Rias, estuaries and incised valleys: is a ria an estuary?

Evans, Graham; Prego, Ricardo

doi:10.1016/s0025-3227(03)00048-3

Cited by 124 publications

(60 citation statements)

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“…So, among the coastal lagoons presenting a prevailing maritime influence (Abreu et al, 2010), this coastal system corresponds to an unusual type of subtropical coastal lagoon where its water is under fertilization by upwelling phenomena. This Bahia-Magdalena pattern was also observed in temperate ria systems (Evans and Prego, 2003) with seasonal upwelling (Fraga, 1981;Prego and Bao, 1997). During spring-summer in the Western and Middle Galician Rias of the Iberian Peninsula the fluvial contributions are very low; hence nutrient input as result of upwelling events is the main reason for the fertilization of the ria (Prego, 2002;Varela et al, 2008).…”

Section: -Discussionmentioning

confidence: 72%

Annual patterns of nutrients and chlorophyll in a subtropical coastal lagoon under the upwelling influence (SW of Baja-California Peninsula)

Cervantes‐Duarte

Prego²,

López-López

et al. 2013

Estuarine, Coastal and Shelf Science

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Abstract. The coastal lagoon of Bahía-Magdalena, located on the west coast of the Peninsula of Baja-California, is a subtropical ecosystem with an arid climate and very little freshwater input. During the 2005-2011 period the thermohaline properties varied between cold and warm halfyearly periods. They were influenced by the Transitional Water mass transported by the South California Current from February to July and by the Subtropical Surface Water from August to January. The nutrient concentrations increased (viz up to 16 µM of nitrate) from March to June, when the upwelling index was the highest. Similarly, the inter-annual variation of chlorophyll-a showed a six-monthly pattern with the highest average monthly concentrations being found in June (5 mg·m -3 in situ or 8 mg·m -3 based on satellite information) and the lowest in DecemberJanuary. A spatial zoning was also observed in the lagoon with a shallow inner zone that is warmer and richer in chlorophyll-a than the deeper closed mouth area. In the Bahía-Magdalena lagoon a spatial-temporal division into two zones and two seasons was repeated year after year with only minor differences. During the first semester in the outer zone, years 2006 and 2007 were colder and nutrient rich while 2010 was warmer, according to the upwelling conditions in the Southern California Region. Hence, among the coastal lagoons that present a prevailing marine influence, the coastal system of Bahía-Magdalena corresponds to an unusual type of subtropical coastal lagoon where the nutrient input is mainly due to upwelling phenomena.Keywords: inter-annual, intra-annual, biogeochemistry, California Current, chocked lagoon, Bahía-Magdalena, Pacific coast, Mexico. -INTRODUCTIONContinental shelf waters represent 8% of the Earth's oceanic surface but it is where nearly 25% of the primary sea production occurs (Walsh, 1989) and where a variety of types of coastal systems, which determine the exchange between land and sea, are found. In these systems, coastal lagoons, making up 13% of the coastal areas worldwide, are predominant (Kjerve 1994). Coastal lagoons are inland water bodies, usually oriented parallel to the coast, separated from the sea by a barrier and connected to the ocean by one or more restricted inlets (Kjerfve and Magill 1989). In the subtropical climate region bordering, as delimited by Perillo et al. (1999), the Tropics of Cancer and Capricorn (23.5° latitude) and the temperate region (40° latitude), coastal lagoons are subject to a wide climatic diversity ranging from monsoons to desert-like conditions. In all of these climate types the availability of nutrients restricts biological richness (Salomons et al., 2005). Despite this fact, subtropical coastal lagoons have not been studied extensively from a biogeochemical viewpoint, rather it is the ecological aspects that have undergone a more indepth examination (Kjerfve, 1994).The wide variety of subtropical coastal lagoons have been classified according to the type of entrance channel into choked, restricted or leaky lago...

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Section: -Discussionmentioning

confidence: 72%

Annual patterns of nutrients and chlorophyll in a subtropical coastal lagoon under the upwelling influence (SW of Baja-California Peninsula)

Cervantes‐Duarte

Prego²,

López-López

et al. 2013

Estuarine, Coastal and Shelf Science

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“…Other rock bounded estuaries have been described in the northwest of Iberian Península (Evans and Prego, 2003;Naughton et al, 2007), France (e.g. Menier, 2006;Chaumillon et al 2008;Sorrel et al, 2010;Tessier, 2012), United Kingdom and Ireland (Burningham and Cooper, 2004;Cooper, 2006) and South Africa (Cooper, 2001).…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic controls of morpho-sedimentary evolution in a rock-bounded wave dominated estuary. Tina Menor (N Spain)

Flor-Blanco

Flor

González

et al. 2016

Journal of Iberian Geology

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The Tina Menor estuary is a highly confined incised valley with advanced sedimentary infilling. The outstanding feature of this estuary is its longitudinal zonation, which forms four segments from the outer to the inner limit: Mouth complex, Bay, Tidal flats and Upper channel. The innermost part of the Bay and the Tidal Flats (semi-reclaimed areas) are broader estuarine zones, whereas the Mouth Complex and outermost Bay are confined by narrow rocky outcrops. This paper explains the dynamics and sedimentary distribution of a highly confined and singular estuary, detailing the fluvial-tidal controls on the variations in water mixing (QF/QT). This estuary is largely of salt wedge type and the dynamics are characterised by recording currents (speed and direction) in the water column during a tidal cycle in a spring tide; this process consists of the tidal waves propagation and their dissipation upstream hypo-synchronously and the mixing of fresh and saline waters.The morphology, dynamics and sedimentary distributions have been integrated to develop a conceptual model that demonstrates the circulation within the estuary. The sinuous geometry of the estuarine valley and the Coriolis Effect detected, play a fundamental role in determining the morphology and sedimentary distribution. Consequently, this study provides an adequate overview of this type of confined mesotidal estuary, quite common in the eastern Atlantic coast.Keywords: estuary, mesotidal, Bay of Biscay, morpho-sedimentary processes Resumen El estuario de Tina Menor es un valle encajado altamente confinado y sedimentariamente en un avanzado estado de colmatación. Se caracteriza por su zonación longitudinal en cuatro segmentos bien diferenciados desde su sector más externo hasta el límite interior: Complejo de Desembocadura, Bahía, Llanuras Mareales y Canal Superior. El interior de la Bahía y las Llanuras Mareales de carácter fangoso (zonas semi-reclamadas) son las más extensas, mientras que el Complejo de Desembocadura y la parte externa de la Bahía, están estrechamente confinadas por afloramientos rocosos. Este trabajo explica la distribución dinámica y sedimentaria de un estuario singular y altamente confinado, detallando los controles fluviales-mareales en la variación de las mezclas de agua (QF/QT). Este estuario es en gran parte del tipo de cuña salina y la dinámica fue caracterizada por las medidas de corrientes (velocidad y dirección) realizadas en la columna de agua durante un ciclo mareal en marea viva; este proceso consiste en la propagación de las ondas de marea y su disipación de aguas arriba hiposincrónicamente y la mezcla de aguas dulces y salinas.La morfología, dinámica y las distribuciones sedimentarias, se han integrado para desarrollar un modelo conceptual que demuestre la circulación dentro del estuario. La geometría sinuosa del valle estuarino y la detección del efecto de Coriolis, juegan un rol fundamental para determinar la distribución morfologica y sedimentaria. Consecuentemente, este estudio proporciona un visión adecuada de...

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“…The Galician rias (NW Spain) are a kind of estuarine system defined as a stretch of coast characterized by the occurrence of a (palaeo) valley occupied by the sea (Richthofen 1886;Evans and Prego 2003). The great variety of habitats and sediments present in the rias results in diverse benthic faunas both in hard and sedimentary substrata (e.g.…”

Section: Introductionmentioning

confidence: 99%

Temporal dynamics of gastropod fauna on subtidal sandy sediments of the Ensenada de Baiona (NW Iberian Peninsula)

2010

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The temporal variation of the gastropod fauna inhabiting sandy sediments of the Ensenada de Baiona (Galicia, Spain) was studied at three subtidal sites from February 1996 to February 1997 by means of quantitative sampling. A total of 5,463 individuals representing 51 gastropod species and 22 families were found. The family Pyramidellidae was the most diverse in number of species (11 species), followed by Rissoidae and Trochidae (4 species each). The dogwhelk, Nassarius reticulatus, and the rissoid snail, Rissoa parva, were the numerically dominant species at the three studied sites; those and other abundant species showed their greatest densities by the end of summer and the beginning of autumn. In general, univariate measures of the assemblage (number of species, abundance, diversity and evenness) showed variations through time; greater values were recorded between summer and autumn depending on the site. Multivariate analyses done on abundance data showed certain seasonality in the evolution of the assemblage as expected for shallow subtidal sandy sediments at temperate latitudes; those seasonal changes were mostly related to variations in abundance of numerically dominant species. Although the measured sedimentary variables did not show significant correlations with faunal univariate parameters, sediment heterogeneity due to the presence of mats of Zostera marina L. and shells of dead bivalves might explain the differences in composition of the gastropod assemblage among sampling sites.

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Rias, estuaries and incised valleys: is a ria an estuary?

Cited by 124 publications

References 10 publications

Annual patterns of nutrients and chlorophyll in a subtropical coastal lagoon under the upwelling influence (SW of Baja-California Peninsula)

Annual patterns of nutrients and chlorophyll in a subtropical coastal lagoon under the upwelling influence (SW of Baja-California Peninsula)

Hydrodynamic controls of morpho-sedimentary evolution in a rock-bounded wave dominated estuary. Tina Menor (N Spain)

Temporal dynamics of gastropod fauna on subtidal sandy sediments of the Ensenada de Baiona (NW Iberian Peninsula)

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