| Abstrakt: |
Soft-bodied annelids, arthropods, and occasionally globular molluscs were primary foods of the threatened Gulf sturgeon Acipenser oxyrinchus desotoi collected from the mouth upriver to kilometer 221 of the Suwannee River, Florida, in 1988-1990. In spring, large subadults and adults that immigrated from the estuary had fed primarily on lancelets, brachiopods, amphipods and other crustaceans, polychaetes, and gastropods. Small Gulf sturgeons that remained near the mouth of the river during spring fed on epibenthic and hyperbenthic amphipods and grass shrimp and on isopods, oligochaetes, polychaetes, and chironomid and ceratopogonid larvae found in the intertidal zone, Subadults of more than 5 kg and adults in the freshwater middle river reaches between km 55 and 221 essentially fasted during the summer and fall. Gulf sturgeons in the Suwannee River were indifferent to abundant potential freshwater foods and apparently had stored sufficient nutrient reserves while in the estuary. A presumably young-of-year or year-old Gulf sturgeon captured in summer at the most upriver site (km 221) had fed on aquatic insects and oligochaetes. Most Gulf sturgeons of all sizes had ingested detritus or biofilm. [ABSTRACT FROM AUTHOR] |
Plný text