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... barrier is an elongated ridge that is composed predominantly of unconsolidated sand and/or gravel and protect the adjacent mainland from open-water processes (Figure 2.1). From the sea to the mainland, the barriers are generally composed of the shoreface, dune and backbarrier environments, and they are separated alongshore by tidal inlets (Figure 2.1). ...
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... barrier is an elongated ridge that is composed predominantly of unconsolidated sand and/or gravel and protect the adjacent mainland from open-water processes (Figure 2.1). From the sea to the mainland, the barriers are generally composed of the shoreface, dune and backbarrier environments, and they are separated alongshore by tidal inlets (Figure 2.1). Barrier islands are dynamic systems, constantly on the move, migrating under the influence of waves, tides, currents, storms, and changing mean sea levels. ...
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... islands are dynamic systems, constantly on the move, migrating under the influence of waves, tides, currents, storms, and changing mean sea levels. The backbarrier is a narrow, elongated, intertidal landform that is located on the lagoon or estuary side of the barrier island and can take the form of sandy beaches, tidal flats or salt marshes (Figure 2.1). Backbarrier beaches tend to be morphodynamically reflective (according to the classification of Wright & Short, 1984), with steep narrow foreshores that have smaller seasonal variations than open ocean beaches. ...
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... Ria Formosa is a highly dynamic multi-inlet barrier island system located in the Algarve region, Southern Portugal (Figure 2.3). The Ria Formosa backbarrier forms a continuum system, ranging from linear sand bodies morphologically indistinguishable from transgressive open-ocean barriers (Pilkey et al., 2009) to extensive fans of tidal marshes, intercepted by very small tidal channels. ...
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... entire Ria Formosa lagoon covers an area of 8.4×10 7 m 2 (Andrade, 1990), and is characterised by i) extensive salt marsh areas, with a dense distribution of shallow meanders composed of silt and fine sand (Bettencourt, 1994); ii) large sand flats, partially flooded and reworked during spring tides ( Pilkey et al., 1989); and iii) a complex network of natural and partially-dredged channels, which get narrower and shallower towards the upper regions of the system ( Andrade et al., 1998). The lagoon is a very shallow area with a maximum depth of 2 m (below mean sea level, Figure 2.3), supporting substantial sedimentary and morphological variability (Andrade, 1990). ...
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... time, salt marshes accumulate organic material, forming a dense layer called peat. Salt marshes and tidal flats also play an important role in capturing carbon (especially Zostera noltii tidal plains in Figure 2.2), by absorbing in biomass the gaseous carbon -carbon dioxide. Carbon fixation in the soil is highly beneficial to slow global warming and other harmful effects of high carbon content in the atmosphere. ...
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... backbarrier system receives minimal ocean swell and is dependent on local winds for wave development. Most backbarrier shores face fetch distances shorter than 2 km (see example Figure 2.4A), and therefore they are exposed to small waves and are characterised by low, narrow sandy beaches ( Figure 2.4B), alternating with portions of tidal flats, salt marshes, and washover plains (flat areas generated by large overwash events and breaches). ...
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... backbarrier system receives minimal ocean swell and is dependent on local winds for wave development. Most backbarrier shores face fetch distances shorter than 2 km (see example Figure 2.4A), and therefore they are exposed to small waves and are characterised by low, narrow sandy beaches ( Figure 2.4B), alternating with portions of tidal flats, salt marshes, and washover plains (flat areas generated by large overwash events and breaches). ...
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... backbarrier shores face fetch distances shorter than 2 km (see example Figure 2.4A), and therefore they are exposed to small waves and are characterised by low, narrow sandy beaches ( Figure 2.4B), alternating with portions of tidal flats, salt marshes, and washover plains (flat areas generated by large overwash events and breaches). Occasionally, intertidal bars are attached to the beach foreshore (sand banks in Figure 2.4C), suggesting that there is sediment exchange between the low-tide terrace and the foreshore (see beach segmentation in Figure 2.4D). ...
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... backbarrier shores face fetch distances shorter than 2 km (see example Figure 2.4A), and therefore they are exposed to small waves and are characterised by low, narrow sandy beaches ( Figure 2.4B), alternating with portions of tidal flats, salt marshes, and washover plains (flat areas generated by large overwash events and breaches). Occasionally, intertidal bars are attached to the beach foreshore (sand banks in Figure 2.4C), suggesting that there is sediment exchange between the low-tide terrace and the foreshore (see beach segmentation in Figure 2.4D). Evolutionary trends calculated from historic aerial photograph analysis show that the extremities of the system (both peninsulas) are immature (recent and under construction), while the rest of the system is characterised by a predominance of mature backbarriers (Carrasco et al., 2008). ...
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... is estimated that about 5000 people depend on the clam industry, out of the about 100,000 people total population around the lagoon ( Cristina et al., 2006). Urban development in the Ria Formosa backbarrier is concentrated in 5 villages, namely Praia de Faro, Farol, Hangares, Culatra e Armona (Figure 2.5). Example human development and activities on the backbarrier of Culatra Island (photo by A. Rita Carrasco, 2006). ...
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... beaches, but at a relatively lower magnitude (Figure 2.6). For instance, wind and wave-setup are much reduced in backbarrier beaches, when compared with wind and wave-setup acting on oceanic beaches; wave-runup is almost null in backbarrier beaches (Figure 2.6). ...
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... beaches, but at a relatively lower magnitude (Figure 2.6). For instance, wind and wave-setup are much reduced in backbarrier beaches, when compared with wind and wave-setup acting on oceanic beaches; wave-runup is almost null in backbarrier beaches (Figure 2.6). ...
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... time-scale analysis (days to years) demonstrates that volumetric beach response is slow and continuous (less than tens of cubic meters of change between months), similar to other sheltered mesotidal beaches described in literature (Carrasco et al 2012; Figure 2.7A and B). ...
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... time-scale analysis (days to years) demonstrates that volumetric beach response is slow and continuous (less than tens of cubic meters of change between months), similar to other sheltered mesotidal beaches described in literature (Carrasco et al 2012; Figure 2.7A and B). Short-term dataset analysis (minutes to days) confirmed the limited sediment transport, with daily rates of change below 0.05 m 3 /m, occurring mostly on the beach face (see example Figure 2.7B). The beach face and the nearshore (sand bank) act as independent morphological sub-systems. ...
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... beach face and the nearshore (sand bank) act as independent morphological sub-systems. Contrary to most oceanic beaches, backbarrier beaches lack cyclic changes, with a slow response to hydrodynamic forcing (Figure 2.8). ...
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... beaches are not very reactive to wind intensity fluctuations and the sand availability is an important factor for beach modulation. Figure 2.8 shows the lack of correlation between beach morphological changes and wind variability (Figure 2.8; Carrasco et al. 2012). ...
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... beaches are not very reactive to wind intensity fluctuations and the sand availability is an important factor for beach modulation. Figure 2.8 shows the lack of correlation between beach morphological changes and wind variability (Figure 2.8; Carrasco et al. 2012). ...
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... operations have removed sediments inside the lagoons, with consequences to the sediment supply of backbarrier shores. This occurred during the last years in the Ancão Peninsula backbarrier, where a dramatic morphological change is noticeable between 1947 and ~2007 ( Figure 2.9). The main reasons for the observed changes are artificial operations to manage the Ancão Channel. ...
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... dredging of Ancão Channel after 1976 and the relocation of Ancão Inlet in 1996, lead to a shoreline advance (i.e. backbarrier shoreline displacement towards the lagoon), development of a detached morphology (sand bank, Figure 2.9), while the channel reduced its width and its margins enlarged (development of a tidal flat). ...
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... meadows (see Figure 2.10) can stabilise sediments and help to facilitate surface elevation accretion (Fonseca, 1996). ...
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... the main drivers and respective timescales of interaction, acting on the backbarrier shores of Ria Formosa. Tidal currents, wind and wind-induced waves, rising sea level and human interventions, are the main natural and anthropogenic forcing mechanisms that drive changes at backbarrier shores (Figure 2.11). Each driving factor operates at different timescales; for instance, human interventions affects the short-to long-term evolution of backbarrier shores, whilst the tidal currents, but at the long-term their effect can be counteracted. ...
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... economic, recreation, amongst others). In Figure 2.12, backbarrier functioning is defined by a flux of sediment (and energy) from the morphology type to the function/service provided. ...
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... Figure 2.12, backbarrier functioning is defined by a flux of sediment (and energy) from the morphology type to the function/service provided. This flux is controlled by internal processes, as smallto long-term behaviours that regulates the morphology type and evolution, and by the environmental characteristics that determines its functioning or provided service (Figure 2.12). External controls account with human interventions that governs the morphological evolutions, and direct uses linked to the provided service. ...
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... controls account with human interventions that governs the morphological evolutions, and direct uses linked to the provided service. This scheme considers the existence of a dynamic equilibrium crossing the morphology and the function/service, controlled by internal and external processes (Figure 2.12). The scheme illustrates what we consider the most important factors affecting the management of backbarrier shores. ...
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... total tidal prisms for the three inlets of the western sector of Ria Formosa in Autumn of 2011 and Spring of 2012 are compared with those previously obtained in campaigns carried out between 2004 and 2007 by , considered as a reference for this study ( Fig. 3.2). The total tidal prism of the western sector of Ria Formosa is of the order of 10 8 m 3 in spring tides and decrease to values around 6 x 10 7 m 3 in neap tides. The total tidal prism remains stable in spring tides, with oscillations that can be related to the range of the specific tides considered. However, this estimate shows a ...
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... with oscillations that can be related to the range of the specific tides considered. However, this estimate shows a temporal increase in neap tides, particularly evident in flood conditions. The lowest tidal prisms were estimated in Ancão inlet, in the order of 2-8x10 6 m 3 , followed by Armona and Faro-Olhão inlets, in the order of 10 7 m 3 ( Fig. 3.2). From these results is was estimated that Ancão inlet contribution is less than 6% of the total tidal prism in spring and neap tide conditions in both seasons ( Jacob et al., 2013;. Faro-Olhão inlet contributes from 59% to 71% and Armona inlet from 25% to 37%, in neap and spring tide, respectively. These results are in accordance with ...
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... are schematically represented in Fig. 3.12. The correspondent net transports, including water are shown in Table 3.1. The mass budget of nutrients, chlorophyll a and suspended solids estimated based on their concentrations and on the discharge of water exchanged in flood and ebb tide, for Ria Formosa in a spring tidal cycle of Spring 2012 ( Fig. 3.12) reflects the tidal rhythm of water volume transporting these compounds through the three inlets (Ancão, Faro-Olhão and Armona inlets). It is important to remark that this sampling period was conducted after a coastal upwelling event, when the coastal water is, enriched in nutrients and chlorophyll a. This may explain the mass values ...
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... generate more than half the oxygen in the earth s atmosphere and constitute the base of all aquatic/marine foodwebs in surface waters. The Ria Formosa lagoon ( Fig. 5.2), located on the Atlantic ocean in the Algarve region of Portugal, is the most south-westerly of European lagoons. In contrast to microtidal conditions in most Southern European lagoons, the Ria has a mesotidal regime with a tidal range varying between 1.3 m at neap and 3.4 m at spring tides. This shallow network of saltmarsh, sediment ...
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... ( ), as well as supporting a fishery and aquaculture industry of national significance. This study presents data on pelagic primary and bacterial production, as well as phytoplankton community structure at three stations representing contrasting situations within the lagoon, namely: an artificial inlet opened in 1997 prior to this study (B in Fig. 5.2), a channel draining salt marsh (P in ...
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... virioplankton (< 0.2 μm): viruses and very small bacteria 2. Picoplankton (0.2 -2 μm): heterotrophic and autotrophic (photosynthetic) bacteria 3. Nanoplankton (2 -20 μm): heterotrophic and autotrophic nanoflagellates, small diatoms 4. Microplankton (20 -200 μm): diatoms, dinoflagellates, ciliates 5.2), and a channel draining both salt marsh (R in Fig. 5.2) and the effluent from the main facility for urban Water Treatment Plant (WTP in Fig. 5.2) of Faro. The new outlet to the ocean (station B) changed hydrodynamics in Ria Formosa substantially (see Newton & Icely, 2002 for details). The sampling strategy was designed to assess microbial dynamics during extreme tidal conditions over the ...
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... and autotrophic (photosynthetic) bacteria 3. Nanoplankton (2 -20 μm): heterotrophic and autotrophic nanoflagellates, small diatoms 4. Microplankton (20 -200 μm): diatoms, dinoflagellates, ciliates 5.2), and a channel draining both salt marsh (R in Fig. 5.2) and the effluent from the main facility for urban Water Treatment Plant (WTP in Fig. 5.2) of Faro. The new outlet to the ocean (station B) changed hydrodynamics in Ria Formosa substantially (see Newton & Icely, 2002 for details). The sampling strategy was designed to assess microbial dynamics during extreme tidal conditions over the year. These conditions occur for neap tides close to Summer (June) and Winter (December) ...
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... were explained by the hydrodynamic regime of the Ria Formosa lagoon. Earlier observations confirmed that 80% of water exchange in the western lagoon occurred through the Faro-Olhão and Armona inlets ( Silva et al., 2002). Newton and Icely (2002) stressed the important influence of the artificial inlet opened in June 1997 at Barra location (B in Fig. 5.2). In effect, floodwater from Barra inlet reduced water inflow of water from Ramalhete channel into the western Ancão basin, allowing rapid and substantial exchange of water between Barra and Ponte stations over a tidal cycle, but effectively reduced water exchange between Ramalhete and other stations. This circulation pattern in the ...
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... in phytoplankton community composition (see Fig. 5.3 and 5.4) could explain PP variations at HW and LW (Table 5.2) between Ramalhete and other stations. Furthermore, Newton and Mudge (2003) reported much lower water exchange rate at Ramalhete than at Barra and Ponte. Since Ramalhete is located at the main sewage treatment plant outlet for Faro ( Fig. 5.2), this station is considerably more vulnerable to anthropogenic impact. When lagoon shifts from an autotrophic to heterotrophic regime during the cold season, this could enhance role of bacteria as DOM consumers and remineralizers, which is an important self-purification process in natural ...
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... new source of organic matter to be remineralized will rapidly increase the nutrients pools in the sediment (a > b), creating conditions for the assimilation by the Ulvales (c > 0) and consequent green macroalgae bloom. This conceptual diagram allowed to create a dynamic model using STELLA visual programming language ( Figure 6.12), where the Ulvales biomass dynamics was simulated based on its intrinsic characteristics, temperature, light, nutrients and meteorological data (Jørgensen & Bendoricchio, 2001). The biomass results obtained from the model were compared with the observed values using statistical methods, that allowed to attain the following outcomes: ...
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... mutual interactions between plants and surrounding chemical environment which determine the role-played by plants on trace metal distribution and uptake, may vary among plant species and, for a single plant, among locations with different characteristics. According Padinha et al., (2000) the dominant producer of the lower salt marshes in Ria Formosa is the small cordgrass Spartina maritima (Poales: Poaceae), which is a pioneer specie in the lower marsh areas with a typical zonation forming clear homogeneous stands (Figure 7.2). S. maritima is an European cordgrass which has an important role as a primary colonist of intertidal mud flats since it is able to trap and stabilize sediment efficiently, thus facilitating successional development. ...
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... bivalves grow and breed in the intertidal areas of the lagoon that are directly influenced by the different pressures. Salt extraction remains an important industry as can be seen from satellite and aerial photographs ( Figure 8.2). There are also large areas devoted to leisure, such as golf courses and swimming pools. ...
