low relief. These shoreline floodplain areas were seasonally inundated and supported extensive monotypic colonies of Phragmites australis. Few species are associated with P australis, although Echinocystis lobata (Wild cucumber) a climbing annual vine, grows extensively over much of the P. australis. Phragmites australis is a recent invader, having first appeared in OWC in the mid-1980s. Sparganium eurycarpum, Scirpus fluviatilis, Sagittaria latifolia, and Polygonum amphibium represented the dominant vegetation of the shallow nearshore waters. These emergent species form the transition from the Phragmites-dominated shoreline to open water. Typically found growing in monotypic stands within OWC, they occasionally grew in association with each other. A large monotypic stand of Scirpus fluviatilis occupied an area of permanent shallow water, sepa

Page  77 ï~~2003 THE MICHIGAN BOTANIST 77 rating the river channel from the quiet waters of the south basin. A zone of Sparganium eurycarpum bordered the Scirpus fluviatilis stand and extended almost the entire length of shoreline behind the railway and into the backwaters of the swamp forest. Species unique to the channel include Nuphar advena and Scirpus validus (Softstem bulrush). Additional areas of shore were either seasonally flooded or wet but free of standing water, and supported a diversity of herbaceous species. The more common species included Hibiscus moscheutos (Rosemallow), Scirpus atrovirens (Green bulrush), Impatiens capensis, Polygonum hydropiperoides (Water-pepper), Asclepias incarnata (Swamp-milkweed), Lycopus americanus (American water-horehound), L. europeaus (European waterhorehound), Scutellaria lateriflora, Iris versicolor, Phalaris arundinacea, Rumex verticillatus (Swamp dock), and Eupatorium perfoliatum (Boneset). In addition, species of Carex, Scirpus, Cyperus, Juncus and various graminoids were scattered throughout these areas. Shoreline and littoral vegetation varied from year to year, depending upon water levels. In 1995, exposed mudflats were characterized by dense stands of Leersia orzyoides and Lindernia dubia (False pimpernel). Bidens cernua (Burmarigold) and Echinochloa walteri were also widespread along the exposed shoreline. Prior to 1995, estuary water levels were sufficiently high to limit the growth of Leersia orzyoides and other mudflat species to occasional patches along the shoreline. High waters may also have restricted the growth of several species common to many Lake Erie wetlands but rare or only locally common in OWC, including Pontederia cordata (Pickerelweed), Peltandra virginica (Arrow arum), Acorus americanus (Sweet flag), Typha latifolia (Broad-leaf cattail), and Nuphar advena. Pontederia cordata had not been observed in OWC since the early 1980s (Gene Wright, pers. comm.). Several plants were growing along the shoreline in the northwest embayment in 1995, apparently the result of exposed sediment allowing seed germination. In 1996 and 1997 the number of plants found scattered along the shoreline continued to increase. Acorus americanus was locally common in a small embayment immediately southwest of Star Island. Typha latifolia was generally limited to a single small stand in the northwest embayment. Peltandra virginica was restricted to a few scattered plants in the shallow embayments. SAND BARRIER-BEACH VEGETATION The barrier-beach is small. West of the mouth, the beach extends approximately 240 m and is about 15 m wide. East of the mouth, the beach extends an additional 210 m and is about 60 meters wide. The exposed beachfront (facing Lake Erie) was relatively vegetation-free, owing to continual wave action reshaping the beachfront. Along protected areas of moist shoreline the dominant vegetation consisted of Bidens cernuua, Cyperus odoratus, Pilea pumila, and several species of Polygonum. Populus deltoides seedlings were scattered about the beach, particularly along the west bank of the mouth. Cakile edentula (Sea rocket), Salsola kali (Saltwort), Xanthium strumarium (Cocklebur), Euphorbia polygonifolia (Seaside-spurge), Strophostyles helvola (Wooly bean), Polygonum

Page  78 ï~~78 THE MICHIGAN BOTANIST Vol. 42 pensylvanicum (Pennsylvania smartweed), Oenothera biennis (Evening primrose), Equisetum arvense (Common horsetail), and Salix exigua were found scattered on the upland portions of the beach. Phragmites australis formed large monotypic stands along the west and east banks, and extended the length of the backshore, fronting the north basin. Triplasis purpurea (Purple sand-grass) and Panicum virgatum (Switchgrass) were common on open upland areas. Other species present, but rare or locally scattered, were Scirpus americanus (American bulrush), S. fluviatilis, Impatiens capensis, Scutellaria lateriflora, and Lycopus americanus. Rhus typhina (Staghorn sumac) and Vitis riparia extended the length of the west beach representing the area of transition from the bordering woodland to the open sand. PLANT COMMUNITY PEAK BIOMASS Peak biomass results show distinct differences between community types (Table 4). Emergent plants such as Phragmites australis and Scirpus fluviatilis produce considerably greater above-ground biomass than either floating-leaf or submersed plants. During periods when the estuary is flooded and few exposed areas are available for emergent growth, these emergents are limited in their areal extent and their peak biomass becomes relatively unimportant when considering total system production (Reeder, 1990). Nelumbo lutea, which is the dominant wetland plant in the estuary, had a considerably lower peak biomass than either Phragmites australis or Scirpus fluviatilis. The reported peak biomass value for Nelumbo lutea is much lower than typical values reported for N. lutea and other floating-leaf plants (Robb 1989; Reeder 1990; Whyte 1996), and may be an indication of a senescing bed. In each year of the study period, N. lutea was observed to decline in areal extent in the northwest embayment. Ceratophyllum demersum peak biomass in the nearshore waters of the northwest TABLE 4. Peak above-ground biomass of selected stands of aquatic and wetland vegetation in the OWC wetland, August 1995. Biomass Community Type (above-ground, g/m2) Location Submerged Ceratophyllum demersum nearshore 96 NW embayment open water 31.6 NW embayment Potamogeton pectinatus 2.5 NW embayment Emergent Phragmites australis 1339.2 NW embayment Nelumbo lutea 141.6 NW embayment Scirpus fluviatilis 2498.1 South Basin

Page  79 ï~~2003 THE MICHIGAN BOTANIST 79 embayment was only slightly lower than that of N. lutea, and increased its area of colonization each year of the study. Prior to the expansion of macrophytes throughout the wetland, Klarer and Millie (1992) indicated OWC to be an algal-based system. Reeder (1990) reported that N. lutea beds accounted for only about 1/10 as much annual carbon fixation as open water planktonic communities. Our data, however, indicate an increasing areal extent of N. lutea. In assessing the relative importance of macrophytes in terms of peak-season carbon assimilation and peak-season productivity in OWC, Francko and Whyte (1999) suggest macrophytes play a more important role than phytoplankton. Francko and Whyte (1999) estimated N. lutea peak productivity vales were 1200 g biomass m2 yr-1, and about 400 g biomass m2 yr-1 for macrophytes on an estuary wide basis, and account for more than twice that of the planktonic open water communities. OWC with increasing macrophyte production has switched from a grazer-based system to detritalbased. One of the reasons for this change to a detrital-based system is that the wetland system studies by Klarer and Millie (1992) and Reeder and Mitsch (1989) occurred during a period when N. lutea coverage was approximately half of that during the current study. A continuing shift in the OWC estuary from a phytoplankton dominated system to an open-water system dominated by N. lutea, to an emergent community dominated by plants such as Sagittaria latifolia, Typha spp., Phragmites australis, and Peltandra virginica will undoubtedly further increase OWC productivity. Phragmites australis above-ground biomass values in OWC average about 1500 g/m2. Extended periods of low water will likely allow the continued expansion of this aggressive wetland plant. Whigham and Simpson (1992) report peak biomass values in several New Jersey coastal marshes for Peltandra virginica and Sagittaria latifolia to be as high as 750 g/m2 and 140 g/m2, respectively. In Dupont marsh, a Lake Erie coastal wetland located on the Huron River and within a few miles of OWC, Peltandra virginica peak biomass was approximately 70g/m2 (unreported data, Robert Whyte). Dupont Marsh may provide an example of what OWC looked like during low water periods. FACTORS AFFECTING VEGETATION DYNAMICS There are a number of physical and biological factors likely affecting the aquatic vegetation in OWC. Great Lakes coastal wetlands are dynamic systems exhibiting a direct relationship between water level fluctuations on the Great Lakes and the physico-chemical and biotic environment of the wetland. Water depth and underwater light attenuation may have been the most important abiotic regulator of submerged plants in OWC for the study period reported (Whyte & Francko 1997). The mean water depth in the northwest embayment was approximately 18 cm lower in 1995 than 1994; yet mean turbidity was unchanged between years. Greater submerged plant growth reported here and elsewhere (Francko & Whyte 1999, Whyte et al. 1997, and Whyte 1996) indicating greater overall macrophyte production in 1995 suggest that the lower mean water depth

Page  80 ï~~80 THE MICHIGAN BOTANIST Vol. 42 in 1995 permitted increased light penetration and complete extension of the 1% compensation depth through the water column. A comprehensive review of the physical and environmental factors regulating plant growth in OWC such as water level fluctuations are discussed in Whyte (1996). The role of biotic factors in influencing community structure should also be considered. Rather than being driven solely by fluctuations in water levels and other physical disturbances, macrophyte community dynamics in OWC may be influenced by inter- and intraspecific competition. For example, evidence suggests that dense Nelumbo lutea beds of floating and aerial leaves effectively diminish the amount of photosynthetically active radiation (PAR) available to existing submersed macrophytes, as well as some nearshore emergent plants (Whyte 1996). This suggests that the disappearance of Peltandra virginica from the embayments in the 1970s, and the present decline in Potamogeton pectinatus is a function of light limitation occurring from a combination of turbidity and N. lutea shading, as well as increased water depths. Competitive displacement of existing vegetation may also be occurring through the invasion of non-native species throughout the Great Lakes region. Many of these non-indigeneous species form large monotypic stands that eliminate native vegetation. Of principal concern to the emergent community is Lythrum salicaria (Purple loosestrife), and in the open water, Myriophyllum spicatum. Lythrum salicaria first appeared in OWC sometime in the early 1980s, but an active management program has limited its spread in the estuary. Phragmites australis, a tall native perennial grass and recent invader, has formed large colonies on the barrier-beach, along the shoreline, and in areas of shallow water. Continued expansion threatens the few sedge and wet meadow communities within the estuary. Phragmites australis first appeared in the estuary along the backside of the barrier beach in the mid-1980s, and has since spread to all open areas along the shore. Although Stuckey (1989) documents Myriophyllum spicaturn in western and central Lake Erie, a literature survey and review of specimen sheets from herbaria at Miami University, Ohio State University and Kent State University provide strong evidence that the present study represents the first documented occurrence of this species in OWC. The fact that Myriophyllum spicatum has been observed only north of Star Island suggests that pioneer populations probably invaded from Lake Erie during periods when the barrier beach was open. Perhaps the best explanation for limited expansion of M. spicatum in OWC is the periodic drawdown of water and freezing of the surficial sediment during the winter (Whyte and Francko 2002). LONG TERM VEGETATION CHANGE General patterns of change in plant communities since 1974 are most noticeable in the embayment marshes. The diverse embayment marsh communities reported by Marshall (1977) have been replaced by large monotypic stands of Phragmites australis. Disturbances such as increased sedimentation, nutrient enrichment, and fluctuating water levels favor the invasion and spread of P. aus

Page  81 ï~~2003 THE MICHIGAN BOTANIST 81 tralis (Marks et al. 1994). Stuckey (1989) reports P australis to be common in the western basin; however, this plant was considered rare in northeastern Ohio prior to the 1980s (Bissell 1982) and there is little mention in the literature of the presence of P australis in the western basin. Pieters (1901) and Jennings (1908) however, both reported the presence of P australis in Sandusky Bay at the turn of the twentieth century. The aggressive appearance of P. australis in OWC and elsewhere throughout the western basin appears to coincide with the high water conditions of the 1980s. In OWC and other coastal wetlands, P australis first appeared on the beachfronts and gradually spread inland. The disappearance of Peltandra virginica and expansion of Nelumbo lutea have coincided with elevated water levels in Lake Erie. Since 1973 water levels have generally been above the long-term mean, with record high levels in 1973 and 1986. Increased water depth and a concomitant decrease in light availability with depth appear to be important factors in limiting the growth of P virginica. Whigham et al. (1979) suggested that successful establishment of P virginica does not occur at depths greater than 0.5 m, a condition periodically found in OWC. The extremely turbid nature of the estuary's waters may inhibit the germination of P virginica seeds at depths less than 0.5 m. A combination of rising water levels and increased Nelumbo lutea cover would also effectively diminish available light to germinating P virginica seeds. Sediment cores collected in conjunction with this study found a large number of ungerminated and nonviable P virginica seeds in existing N. lutea beds, an indication of the estuary's once extensive P virginica beds (unpublished data, Robert Whyte). Additional factors contributing to the disappearance of P virginica may include fish predation on seeds, scouring of sediment, and allelopathy from N. lutea and Nymphaea tuberosa (Vance & Francko 1997). SUMMARY The diversity and abundance of aquatic and wetland vegetation in OWC observed for the 1993 through 1997 growing seasons varied both seasonally and annually. Survey data showed an estuary dominated by perennial beds of the floating-leaved Nelumbo lutea, and locally extensive beds of the submersed species Potamogeton pectinatus and Ceratophyllum demersum. A pioneer population of Myriophyllum spicatum was documented in 1992 and had expanded slightly by 1995. The number of aquatic and wetland plant species is greater than previously documented, and is similar to other wetlands of southern Lake Erie. OWC is an extremely dynamic system affecting the species composition, abundance, and species-specific biomass of the plant communities. Natural disturbances are driven by water level fluctuations controlled by the sand barrier-beach and lake levels. Existing plant communities appear to be the result of a prolonged period of water levels above the long-term mean that existed through the early 1990's. The flooded basin has been favorable to the growth of Nelumbo lutea, but has restricted emergent plant growth to the immediate shoreline. A variety of wetland habitats enhance plant species diversity within OWC. The low diversity within each of the respective plant communities suggests that disturbance (i.e.,

Page  82 ï~~82 THE MICHIGAN BOTANIST Vol. 42 water level fluctuations, biotic interactions, wave and wind activity, and watershed activity) may be a significant regulator of plant community structure. The lack of recent inventories of the aquatic and wetland plants occurring in the wetlands along the south shore of Lake Erie makes any analysis of vegetation response to environmental factors difficult. Krieger et al. (1990) summarized a priority research agenda for Great Lakes wetlands which included an immediate need to document major floral species involved in community dynamics, and the characterization of the present dynamics of wetland vegetation and the potential importance of invasive plant species in future dynamics. Klarer and Millie (1992) emphasized the need for increased focus on the long-term effects of environmental factors such as fluctuating water levels. It is also unclear if coastal wetland systems respond similarly to environmental variables and how physical, chemical and biological characteristics of each system effect plant community response. The classification of coastal wetlands (e.g., based on dominant vegetation or complete flora) would allow the discrete grouping of wetlands, and facilitate analyses of various factors in regulating plant community structure. Higher priority must be given to the inventorying of Lake Erie's coastal wetlands, as well as further study of the interrelationships between biotic and abiotic components of the land, air, and water (Hartig and Vallentyne 1989). Such an approach may best help us define the interrelationships that exist between biotic and abiotic elements that comprise the Great Lakes coastal wetland environment (Hartig 1995). ACKNOWLEDGMENTS This study was supported by a grant from the Ohio Department of Natural Resources-Old Women Creek SNP & NERR, Ohio Sea Grant Research Award #R/ER-32, and by the Department of Botany, Miami University. We appreciate the assistance provided by staff of the OWC SNP & NERR, NASA-Lewis Research Facility, Mike Vincent (Willard Sherman Turrell Herbarium, Miami University), and numerous other individuals who provided input and field assistance. LITERATURE CITED Bissell, J. K. 1982. History, geology, and vegetation survey of Arcola Creek marsh, Lake County, Ohio. Cleveland Museum of Natural History, Cleveland, OH. 44 pp. Brant, R. A. & Herdendorf, C. E. 1972. Delineation of Great Lakes estuaries. In Proceedings, 15th Conference on Great Lakes Research, International Association for Great Lakes Research, Ann Arbor, MI. pp. 710-718. Buchanan, D. B. 1982. Transport and deposition of sediment in Old Women Creek Estuary, Erie County, Ohio. M.S. Thesis, The Ohio State University. 198 pp. Dyer, K. 1990. The rich diversity of estuaries. Estuaries 13(4): 504-505. Francko, D. A. & R. S. Whyte. 1999. A mid-summer photosynthetic carbon budget for the Old Woman Creek wetland, Huron, Ohio: Relative contribution of aquatic macrophytes versus phytoplankton. Ohio Journal of Science 99(2): 6-9. Frizado, J., R. Anderhalt, C. Mancuso, & L. Norman. 1986. Depositional and diagenetic processes in a freshwater estuary. Final Report submitted to Sanctuary Programs Division, NOAA and Ohio Dept. Natural Resources. Gleason, H. A. & A. C. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, NY. Gordon, R. B. 1969. The natural vegetation of Ohio in pioneer days. Bulletin of the Ohio Biological Survey 3(2). 113 pp.

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