HR: 12:06h
AN: OS22B-08    [Abstracts]
TI: Biological Implications of Internal Waves and Internal Tidal Bores in the Southern Part of the California Current System
AU: * Ladah, L B
EM: lladah@cicese.mx
AF: CICESE, Division de Oceanologia, Dept. de Oceanografia Biologica, Km 107 Carr. Tij-Ens, Ensenada, B.C CP22800, Mexico
AU: Leichter, J J
EM: jleichter@ucsd.edu
AF: Estacion Costera de Inv. Marinas, Pontifica Univ. Catholica de Chile, Castilla 114-D, Santiago 6513677, Chile
AU: Tapia, F J
EM: ftapia@bio.puc.cl
AF: Scripps Institute of Oceanography, UCSD, 9500 Gilman Dr., La Jolla, CA 92093, United States
AB: Internal waves and internal tidal bores have been shown to cause rapid changes in temperature associated with vertical and horizontal displacements of water masses in many settings. Their role in the cross-shore transport of matter and energy implies that internal motions have important biological ramifications, particularly in biogeographic transition zones, such as the Southern California Current. Benthic invertebrates and macroalgae depend greatly on the nearshore pelagic environment for the transport of larvae and nutrients. We present 2 examples of how internal motions may modulate benthic populations in this transition zone by enhancing the transport of larvae or the provision of nutrients from offshore sites to the coast. At two sites along the Baja California peninsula, high-frequency variability in thermal structure and horizontal flows were observed. Physical observations show episodes (lasting about 1 h) of rapid variations (every 1 to 5 min) in horizontal flows and temperature in the nearshore water column. We show that the timing and intensity of larval settlement, as well as the residence of cold nutrient - rich water on the shelf, is related with internal motions just offshore. Variability in the direction from which these perturbations propagate may determine small-scale spatial patterns in demography of benthic populations. We discuss the importance of these events in modulating benthic invertebrate and macroalgal populations and how climate change in this transition zone may have important biological consequences via changes in thermocline depth and its subsequent impact on the occurrence of internal motions.
DE: 0408 Benthic processes (4804)
DE: 0460 Marine systems (4800)
DE: 1630 Impacts of global change (1225)
SC: Ocean Sciences [OS]
MN: 2007 Joint Assembly