Shallow Water Ecology of Chesapeake Bay (Nearshore)
The Nearshore Survey is a long term research study on population and community dynamics of shallow water habitats of the Chesapeake Bay. Field studies have been conducted every summer since 1991 at the Smithsonian Environmental Research Center (SERC). The Rhode River, a lower mesohaline sub-estuary of the central Chesapeake Bay, has a mean depth of 2 m and an average tidal range of 0.5 m. Salinity ranges from 4ppt in the spring to 15ppt in the fall. Water temperatures vary seasonally from 2-4ºC in January to a high of 27-28ºC in July. Shoreline water temperatures are more extreme - reaching 30ºC in the summer and freezing in the winter.
Research is carried out at two sites: 1) Canning House Bay, a half-moon shaped embayment of the Chesapeake Bay in the Rhode River. It is characterized by sandy beaches intermingled with coarse woody debris, marsh plants, and ever-encroaching Phragmites populations. 2) Fox Point, a more sheltered spit of land at the mouth of Muddy Creek in the Rhode River, characterized by forested shore line intermingled with marsh plants and coarse woody debris. The sediment at this site is typically bare, whereas submerged aquatic vegetation is often found at Canning House Bay.
There are three sampling components to this study:
Seine Survey - Seining is used to characterize predator guild composition and abundance in the near shore zone. Seines are conducted once a month during the summer at low tide. All predator species (fish, turtles and crabs) are identified to species, measured for total body length and counted and returned to the water. Crabs are also characterized by gender, molt stage and autonomy.
Shrimp Tethering - Tethering the grass shrimp, Palaemonetes pugio, allows us to examine its predator-prey interactions with demersal fish and crabs. This data allows us to 1) assess the nearshore zone as refuge habitat and 2) indirectly measure the abundance of predators. The study was initiated in May 1991 and has continued annually for 3 days a month during the summer. Shrimp mortality as well as predator capture rate, identification and size are recorded.
Sweeps Survey - Grass shrimp distribution and abundance is monitored at permanent transects at Canning House Bay and Fox Point. Six 10m transects are sampled at four depths by pushing a long handled dip net along the river bottom. Shrimp are collected, identified, measured, examined for parasites and reproductive state and returned to the depth at which they were caught. This data allows us to quantify the fluctuations in grass shrimp parasite load and population dynamics.
Here are some of the publications from this study:
Diel variation in predator abundance, predation risk and prey distrubution in shallow-water estuarine habitats. Clark Kelton L., Ruiz Gregory M., Hines Anson H. Journal of experimental Marine Biology and Ecology, 287:37-55, 2003.
Effects of shallow water refuge on behavior and density-dependant mortality of juvenile blue crabs in Chesapeake Bay. Dittel Ana I., Hines Anson H., Ruiz Gregory M., Ruffin K. Keith. Bulletin of Marine Science, 57(3): 902-916, 1995.
Temporal variation in juvenile blue crab mortality: Nearshore shallows and cannibalism in Chesapeake Bay. Hines Anson H., Ruiz Gregory M. Bulletin of Marine Science, 57(3): 884-901, 1995.
Shallow water as a refuge habitat for fish and crustaceans in non-vegetated estuaries: an example from Chesapeake Bay. Ruiz, Gregory M., Hines Anson H., Posey Martin H. Marine Ecology Progress Series, 99: 1-16, 1993.
Coarse woody debris as a refuge from predation in aquatic communuties. Everett R.A., Ruiz G.M. Oecologia, 93:475-486, 1993.