Eriocaulon parkeri is restricted to tidal rivers and estuaries along the east coast of North America; it occurs in Quebec and New Brunswick and from Maine south to North Carolina. Approximately 114 occurrences are believed extant, with the most in Quebec, followed by Maryland, Maine, Delaware, and Virginia. Another 75 occurrences are considered historical, mostly in New Jersey, and 22 have been extirpated, mostly in New York and Pennsylvania. Population sizes vary greatly from year to year; some large, dense populations with over 10,000 plants are know, but many others are small. Population declines have occurred in most states and provinces from which this species is known, especially in the southern part of its range. It apparently was once abundant in the Delaware River Estuary, but has now disappeared from all sites along the River itself and from most other sites in the system; it persists in a few Delaware tributaries in New Jersey, but has been extirpated from Pennsylvania. It has also been extirpated from the Hudson Estuary and thus from New York state. There may also be some loss in the Chesapeake Estuary; it is considered historical in the District of Columbia. In New England, most historical sites are located in urban areas; two thirds of Connecticut sites are historical or extirpated. Threats include habitat loss/degradation due to shoreline development, hydrologic changes (e.g. from dams and floodgates), dredging and landfilling, changes in sediment dynamics (e.g. from management that changes stream velocity), water pollution, shoreline scouring due to ship traffic, ATV activity in the intertidal zone, and sea level rise from climate change.

Changes in hydrology from tide gates, dams, beavers, etc. that alter river levels and flooding regimes (Haines 2001) Changes in sedimentation regimes resulting in shoreline erosion or burial of plants Dredging of habitat and dumping of dredge spoi

Eriocaulon parkeri is known from 50+ current occurrences, 31 of which are in Maine; 5 in Connecticut; 1 in Maryland; 4 in Massachusetts; 8 in New Jersey; 2 in Virginia (Haines 2001).

The New England Wild Flower Society (Framingham, Massachusetts) has germinated plants from seed of this species (1994), and the plants flowered. However, all plants died following flowering, indicating that the species behaves as an annual rather than a perennial. The plants germinate after a period of cold, moist storage (either refrigeration/freezing or maintenance over winter outdoors). The closely related congener, Eriocaulon septangulare, germinated with 210 days of cold treatment and a 19oC/15 oC temperature (Muenscher 1936). Schuster et al. (1999) from the University of Connecticut in Storrs are studying Parker's pipewort phenology and ecology in the Connecticut River estuary. These studies focus on determining the correlation between environmental variables (substrate condition and elevation) and population size and vigor. Donald Les (1999) and Leslie Mehrhoff, both of the University of Connecticut, are researching the effects of docks and piers on population vitality. This study will examine both the effects of existing coastal structures and recolonization rates in artificially disturbed and control sites. Contact Botanist David Snyder with the New Jersey Natural Heritage Program for more information on research activities on Eriocaulon parkeri in that state. Gerry Moore (Brooklyn Botanical Garden), has conducted many botanical surveys documenting occurrences of Eriocaulon parkeri in the Maurice River of New Jersey.

The New Jersey Department of Environmental Protection has issued a guide to minimizing discharges that impact rare aquatic plant species. Volunteer task forces of the New England Plant Conservation Program of The New England Wild Flower Society (Framingham, Massachusetts) monitor populations of Eriocaulon parkeri in New England.

Field surveys to document the true distribution of the species Multi-year demographic studies to assess variability in population numbers and to analyze population viability Studies of correlations between distribution and habitat characteristics Field transplant experiments to determine precise habitat requirements of the species Studies of reproductive biology to determine flowering phenology, pollination mechanisms, pollen viability, seed production, seed longevity, seed dispersal, and seed dormancy and germination

Studies are needed of its longevity in seed banks and seed storage, as well as the best methods for reintroduction of seeds or plants.