Oceanography The Official Magazine of
The Oceanography Society
Volume 31 Issue 04

View Issue TOC
Volume 31, No. 4
Pages 60 - 69


High-Frequency Frontal Displacements South of San Jorge Gulf During a Tidal Cycle Near Spring and Neap Phases: Biological Implications Between Tidal States

By Juan Cruz Carbajal , Andrés Luján Rivas, and Cédric Chavanne 
Jump to
Article Abstract Citation References Copyright & Usage
Article Abstract

San Jorge Gulf (SJG) is a region of high biological productivity that supports important shrimp (Pleoticus muelleri) and hake (Merluccius hubbsi) fisheries, as well as high marine biodiversity associated, in part, with a tidal front located in the southern part of the gulf. In situ high-resolution cross-frontal measurements were collected using a remotely operated towed vehicle to characterize the three-dimensional structure of the tidal front and to investigate how its position varies during the semidiurnal tidal cycle (high/low) and the spring to neap transition, together with its impact on the distribution of nutrients and chlorophyll-a. Estimates of tidal height and flow velocity derived from a numerical model support the conclusion that frontal displacements mostly result from advection by cross-frontal tidal currents. The frontal position was also modified by baroclinic instabilities that significantly distort the front. Measurements reveal intrusions of low-salinity, nutrient-rich waters from the mixed side into the pycnocline on the stratified side cause a subsurface chlorophyll-a peak near the neap phase. Most prior studies of fronts in the SJG have been limited to their surface manifestations because they were conducted using satellite images. This article aims to contribute to the understanding of the complex southern tidal front dynamics, highlighting that maximum primary productivity occurs in a subsurface layer that is not visible by satellite sensors.


Carbajal, J.C., A.L. Rivas, and C. Chavanne. 2018. High-frequency frontal displacements south of San Jorge Gulf during a tidal cycle near spring and neap phases: Biological implications between tidal states. Oceanography 31(4):60–69, https://doi.org/10.5670/oceanog.2018.411.


Allen, C., J.H. Simpson, and R.M. Carson. 1980. Structure and variability of shelf sea fronts as observed by an undulating CTD system. Oceanologica Acta 3(1):59–68.

Anderson, D.M. 2001. Phytoplankton Blooms. Pp. 2,179–2,192 in Encyclopedia of Ocean Sciences, https://doi.org/10.1006/rwos.2001.0050.

Badin, G., R.G. Williams, and J. Sharples. 2010. Water-mass transformation in the shelf seas. Journal of Marine Research 68(2):189–214, https://doi.org/​10.1357/002224010793721442.

Barth, J.A., S.D. Pierce, and T.J. Cowles. 2005. Mesoscale structure and its seasonal evolution in the northern California Current System. Deep Sea Research Part II 52(1–2):5–28, https://doi.org/​10.1016/j.dsr2.2004.09.026.

Bianchi, A.A., L. Bianucci, A.R. Piola, D.R. Pino, I. Schloss, A. Poisson, and C.F. Balestrini. 2005. Vertical stratification and air-sea CO2 fluxes in the Patagonian shelf. Journal of Geophysical Research 110(C7), https://doi.org/​10.1029/2004JC002488.

Brown, J., L. Carrillo, L. Fernand, K.J. Horsburgh, A.E. Hill, E.F. Young, and K.J. Medler. 2003. Observations of the physical structure and seasonal jet-like circulation of the Celtic Sea and St. George’s Channel of the Irish Sea. Continental Shelf Research 23(6):533–561, https://doi.org/​10.1016/S0278-4343(03)00008-6.

Castelao, R.M., T.P. Mavor, J.A. Barth, and L.C. Breaker. 2006. Sea surface temperature fronts in the California Current System from geostationary satellite observations. Journal of Geophysical Research 111(C9), https://doi.org/​10.1029/2006JC003541.

Dogliotti, A.I., V.A. Lutz, and V. Segura. 2014. Estimation of primary production in the southern Argentine continental shelf and shelf-break regions using field and remote sensing data. Remote Sensing of Environment 140:497–508, https://doi.org/​10.1016/​j.rse.2013.09.021.

Fearnhead, P.G. 1975. On the formation of fronts by tidal mixing around the British Isles. Deep Sea Research and Oceanographic Abstracts 22(5):311–321, https://doi.org/​10.1016/​0011-7471(75)90072-8.

Flores-Melo, X., I.R. Schloss, C. Chavanne, G.O. Almandoz, M. Latorre, and G.A. Ferreyra. 2018. Phytoplankton ecology during a spring-neap tidal cycle in the southern tidal front of San Jorge Gulf, Patagonia. Oceanography 31(4):70–80, https://doi.org/​10.5670/oceanog.2018.412.

Glorioso, P.D., and R.A. Flather. 1995. A barotropic model of the currents off SE South America. Journal of Geophysical Research 100(C7):13,427–13,440, https://doi.org/​10.1029/​95JC00942.

Glorioso, P.D., and R.A. Flather. 1997. The Patagonian shelf tides. Progress in Oceanography 40(1–4):263–283, https://doi.org/​10.1016/S0079-6611(98)00004-4.

Guerrero, R.A., and A.R. Piola. 1997. Masas de agua en la plataforma continental. Pp. 107– 118 in El Mar Argentino y sus recursos pesqueros. Antecedentes históricos de las exploraciones en el mar y las características ambientales, vol. 1. E.E. Boschi, ed., Instituto Nacional de Investigación y Desarrollo Pesquero, Mar del Plata, Argentina.

Holligan, P.M., P.J.B. Williams, D. Purdie, and R. Harris. 1984. Photosynthesis, respiration and nitrogen supply of plankton populations in stratified, frontal and tidally mixed shelf waters. Marine Ecology Progress Series 17:201–213, https://doi.org/10.3354/meps017201.

Hopkins, J., and J.A. Polton. 2012. Scales and structure of frontal adjustment and freshwater export in a region of freshwater influence. Ocean Dynamics 62(1):45–62, https://doi.org/10.1007/s10236-011-0475-7.

Kahl, L.C., A.A. Bianchi, A.P. Osiroff, D.R. Pino, and A.R. Piola. 2017. Distribution of sea-air CO2 fluxes in the Patagonian Sea: Seasonal, biological and thermal effects. Continental Shelf Research 143:18–28, https://doi.org/10.1016/j.csr.2017.05.011.

Kasai, A., T.P. Rippeth, and J.H. Simpson. 1999. Density and flow structure in the Clyde Sea front. Continental Shelf Research 19(14):1,833–1,848, https://doi.org/10.1016/S0278-4343(99)00042-4.

Le Fevre, J. 1987. Aspects of the biology of frontal systems. Advances in Marine Biology 23:163–299, https://doi.org/10.1016/S0065-2881(08)60109-1.

Lips, U., I. Lips, T. Liblik, V. Kikas, K. Altoja, N. Buhhalko, and N. Rünk. 2011. Vertical dynamics of summer phytoplankton in a stratified estuary (Gulf of Finland, Baltic Sea). Ocean Dynamics 61(7):903–915, https://doi.org/10.1007/s10236-011-0421-8.

Loder, J., and T. Platt. 1985. Physical controls on phytoplankton production at tidal fronts. Pp. 3–22 in Proceedings of the 19th European Marine Biology Symposium. P.E. Gibbs, ed., Cambridge University Press, Cambridge.

Lund-Hansen, L.C., and T. Vang. 2004. An inflow and intrusion event in the Little Belt at the North Sea–Baltic Sea transition and a related sub-surface bloom of Pseudo-nitzschia pseudodelicatissima. Estuarine, Coastal and Shelf Science 59(2):265–276, https://doi.org/10.1016/​j.ecss.2003.09.004.

Matano, R.P., and E.D. Palma. 2018. Seasonal variability of the oceanic circulation in the Gulf of San Jorge, Argentina. Oceanography 31(4):16–24, https://doi.org/​10.5670/oceanog.2018.402.

Moreira, D., C.G. Simionato, and W. Dragani. 2011. Modeling ocean tides and their energetics in the North Patagonia Gulfs of Argentina. Journal of Coastal Research 27(1):87–102, https://doi.org/​10.2112/JCOASTRES-D-09-00055.1.

Paden, C.A., M.R. Abbott, and C.D. Winant. 1991. Tidal and atmospheric forcing of the upper ocean in the Gulf of California: Part 1. Sea surface temperature variability. Journal of Geophysical Research 96(C10):18,337–18,359, https://doi.org/​10.1029/91JC01597.

Palma, E.D., and R.P. Matano. 2012. A numerical study of the Magellan Plume. Journal of Geophysical Research 117, C05041, https://doi.org/​10.1029/2011JC007750.

Palma, E.D., R.P. Matano, and A.R. Piola. 2004. A numerical study of the Southwestern Atlantic Shelf circulation: Barotropic response to tidal and wind forcing. Journal of Geophysical Research 109, C08014, https://doi.org/10.1029/2004JC002315.

Pedersen, F.B. 1994. The oceanographic and biological tidal cycle succession in shallow sea fronts in the North Sea and the English Channel. Estuarine, Coastal and Shelf Science 38(3):249–269, https://doi.org/10.1006/ecss.1994.1017.

Pingree, R.D. 1978. Cyclonic eddies and cross-​frontal mixing. Journal of the Marine Biological Association of the United Kingdom 58(4):955–963, https://doi.org/10.1017/S0025315400056885.

Pingree, R.D. 1979. Baroclinic eddies bordering the Celtic Sea in late summer. Journal of the Marine Biological Association of the United Kingdom 59(3):689–703, https://doi.org/10.1017/S0025315400045677.

Pisoni, J.P., A.L. Rivas, and A.R. Piola. 2015. On the variability of tidal fronts on a macrotidal continental shelf, Northern Patagonia, Argentina. Deep Sea Research Part II 119:61–68, https://doi.org/10.1016/​j.dsr2.2014.01.019.

Richardson, K., A.W. Visser, and F.B. Pedersen. 2000. Subsurface phytoplankton blooms fuel pelagic production in the North Sea. Journal of Plankton Research 22(9):1,663–1,671, https://doi.org/10.1093/plankt/22.9.1663.

Rivas, A.L. 1994. Spatial variation of the annual cycle of temperature in the Patagonian shelf between 40 and 50° of south latitude. Continental Shelf Research 14(13–14):1,539–1,554, https://doi.org/​10.1016/0278-4343(94)90089-2.

Rivas, A.L., A.I. Dogliotti, and D.A. Gagliardini. 2006. Seasonal variability in satellite-measured surface chlorophyll in the Patagonian Shelf. Continental Shelf Research 26(6):703–720, https://doi.org/​10.1016/j.csr.2006.01.013.

Rivas, A.L., and A.R. Piola. 2002. Vertical stratification at the shelf off northern Patagonia. Continental Shelf Research 22(10):1,549–1,558, https://doi.org/​10.1016/S0278-4343(02)00011-0.

Rivas, A.L., and J.P. Pisoni. 2010. Identification, characteristics and seasonal evolution of surface thermal fronts in the Argentinean Continental Shelf. Journal of Marine Systems 79(1–2):134–143, https://doi.org/​10.1016/j.jmarsys.2009.07.008.

Rogachev, K.A., E.C. Carmack, A.S. Salomatin, and M.G. Alexanina. 2001. Lunar fortnightly modulation of tidal mixing near Kashevarov Bank, Sea of Okhotsk, and its impacts on biota and sea ice. Progress in Oceanography 49(1–4):373–390, https://doi.org/10.1016/S0079-6611(01)00031-3.

Romero, S.I., A.R. Piola, M. Charo, and C.A.E. Garcia. 2006. Chlorophyll-a variability off Patagonia based on SeaWiFS data. Journal of Geophysical Research 111(C5), https://doi.org/​10.1029/​2005JC003244.

Sabatini, M., and P. Martos. 2002. Mesozooplankton features in a frontal area off northern Patagonia (Argentina) during spring 1995 and 1998. Scientia Marina 66(3):215–232, https://doi.org/10.3989/scimar.2002.66n3215.

Sabatini, M.E., F.C. Ramírez, and P. Martos. 2000. Distribution pattern and population structure of Calanus australis Brodsky, 1959 over the southern Patagonian Shelf off Argentina in summer. ICES Journal of Marine Science 57(6):1,856–1,866, https://doi.org/10.1006/jmsc.2000.0969.

Sabatini, M., R. Reta, and R. Matano. 2004. Circulation and zooplankton biomass distribution over the southern Patagonian shelf during late summer. Continental Shelf Research 24(12):1,359–1,373, https://doi.org/10.1016/j.csr.2004.03.014.

Saraceno, M., C. Provost, and A.R. Piola. 2005. On the relationship between satellite-​retrieved surface temperature fronts and chlorophyll a in the western South Atlantic. Journal of Geophysical Research 110(C11), https://doi.org/​10.1029/2004JC002736.

Sharples, J., J.F. Tweddle, J.A. Mattias Green, M.R. Palmer, Y.N. Kim, A.E. Hickman, P.M. Holligan, C.M. Moore, T.P. Rippeth, J.H. Simpson, and V. Krivtsov. 2007. Spring-neap modulation of internal tide mixing and vertical nitrate fluxes at a shelf edge in summer. Limnology and Oceanography 52(5):1,735–1,747, https://doi.org/​10.4319/lo.2007.52.5.1735.

Simpson, J.H. 1971. Density stratification and microstructure in the western Irish Sea. Deep Sea Research and Oceanographic Abstracts 18(3):309–319, https://doi.org/​10.1016/​0011-7471(71)90036-2.

Simpson, J.H., and D. Bowers. 1981. Models of stratification and frontal movement in shelf seas. Deep Sea Research Part A 28(7):727–738, https://doi.org/​10.1016/0198-0149(81)90132-1.

Simpson, J.H., and R.D. Pingree. 1978. Shallow sea fronts produced by tidal stirring. Pp. 29–42 in Oceanic Fronts in Coastal Processes. Springer, Berlin, Heidelberg.

Takeoka, H., O. Matsuda, and T. Yamamoto. 1993. Processes causing the chlorophyll a maximum in the tidal front in Iyo-nada, Japan. Journal of Oceanography 49(1):57–70, https://doi.org/10.1007/BF02234009.

Tonini, M., E.D. Palma, and A. Rivas. 2006. Modelo de alta resolución de los Golfos Patagónicos. Mecánica Computacional 25:1,441–1,460.

Villacorte, L.O., S.A.A. Tabatabai, D.M. Anderson, G.L. Amy, J.C. Schippers, and M.D. Kennedy. 2015. Seawater reverse osmosis desalination and (harmful) algal blooms. Desalination 360:61–80, https://doi.org/10.1016/j.desal.2015.01.007.

Yanagi, T., T. Shimizu, and T. Matsuno. 1996. Baroclinic eddies south of Cheju Island in the East China Sea. Journal of Oceanography 52(6):763–769, https://doi.org/10.1007/BF02239464.

Zatsepin, A.G., A.I. Ginzburg, A.G. Kostianoy, V.V. Kremenetskiy, V.G. Krivosheya, S.V. Stanichny, and P.M. Poulain. 2003. Observations of Black Sea mesoscale eddies and associated horizontal mixing. Journal of Geophysical Research 108(C8), https://doi.org/10.1029/2002JC001390.

Copyright & Usage

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.