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Exchange and flux of larval fishes across the western Gulf Stream front south of Cape Hatteras, USA, in winter
Author(s) -
Govoni,
Spach
Publication year - 1999
Publication title -
fisheries oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 80
eISSN - 1365-2419
pISSN - 1054-6006
DOI - 10.1046/j.1365-2419.1999.00020.x
Subject(s) - gulf stream , oceanography , front (military) , water mass , transect , geology , spawn (biology) , continental shelf , bay , boundary current , ichthyoplankton , submarine pipeline , mesopelagic zone , cape , pelagic zone , ocean current , fishery , geography , abundance (ecology) , biology , archaeology
To describe exchange and to frame the magnitude of the flux of larval fishes across the Gulf Stream front in winter, collections were taken on the inshore and offshore sides of the frontal zone in 1991, 1993, 1994 and 1995, off Onslow Bay, North Carolina. Collections yielded larval fishes representing 75 families. Of these, the larvae of the families Gonostomatidae or Phosichthyidae consistently occurred on both sides of the frontal zone, yet are exclusively of mesopelagic, deep‐oceanic origin; hence, they indicate Gulf Stream‐to‐shelf water‐exchange. The larvae of the clupeid, Brevoortia tyrannus , and the sciaenid, Leiostomus xanthurus , occurred on both sides of the frontal zone, yet spawn on the outer continental shelf in or near the Gulf Stream front; hence these taxa indicate shelf‐to‐Gulf Stream water‐exchange. The mechanisms of exchange, as indicated by the distribution of heat and salt across the front, along with satellite images of sea‐surface temperature, were not completely resolved, largely because of the two‐dimensional ( x , z ) rather than three‐dimensional ( x , y , z ) coordination employed. The observed distributions of indicator taxa did not always conform with expected, given the distribution of heat and salt across the front. Parcels of water exchanged across the front upstream (to the south) and encountered during observation along the cross‐shelf transects explains the lack of conformity. Where the expected and observed distributions agreed, the flux was 0.0009 larvae m −1 s −1 for the indicators of Gulf Stream‐to‐shelf exchange, and 0.0007–0.0030 larvae m −1 s −1 for the indicators of shelf‐to‐Gulf Stream exchange.