Rooted Vascular Beds in the AP Estuarine System
Marine and estuarine aquatic beds are nurseries for estuarine-dependent commercially and recreationally exploited fish and shellfish. In the Albemarle-Pamlico Estuarine System of North Carolina, submersed rooted vascular beds (SRV) are extremely important, comprising an area approximately equal to that for salt marshes. These SRV provide nursery and feeding habitat for many fish, shellfish and wading birds. About 90% of commercial fishery landings in North Carolina are composed of estuarine-dependent species, many of which utilize these habitat types.
SRV occur in the sounds and estuaries of the Albernarle-Pamlico Estuarine System but not seaward of the Outer Banks. The geographic distribution of SRV in estuaries and sounds landward of the Outer Banks is associated with water depth, water clarity and salinity. SRV occurs at water depths of up to 2.4m. Although quite variable, water clarity in this system is typical of estuaries of the soUtheast coast of the US; freshwater and oceanic water are clearer than estuarine water. The distribution of SRV reflects this trend.
The distribution of species of SRV in The Albemarle-Pamlico Estuarine System is strongly associated with salinity. For our purposes, high salinity is >5.0 - <40 ppt. Two of the three species that occurred in high salinity waters are seagrasses which require high salinity: eelgrass (Zostera marina), a temperate species, and shoal grass (Halodule wrightii), a tropical species. The third is the euryhaline and panlatitudinal specles, widgeon grass (Ruppia maritima). Eleven species of SRV occur in low salinity. For our purposes low salinity is <5 ppt. Six of these eleven species were observed in the present study: widgeon grass, wild celery (Vallisneria americana), Eurasian water milfoil (Myriophyllum spicatum), bushy pondweed (Najas guadalupensis), redhead grass (Potamogeton perfoliatus), and sago pondweed (Potamogeton pectinatus). Species of SRV that require low salinity were less abundant and wide spread than species which require or tolerate high salinity. A notable exception was in the low salinity Currituck Sound.
Nine subregions partition the Albemarle-Pamlico Estuarine System. The subregions are: Currituck, Albemarle, Roanoke/Croatan, Pamlico River estuary, Neuse River estuary, western Pamlico Sound, eastern Pamlico Sound, Core, and Bogue. This report focuses on the Currituck, Albemarle, Roa.noke/Croatan, Pamlico River estuary, Neuse River estuary, western Pamlico Sound, and Core Subregions which were included in the funding agreement with EPA's National Estuary Program (NEP) and NOAA, National Marine Fisheries Service, Beaufort Laboratory, Southeast Fisheries Science Center. Data from the Bogue and eastern Pamlico Sound Subregions, generated by research funded by NOAA's Coastal Ocean Program (COP), are included at the request of the Albemarle-Pamlico Estuarine Program Office.
The aquatic bed spatial data, interpreted from natural color metric quality aerial photography, have been digitized and are available through the North Carolina Center for Geographic Information and Analysis (NC-CGIA) . The exception is the Currituck subregion for which base maps have recently (March 1994) been generated by NOAA, National Ocean Service (NOS) . Base maps are required for registration of spatial habitat data to the external georeference system. Field inventories verified SRV signatures in the photographs and determined the geographic distribution of species of SRV relative to salinity, water clarity, and water depth. Charts, photographs, and digital data produced in this project form a baseline of location and abundance data of this critical fishery habitat for research and for environmental planning and impact evaluation.