Circulation and transport in short, low-inflow estuaries under anthropogenic stresses

Schettini, Carlos Augusto França; Valle‐Levinson, Arnoldo; Truccolo, Eliane Cristina

doi:10.1016/j.rsma.2017.01.004

Cited by 31 publications

(14 citation statements)

References 51 publications

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“…Their response to the hydrodynamics will determine the time the SPM, and the associated DDPHs, remain in the water column, and thus their transport. The Suape estuarine system was a relatively wellpreserved environment until the early 1970s, from when it suffered major human induced changes similarly to many other small estuaries along Brazilian shores (Schettini et al, 2017). In order to overcome the problems related to the presence of the port of Recife inside the Recife Metropolitan Area, the Pernambuco State sought to create a new integrated port and industrial zone from scratch in the Suape estuary and its hinterland, the Suape Industrial Port Complex (SIPC; Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Intratidal variability and transport of petroleum aromatic hydrocarbons in an anthropized tropical estuarine system: the Suape estuary (8.4S 35W)

et al. 2018

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The Suape Estuary encompasses the Suape Industrial Port Complex (SIPC), a major industrial development in Brazil's Northeast region, which, in order to be implanted, caused drastic environmental changes in this system. This study presents the first physical characterization of the Suape estuarine system, focusing on the local hydrodynamics, material transport and its influence on some specific properties. Physical properties were also associated to dissolved dispersed petroleum hydrocarbons (DDPHs). A study was undertaken during a complete semi-diurnal tidal cycle (13 hr), during which water level, water flow, current velocity and direction, water properties (salinity, temperature, suspended particulate matter - SPM -, chlorophyll and dissolved oxygen) were recorded using ADCP and CTD systems. The DDPHs were investigated in surface and bottom waters, by spectrofluorescence, using Carmópolis oil and chrysene as analytical standards. Results showed a well-mixed vertical structure, a semi-diurnal tide regime and a diurnal thermal pattern. There was no statistical difference between DDPH concentrations at surface and bottom, due to the tide acting as an important homogenizer. DDPHs were low and the main contribution seems to be that from SIPC, as the residual transport of DDPHs, chlorophyll and dissolved oxygen, was towards the Massangana estuary. An opposite pattern was observed for salinity and SPM, whose residual transport was towards the lagoon. The results pointed local hydrodynamics as an essential tool for understanding material transport and exchanges among the estuarine segments. A longer time series should be studied in order to obtain more robust conclusions.

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Section: Introductionmentioning

confidence: 99%

Intratidal variability and transport of petroleum aromatic hydrocarbons in an anthropized tropical estuarine system: the Suape estuary (8.4S 35W)

et al. 2018

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“…The development of hypersalinity, both seasonally and over longer time periods, is sensitive to a host of natural and anthropogenic processes (see discussion in Largier et al, 1997), especially for shorter estuaries like Morro Bay (cf. Schettini et al, 2017). In particular, the longitudinal diffusivity and hydrodynamic exchange are strongly dependent on the geomorphology of the estuary.…”

Section: Implications For Eelgrassmentioning

confidence: 99%

“…As noted by Largier (2010), there is a growing need to not only document and describe the dynamics and exchange processes in small to moderate-sized LIEs, but also to better understand the ecological linkages such as larval retention, species distribution, and habitat suitability (cf. Buck et al, 2014;Morgan et al, 2014;Schettini et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamics in a shallow seasonally low-inflow estuary following eelgrass collapse

Walter

Rainville

O’Leary

2018

Estuarine, Coastal and Shelf Science

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Hydrodynamics play a critical role in mediating biological and ecological processes and can have major impacts on the distribution of habitat-forming species. Low-inflow estuaries are widespread in arid regions and during the dry season in Mediterranean climates. There is a growing need to evaluate dynamics and exchange processes in these systems and the resultant ecological linkages. We investigate the role that hydrodynamics play in shaping environmental gradients in a short and seasonally low-inflow estuary located along the central California coast. Since 2007, eelgrass meadows in Morro Bay have declined by more than 90%, representing the collapse of the major biogenic habitat. Despite the large-scale decline, eelgrass beds near the mouth of the bay remain resilient, suggesting that conditions in certain areas of the bay might allow or impede eelgrass retention and recovery. Oceanographic moorings were deployed throughout the bay during the summer dry season to assess spatial differences in environmental conditions and hydrodynamics across gradients in eelgrass survival. Relative to the mouth of the bay, the back bay water mass was significantly warmer (hyperthermal), more saline (hypersaline), less oxygenated, and more turbid, with longer flushing times, all of which have been identified as significant stressors on seagrasses. Moreover, there is weak exchange between the mouth and the back bay that effectively decouples the two water masses during most periods. Though the causes of the decline are not clear, gradients in environmental conditions driven by bay hydrodynamics appear to be preventing eelgrass recovery and restoration attempts in the back bay and keeping this region in an alternative state dominated by unvegetated intertidal mudflats. Ecosystems in low-inflow estuaries may be especially prone to ecological regime shifts or collapse and may require precautionary monitoring and management. This system and the dramatic ecological change that it has experienced, demonstrate the critical role that hydrodynamics play in ecosystem health and habitat suitability.

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“…In long estuaries, however, tidal return flow can generate strong seaward residual flow (Dronkers 1986). Moreover, the residual salt flux due to tidal advection of salinity (i.e., tidal pumping) dominates the landward salt transport in long estuaries (Wei et al 2017), but is close to zero in very short estuaries due to weak correlations between the tidal velocity and salinity (Schettini et al 2017). Another important distinction is linked to the along-channel salinity gradients, which are usually large in short estuaries (such as the Tamar, Tees, and Wyre estuaries in the United Kingdom) compared to long estuaries (Lewis and Uncles 2003) and can lead to stronger gravitational circulation in shorter estuaries (with large S i number).…”

Section: Introductionmentioning

confidence: 99%

Unraveling Interactions between Asymmetric Tidal Turbulence, Residual Circulation, and Salinity Dynamics in Short, Periodically Weakly Stratified Estuaries

Wei

Schuttelaars

Williams

et al. 2021

Journal of Physical Oceanography

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Asymmetric tidal turbulence (ATT) strongly influences estuarine health and functioning. However, its impact on the three-dimensional estuarine dynamics and the feedback of water motion and salinity distribution on ATT remain poorly understood, especially for short estuaries (estuarine length ≪ tidal wavelength). This study systematically investigates the above-mentioned interactions in a short estuary for the first time, considering periodically weakly stratified conditions. This is done by developing a three-dimensional semi-analytical model (combining perturbation method with finite element method) that allows a dissection of the contributions of different processes to ATT, estuarine circulation, and salt transport. The generation of ATT is dominated by (i) strain-induced periodic stratification and (ii) asymmetric bottom shear generated turbulence, and their contributions to ATT are different both in amplitude and phase. The magnitude of the residual circulation related to ATT and the eddy viscosity-shear covariance (ESCO) is about half of that of the gravitational circulation (GC) and shows a ‘reversed’ pattern as compared to GC. ATT generated by (i) contributes to an ESCO circulation with a spatial structure similar to GC. This circulation reduces the longitudinal salinity gradients and thus weakens GC. Contrastingly, the ESCO circulation due to (ii) shows patterns opposite to GC and acts to enhance GC. Concerning the salinity dynamics at steady state, GC and tidal pumping are equally important to salt import, whereas ESCO circulation yields a significant seaward salt transport. These findings highlight the importance of identifying the sources of ATT to understand its impact on estuarine circulation and salt distribution.

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Circulation and transport in short, low-inflow estuaries under anthropogenic stresses

Cited by 31 publications

References 51 publications

Intratidal variability and transport of petroleum aromatic hydrocarbons in an anthropized tropical estuarine system: the Suape estuary (8.4S 35W)

Intratidal variability and transport of petroleum aromatic hydrocarbons in an anthropized tropical estuarine system: the Suape estuary (8.4S 35W)

Hydrodynamics in a shallow seasonally low-inflow estuary following eelgrass collapse

Unraveling Interactions between Asymmetric Tidal Turbulence, Residual Circulation, and Salinity Dynamics in Short, Periodically Weakly Stratified Estuaries

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