Volume 59

Implications of Tidal Transport and Internal Tides on the Cross-Shelf Transport of Pink Shrimp Larvae at the SW Florida Shelf

Criales, M.M., Browder., Mooers, C., Robblee, M.B., Cardenas, H., Jackson, T.
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Date: November, 2006

Pages: 640

Event: Proceedings of the Fifty Nine Annual Gulf and Caribbean Fisheries Institute

City: Belize City

Country: Belize


Vertical migrations linked to tides or selective tidal stream transport (STST) is an important cross-shelf mechanism by which planktonic organisms use vertical differences of water velocity to promote transport in an appropriate direction. During a summer cruise on the Southwestern Florida (SWF) shelf of the Gulf of Mexico we identified a STST transport for myses and postlarval stages of the pink shrimp, near Marquesas, midway between Dry Tortugas and Florida Bay spawning and nursery grounds of the pink shrimp respectively. Myses and postlarvae occurred in the upper layer in two large peaks, with a semidiurnal periodicity in phase with the flood tides. This tidal behavior was synchronized with ontogenetic migrations. Larval flux and water velocity indicated that larvae that migrate vertically with a semidiurnal periodicity and a shallow distribution experienced considerable onshore transport. This constitutes the first  tidal transport mechanism reported for decapod larvae migrating in continental shelf waters far away (ca. 100 km) from the coastal nursery grounds, and is also significant in including myses, an earlier development stage than previously observed to engage in STST. This larval behavior was observed during the presence of internal tides, which were recognized by anomalously cool water, a shallow thermocline with strong density gradients, and current reversal and intensification at the pycnocline depth (8-12 m). Pink shrimp larvae and zooplankton biomass were highly concentrated at the shallow thermocline at the Marquesas station. The interaction between larval behavior and the physical mechanisms that concentrate and transport larvae onshore by tidal currents and internal tides need further investigation

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