Ichthyoplankton community structure and comparative trophodynamics in an estuarine transition zone
Surveys were conducted to evaluate and compare assemblagestructure and trophodynamics of ichthyoplankton, and their variability, in an estuarine transition zone.Environmental gradients in the saltfront region of the Patuxent River subestuary, Chesapeake Bay, were hypothesized to define spatiotemporal distributions and assemblages of ichthyoplankton. Larval fishes, zooplankton,and hydrographic data were collected during spring through early summer 2000 and 2001. Larvae of 28 fish species were collected and species richness was similar each year. Totallarval abundance was highest in the oligohaline region down-estuary of the salt front in 2000, but highest at the salt front in 2001. Larvae of anadromous fishes were most abundant at or up-estuary of the salt front in both years. Two ichthyoplankton assemblages were distinguished: 1) riverine—characterized predominantly by anadromous species (Moronidae and Alosinae); and 2) estuarine—characterizedpredominantly by naked goby (Gobiosoma bosc) (Gobiidae). Temperature, dissolved oxygen, salinity-associatedvariables (e.g., salt-front location), and concentrations of larval prey, specifically the calanoid copepodEurytemora affinis and the cladoceran Bosmina longirostris, were important indicators of larval fish abundance. Inthe tidal freshwater region up-estuary of the salt front, there was substantial diet overlap between congenericstriped bass (Morone saxatilis) and white perch (M. americana) larvae, and also larvae of alewife (Alosapseudoharengus) (overlap= 0.71–0.93). Larval abundance, taxonomic diversity, and dietary overlap were highestwithin and up-estuary of the salt front, which serves to both structure the ichthyoplankton community and control trophic relationships in the estuarine transition zone.
| Main Authors: | , |
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| Format: | article biblioteca |
| Language: | English |
| Published: |
2011
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| Subjects: | Biology, Ecology, Fisheries, |
| Online Access: | http://hdl.handle.net/1834/25370 |
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