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Home » ESL » Research » Sea Duck » Methods

Sea Duck Ecology - Methods

Methods Summary
Study Areas
  1. Chesapeake Bay (Pungoteague/Onancock Flats)
    1. Polyhaline (salinity ranging from 18-22 psu) area encompassing water depths ranging from 1-10 m that had discrete regions of muddy and sandy sediments (Fig. 1).
    2. Encompassed 102 km2 in the vicinity of Onancock, Pungoteague and Nandua creeks.
  2. Coastal Lagoon (Hog Island Bay)
    1. Coastal bay seaward of the Delmarva Peninsula that is a shallow, partially intertidal bay which lies between a barrier island to the east and the mainland to the west
    2. ~30 psu salinity and a diversity of fine-scale habitats ranging from intertidal flats and oyster reefs to deeper channels
    3. A diversity of discrete sediment types was also encountered.
 Sea Duck Distribution
  • Vessel and fixed-wing surveys from November 2008 until the end of April 2009
  • Locations recorded using a global positioning system (GPS)
  • Abundance of surf scoters and long tailed ducks was enumerated for each aggregation
 Habitat Characteristics
  • Benthic sampling based on sea duck aggregations from surveys
  • Samples were collected using a Smith-McIntyre grab
  • Sampled seabed to a depth of 10-15 cm, depending on sediment characteristics.
  • Water depth was measured at the approximate centroid of each sampling and manually corrected to mean higher high water (MHHW) based on predicted vs. observed tides at appropriate reference stations.
  • Percentage of organic matter and grain size analysis of sediment was determined from grabs.
  • Sample washed on a 1-mm mesh sieve. Flora and fauna retained on this sieve were identified to the lowest practical taxonomic level for each individual grab.
  • Bivalves, gastropods, fish and amphioxus (up to 50 per grab) were measured to the nearest mm in the organisms' longest dimension.
  • Ash-free dry weight (i.e. dry tissue biomass) was determined.
Diet
  • Limited number of LTDU and SUSC were haphazardly collected from groups observed to be foraging.
  • Field necropsies were performed within ~30 min of collection.
  • Several anatomical measurements were then taken.
  • Esophagus from the bill to the gizzard (including the proventriculus) was removed with contents intact and preserved in 10% formalin.
  • Gizzard was then removed and preserved separately.
  • Macroflora and fauna from esophagus/proventriculus and gizzard samples were identified to the lowest practical taxonomic level for each bird.
  • All bivalves, gastropods, fish and amphioxus were measured to the nearest mm in the organisms' longest dimension.
  • Ash-free dry weight (i.e. dry tissue biomass) was determined.