Artykuły w czasopismach: „Estuaire inverse”

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Descroix, Luc, Yancouba Sané, Mamadou Thior, Sylvie-Paméla Manga, Boubacar Demba Ba, Joseph Mingou, Victor Mendy i in. "Inverse Estuaries in West Africa: Evidence of the Rainfall Recovery?" Water 12, nr 3 (28.02.2020): 647. http://dx.doi.org/10.3390/w12030647.

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In West Africa, as in many other estuaries, enormous volumes of marine water are entering the continent. Fresh water discharge is very low, and it is commonly strongly linked to rainfall level. Some of these estuaries are inverse estuaries. During the Great Sahelian Drought (1968–1993), their hyperhaline feature was exacerbated. This paper aims to describe the evolution of the two main West African inverse estuaries, those of the Saloum River and the Casamance River, since the end of the drought. Water salinity measurements were carried out over three to five years according to the sites in order to document this evolution and to compare data with the historical ones collected during the long dry period at the end of 20th century. The results show that in both estuaries, the mean water salinity values have markedly decreased since the end of the drought. However, the Saloum estuary remains a totally inverse estuary, while for the Casamance River, the estuarine turbidity maximum (ETM) is the location of the salinity maximum, and it moves according to the seasons from a location 1–10 km downwards from the upstream estuary entry, during the dry season, to a location 40–70 km downwards from this point, during the rainy season. These observations fit with the functioning of the mangrove, the West African mangrove being among the few in the world that are markedly increasing since the beginning of the 1990s and the end of the dry period, as mangrove growth is favored by the relative salinity reduction. Finally, one of the inverse estuary behavior factors is the low fresh water incoming from the continent. The small area of the Casamance and Saloum basins (20,150 and 26,500 km² respectively) is to be compared with the basins of their two main neighbor basins, the Gambia River and the Senegal River, which provide significant fresh water discharge to their estuary.

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Shaha, Dinesh Chandra, Yang-Ki Cho, Bong Guk Kim, M. Rafi Afruz Sony, Sampa Rani Kundu i M. Faruqul Islam. "Spatiotemporal variation of Van der Burgh's coefficient in a salt plug estuary". Hydrology and Earth System Sciences 21, nr 9 (13.09.2017): 4563–72. http://dx.doi.org/10.5194/hess-21-4563-2017.

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Abstract. Salt water intrusion in estuaries is expected to become a serious global issue due to climate change. Van der Burgh's coefficient, K, is a good proxy for describing the relative contribution of tide-driven and gravitational (discharge-driven and density-driven) components of salt transport in estuaries. However, debate continues over the use of the K value for an estuary where K should be a constant, spatially varying, or time-independent factor for different river discharge conditions. In this study, we determined K during spring and neap tides in the dry (< 30 m−3 s−1) and wet (> 750 m−3 s−1) seasons in a salt plug estuary with an exponentially varying width and depth, to examine the relative contributions of tidal versus density-driven salt transport mechanisms. High-resolution salinity data were used to determine K. Discharge-driven gravitational circulation (K ∼ 0.8) was entirely dominant over tidal dispersion during spring and neap tides in the wet season, to the extent that salt transport upstream was effectively reduced, resulting in the estuary remaining in a relatively fresh state. In contrast, K increased gradually seaward (K ∼ 0.74) and landward (K ∼ 0.74) from the salt plug area (K ∼ 0.65) during the dry season, similar to an inverse and positive estuary, respectively. As a result, density-driven inverse gravitational circulation between the salt plug and the sea facilitates inverse estuarine circulation. On the other hand, positive estuarine circulation between the salt plug and the river arose due to density-driven positive gravitational circulation during the dry season, causing the upstream intrusion of high-salinity bottom water. Our results explicitly show that K varies spatially and depends on the river discharge. This result provides a better understanding of the distribution of hydrographic properties.

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Lorenz, Marvin, Knut Klingbeil i Hans Burchard. "Impact of Evaporation and Precipitation on Estuarine Mixing". Journal of Physical Oceanography 51, nr 4 (kwiecień 2021): 1319–33. http://dx.doi.org/10.1175/jpo-d-20-0158.1.

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AbstractRecent studies could link the quantities of estuarine exchange flows to the volume-integrated mixing inside an estuary, where mixing is defined as the destruction of salinity variance. The existing mixing relations quantify mixing inside an estuary by the net boundary fluxes of volume, salinity, and salinity variance, which are quantified as Knudsen or total exchange flow bulk values. So far, river runoff is the only freshwater flux included, and the freshwater exchange due to precipitation and evaporation is neglected. Yet, the latter is the driving force of inverse estuaries, which could not be described by the existing relations. To close this gap, this study considers evaporation and precipitation to complete the existing mixing relations by including cross-surface salinity variance transport. This allows decomposing the mixing into a riverine and a surface transport contribution. The improved relations are tested against idealized two-dimensional numerical simulations of different combinations of freshwater forcing. The mixing diagnosed from the model results agrees exactly with the derived mixing relation. An annual hindcast simulation of the Persian Gulf is then used to test the mixing relations, both exact and approximated, e.g., long-term averaged, for a realistic inverse estuary. The results show that the annual mean mixing contributions of river discharge and evaporation are almost equal, although the freshwater transport due to evaporation is about one order of magnitude larger than the river runoff.

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BITTENCOURT, ABÍLIO C. S. P., GUILHERME C. LESSA, JOSÉ M. L. DOMINGUEZ, LOUIS MARTIN, GERALDO S. VILAS BÔAS i FÉLIX F. FARIAS. "High and low frequency erosive and constructive cycles in estuarine beaches: an example from Garcez Point, Bahia/Brazil". Anais da Academia Brasileira de Ciências 73, nr 4 (grudzień 2001): 599–610. http://dx.doi.org/10.1590/s0001-37652001000400013.

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Monitoring of the morphodynamic variations of the beaches associated with an estuary contiguous with Garcez Point, Bahia, Brazil, and the superposition of aerial photographs from the region, show the presence of distinctive erosive and constructive cycles of low and high frequencies. Between 1959 and 1989, one event of shoreline erosion and progradation was recognized on the oceanic beaches just outside the estuary. Inside the estuary, an erosion phase at the southern margin coincides with a constructive phase at the other side, and vice-versa. On the southern estuarine beach, low-frequency cycles of erosion and progradation are also perceived, but with the inverse trend when compared to the contiguous oceanic beach. During the beach monitoring period (February/1991 to July/1992), the oceanic beach showed retreat rates varying from 23.7m/year, at the channel entrance, to 1.0m/year, three kilometers away from it. During the same period, the estuarine beach advanced at a rate of 60.3m/year. The long-term dynamics of the shoreline position in both sides of the estuarine entrance appears to be related to the position of the channel in the ebb-tidal delta.

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Panfili, Jacques, Jean-Dominique Durand, Khady Diop, Béatrice Gourène i Monique Simier. "Fluctuating asymmetry in fish otoliths and heterozygosity in stressful estuarine environments (West Africa)". Marine and Freshwater Research 56, nr 5 (2005): 505. http://dx.doi.org/10.1071/mf04138.

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Fluctuating asymmetry (FA) is assumed to reflect the developmental instability caused by environmental or genetic stress. Fish otoliths represent a very good tool for investigating the consequence of different effects on FA. Otolith FA analysis, coupled with genetic analysis, has been undertaken on two common West African estuarine species, Ethmalosa fimbriata (EFI) and Sarotherodon melanotheron (SME), in two neighbouring estuaries, in order to highlight the impact of salinity on developmental stability. The Gambia estuary has a normal functioning and the Saloum estuary is inverse (saltier waters in the upper river), reaching extremely high salinities (>100 psu) and constituting severe environmental stress. Five sub-populations of EFI and six of SME were studied along a salinity gradient. The differences between right and left otoliths were estimated with image processing by measuring five dimensions (area, perimeter, diameter, rostrum and posterior radii). Analyses of genetic differentiation at three EPIC and one anonymous nuclear gene loci for EFI and six polymorphic enzymatic loci for SME were carried out to measure the level of heterozygosity. Absolute FA in all otolith traits examined was unaffected by gender but increased significantly with fish size. Size-corrected absolute FA did not show any significant difference among sites differing largely in salinity, although a higher asymmetry in otolith area was recorded in the saltiest site. These findings suggest that otolith asymmetry is a poor indicator of osmotic stress. The individual heterozygosity level did not seem to have an effect on otolith FA for either species, even though a slight correlation appeared with otolith area or perimeter. Otolith FA cannot be considered to be a useful indicator for estimating changes linked with environmental or genetic stress in these estuaries.

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Hofmann, A. F., F. J. R. Meysman, K. Soetaert i J. J. Middelburg. "Factors governing the pH in a heterotrophic, turbid, tidal estuary". Biogeosciences Discussions 6, nr 1 (7.01.2009): 197–240. http://dx.doi.org/10.5194/bgd-6-197-2009.

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Abstract. A method to quantify the influence of kinetically modelled biogeochemical processes on the pH of an ecosystem with time variable acid-base dissociation constants is presented and applied to the heterotrophic, turbid Scheldt estuary (SW Netherlands, N Belgium). Nitrification is identified as the main process governing the pH profile of this estuary, while CO2 degassing and advective-dispersive transport "buffer" the effect of nitrification. CO2 degassing accounts for the largest proton turnover per year in the whole estuary. There is a clear inverse correlation between oxygen turnover and proton turnover. The main driver of long-term changes in the mean estuarine pH from 2001 to 2004 is a changing freshwater flow which influences the pH "directly" via [∑CO2] and [TA] and to a significant amount also "indirectly" via [∑NH4+] and the nitrification rates in the estuary.

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Medeiros, AMA, JEL Barbosa, PR Medeiros, RM Rocha i LF Silva. "Salinity and freshwater discharge determine rotifer distribution at the Mossoró River Estuary (Semiarid Region of Brazil)". Brazilian Journal of Biology 70, nr 3 (sierpień 2010): 551–57. http://dx.doi.org/10.1590/s1519-69842010000300011.

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The present study aimed at evaluating differences in rotifer distribution in three estuarine zones in an inverse estuary located in the Semiarid Region of Brazil. Zones were chosen based on their proximity to the ocean and river border as a means of reflecting a horizontal salinity gradient. High freshwater discharge during the rainy season was the major determinant of rotifer composition. On the other hand, due to higher salinity values during the dry season, very low values of species richness and abundance were observed in all zones. Therefore, the study highlights the constraints of salinity and the positive influence of seasonality and river proximity on rotifer species in a semiarid estuarine environment.

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Cai, Huayang, Ping Zhang, Erwan Garel, Pascal Matte, Shuai Hu, Feng Liu i Qingshu Yang. "A novel approach for the assessment of morphological evolution based on observed water levels in tide-dominated estuaries". Hydrology and Earth System Sciences 24, nr 4 (16.04.2020): 1871–89. http://dx.doi.org/10.5194/hess-24-1871-2020.

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Abstract. Assessing the impacts of both natural (e.g. tidal forcing from the ocean) and human-induced changes (e.g. dredging for navigation and land reclamation) on estuarine morphology is particularly important for the protection and management of the estuarine environment. In this study, a novel analytical approach is proposed for the assessment of estuarine morphological evolution in terms of tidally averaged depth on the basis of the observed water levels along the estuary. The key lies in deriving a relationship between wave celerity and tidal damping or amplification. For given observed water levels at two gauging stations, it is possible to have a first estimation of both wave celerity (distance divided by tidal travelling time) and tidal damping or amplification rate (tidal range difference divided by distance), which can then be used to predict the morphological changes via an inverse analytical model for tidal hydrodynamics. The proposed method is applied to the Lingdingyang Bay of the Pearl River Estuary, located on the southern coast of China, to analyse the historical development of the tidal hydrodynamics and morphological evolution. The analytical results show surprisingly good correspondence with observed water depth and volume in this system. The merit of the proposed method is that it provides a simple approach for understanding the decadal evolution of the estuarine morphology through the use of observed water levels, which are usually available and can be easily measured.

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Burchard, Hans. "Combined Effects of Wind, Tide, and Horizontal Density Gradients on Stratification in Estuaries and Coastal Seas". Journal of Physical Oceanography 39, nr 9 (1.09.2009): 2117–36. http://dx.doi.org/10.1175/2009jpo4142.1.

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Abstract The aim of this one-dimensional water column study is to combine modified versions of three characteristic parameters for periodic tidal flow under the influence of a longitudinal buoyancy gradient—the horizontal Richardson number, the inverse Strouhal number, and the inverse Ekman number—into a parameter space study, including constant wind forcing from various directions. It is shown how the underlying dynamical equations can be cast into nondimensional form, depending mainly on these three nondimensional parameters plus the relative wind speed and the wind direction. Idealized model simulations are carried out for the whole realistic range of horizontal Richardson and inverse Strouhal numbers for various latitudes, showing the amplitude of the tidally induced stratification for a wide range of scenarios. It is found that classical threshold values for the horizontal Richardson number, indicating the switch from periodic stratification to permanent stratification, are valid only for special cases, and that this switch also strongly depends on the inverse Strouhal number, the inverse Ekman number, and the wind vector. The transverse residual flow is close to the thermal wind balance for a variety of parameters, and nondimensionalized longitudinal residual flow shows the classical estuarine exchange flow pattern with little variation in the near-bed onshore component. Wind straining is confirmed as an important estuarine and coastal process, enhancing estuarine circulation for offshore (down estuary) winds and vice versa. Agreement with field data from Liverpool Bay is good, including the explanation of a flood tide local maximum of the dissipation rate in the upper half of the water column. An equation for the second time derivative of the potential energy anomaly is derived for quantifying the dynamical processes leading to stratification due to the straining of the horizontal density gradient.

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Abdul Aziz, Nandi, Yonvitner, Sigid Hariyadi, Syamsul Bahri Agus i I. Wayan Nurjaya. "Sedimentation Profile in Coastal Water Jakarta Bay". Journal of Tropical Fisheries Management 6, nr 1 (12.01.2023): 35–44. http://dx.doi.org/10.29244/jppt.v6i1.43452.

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The waters of Jakarta Bay are one of the waters that are influenced by several fresh water flows that enter from the DKI Jakarta area and its surroundings. Sediment that enters the waters of Jakarta Bay is produced by the activities of the people who live in the Jakarta area and its surroundings. This study aims to analyze the sedimentation and distribution of suspended solids in the Jakarta Bay estuary using an observational approach and spatial analysis. This study uses the Inverse Distance Weighting (IDW) interpolation method. The dominant distribution of sediment in Jakarta Bay is sand with a size ranging from 0.25 to 0.125 mm. TSS (Total Suspended Solids) levels in 11 estuaries in Jakarta Bay ranged from 21 to 150 mg/L in first period and 11 ˗ 259 mg/L in second period. Sedimentation rates that occurred in 11 Jakarta Bay estuaries ranged from 11.12 g/cm2/day to 619.5 g/cm2/day in period one and 10.96 g/cm2/day to 1232.06 g/cm2/day in the second period which is located in Muara Cilincing in both periods. There is a suitable relationship between the TSS value and the sedimentation rate. Estuary TSS values and sedimentation rates are influenced by seasons and anthropogenic activities that occur in the estuary such as reclamation.

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Hein, Sebastian S. V., Vanessa Sohrt, Edgar Nehlsen, Thomas Strotmann i Peter Fröhle. "Tidal Oscillation and Resonance in Semi-Closed Estuaries—Empirical Analyses from the Elbe Estuary, North Sea". Water 13, nr 6 (19.03.2021): 848. http://dx.doi.org/10.3390/w13060848.

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Many tidal influenced estuaries and coastal basins feature tidal amplification because of, e.g., convergence and reflection. Increasing amplification rates were observed in the Elbe estuary, with consequences for construction measures, nautical manoeuvring, flood protection, riverbed morphology and ecosystems. Although many studies were conducted investigating the tidal wave transformation in estuaries, studies based on spatially well-distributed empirical data covering periods over more than a year are rare. To fill this gap, a self-developed adapted harmonic analysis method of least squares was applied to hydrographs from 25 gauges, distributed over the tidal influenced estuary from the river mouth to the tidal border which is given by the weir 160 km upstream of the river mouth. The investigation period for the harmonic analyses covers a whole nodal cycle of 18.613 a beginning in the year 2000. The tidal constituents’ oscillatory behaviour including the appearance of compound tides, generated by nonlinear shallow water processes, and the formation of reflection induced partially standing waves are determined. The tidal constituents show shared frequency-group specific partial clapotis, but also have significant differences in amplification within those groups. The latter fact contributes to the detected inverse proportionality of tidal range amplification inside the estuary to incoming tidal wave height. As reflection can cause resonance in tidal influenced rivers, tests are developed to analyse whether criteria for resonance are met. To determine the system’s specific resonance frequency, a new method was introduced with the three-parameter Lorentzian curve-fitting. As the detected resonance frequency is not close to tidal frequencies, full-established resonance of the tidal wave and of the tidal constituents is not observed in the Elbe estuary. Migrating nodes of the partially standing tidal wave hint at increasing latent resonance.

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Lau, Clive L. F., i David K. Jacobs. "Introgression between ecologically distinct species following increased salinity in the Colorado Delta- Worldwide implications for impacted estuary diversity". PeerJ 5 (12.12.2017): e4056. http://dx.doi.org/10.7717/peerj.4056.

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We investigate hybridization and introgression between ecologically distinct sister species of silverside fish in the Gulf of California through combined analysis of morphological, sequence, and genotypic data. Water diversions in the past century turned the Colorado River Delta from a normal estuary to a hypersaline inverse estuary, raising concerns for the local fauna, much of which is endangered. Salinity differences are known to generate ecological species pairs and we anticipated that loss of the fresher-water historic salinity regime could alter the adaptive factors maintaining distinction between the broadly distributed Gulf-endemicColpichthys regisand the narrowly restricted Delta-endemicColpichthys hubbsi, the species that experienced dramatic environmental change. In this altered environmental context, these long-isolated species (as revealed by Cytochromebsequences) show genotypic (RAG1, microsatellites) evidence of active hybridization where the species ranges abut, as well as directional introgression fromC. regisinto the range center ofC. hubbsi. Bayesian group assignment (STRUCTURE) on six microsatellite loci and multivariate analyses (DAPC) on both microsatellites and phenotypic data further support substantial recent admixture between the sister species. Although we find no evidence for recent population decline inC. hubbsibased on mitochondrial sequence, introgression may be placing an ancient ecological species at risk of extinction. Such introgressive extinction risk should also pertain to other ecological species historically sustained by the now changing Delta environment. More broadly, salinity gradient associated ecological speciation is evident in silverside species pairs in many estuarine systems around the world. Ecological species pairs among other taxa in such systems are likely poorly understood or cryptic. As water extraction accelerates in river systems worldwide, salinity gradients will necessarily be altered, impacting many more estuary and delta systems. Such alteration of habitats will place biodiversity at risk not only from direct effects of habitat destruction, but also from the potential for the breakdown of ecological species. Thus, evolutionary response to the anthropogenic alteration of salinity gradients in estuaries merits investigation as the number of impacted systems increases around the globe, permitting parallel study of multiple systems, while also permitting a conservation management response to help preserve this little championed component of biodiversity.

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Cai, H., H. H. G. Savenije i C. Jiang. "Analytical approach for predicting fresh water discharge in an estuary based on tidal water level observations". Hydrology and Earth System Sciences 18, nr 10 (17.10.2014): 4153–68. http://dx.doi.org/10.5194/hess-18-4153-2014.

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Abstract. As the tidal wave propagates into an estuary, the tidally averaged water level tends to rise in landward direction due to the density difference between saline and fresh water and the asymmetry of the friction. The effect of friction on the residual slope is even more remarkable when accounting for fresh water discharge. In this study, we investigate the influence of river discharge on tidal wave propagation in the Yangtze estuary with specific attention to residual water level slope. This is done by using a one-dimensional analytical model for tidal hydrodynamics accounting for the residual water level. We demonstrate the importance of the residual slope on tidal dynamics and use it to improve the prediction of the tidal propagation in estuaries (i.e. tidal damping, velocity amplitude, wave celerity and phase lag), especially when the influence of river discharge is significant. Finally, we develop a new inverse analytical approach for estimating fresh water discharge on the basis of tidal water level observations along the estuary, which can be used as a tool to obtain information on the river discharge that is otherwise difficult to measure in the tidal region.

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Cai, H., H. H. G. Savenije i C. Jiang. "Analytical approach for predicting fresh water discharge in an estuary based on tidal water level observations". Hydrology and Earth System Sciences Discussions 11, nr 6 (27.06.2014): 7053–87. http://dx.doi.org/10.5194/hessd-11-7053-2014.

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Abstract. As the tidal wave propagates into an estuary, the tidally averaged water level tends to rise in landward direction due to the density difference between saline and fresh water and the asymmetry of the friction. The effect of friction on the residual slope is even more remarkable when accounting for fresh water discharge. In this study, we investigate the influence of river discharge on tidal wave propagation in the Yangtze estuary with specific attention to residual water level slope. This is done by using a one-dimensional analytical model for tidal hydrodynamics accounting for the residual water level. We demonstrate the importance of the residual slope on tidal dynamics and use it to improve the prediction of the tidal propagation in estuaries (i.e., tidal damping, velocity amplitude, wave celerity and phase lag), especially when the influence of river discharge is significant. Finally, we develop a new inverse analytical approach for estimating fresh water discharge on the basis of tidal water level observations along the estuary, which can be used as a tool to obtain information on the river discharge that is otherwise difficult to measure in the tidal region.

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Bange, Hermann W., Chun Hock Sim, Daniel Bastian, Jennifer Kallert, Annette Kock, Aazani Mujahid i Moritz Müller. "Nitrous oxide (N2O) and methane (CH4) in rivers and estuaries of northwestern Borneo". Biogeosciences 16, nr 22 (15.11.2019): 4321–35. http://dx.doi.org/10.5194/bg-16-4321-2019.

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Abstract. Nitrous oxide (N2O) and methane (CH4) are atmospheric trace gases which play important roles in the climate and atmospheric chemistry of the Earth. However, little is known about their emissions from rivers and estuaries, which seem to contribute significantly to the atmospheric budget of both gases. To this end concentrations of N2O and CH4 were measured in the Rajang, Maludam, Sebuyau and Simunjan rivers draining peatland in northwestern (NW) Borneo during two campaigns in March and September 2017. The Rajang River was additionally sampled in August 2016 and the Samunsam and Sematan rivers were additionally sampled in March 2017. The Maludam, Sebuyau, and Simunjan rivers are typical “blackwater” rivers with very low pH (3.7–7.8), very high dissolved organic carbon (DOC) concentrations (235–4387 mmol L−1) and very low O2 concentrations (31–246 µmol L−1; i.e. 13 %–116 % O2 saturation). The spatial and temporal variability of N2O and CH4 concentrations (saturations) in the six rivers or estuaries was large and ranged from 2.0 nmol L−1 (28 %) to 41.4 nmol L−1 (570 %) and from 2.5 nmol L−1 (106 %) to 1372 nmol L−1 (57 459 %), respectively. We found no overall trends of N2O with O2 or NO3-, NO2- or NH4+, and there were no trends of CH4 with O2 or dissolved nutrients or DOC. N2O concentrations showed a positive linear correlation with rainfall. We conclude, therefore, that rainfall is the main factor determining the riverine N2O concentrations since N2O production or consumption in the blackwater rivers themselves seems to be low because of the low pH. CH4 concentrations were highest at salinity = 0 and most probably result from methanogenesis as part of the decomposition of organic matter under anoxic conditions. CH4 in the concentrations in the blackwater rivers showed an inverse relationship with rainfall. We suggest that CH4 oxidation in combination with an enhanced river flow after the rainfall events might be responsible for the decrease in the CH4 concentrations. The rivers and estuaries studied here were an overall net source of N2O and CH4 to the atmosphere. The total annual N2O and CH4 emissions were 1.09 Gg N2O yr−1 (0.7 Gg N yr−1) and 23.8 Gg CH4 yr−1, respectively. This represents about 0.3 %–0.7 % of the global annual riverine and estuarine N2O emissions and about 0.1 %–1 % of the global riverine and estuarine CH4 emissions. Therefore, we conclude that rivers and estuaries in NW Borneo – despite the fact their water area covers only 0.05 % of the global river/estuarine area – contribute significantly to global riverine and estuarine emissions of N2O and CH4.

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Rochelle-Newall, E. J., V. T. Chu, O. Pringault, D. Amouroux, R. Arfi, Y. Bettarel, T. Bouvier i in. "Phytoplankton diversity and productivity in a highly turbid, tropical coastal system (Bach Dang Estuary, Vietnam)". Biogeosciences Discussions 8, nr 1 (18.01.2011): 487–525. http://dx.doi.org/10.5194/bgd-8-487-2011.

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Abstract. The factors controlling estuarine phytoplankton diversity and production are relatively well known in temperate systems. Less however is known about the factors affecting phytoplankton community distribution in tropical estuaries. This is surprising given the economic and ecological importance of these large, deltaic ecosystems, such as are found in South East Asia. Here we present the results from an investigation into the factors controlling phytoplankton distribution and phytoplankton-bacterial coupling in the Bach Dang Estuary, a sub-estuary of the Red River system, in Northern Vietnam. Phytoplankton diversity and primary and bacterial production, nutrients and metallic contaminants (mercury and organotin) were measured during two seasons: wet (July 2008) and dry (March 2009). Phytoplankton community composition differed between the two seasons with only a 2% similarity between July and March. The large spatial extent and complexity of defining the freshwater sources meant that simple mixing diagrams could not be used in this system. We therefore employed multivariate analyses to determine the factors influencing phytoplankton community structure. Salinity and suspended particulate matter were important factors in determining phytoplankton distribution, particularly during the wet season. We also show that phytoplankton community structure is probably influenced by the concentrations of mercury species (inorganic mercury and methyl mercury in both the particulate and dissolved phases) and of tri-, di, and mono-butyl tin species found in this system. Freshwater phytoplankton community composition was associated with dissolved methyl mercury and particulate inorganic mercury concentrations during the wet season, whereas, during the dry season, dissolved methyl mercury and particulate butyl tin species were important factors for the discrimination of the phytoplankton community structure. Phytoplankton-bacterioplankton coupling was also investigated during both seasons. In the inshore, riverine stations the ratio between bacterial production and dissolved primary production was high supporting the hypothesis that bacterial carbon demand is supported by allochthonous riverine carbon sources. The inverse was true in the offshore stations, where BP:DPP values were less than 1, potentially reflecting differences in primary production due to shifting phytoplankton community diversity.

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Gning, Ndombour, François Le Loc'h, Omar T. Thiaw, Catherine Aliaume i Guy Vidy. "Estuarine resources use by juvenile Flagfin mojarra (Eucinostomus melanopterus) in an inverse tropical estuary (Sine Saloum, Senegal)". Estuarine, Coastal and Shelf Science 86, nr 4 (marzec 2010): 683–91. http://dx.doi.org/10.1016/j.ecss.2009.11.037.

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Burchard, Hans, i Robert D. Hetland. "Quantifying the Contributions of Tidal Straining and Gravitational Circulation to Residual Circulation in Periodically Stratified Tidal Estuaries". Journal of Physical Oceanography 40, nr 6 (1.06.2010): 1243–62. http://dx.doi.org/10.1175/2010jpo4270.1.

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Abstract This numerical modeling study quantifies for the first time the contribution of various processes to estuarine circulation in periodically stratified tidal flow under the impact of a constant horizontal buoyancy gradient. The one-dimensional water column equations with periodic forcing are first cast into nondimensional form, resulting in a multidimensional parameter space spanned by the modified inverse Strouhal number and the modified horizontal Richardson number, as well as relative wind speed and wind direction and the residual runoff. The along-tide momentum equation is then solved for the tidal-mean velocity profile in such a way that it is equated to the sum of the contributions of tidal straining (resulting from the temporal correlation between eddy viscosity and vertical shear), gravitational circulation (resulting from the depth-varying forcing by a constant horizontal buoyancy gradient), wind straining, and depth-mean residual flow (resulting from net freshwater runoff). This definition of tidal straining does not only account for tidal asymmetries resulting from horizontal buoyancy gradients but also from wind straining and residual runoff. For constant eddy viscosity, the well-known estuarine circulation analytical solution with polynomial residual profiles is directly obtained. For vertically parabolic and constant-in-time eddy viscosity, a new analytic solution with logarithmic residual profiles is found, showing that the intensity of the gravitational circulation scales with the horizontal Richardson number. For scenarios with realistic spatially and temporally varying eddy viscosity, a numerical water column model equipped with a state-of-the-art two-equation turbulence closure model is applied to quantify the individual contributions of the various processes to estuarine circulation. The fundamental outcome of this study is that, for irrotational flow with periodic stratification and without wind forcing and residual runoff, the tidal straining is responsible for about two-thirds and gravitational circulation is responsible for about one-third of the estuarine circulation, proportionally dependent on the horizontal Richardson number, and weakly dependent on the Strouhal number. This new and robust result confirms earlier estimates by H. Burchard and H. Baumert, who suggested that tidal straining is the major generation mechanism for estuarine turbidity maxima. However, a sensitivity analysis of the model results to details of the turbulence closure model shows some uncertainty with respect to the parameterization of sheared convection during flood. Increasing down-estuary wind straining and residual runoff reduce the quantitative contribution of tidal straining. For relatively small horizontal Richardson numbers, the tidal straining contribution to estuarine circulation may even be reversed by down-estuary wind straining.

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Li, Mingming, i Chunyan Li. "Comparison of Flows through a Tidal Inlet in Late Spring and after the Passage of an Atmospheric Cold Front in Winter Using Acoustic Doppler Profilers and Vessel-Based Observations". Sensors 22, nr 9 (3.05.2022): 3478. http://dx.doi.org/10.3390/s22093478.

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This paper discusses the application of acoustic Doppler current profilers (ADCP) for the quantification of transport of water and the underlining physical mechanism. The transport of water through estuaries and tidal inlets is affected by tide, river flow, and wind. It is often assumed that wind effects in such systems are negligible unless under severe weather conditions. This study compares the ADCP-measured flows across a tidal inlet under weak wind conditions in late spring and those after the passage of an atmospheric cold front in winter. The Barataria Pass is a major inlet connecting Barataria Bay and northern Gulf of Mexico. The water exchange between the bay and coastal ocean is influenced by wind, especially in winter, because tide in the region is small (microtidal). The winter weather and late spring–summer weather are different. This difference results in different estuarine circulations. To examine this, two surveys were carried out with ship-mounted ADCPs—one in winter (19 December 2014) shortly after the passage of a cold front from the northwest, and the other in late spring (4 May 2015) with weak southeasterly winds. Distinctly different features of mean transport through the inlet were observed between the two surveys. The results from the first survey in winter showed that the total water transport was from the bay to the coastal ocean under northerly winds with intense outflows in shallow water, which is a typical signature of wind effects. The net flow was outward when the water level dropped. Data from the second survey in spring showed that the mid-channel water flew out of the bay (against the wind), whilst inflow appeared at both ends across the inlet, which was also a response to the weak wind stress and outward pressure gradient force set by the estuarine flow. The inflow at the eastern end (exceeding 0.1 m/s) is consistent with the idea that the coastal current resulted from the Mississippi River outflow enters the bay from the eastern end. The influence of tidal oscillations on water exchange appeared to be higher in the late spring data. The hydrographic observations in spring showed typical tidal straining features of an inverse estuary during the ebb–flood cycle, while salinity in the eastern shallow water generally varied with time, indicating the inflow of fresher water into the bay, confirming previous observations from summer 2008.

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Kämpf, Jochen, Nicholas Payne i Paul Malthouse. "Marine Connectivity in a Large Inverse Estuary". Journal of Coastal Research 26 (listopad 2010): 1047–56. http://dx.doi.org/10.2112/jcoastres-d-10-00043.1.

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Feng, Jiangang, Huangrong Chen, Hailong Zhang, Zhaoxin Li, Yang Yu, Yuanzhi Zhang, Muhammad Bilal i Zhongfeng Qiu. "Turbidity Estimation from GOCI Satellite Data in the Turbid Estuaries of China’s Coast". Remote Sensing 12, nr 22 (17.11.2020): 3770. http://dx.doi.org/10.3390/rs12223770.

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Knowledge of the distribution and variation of water turbidity directly represent important information related to the marine ecology and multiple biogeochemical processes, including sediment transport and resuspension and heat transfer in the upper water layer. In this study, a neural network (NN) approach was applied to derive the water turbidity using the geostationary ocean color imager (GOCI) data in turbid estuaries of the Yellow River and the Yangtze River. The results showed a good agreement between the GOCI-derived turbidity and in situ measured data with a determination coefficient (R2) of 0.84, root mean squared error (RMSE) of 58.8 nephelometric turbidity unit (NTU), mean absolute error of 25.1 NTU, and mean relative error of 34.4%, showing a better performance than existing empirical algorithms. The hourly spatial distributions of water turbidity in April 2018 suggested that high turbidity regions were distributed in the Yellow River estuary, Yangtze River estuary, Hangzhou Bay, and coastal waters of Zhejiang Province. Furthermore, the relationship between water turbidity and tide were estimated. A defined turbid zone was defined to evaluate the diurnal variations of turbidity, which has subtle changes at different times. Our results showed an inverse relationship between turbidity and tide over six selected stations, i.e., when the value of turbidity is high, then the corresponding tidal height is usually low, and vice versa. The combined effects of tidal height and tidal currents could explain the phenomena, and other factors such as winds also contribute to the turbidity distributions.

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Mingelbier, M., F. Lecomte i J. J. Dodson. "Climate change and abundance cycles of two sympatric populations of smelt (Osmerus mordax) in the middle estuary of the St. Lawrence River, Canada". Canadian Journal of Fisheries and Aquatic Sciences 58, nr 10 (1.10.2001): 2048–58. http://dx.doi.org/10.1139/f01-140.

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Commercial catches of two ecologically distinct sympatric smelt (Osmerus mordax) populations segregated along the two shores of the St. Lawrence middle estuary exhibited inverse patterns with periodicities on the order of 30 years. The influence of water level in the St. Lawrence River and air temperature, chosen to reflect variations in hydrology and climate, differed markedly between the two populations. Analyses revealed that both water level and temperature were generally positively related with north-shore smelt landings and negatively related with south-shore smelt landings. For both populations, a number of significant climatic factors contributing to variance in smelt landings were lagged by one to three years relative to the year of landings, indicating that climatic variables influenced smelt recruitment. The contrasting role of hydroclimatic variables in driving these abundance cycles is likely related to differential exploitation of estuarine habitats; the south-shore population is associated with shallow shoal habitat, whereas the north-shore population is associated with deep channel habitat. The responses of the two smelt populations also reflect the fundamental ecological differences existing between shoal and channel habitats, indicating that future climate change may differentially affect other populations or species that are segregated between these two habitats.

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Karunarathna, Harshinie, Dominic Reeve i Mark Spivack. "Long-term morphodynamic evolution of estuaries: An inverse problem". Estuarine, Coastal and Shelf Science 77, nr 3 (kwiecień 2008): 385–95. http://dx.doi.org/10.1016/j.ecss.2007.09.029.

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Shen, J., i A. Y. Kuo. "Inverse Estimation of Parameters for an Estuarine Eutrophication Model". Journal of Environmental Engineering 122, nr 11 (listopad 1996): 1031–40. http://dx.doi.org/10.1061/(asce)0733-9372(1996)122:11(1031).

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Shen, J., i A. Y. Kuo. "Application of Inverse Method to Calibrate Estuarine Eutrophication Model". Journal of Environmental Engineering 124, nr 5 (maj 1998): 409–18. http://dx.doi.org/10.1061/(asce)0733-9372(1998)124:5(409).

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Lavı́n, M. F., V. M. Godı́nez i L. G. Alvarez. "Inverse-estuarine Features of the Upper Gulf of California". Estuarine, Coastal and Shelf Science 47, nr 6 (grudzień 1998): 769–95. http://dx.doi.org/10.1006/ecss.1998.0387.

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Messer, Lauren F., Mark V. Brown, Paul D. Van Ruth, Mark Doubell i Justin R. Seymour. "Temperate southern Australian coastal waters are characterised by surprisingly high rates of nitrogen fixation and diversity of diazotrophs". PeerJ 9 (1.03.2021): e10809. http://dx.doi.org/10.7717/peerj.10809.

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Biological dinitrogen (N2) fixation is one mechanism by which specific microorganisms (diazotrophs) can ameliorate nitrogen (N) limitation. Historically, rates of N2 fixation were believed to be limited outside of the low nutrient tropical and subtropical open ocean; however, emerging evidence suggests that N2 fixation is also a significant process within temperate coastal waters. Using a combination of amplicon sequencing, targeting the nitrogenase reductase gene (nifH), quantitative nifH PCR, and 15N2 stable isotope tracer experiments, we investigated spatial patterns of diazotroph assemblage structure and N2 fixation rates within the temperate coastal waters of southern Australia during Austral autumn and summer. Relative to previous studies in open ocean environments, including tropical northern Australia, and tropical and temperate estuaries, our results indicate that high rates of N2 fixation (10–64 nmol L−1 d−1) can occur within the large inverse estuary Spencer Gulf, while comparatively low rates of N2 fixation (2 nmol L−1 d−1) were observed in the adjacent continental shelf waters. Across the dataset, low concentrations of NO3/NO2 were significantly correlated with the highest N2 fixation rates, suggesting that N2 fixation could be an important source of new N in the region as dissolved inorganic N concentrations are typically limiting. Overall, the underlying diazotrophic community was dominated by nifH sequences from Cluster 1 unicellular cyanobacteria of the UCYN-A clade, as well as non-cyanobacterial diazotrophs related to Pseudomonas stutzeri, and Cluster 3 sulfate-reducing deltaproteobacteria. Diazotroph community composition was significantly influenced by salinity and SiO4 concentrations, reflecting the transition from UCYN-A-dominated assemblages in the continental shelf waters, to Cluster 3-dominated assemblages in the hypersaline waters of the inverse estuary. Diverse, transitional diazotrophic communities, comprised of a mixture of UCYN-A and putative heterotrophic bacteria, were observed at the mouth and southern edge of Spencer Gulf, where the highest N2 fixation rates were observed. In contrast to observations in other environments, no seasonal patterns in N2 fixation rates and diazotroph community structure were apparent. Collectively, our findings are consistent with the emerging view that N2 fixation within temperate coastal waters is a previously overlooked dynamic and potentially important component of the marine N cycle.

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Nunes Vaz, Richard A., Geoffrey W. Lennon i David G. Bowers. "Physical behaviour of a large, negative or inverse estuary". Continental Shelf Research 10, nr 3 (marzec 1990): 277–304. http://dx.doi.org/10.1016/0278-4343(90)90023-f.

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Adama, Gueye, Badiane Insa, Youm Cheikh Ibrahima, Sow El Hadji i Fofana Cheikh Abdoul Kader. "Les Diatomées Sub-fossiles de L’estuaire du Saloum, Sénégal: inventaire floristique et paléo-environnement fournis par la carotte de Ndangane Babou". European Scientific Journal, ESJ 18, nr 33 (31.10.2022): 55. http://dx.doi.org/10.19044/esj.2022.v18n33p55.

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Dans le programme de reconstitution de l’histoire des estuaires et lagunes du Sénégal et de l’inventaire de la microflore à diatomées de la Séné-Gambie, une carotte de sondage de 400 cm de long a été réalisée à Ndangane Babou sur un des bras de l’estuaire du Saloum (14°07′53.86″ N/16°17′40.08″ W) à 95 km de l’embouchure. L’analyse comparée de la lithologie et de la microflore a montré une corrélation significative entre la fraction pélitique, l’abondance absolue des diatomées et leur diversité spécifique. Le faible taux de sable, majoritairement d’origine marine tout au long de la carotte pourrait s’expliquer par l’éloignement du site de prélèvement par rapport à l’embouchure du fleuve. L’étude a permis d’inventorier 89 espèces et variétés de diatomées appartenant à 48 genres. Les genres les plus représentés sont Nitzschia (11 espèces), Coscinodiscus (7 espèces), Amphora et Navicula (4 espèces chacune). Huit espèces sont citées pour la première fois en Séné-Gambie. La dominance des espèces euryhalines tout au long de la carotte ainsi que la présence constante des formes d’eau douce témoignent de variations de la salinité entre les saisons hivernales marquées par des apports d’eau douce et les saisons sèches. D’un milieu deltaïque ouvert aux influences marines (Zone A), le Saloum a été marqué par des upwellings qui ont apportés des sels nutritifs jusqu’à la hauteur de Ndangane Babou durant le dépôt de la zone B. Par la suite, l’installation d’un climat chaud et humide a entrainé une augmentation de la pluviométrie et permis d’atteindre une paléo-productivité primaire et une paléo-biodiversité maximales au sommet de la zone C, avant l’installation d’un climat aride à l’origine du caractère inverse de l’estuaire (zone D). Dans ce milieu, l’hydrodynamisme serait à l’origine de l’augmentation du taux de sable et corrélativement la diminution des diatomées suivie de leur disparition. As part of the program to rebuilt the estuaries and lagoons history in Senegal and the inventory of the diatom microflora in Senegal and Gambia, a 400 cm long core was taken at Ndangane Babou on one of the arms from the Saloum estuary (14°07′53.86″ N/16°17′40.08″ W), 95 km from the ocean. The comparative analysis of the lithology and the microflora showed a significant correlation between the lutite fraction, the absolute abundance of diatoms and their specific diversity. The low rate of sand, mostly of marine origin throughout the core, could be explained by the distance of the site from the mouth of the estuary. The study allowed to inventory 89 species and varieties of diatom belonging to 48 genera. The most represented genera are Nitzschia (11 species), Coscinodiscus (7 species each), Amphora and Navicula (4 species each). Eight species are cited for the first time in Sene-Gambia. The dominance of euryhaline species throughout the core as well as the constant presence of freshwater forms attest to variations in salinity between the rainy seasons marked by freshwater inflows and the dry seasons. From a delta environment open to marine influences (Zone A), the Saloum estuary was marked by upwellings brought nutritive salts up to the height of Ndangane Babou during Zone B deposit. Subsequently, the installation of a hot and humid climate led to an improvement in rainfall and allowed to achieve maximum primary paleo-productivity and paleo-biodiversity at the top of zone C, before the installation of an arid climate at the origin of the opposite character of the estuary (zone D). In this environment, hydrodynamics would be the cause of the increase in the rate of sand and correlatively the decrease in diatoms followed by their disappearance.

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Veeh, H. Herbert, Willard S. Moore i Stephen V. Smith. "The behaviour of uranium and radium in an inverse estuary". Continental Shelf Research 15, nr 13 (listopad 1995): 1569–83. http://dx.doi.org/10.1016/0278-4343(95)00031-u.

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Nunes, RA, i GW Lennon. "Physical property distributions and seasonal trends in Spencer Gulf, South Australia: an inverse estuary". Marine and Freshwater Research 37, nr 1 (1986): 39. http://dx.doi.org/10.1071/mf9860039.

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Results are described from the first long-term, systematic program of oceanographic measurements in Spencer Gulf, South Australia. The gulf belongs to a subset of semi-enclosed seas that are characterized by a net fluid loss, in this case induced by excess evaporation, and a resulting circulation that is the reverse of that found in a classical estuary. In Spencer Gulf, this inverse estuary character involves the production of salinities as high as 48 at the head in late summer. The seasonal variations of temperature and salinity, from both large-scale CTD surveys and time-series observations at a fixed station, reveal the manner in which the gulf responds to seasonal influences. From such information, the gulf's dispersive capabilities are quantitatively assessed, and the implications of thermohaline processes for gulf-ocean exchange are discussed.

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Suteja, Yulianto, Anna Ida Sunaryo Purwiyanto i Fitri Agustriani. "Merkuri (Hg) di Permukaan Perairan Muara Sungai Banyuasin, Sumatera Selatan, Indonesia". Journal of Marine and Aquatic Sciences 5, nr 2 (24.10.2018): 177. http://dx.doi.org/10.24843/jmas.2019.v05.i02.p03.

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The purposes of this study were to determine the water quality, concentration and distribution of Hg in the surface water of Banyuasin river estuary. This research was conducted in June 2016 with 26 sampling stations. Measurement of in situ water quality was done using Conductivity Temperature Depth (CTD) multiparameter profiler while Hg metal was measured using Atomic Absorption Spectroscopy (AAS). The data obtained was interpolated by Inverse Distance Weighted (IDW) and then mapped spatially. The results showed that in general the water quality in Banyuasin river estuary still meets the seawater quality standards for marine biota based on KepMenLH no. 51 in 2004. The concentration of Hg in Banyuasin river estuary ranges from 0.001-0.032 mg/L with a distribution pattern that generally increases towards the ocean. The Hg concentration at the Banyuasin river estuary is on the maximum limit and exceeds the quality standard for marine biota.

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Diadhiou, H. D., P. Diop, I. Diedhiou i A. B. Badji. "Variations inter annuelles de la production de la crevette géante tigrée Penaeus Monodon fabricius, 1798 (penaeidae) pêchée dans l’estuaire de Casamance, au Sénégal". Journal de la Recherche Scientifique de l’Université de Lomé 26, nr 1 (17.04.2024): 25–39. http://dx.doi.org/10.4314/jrsul.v26i1.5.

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La crevette géante tigrée, Penaeus monodon (Fabricius, 1798) est pêchée de façon régulière dans l’estuaire inversé de Casamance depuis 2012 par les pêcheurs migrants maliens. Sa présence dans cet estuaire est atypique, car ce n’est pas son habitat naturel. Les principales zones de pêche pour cette ressource sont les affluents et le cours principal de l'estuaire de Casamance, s'étendant de l'embouchure des cours d'eau à la ville de Ziguinchor. Dans cette zone, la crevette géante tigrée est capturée à l'aide d'un filet maillant dérivant de fond, qui est également utilisé pour la pêche du Drepane africana, Arius spp et Plectorhuncus spp. Les débarquements de la crevette géante tigrée dans l'estuaire de la Casamance sont analysés et discutés dans cet article scientifique. Les données sont collectées à Ziguinchor, le principal marché de commercialisation de l’espèce en Casamance. Cette étude a permis d'évaluer les quantités de crevettes tigrées débarquées sur la période allant de 2012 à 2018, se situant entre 3 et 9 tonnes par an, sur une période de pêche de trois à cinq mois. Une analyse de variance entre les tonnages débarqués et le nombre d'engins de pêche ciblant l'espèce indique une différence significative dans les résultats d'une année à l'autre. Les résultats obtenus ont permis de déterminer que la principale période d'abondance de la ressource dans la zone de pêche se situe pendant la saison chaude sèche, entre les mois d'avril et juin. The giant tiger shrimp, Penaeus monodon (Fabricius, 1798) has been regularly fished in the inverted Casamance estuary since 2012 by Malian migrant fishermen. This presence in the estuary is atypical because it is not its natural habitat. The tributaries and the main course of the Casamance estuary, stretching from the mouth of the river to the town of Ziguinchor, constitute the primary fishing zones for the fishing units targeting this resource. In this area, the giant tiger shrimp is exclusively captured using bottom drifting gillnets. The drift gillnet, which targets Drepane africana, Arius spp, and Plectorhuncus spp, is loaded onto the same canoe for fishing the fish. Landings of the giant tiger shrimp in the Casamance estuary are analyzed and discussed in this scientific article. The data is collected in Ziguinchor, the main marketing market for the species in Casamance. This study enabled the evaluation of the quantities of tiger shrimp landed from 2012 to 2018, ranging between 3 and 9 tons per year over a fishing period of three to five months. An analysis of variance between the landed tonnages and the number of fishing gears targeting the species indicates a significant difference in the results recorded from one year to the next. The obtained results pinpointed the main period of the abundance of the resource in the fishing zone during the hot dry season, between April and June.

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Messer, LF, M. Doubell, TC Jeffries, MV Brown i JR Seymour. "Prokaryotic and diazotrophic population dynamics within a large oligotrophic inverse estuary". Aquatic Microbial Ecology 74, nr 1 (12.01.2015): 1–15. http://dx.doi.org/10.3354/ame01726.

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Winant, Clinton D., i Guillermo Gutiérrez de Velasco. "Tidal Dynamics and Residual Circulation in a Well-Mixed Inverse Estuary". Journal of Physical Oceanography 33, nr 7 (lipiec 2003): 1365–79. http://dx.doi.org/10.1175/1520-0485(2003)033<1365:tdarci>2.0.co;2.

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Gutiérrez de Velasco, Guillermo, i Clinton D. Winant. "Wind- and Density-Driven Circulation in a Well-Mixed Inverse Estuary". Journal of Physical Oceanography 34, nr 5 (maj 2004): 1103–16. http://dx.doi.org/10.1175/1520-0485(2004)034<1103:wadcia>2.0.co;2.

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Lennon, G. W., D. G. Bowers, R. A. Nunes, B. D. Scott, M. Ali, J. Boyle, Cai Wenju i in. "Gravity currents and the release of salt from an inverse estuary". Nature 327, nr 6124 (czerwiec 1987): 695–97. http://dx.doi.org/10.1038/327695a0.

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Jendyk, Jan, Deevesh A. Hemraj, Melissa H. Brown, Amanda V. Ellis i Sophie C. Leterme. "Environmental variability and phytoplankton dynamics in a South Australian inverse estuary". Continental Shelf Research 91 (grudzień 2014): 134–44. http://dx.doi.org/10.1016/j.csr.2014.08.009.

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Denis, Jérémy, Khalef Rabhi, François Le Loc’h, Frida Ben Rais Lasram, Kévin Boutin, Maria Kazour, Mamadou Diop, Marie-Christine Gruselle i Rachid Amara. "Role of estuarine habitats for the feeding ecology of the European eel (Anguilla anguilla L.)". PLOS ONE 17, nr 7 (6.07.2022): e0270348. http://dx.doi.org/10.1371/journal.pone.0270348.

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This study aims to characterize and compare the feeding ecology of the European eels (Anguilla anguilla L.) during the continental phase (i.e. yellow and silver) along a salinity gradient (i.e. lower, middle and upper) in six northern France estuaries (i.e. brackish water). The diet and stable isotopic (i.e. δ15N and δ13C values) compositions of eels collected with a fyke net in six estuaries (Slack, Wimereux, Liane, Canche, Authie and Somme estuaries) located along the French coast of the eastern English Channel per season over a year were described by combining gut content and stable isotope analyses. Eel guts were dominated by typical BW prey, Malacostraca and Actinopterygii (54% and 40%, respectively), with the gammare Gammarus zaddachi and the green crab Carcinus maenas (38% and 14%, respectively), and smaller yellow eels of A. anguilla and juvenile European flounder, Platichthys flesus (19% and 14%, respectively) being the most frequently found in their guts. The δ13C values of a majority of eels confirmed the sea- and brackish water-specific carbon resources. Dietary and isotopic niche revealed no clear change between total length, silvering stages and seasons, but a significant difference between salinity gradients and estuaries. Eels δ13C values showed significant enrichment from upper to lower along the estuaries while the δ15N values showed an inverse effect, with the lowest values in the lower part and highest in the upper part. Higher variability in δ13C values in larger estuaries suggested that eels feed on a wide range of food sources than in smaller estuaries. While eels in the smaller estuaries fed mainly on Actinopterygii prey, eels in the larger ones had a lower trophic level (i.e. δ15N values) and fed mainly on Malacostraca prey. This spatial difference in dietary and isotopic niche is discussed in relation to biological structure of eel and environmental variables.

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Otsuka, Amanda Yumi, Fernando Antônio do Nascimento Feitosa, Manuel de Jesus Flores Montes i Alex Costa da Silva. "Influence of fluvial discharge on the dynamics of Chlorophyll-α in the continental shelf adjacent to the Recife Port Basin (Pernambuco-Brazil)". Brazilian Journal of Oceanography 66, nr 1 (marzec 2018): 91–103. http://dx.doi.org/10.1590/s1679-87592018149106601.

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Abstract This study was undertaken in the coastal zone of the state of Pernambuco adjacent to the Recife port area, which corresponds to the inner shelf. This research aimed to analyze the dynamics of chlorophyll-a and several other environmental variables. Sampling was undertaken bimonthly on the surface from September 11th to May 10th, thus including the rainy and dry periods, and during low tide in spring tide. The parameters analyzed were chlorophyll-a, salinity, temperature, transparency, dissolved oxygen, oxygen saturation rate, pH, suspended solids, dissolved inorganic nutrients. Phytoplankton biomass ranged from 13.48 to 145.09 mg m-3 in the estuarine area and on the inner shelf, the variation being from 0.24 to 19.29 mg m-3 in the dry season and from 0.78 to 5.20 mg m-3 in the rainy season. PCA showed a direct relationship of chlorophyll-a with ammonia, phosphate and transparency and an inverse relationship with suspended particulate matter and nitrate. Biomass did not vary significantly different as a result of seasonal or spatial dynamics. The estuary of the Capibaribe River is considered highly impacted, and as it forms the Recife port basin, it joins with two more strongly eutrophic water bodies, the Beberibe River and the Pina Basin, leading to an amplification of its influence on the adjacent shelf. In terms of the river plume's dispersion in the Port of Recife, the presence of a dike causes some disturbance in the direction of the current, limiting the plume to the area close to the coast and influences the oceanographic variables on the inner continental shelf.

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Nunes-Vaz, Richard A. "The salinity response of an inverse estuary to climate change & desalination". Estuarine, Coastal and Shelf Science 98 (luty 2012): 49–59. http://dx.doi.org/10.1016/j.ecss.2011.11.023.

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Passadore, Cecilia, Luciana Möller, Fernando Diaz-Aguirre i Guido J. Parra. "Demography of southern Australian bottlenose dolphins living in a protected inverse estuary". Aquatic Conservation: Marine and Freshwater Ecosystems 27, nr 6 (12.05.2017): 1186–97. http://dx.doi.org/10.1002/aqc.2772.

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Petrusevics, PM. "SST fronts in inverse estuaries, South Australia-indicators of reduced gulf-shlef exchange". Marine and Freshwater Research 44, nr 2 (1993): 305. http://dx.doi.org/10.1071/mf9930305.

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During the austral summer, the entrance to the South Australian gulfs exhibits sea surface temperature (SST) fronts of between 3 and 3.5°C that are clearly discernible on NOAA/AVHRR imagery. The surface fronts are formed by seasonal juxtaposition of relatively warm gulf and cooler bight water. Field surveys indicate that the SST fronts coexist with and overlay strong benthic temperature and salinity differentials of 74°C and 1.2-1.5, respectively. Density variation in the entrance to both gulfs exhibits a density minimum at all depths and suggests bottom convergence of density currents that effectively isolates gulf from shelf waters during the summer. Analysis of field temperature-salinity data, using the 1-atmosphere equation of state, indicates that the density minimum is formed by mutual compensation of the salinity and temperature dependent terms. The effect of the combined salinitytemperature dependent terms is less but not insignificant. The value of satellite SST imagery as a tool to signal periods of reduced communication between the gulfs and the shelf is revealed.

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Lomakin, P. D. "Investigation of the field of colored dissolved organic matter concentration and its relationship to the salinity field in Dnieper-Bug estuary". Monitoring systems of environment, nr 2 (24.06.2021): 72–80. http://dx.doi.org/10.33075/2220-5861-2021-2-72-80.

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Based on the data of the expedition carried out in August 2012, the features of the structure of the salinity and fDOM concentration fields, as well as the correlation between these values in the Dnieper-Bug estuary, are analyzed. It is shown that the salinity field in the Dnieper-Bug estuary is characterized by all structural features typical of coastal sea areas freshened by river runoff, while the fDOM concentration field has anomalous properties due to the presence of an anthropogenic component of this value. The presence of fDOM of anthropogenic origin is most significant in the western part of the Dnieper estuary and is related to the influence of the city and port of Ochakov. The maximum content of fDOM was recorded here, which caused an anomalous horizontal distribution of this substance concentration, increasing from the mouth of the Dnieper to the open Black Sea waters. The contaminated areas of the studied water areas, which are adjacent to settlements and occupy the predominant part of the water surface of the Dnieper-Bug estuary, are characterized by an increased fDOM content and intrusive feature of the vertical structure of this substance concentration field of. It is revealed that in the Dnieper-Bug estuary there is no inverse correlation between the salinity fields and fDOM concentration, which is typical for unpolluted coastal waters, freshened by river runoff. A similar anomaly is an indicator of the pollution of coastal waters with organic matter.

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Corlis, Nicholas J., H. Herbert Veeh, John C. Dighton i Andrew L. Herczeg. "Mixing and evaporation processes in an inverse estuary inferred from δ2H and δ18O". Continental Shelf Research 23, nr 8 (maj 2003): 835–46. http://dx.doi.org/10.1016/s0278-4343(03)00029-3.

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Petrusevics, P., J. A. T. Bye, V. Fahlbusch, J. Hammat, D. R. Tippins i E. van Wijk. "High salinity winter outflow from a mega inverse-estuary—the Great Australian Bight". Continental Shelf Research 29, nr 2 (luty 2009): 371–80. http://dx.doi.org/10.1016/j.csr.2008.10.003.

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Parolin, Radael de Souza, Antônio José da Silva Neto, Pedro Paulo Gomes Watts Rodrigues i Orestes Llanes Santiago. "Estimation of a contaminant source in an estuary with an inverse problem approach". Applied Mathematics and Computation 260 (czerwiec 2015): 331–41. http://dx.doi.org/10.1016/j.amc.2015.03.054.

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de Silva Samarasinghe, J. R., i G. W. Lennon. "Hypersalinity, flushing and transient salt-wedges in a tidal gulf—an inverse estuary". Estuarine, Coastal and Shelf Science 24, nr 4 (kwiecień 1987): 483–98. http://dx.doi.org/10.1016/0272-7714(87)90129-6.

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Vallino, J. J., C. S. Hopkinson i R. H. Garritt. "Estimating estuarine gross production, community respiration and net ecosystem production: a nonlinear inverse technique". Ecological Modelling 187, nr 2-3 (wrzesień 2005): 281–96. http://dx.doi.org/10.1016/j.ecolmodel.2004.10.018.

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Ferreira, Inês, Felippe A. Daros, Cláudia Moreira, Diana Feijó, Alberto Rocha, Ana Mendez-Vicente, Jorge Pisonero i Alberto Teodorico Correia. "Is Chelidonichthys lucerna (Linnaeus, 1758) a Marine Estuarine-Dependent Fish? Insights from Saccular Otolith Microchemistry". Fishes 8, nr 7 (24.07.2023): 383. http://dx.doi.org/10.3390/fishes8070383.

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Tub gurnard, Chelidonichthys lucerna (Linnaeus, 1758), is a Mediterranean-Atlantic benthic species usually captured as by-catch by Portuguese traditional fisheries and considered the most important commercial fish species of the family Triglidae. However, to date, little is known about its habitat residency and whether the species can be considered a marine estuarine-dependent fish. Otolith microchemistry has proven effective in providing information about fish movement patterns throughout different water salinities. In this study, core-to-edge transects of Sr:Ca in the fish saccular otoliths of 35 juveniles of C. lucerna captured in March 2007 by a scientific survey along the Portuguese coast were used to assess the species movement between brackish and marine waters. Data suggest that most individuals (97%) have an estuarine-dependent profile, with 63% showing a clear presence in marine waters during the early life history periods. Evidence of an estuarine residence throughout the fish life cycle was found in only 3% of individuals. Ba:Ca profiles did not reflect an inverse relationship with Sr:Ca salinity results but corroborated findings from other authors about the influence of upwelling processes and freshwater runoffs on Ba incorporation into the otoliths of coastal fish. Furthermore, the data also showed that C. lucerna can occupy and migrate among habitats with diverse salinity degrees, showing high environmental plasticity and adaptation.

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