Measurements in San Bernardino Strait, one of two major connections between the Pacific Ocean and the interior waters of the Philippine Archipelago, captured 2–3 m s^-1 tidal currents that drove vertical mixing and net landward transport. A TRIAXUS towed profiling vehicle equipped with physical and optical sensors was used to repeatedly map subregions within the strait, employing survey patterns designed to resolve tidal variability of physical and optical properties. Strong flow over the sill between Luzon and Capul islands resulted in upward transport and mixing of deeper high-salinity, low-oxygen, high-particle-and-nutrient-concentration water into the upper water column, landward of the sill. During the high-velocity ebb flow, topography influences the vertical distribution of water, but without the diapycnal mixing observed during flood tide. The surveys captured a net landward flux of water through the narrowest part of the strait. The tidally varying velocities contribute to strong vertical transport and diapycnal mixing of the deeper water into the upper layer, contributing to the observed higher phytoplankton biomass within the interior of the strait.

Jones, B.H., C.M. Lee, G. Toro-Farmer, E.S. Boss, M.C. Gregg, and C.L. Villanoy. 2011. Tidally driven exchange in an archipelago strait: Biological and optical responses. Oceanography 24(1):142–155, https://doi.org/10.5670/oceanog.2011.11.

Boss, E., W.S. Pegau, W.D. Gardner, J.R.V. Zaneveld, A.H. Barnard, M.S. Twardowski, G.C. Chang, and T.D. Dickey. 2001. Spectral particulate attenuation and particle size distribution in the bottom boundary layer of a continental shelf. Journal of Geophysical Research 106(C5):9,509–9,516.

Boss, E.S., R. Collier, G. Larson, K. Fennel, and W.S. Pegau. 2007. Measurements of spectral optical properties and their relation to biogeochemical variables and processes in Crater Lake, Crater Lake National Park, OR. Hydrobiologia 574:149–159. [CrossRef]

Boyer, T.P., J.I. Antonov, H.E. Garcia, D.R. Johnson, R.A. Locarnini, A.V. Mishonov, M.T. Pitcher, O.K. Baranova, and I.V. Smolyar. 2006. World Ocean Database 2005. S. Levitus, ed., NOAA Atlas NESDIS 60, US Government Printing Office, Washington, DC, 190 pp., DVDs.

Bryden, H.L., J. Candela, and T.H. Kinder. 1994. Exchange through the Strait of Gibraltar. Progress in Oceanography 33(3):201–248. [CrossRef]

Davis, R.F., C.C. Moore, J.R.V. Zaneveld, and J.M. Napp. 1997. Reducing the effects of fouling on chlorophyll estimates derived from long-term deployments of optical instruments. Journal of Geophysical Research 102:5,851–5,855.

Gomez, F., N. Gonzalez, F. Echevarria, and C.M. Garcia. 2000. Distribution and fluxes of dissolved nutrients in the Strait of Gibraltar and its relationships to microphytoplankton biomass. Estuarine Coastal and Shelf Science 51(4):439-449. [CrossRef]

Gordon, A.L., J. Sprintall, and A. Ffield. 2011. Regional oceanography of the Philippine Archipelago. Oceanography 24(1):14–27. [CrossRef]

Gregg, M.C., and L.J. Pratt. 2010. Flow and hydraulics near the sill of Hood Canal, a strongly sheared, continuously stratified fjord. Journal of Physical Oceanography 40(5):1,087–1,105. [CrossRef]

Jones, A.T., and W. Rowley. 2002. Global perspective: Economic forecast for renewable ocean energy technologies. IEEE Marine Technology Society Journal 36(4):85–90. [CrossRef]

Kinder, T.H., and G. Parrilla. 1987. Yes, some of the Mediterranean outflow does come from great depth. Journal of Geophysical Research 92(C3):2,901–2,906. [CrossRef]

Klymak, J.M., and M.C. Gregg. 2001. Three-dimensional nature of flow near a sill. Journal of Geophysical Research 106(C10):22,295–22,311. [CrossRef]

Lafuente, J.G., J.M. Vargas, F. Plaza, T. Sarhan, J. Candela, and B. Bascheck. 2000. Tide at the eastern section of the Strait of Gibraltar. Journal of Geophysical Research 105(C6):14,197–14,213. [CrossRef]

Lamb, K.G. 2004. On boundary-layer separation and internal wave generation at the Knight Inlet sill. Proceedings of the Royal Society of London Series A 460(2048):2,305–2,337.

Lane-Serff, G.F. 2004. Topographic and boundary effects on steady and unsteady flow through straits. Deep-Sea Research Part II 51(4–5):321–334. [CrossRef]

Longo, A., M. Manzo, and S. Pierini. 1992. A model for the generation of nonlinear internal tides in the Strait of Gibraltar. Oceanologica Acta 15(3):233–243.

Macias, D., A.P. Martin, J. Garcia-Lafuente, C.M. Garcia, A. Yool, M. Bruno, A. Vazquez-Escobar, A. Izquierdo, D.V. Sein, and F. Echevarria. 2007. Analysis of mixing and biogeochemical tides on the Atlantic-Mediterranean effects induced by flow in the Strait of Gibraltar through a physical-biological coupled model. Progress in Oceanography 74(2–3):252–272. [CrossRef]

Morozov, E.G., K. Trulsen, M.G. Velarde, and V.I. Vlasenko. 2002. Internal tides in the Strait of Gibraltar. Journal of Physical Oceanography 32(11):3,193–3,206.

Ohlmann, J.C. 2011. Drifter observations of small-scale flows in the Philippine Archipelago. Oceanography 24(1):122–129. [CrossRef]

Peña, N.A., and A.G. Mariño. 2009. Marine current energy initiatives in the Philippines. Paper presented at the East Asian Seas Congress 2009, Manila, Philippines. Powerpoint slides available at: http://pemsea.org/eascongress/international-conference/presentation_t4-1_pena.pdf (accessed January 15, 2011).

Pullen, J., J.D. Doyle, P. May, C. Chavanne, P. Flament, and R.A. Arnone. 2008. Monsoon surges trigger oceanic eddy formation and propagation in the lee of the Philippine Islands. Geophysical Research Letters 35(7), L07604. [CrossRef]

Richez, C. 1994. Airborne synthetic-aperture radar tracking of internal waves in the Strait of Gibraltar. Progress in Oceanography 33(2):93–97. [CrossRef]

Sannino, G., A. Bargagli, and V. Artale. 2002. Numerical modeling of the mean exchange through the Strait of Gibraltar. Journal of Geophysical Research 107(C8), 3094. [CrossRef]

Seim, H.E., and M.C. Gregg. 1997. The importance of aspiration and channel curvature in producing strong vertical mixing over a sill. Journal of Geophysical Research 102(C2):3,451–3,472. [CrossRef]

Sharples, J., C.M. Moore, T.P. Rippeth, P.M. Holligan, D.J. Hydes, N.R. Fisher, and J.H. Simpson. 2001. Phytoplankton distribution and survival in the thermocline. Limnology and Oceanography 46(3):486–496. [CrossRef]

Stommel, H., H. Bryden, and P. Mangelsdorf. 1973. Does some of the Mediterranean outflow come from great depth? Pure and Applied Geophysics 105:879–889. [CrossRef]

Sullivan, J.M., M.S. Twardowski, J.R.V. Zaneveld, C.M. Moore, A.H. Barnard, P.L. Donaghay, and B. Rhoades. 2006. Hyperspectral temperature and salt dependencies of absorption by water and heavy water in the 400–750 nm spectral range. Applied Optics 45(21):5,294–5,309. [CrossRef]

Tsimplis, M.N. 2000. Vertical structure of tidal currents over the camarinal sill at the Strait of Gibraltar. Journal of Geophysical Research 105(C8):19,709–19,728. [CrossRef]

Twardowski, M.S., E. Boss, J.M. Sullivan, and P.L. Donaghay. 2004. Modeling the spectral shape of absorption by chromophoric dissolved organic matter. Marine Chemistry 89(1–4):69–88. [CrossRef]

Valle-Levinson, A., F. Jara, C. Molinet, and D. Soto. 2001. Observations of intratidal variability of flows over a sill/contraction combination in a Chilean fjord. Journal of Geophysical Research 106(C4):7,051–7,064.

Vargas, J.M., J. Garcia-Lafuente, J. Candela, and A.J. Sanchez. 2006. Fortnightly and monthly variability of the exchange through the Strait of Gibraltar. Progress in Oceanography 70(2–4):466–485. [CrossRef]

Zaneveld, R.V., J.C. Kitchen, and C. Moore. 1994. The scattering error correction of reflecting-tube absorption meters. Ocean Optics XII 2258:44–55. [CrossRef]

This is an open access article made available under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution, and reproduction in any medium or format as long as users cite the materials appropriately, provide a link to the Creative Commons license, and indicate the changes that were made to the original content. Images, animations, videos, or other third-party material used in articles are included in the Creative Commons license unless indicated otherwise in a credit line to the material. If the material is not included in the article’s Creative Commons license, users will need to obtain permission directly from the license holder to reproduce the material.