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The brown alga Pelvetia canaliculata is one of the species successfully adapted to intertidal conditions. Inhabiting the high intertidal zone, Pelvetia spends most of its life exposed to air, where it is subjected to desiccation, light, and temperature stresses. However, the physiological and biochemical mechanisms allowing this alga to tolerate such extreme conditions are still largely unknown. The objective of our study is to compare the biochemical composition of Pelvetia during the different phases of the tidal cycle. To our knowledge, this study is the first attempt to draft a detailed biochemical network underneath the complex physiological processes, conferring the successful survival of this organism in the harsh conditions of the high intertidal zone of the polar seas. We considered the tide-induced changes in relative water content, stress markers, titratable acidity, pigment, and phlorotannin content, as well as the low molecular weight metabolite profiles (GC-MS-based approach) in Pelvetia thalli. Thallus desiccation was not accompanied by considerable increase in reactive oxygen species content. Metabolic adjustment of P. canaliculata to emersion included accumulation of soluble carbohydrates, various phenolic compounds, including intracellular phlorotannins, and fatty acids. Changes in titratable acidity accompanied by the oscillations of citric acid content imply that some processes related to the crassulacean acid metabolism (CAM) may be involved in Pelvetia adaptation to the tidal cycle.

22 pages, 11 figures, 1 table [EN] Good knowledge of the coastal circulation patterns is essential for a proper management of the coastline, especially in areas with a high anthropic pressure. In order to determine the main characteristics of the coastal currents in the Gulf of Urabá, the seasonal patterns of surface circulation were measured and analyzed during times of high and low rainfall along 6 km of coastline, between the Punta de Las Vacas and Punta Yarumal coastal spit systems, in the municipality of Turbo, Antioquia. These measurements were made with surface drifters, which were launched at different tide stages and tracked for time periods based on the semi-diurnal cycle. The in-situ measurements were analyzed alongside tide and wind data from a climatic station located near the gulf. The circulation patterns behaved differently depending on the season of the year. In the rainy season, with southerly winds, the drifters moved mainly towards the north while during the dry season, with northerly winds, all the drifters moved to the south. Although the circulation patterns showed a strong relationship with the tidal cycle and wind conditions, the Turbo and El Uno Bays modified some of the drifter’s paths [ES] Conocer los patrones de circulación costera es fundamental para gestionar adecuadamente la franja litoral, especialmente en áreas con alta presión antrópica. Con el objetivo de determinar las características de las corrientes costeras en el golfo de Urabá, se midieron y analizaron los patrones estacionales de circulación superficial durante las épocas de mucha y poca lluvia a lo largo de 6 km de costa, entre las espigas litorales de punta de Las Vacas y punta Yarumal del municipio de Turbo, Antioquia. Estas mediciones se realizaron con derivadores superficiales, que fueron lanzados en diversos estadios de la marea y rastreados durante periodos cercanos al ciclo semidiurno. Las mediciones in situ se analizaron considerando la evolución de la marea y los vientos observados en una estación climática ubicada cerca del golfo. Los patrones de circulación mostraron un comportamiento diferente durante las dos estaciones del año. La temporada de mucha lluvia, con vientos del sur, presentó trayectorias hacia el norte y la temporada de poca lluvia, con vientos del norte, las trayectorias fueron hacia el sur. Aunque los patrones de circulación mostraron una fuerte relación con la marea y el viento, las trayectorias de algunos derivadores se modificaron localmente por la presencia de geoformas como las bahías de Turbo y El Uno Part of this research was carried out within the framework of the project “Collaboration for the development of an oceanographic, atmospheric and environmental observatory project for the Gulfs of Darién and Urabá, Colombia”, reference COOPB20337, financed by the State Agency: Consejo Superior de Investigaciones Científicas, Spain (CSIC) With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)

This study assessed the effects of tidal stages and habitat conditions on nekton assemblage and distribution in the Kakum River estuarine mangrove system in the Central Region of Ghana. Teleosts an...

The main objective of this chapter is to demonstrate developments in port maintenance techniques that have been intensively tested in major European ports. As regular port maintenance is highly expensive, port authorities are considering alternative strategies. Water Injection Dredging (WID) can be one of the most efficient alternatives. Using this dredging method, density currents near the bed are created by fluidizing fine-grained sediments. The fluidized sediment can leave the port channels and be transported away from the waterways via the natural force of gravity. WID actions can be successfully coupled with the tidal cycle for extra effectiveness. In addition, WID is combined with another strategy to reduce maintenance dredging: the nautical bottom approach, which enables the vessel to navigate through the WID-induced fluid mud layer. The nautical bottom approach uses the density or the yield stress of sediment to indicate the navigability after WID rather than the absolute depth to the sediment bed. Testing WID-based port maintenance requires thorough preparation. Over the years modeling and monitoring tools have been developed in order to test and optimize WID operations. In this chapter, the application of the recently developed tools is discussed.

In the fall of 2018, studies of suspended particulate matter and its organic part in the water column and their lateral flux on the Karelian coast of the White Sea were carried out. The concentration of suspended particulate matter varied from 0.42 to 0.93 μg/L, and the concentration of Corg ranged from 124 to 249 μg/L. In the water column, 25 registration taxa of phytoplankton were recorded; it was shown that its species composition changed from the surface to the bottom. The lateral flux values varied from 159 to 439 μg m–2 h–1. As part of lateral flux, 49 phytoplankton taxa were revealed. It was shown that, depending on the tidal cycle phase, not only the quantitative characteristics of the lateral flux of phytoplankton change, but also the species composition of microalgae. In the tidal phase, more organic matter enters the inner regions of the bays than is carried out from these areas to the low-tide phase. At high tide, the proportion of phytoplankton organisms in the lateral flux is more than 80%; at low tide, it is less than 55%.

Despite sea turtles in Papua New Guinea being culturally important and heavily harvested, no in-country density estimates have been previously established. We provide the first estimates of sea turtle density in Papua New Guinea from two locations around Mussau Island where turtle consumption is banned due to religious beliefs. We obtained density estimates using a low-cost, in-water distance sampling method. Our monitoring shows that the island has a high density of sea turtles (almost exclusively Chelonia mydas). At Lolieng, a site with a steep reef drop off, we recorded a mean of 7.4 turtles ha−1 (s.d. = 2.6) at the reef crest during low tide (across all sampling occasions), which is comparable to high density sites globally. By comparison, we recorded a much lower estimate of 1.1 turtles ha−1 (s.d. = 0.4) at Nae, a site with an extensive, low profile reef system. Additionally, our modelling shows that tidal cycle is an essential covariate for assessing sea turtle density for in-water distance sampling. We advocate that Papua New Guinea needs to invest in long-term monitoring at a national scale to track the sustainability of this important cultural resource, and that in-water distance sampling is a low cost monitoring method that potentially could be used for this purpose albeit subject to certain caveats.

A faecal indicator bacteria, Escherichia coli (E. coli), is widely used in monitoring health of estuaries, where tidal amplitude plays a critical role in its variability. Mahanadi estuary, formed at the mouth of a major tropical river Mahanadi, has large socio-economic importance. This anthropogenically stressed estuary remains understudied with respect to E. coli. Hence, this study addressed E. coli variability in Mahanadi estuary with novel sampling strategy that can be implemented at other tropical estuaries. The sampling strategy includes simultaneous measurements, at lesser-saline upper-estuary and higher-saline lower-estuary, over a tidal cycle. Although no significant variability of E. coli was observed between upper and lower-estuary, overall average count was higher during low tide and lower during high tide attributed to salinity fluctuations. Intermittent surpass of E. coli counts above recommended limits in Mahanadi estuary, indicated potential health risk, thus demands for frequent water quality monitoring and management strategies.

This study analyzed the reproductive cycle of Chiton virgulatus and its relationship with air temperature (AT) sea and surface temperature (SST), photoperiod, and tidal cycle (TC) in Bahía de La Paz, in the coast of the Gulf of California. Monthly samples were collected from September 2008 to September 2009. The parameters recorded included total length, total weight, and gonad weight of each organism; the gonad was processed using a histological technique, and the gonadal index and length at first maturity (L50) were estimated. C. virgulatus displays partial spawning with a reproductive peak in summer and autumn (July to December). The frequency of ripe organisms was associated with rises in SST (30.6 ºC), AT (29.9 ºC), and TC (68 cm, high tidal), while photoperiod (longer days) regulated the frequency of developing organisms. The length at first maturity was 29.7 mm. Chiton virgulatus is a polyplacophoran species in which high temperatures and high tides influence reproductive timing, while an increase in daylight boosts gonad development.

Olivella minuta is an abundant neogastropod on sandy beaches from Texas (USA) to southern Brazil. This study aimed to characterize and compare the feeding activity and diet of a Brazilian population of O. minuta in different tidal zones (intertidal and subtidal), and different tidal levels (high and low tides), with three combinations of tidal zone and level being studied (intertidal during low tide, intertidal during high tide and subtidal). The results showed that diet composition was generally similar among tidal conditions, with O. minuta being a generalist, feeding on 45 different food items. Feeding activity, however, was higher in the intertidal during low tide, whereas the richness and diversity of food items were higher in the intertidal during high tide. The higher feeding activity of O. minuta during low tide may be linked to a lower risk of predation; at low tide organisms may be able to feed for a longer time, and this may be particularly true on beaches with fine sand, where water retention is higher than that on beaches with coarse sand. The higher diversity of food items consumed in the intertidal during high tide is likely related to the increased prevalence of planktonic food during high tide. Our results indicate that tidal zone and level may strongly influence the feeding activity of coastal soft-bottom species and that species may show higher feeding activity during low tide. Given the current loss of intertidal habitats due to anthropogenic activity and climate-change associated factors, our study has important implications, highlighting the importance of intertidal areas for the ecology and conservation of sandy beach species.

Europa likely has an active surface ice shell producing numerous low-magnitude (

In this study we investigate important abiotic factors that may help Monodonta lineata to orient itself in tis natural environment, for example to get into crevices during low tide. To examine these factors, we designed four biological tests with sea-snails collected at the Plage du Cabellou (Atlantic Ocean). Within these tests we found out, that Monodonta lineata prefers shady places, that the activity-phases of this species is possibly correlated with the tidal cycle and that their movement is not directional towards the open sea. In dieser Studie untersuchen wir wichtige abiotische Faktoren, die Monodonta lineata helfen können, sich in dieser natürlichen Umgebung zu orientieren, beispielsweise um bei Ebbe in Spalten zu gelangen. Um diese Faktoren zu untersuchen, haben wir vier biologische Tests mit Meeresschnecken entworfen, die am Plage du Cabellou (Atlantischer Ozean) gesammelt wurden. Bei diesen Tests haben wir festgestellt, dass Monodonta lineata schattige Plätze bevorzugt, dass die Aktivitätsphasen dieser Art möglicherweise mit dem Gezeitenzyklus korreliert sind und ihre Bewegung nicht Richtung offenes Meer gerichtet ist.

A setup of a two-dimensional hydrodynamic model based on Delft3D modeling system for the coastal waters of Jeddah is described. Sensitivity tests of both numerical and physical parameters defined in the model and validation of the numerical model are also described. The model was forced by major tidal constituents along the open boundary. The performance of the model was evaluated using available water level observations at four sites along Jeddah coast. The simulated tidal elevations showed a very good matching with the observed tidal elevations. The spring and neap tidal cycle are reproduced by the model with good degree. Statistical analysis showed that RMSD error ranges between 0.001 and 0.17 m, while the MAD values vary between 0.02 and 0.08 m. Comparison of simulated and observed amplitudes and phases of the main tidal components also showed a good agreement. The predicted tide-induced current flooding and ebbing features during spring and neap tides were analyzed. The model suggests that the flow in the region is weak where the strengths of the currents increase towards the shallow areas.

The current research focuses on a thorough sea level analysis in Mersa Matruh. Hourly sea level observations from 18th January, 2004 to 31st December, 2004 are used in the study. The T_Tide package is applied to obtain the different tidal constituents and the residuals. Results reveal a mean sea level of 53.6 cm. The present study indicated that the observed sea level at Mersa Matruh is significantly affected by the mixed semidiurnal tide with a tidal cycle ratio of 0.26, and the ratio of spring to neap tides is 4.7. The hourly and monthly observed sea level confirmed their maximum values during January, while the minimum is during December. The monthly mean sea level exhibit a seasonal pattern of variation, with low values in spring and high in summer. Finally, the relation between hourly observed sea level and the air temperature, mean sea level pressure together with 10-m wind speed components are used to understand the dynamic of sea level variability. This partially shows the great importance of the zonal wind speed U10 and the air temperature than the other studied parameters. Twenty percent of the residual elevations represents storm surge events in the investigated area.

Accurate predictions of the effects of warming temperatures under climate change on an individual species require an accurate characterization of its current and future thermal environment. Behavioral responses to environmental heterogeneity are an important but poorly understood determinant of species’ body temperatures and thermal risks. In this paper we describe the steps necessary for determining a species’ opportunities for behavioral buffering of climate change, and provide examples using a combination of previously published studies and new results for the intertidal snail Nucella ostrina. We find that N. ostrina’s current patterns of daily microhabitat selection have the potential to buffer it from warming temperatures under climate change. N. ostrina’s foraging behavior is highly correlated with the 14.5 d semilunar tidal cycle, shielding it from both current and future thermal stress.

A new sedimentation device was developed and tested. "Device of registration the lateral flow of sedimentary matter" is intended for sampling a sedimentary particulate matter moving in the water column in the lateral directions. The device can be successfully used to solve sedimentological, biological, ecological problems, including the monitoring of solid pollutants transfer.

Intertidal culture in meshed bags on trestles is worldwide the most established culture method for oysters. Culturists can affect oyster performance by adjusting stocking density and immersion time, and it can be expected that these factors are not independent. The combined effect of stocking density and immersion time on survival, growth and condition of oysters was investigated on a culture site, where oysters are usually stocked at 8 kg bag−1. Half-grown oysters were stocked in three biomass densities: 4, 8 and 12 kg bag−1, nested within three immersion times (87%, 76% and 73% of tidal cycle). Chlorophyll-a concentration peaked in summer (~ 3–10 μg l−1) and was low in autumn (~ 1 μg l−1), and high chlorophyll-a levels coincided with oyster spawning period. Survival was not affected by density or immersion time. Shell growth per oyster and biomass production per bag were density dependent—higher at 4 than at 12 kg bag−1—but neither were different from 8 kg bag−1. Growth rates were negativity related with immersion over the spawning period but showed a (non-significant) positive trend over other periods. At harvest, condition per oyster decreased with stocking density and increased with immersion. There was no interaction between density and immersion. Treatments had a more pronounced effect on meat content than on biomass production. Hence, oysters might be kept at higher stocking densities to increase biomass production during most of the growth cycle but restocked in lower densities, with longer immersion times prior to harvest to maximize meat content at harvest.

The intertidal beach profile provides coastal engineers and managers with a good indication of the current state of a sandy coastline, however regular beach profile measurements are time consuming and expensive to obtain using conventional surveying methods. The potential to reconstruct the intertidal beach profile from measurements of reflected waves is tested here using three field datasets covering a different range of hydro-morphological conditions from dissipative, to reflective. The swash is found to behave as a low-pass filter on reflected waves, with a cut-off frequency that primarily depends on the swash slope. An agreement is found between video-derived swash spectrum saturation tail and the shortest reflected waves, computed from deep water directional wave measurements. By integrating this swash slope over a tidal cycle, the shape of the intertidal beach profile can be reconstructed. Our results clearly show the potential of such method to estimate complex intertidal beach profile, such as double-slope beaches.

© 2019 Elsevier B.V. Intertidal flats are shallow-water environments that undergo cyclical variations in water depth, leading to a frequent occurrence of extremely shallow water stages (ESWS; water depths 0.2 m), and the rate of change was an order of magnitude faster than during RDWS. This larger and faster bed-level change occurred even though the ESWS duration only accounted for 10% of the entire tidal cycle. This result occurred because the bed shear stress due to combined current–wave action during ESWS, was, on average, two times higher than during RDWS at the flood stage causing more extensive erosion. Whereas during the ebb stage, this shear stress during ESWS was only half of that during RDWS resulting in greater accretion. The main implications of these results are that, because ESWS occur frequently (twice every tide) and are associated with large bed shear stress and bed-level changes, these conditions are likely to play an important role in morphological changes of intertidal flats. Our study shows that ESWS have a key influence on intertidal flat hydrodynamics and sediment dynamics. Thus our results are the basis for an improved understanding of the coastal morphodynamic processes on intertidal flats.

When conducting ecological research on tidal mudflats, understanding how long any given area is underwater is vitally important. This paper describes a method for calculating the percent inundation time for a single tidal cycle (neap to spring tide) within a GIS environment. The primary variable is elevation, thus, having an accurate digital elevation model (DEM) is critical. Output from the model can then be integrated into existing biological databases to help interpret and understand the ecology of tidal mudflats.

The expression of individual behaviour as a function of environmental variation (behavioural plasticity) is recognized as a means for animals to modify their phenotypes in response to changing conditions. Plasticity has been studied extensively in recent years, leading to an accumulation of evidence for behavioural plasticity within natural populations. Despite the recent attention given to studying individual variation in behavioural plasticity, there is still a lack of consensus regarding its causes and constraints. One pressing question related to this is whether individual plasticity carries over across temporal and environmental gradients. That is, are some individuals more plastic (responsive) than others in general? Here, we examined the influence of temporal and environmental gradients on individual behavioural responses in a marine gastropod, Littoraria irrorata. We measured individual boldness repeatedly over time and in response to tidal cycle (high vs. low, an index of risk) and daily temperature fluctuations (known to affect metabolism), in a controlled field experiment. On average, boldness increased from high to low tide and with increasing temperature but decreased marginally over time. Individuals also differed in their responses to variation in tide and temperature, but not over time. Those which were relatively bold at high tide (when predation risk is greater) were similarly bold at low tide, whereas shy individuals became much more "bold" at low tide. Most notably, individuals that were more responsive to tide (and thus risk) were also more responsive to temperature changes, indicating that plasticity was correlated across contexts (r = 0.57) and that bolder individuals were least plastic overall. This study provides a rare and possibly first example of consistency of individual behavioural plasticity across contexts, suggesting underlying physiology as a common mechanism, and raises the possibility of correlational selection on plasticity.

The lunar nodal cycle, produced by the varying declination of the Moon over a period of 18.61 years, drives changes in tidal amplitude globally. However, constraining the range of changes in tidal amplitude that can be expected over a nodal cycle from real observations is rarely considered for coastal hazard planning. In this study, we use hourly tide gauge observations with record lengths >19 years from 574 stations distributed worldwide to examine the contribution of the nodal modulation to monthly high water levels. Our results show that the influence of the lunar nodal cycle on high water levels is largest at tide gauge stations located in the Gulf of Tonkin, English Channel, and Bristol Channel, amounting up to 30 cm in range, suggesting that in the coming decades the impact of the nodal cycle on high water levels in those regions could be greater than that of global mean sea level rise, which is up to 17 cm by 2030, according to the Intergovernmental Panel on Climate Change fifth assessment report projections. We also examine the phase of nodal modulation and show that the estimated phases exhibit two clusters: one cluster (111° ± 10°) corresponds with the locations having a diurnal form of tides, whereas the other cluster (−59° ± 11°) corresponds with the locations exhibiting a semidiurnal form of tides. Nodal modulation in the diurnal and semidiurnal locations will peak again in 2025 and 2034, respectively, resulting in enhanced potential for coastal hazard in the respective regions. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Published version

International audience; Productive and ecologically highly valuable ecosystems, macrotidal estuaries are also characterised by complex habitat and connectivity dynamics driven by tidal and freshwater influence. Organisms living in these constantly changing systems have to match their movement patterns to the shifting habitat mosaic using available windows of connectivity to access habitat patches of interest. This appears particularly important for the juvenile stages of many fish species colonising shallow and intertidal areas of the estuaries as summer nurseries. We apply tools from landscape ecology to investigate the estuarine habitat and connectivity dynamics on the example of juvenile seabass (Dicentrarchus labrax). We test under which conditions spatio-temporal bottlenecks to estuarine nursery colonisation may emerge for this species in a human-modified estuary. Combining a hydrodynamic model of the Seine estuary with remote sensing data allows us to capture structural changes in habitat availability and connectivity at the estuarine scale and at a fine spatio-temporal resolution. With chronological least-cost modelling of successive tidal steps, we assess patterns of nursery accessibility and estimate tidal colonisation fronts for different mobility scenarios. We show that, at certain hydrological conditions, tidal water level variation causes local disruptions of habitat availability and connectivity, creating temporary bottlenecks for seabass juveniles’ movement. Fish mobility appears determinant for their vulnerability to these connectivity disruptions. Our approach allows for quantitative assessment and visualisation of riverscape complexity related to tidal dynamics. It is applicable to other highly dynamic ecosystems, where the mobile nature of connectivity and habitats needs to be integrated into conservation and management planning.

Numerous studies have evaluated the acoustic characteristics of soniferous snapping shrimp, but a few are based on long-term mooring measurements. In this study, underwater ambient noise signals were collected from a hydrophone moored 10 m from the sea bed in the coastal sea of western Jeju, South Korea, from mid-September 2019 for 90 days to analyze the variation in the sound of snapping shrimp. The kernel signal and a threshold value were utilized to identify the snapping shrimp, and the snap rate per minute was computed for quantitative analysis. The results show that the mean and standard deviation of the snap rate in the western sea of Jeju was 2132 ± 432 per minute during the whole measurement period. The surface water temperature and tidal level decreased by 7 °C from 25 °C and 50 cm from 190 cm, respectively, over 90 days. The snap rate decreased from September mainly due to the decrease in water temperature by 71 times per minute for every 1 °C decrease. It showed a circadian cycle, increasing by 17~24% at sunrise and sunset compared to the daytime minimum. The snap rate at night was the highest in late summer but the rate dropped like the one during the day in late fall. The snap rate at high tide was 13% higher on average than at low tide. The circadian and tidal changes of the snapping shrimp sound from long-term mooring measurements may be used as primary data for underwater ambient noise and the ecological behavior of snapping shrimp.

El delfín austral es uno de los cetáceos más comunes de Tierra del Fuego, Argentina. Sin embargo, ciertos aspectos de su población aún se desconocen. Con el objetivo de caracterizar el uso de hábitat de la especie en la zona, se realizaron observaciones desde costa y se analizaron sus patrones comportamentales en función del estado de la marea y el bosque de macroalgas. Los resultados obtenidos sugieren que ambas variables in uyen en la frecuencia de los comportamientos. Las actividades más frecuentes fueron búsqueda de alimento y descanso. Este estudio aporta datos que pueden contribuir a planes de manejo en el ecosistema marino austral. Peale’s dolphin is one of the most common species of cetaceans in Tierra del Fuego, Argentina. However, limited information exists about the local population. In order to characterize the habitat use by Peale’s dolphin, land-based observations were carried out during a summer season. Behavioral patterns were studied in relation to tidal cycles and kelp forest, and the main activities displayed were determined. Foraging and resting were the most frequent behaviors observed. Dolphin’s behavior seems to be related to the tidal cycle and to its position relative to the kelp bed. This study provides data that can contribute to management plans of the austral marine ecosystem. Fil: Ordoñez, Constanza. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Diez, Mariano Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Torres, Monica Analia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Dellabianca, Natalia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

The concentrations of Cr, Ni, Cu, Zn, As, Cd, Pb, and Al in suspended particles were measured, and temperature, salinity, flow velocity and direction during a tidal cycle were observed before and after Typhoon Fung-wong at six stations in Quanzhou Bay, respectively. The comparison results show that, after the typhoon, the salinity in Quanzhou Bay decreased, whereas the concentrations of heavy metals increased by a factor of between 2 and 10, and the high heavy metal concentration corresponded to the low value of ratio between heavy metals and Al (HMs/Al), suggesting that these increased heavy metals were mainly from natural sources. Instantaneous unit width flux calculations for heavy metals at different stations indicate that sediments are an important source of heavy metals in suspended particles under the influence of typhoon, which has significantly contribution to understanding the impact of typhoons on the heavy metal pollution in the coastal area.

The feeding habitats of Great (Ardea alba) and Snowy (Egretta thula) egrets at the Great Marsh in Northeastern Massachusetts, USA, were characterized through field observations over two years during the breeding seasons of 2012 and 2013. Both species were from a large breeding colony making a daily commute to the Great Marsh for foraging. Habitats at the Great Marsh were delineated as marsh pools, the vegetated marsh, impoundments, open water, tidal flats, and tidal creeks and ditches. Observations (45 counts in 2012 and 48 in 2013) consisted of recording the number of birds, behavior (feeding or not), habitat, and the time of observation and relating these observations to the tidal cycle. The preferred feeding habitats of Snowy Egrets were in marsh pools and along the edges of large impoundments. The preferred feeding habitats of Great Egrets were on the marsh platform, particularly at high tides, and marsh pools. An analysis of physical characteristics with locations of feeding sites revealed no consistent patterns. Certain sites would occasionally support large numbers of feeding Great and Snowy egrets one day only to be ignored the next day at the same tide. The results suggest that Great and Snowy egrets are opportunistic in their selection of feeding sites at the Great Marsh. A future of wetter marshes might provide more feeding opportunities for Great and Snowy egrets, at least in the short-term.

The tide-induced resuspension of sediments plays important roles in the efflux of particulate organic carbon (POC) from rivers to the coastal sea. Although dissolved organic carbon (DOC) comprises more than half of the riverine flux of organic carbon to the ocean, the influence of sediment resuspension induced by the tidal cycle on DOC dynamics is largely unknown. This study examined the dynamics of POC, particulate organic nitrogen (PON), DOC, humic-like and protein-like fluorescent dissolved organic matter (DOM) in relation to the tidal cycle in the Chikugo and Hayatsue River Estuaries, Kyushu, Japan. This study is the first to show both the particulate organic matter (POM) and DOM dynamics in relation to the tidal cycle in the macrotidal estuaries. We found that the turbidity changed with the tidal cycle and that there were significant positive correlations of turbidity with POC and PON in the Chikugo River mouth, suggesting that tide-induced sediment resuspension supplied POM to the water column. The DOC concentration, humic-like and protein-like fluorescent DOM were not correlated with turbidity but were negatively correlated with salinity. These results suggest that POM efflux, but not DOM efflux, can be accelerated by tide-induced sediment resuspension in the macrotidal estuaries., Water, 12(9), art.no.2561; 2020

International audience; From 2015 to 2019 we installed high-frequency (HF) sea surface temperature (SST), salinity, fluorescence, dissolved oxygen (DO) and partial pressure of CO 2 (pCO 2) sensors on a cardinal buoy of opportunity (ASTAN) at a coastal site in the southern Western English Channel (sWEC) highly influenced by tidal cycles. The sensors were calibrated against bimonthly discrete measurements performed at two long-term time series stations near the buoy, thus providing a robust multi-annual HF dataset. The tidal transport of a previously unidentified coastal water mass and an offshore water mass strongly impacted the daily and seasonal variability of pCO 2 and pH. The maximum tidal variability associated to spring tides (>7 m) during phytoplankton blooms represented up to 40% of the pCO 2 annual signal at ASTAN. At the same time, the daily variability of 0.12 pH units associated to this tidal transport was 6 times larger than the annual acidification trend observed in the area. A frequency/time analysis of the HF signal revealed the presence of a day/night cycle in the tidal signal. The diel biological cycle accounted for 9% of the annual pCO 2 amplitude during spring phytoplankton blooms. The duration and intensity of the biologically productive periods, characterized by large inter-annual variability, were the main drivers of pCO 2 dynamics. HF monitoring enabled us to accurately constrain, for the first-time, annual estimates of air-sea CO 2 exchanges in the nearshore tidally-influenced waters of the sWEC, which were a weak source to the atmosphere at 0.51 mol CO 2 m −2 yr −1. This estimate, combined with previous studies, provided a full latitudinal representation of the WEC (from 48 • 75 N to 50 • 25 N) over multiple years for air-sea CO 2 fluxes in contrasted coastal ecosystems. The latitudinal comparison showed a clear gradient from a weak source of CO 2 in the tidal mixing region toward sinks of CO 2 in the stratified region with a seasonal thermal front separating these hydrographical provinces. In view of the fact that several continental shelf regions have been reported to have switched from sources to sinks of CO 2 in the last century, weak CO 2 sources in such tidal mixing areas could potentially become sinks of atmospheric CO 2 in coming decades.

From 2015 to 2019 we installed high-frequency (HF) sea surface temperature (SST), salinity, fluorescence, dissolved oxygen (DO) and partial pressure of CO2 (pCO2) sensors on a cardinal buoy of opportunity (ASTAN) at a coastal site in the southern Western English Channel (sWEC) highly influenced by tidal cycles. The sensors were calibrated against bimonthly discrete measurements performed at two long-term time series stations near the buoy, thus providing a robust multi-annual HF dataset. The tidal transport of a previously unidentified coastal water mass and an offshore water mass strongly impacted the daily and seasonal variability of pCO2 and pH. The maximum tidal variability associated to spring tides (>7 m) during phytoplankton blooms represented up to 40% of the pCO2 annual signal at ASTAN. At the same time, the daily variability of 0.12 pH units associated to this tidal transport was 6 times larger than the annual acidification trend observed in the area. A frequency/time analysis of the HF signal revealed the presence of a day/night cycle in the tidal signal. The diel biological cycle accounted for 9% of the annual pCO2 amplitude during spring phytoplankton blooms. The duration and intensity of the biologically productive periods, characterized by large inter-annual variability, were the main drivers of pCO2 dynamics. HF monitoring enabled us to accurately constrain, for the first-time, annual estimates of air-sea CO2 exchanges in the nearshore tidally-influenced waters of the sWEC, which were a weak source to the atmosphere at 0.51 mol CO2 m–2 yr–1. This estimate, combined with previous studies, provided a full latitudinal representation of the WEC (from 48°75′ N to 50°25′ N) over multiple years for air-sea CO2 fluxes in contrasted coastal ecosystems. The latitudinal comparison showed a clear gradient from a weak source of CO2 in the tidal mixing region toward sinks of CO2 in the stratified region with a seasonal thermal front separating these hydrographical provinces. In view of the fact that several continental shelf regions have been reported to have switched from sources to sinks of CO2 in the last century, weak CO2 sources in such tidal mixing areas could potentially become sinks of atmospheric CO2 in coming decades.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2020JG005739; International audience; There is growing evidence that a substantial fraction of the dissolved organic and inorganic carbon (DOC and DIC) and particulate organic carbon (POC) can be exported from mangroves to the ocean. Yet our understanding of C fluxes in mangrove forests is limited to only few regional studies that exclude the world's longest sediment dispersal system connected to the Amazon River. The present study aims at (1) examining tidal fluctuations of DOC, POC, and DIC; their isotopes; and optical properties such as chromophoric dissolved organic matter (CDOM) and (2) estimating their exchange fluxes between the mangroves and adjacent coastal water in the Sinnamary estuary, French Guiana. Time series observation highlighted that physical processes coupled to tides controlled diel dynamics and sources of DOC (e.g., litter leaching and pore water seepage) and POC (microphytobenthos, sediment resuspension, and bioturbation activities). Intense benthic remineralization could account for high water column pCO2 and DIC exchange flux during the low tide. Mangrove-derived DOC export to inner shelf (8.14 g C m−2 day−1) was exceeding import of POC and DIC from the mud bank and marine sources to the mangroves (1.35 and 0.90 g C m−2 day−1, respectively). Because of specific dynamics of the Amazon mobile muds, local geomorphology, water column stratification, and environmental forcing, Guianese mangroves cannot be seen as simple C exporters to the Atlantic waters. These first data setting on C fluxes for the region should be included along with other studies to improve global mangrove C budget estimate.

Microplastic contamination of coastal environments is a global problem and pellets used in industrial processes are a persistent and worldwide form of microplastic pollution. Regions that host port and petrochemical facilities are well known sources of plastic pellets to local and adjacent coastal areas. This study assessed pellet densities over regional and local scales to provide a greater understanding of the spatio-temporal variation in inputs to sandy beaches. Pellets were used as a proxy to undertake a multi-scale assessment of the spatial (local vs. regional) and temporal (tides and weather) stranding of microplastics. Microplastic variability differed between local and regional scales. Regional variation was driven by weather (i.e., rainfall) and distance from source. Local-scale variability was driven by distance from source (along shore), tidal cycle, and beach hydrodynamics. Our results address the drivers of large spatio-temporal variability in microplastic pollution and provide useful information for monitoring programs by pointing to the need to consider variability in inputs over both regional and local scales.

Safaga and Qusseir are two important harbours on the Egyptian Proper Red Sea coast. To the best of the authors’ knowledge, this is the first work to describe the sea level characteristics at these two ports. The study is based on hourly sea level records over 3 years (2012–2014). There are no missed data at Qusseir site, but Safaga dataset missed 25% of records (April–December 2014). The hourly water level ranged between 0.02 m and 1.70 m at Safaga and between 0.04 m and 1.03 m at Qusseir, with a mean sea level (MSL) of 0.56 m and 0.50 m at the two Harbours, respectively. The T_TIDE package was used to produce astronomical and residual elevations at the two Harbours. Results revealed that the two Harbours examine explicit semidiurnal tidal cycle, with a bit higher astronomical amplitudes in Safaga. Moreover, the two sites exhibit almost the same seasonal sea level trend with very slight differences. The monthly mean levels at the two Harbours are always below their averages except during the summer months. The principal features of the semidiurnal tides indicated a ratio of 1.3 and 1.5 between spring and neap ranges at Safaga and Qusseir, respectively. The most pronounced sea level range at Safaga Harbour was 0.50 m, while it was 0.60 m at Qusseir Harbour. The astronomical elevations fluctuated between − 0.55 m and + 0.71 m and between − 0.47 m and + 0.53 m in Safaga and Qusseir Harbours, respectively.

We investigated the spatio-temporal variability of chlorophyll-a (Chl-a) and total suspended matter (TSM) associated with spring&ndash, neap tidal cycles in the Ariake Sea, Japan. Our study relied on significantly improved, regionally-tuned datasets derived from the ocean color sensor Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua over a 16-year period (2002&ndash, 2017). The results revealed that spring&ndash, neap tidal variations in Chl-a and TSM within this macrotidal embayment (the Ariake Sea) are clearly different regionally and seasonally. Generally, the spring&ndash, neap tidal variability of Chl-a in the inner part of the Ariake Sea was controlled by TSM for seasons other than summer, whereas it was controlled by river discharge for summer. On the other hand, the contribution of TSM to the variability of Chl-a was not large for two areas in the middle of Ariake Sea where TSM was not abundant. This study demonstrates that ocean color satellite observations of Chl-a and TSM in the macrotidal embayment offer strong advantages for understanding the variations during the spring&ndash, neap tidal cycle.

(IF 2.98; Q1); International audience; Modelling three-dimensional wave-current-turbulence interactions in extreme tidal environments is still challenging and necessary for the development of the tidal industry, particularly for the dimensioning of tidal converters. Following this objective, we focus our study on the Alderney Race (France) where the strongest tidal current in Western Europe and various sea states occur. Due to the strong tidal current at this location, wave-current interactions were poorly studied by the past. Therefore, we propose to assess the impacts of wave-current interactions in Alderney Race by the use of a 3D fully-coupled wave-current numerical model and in-situ measurements. The following wave-current interactions were observed : i) Stokes drift e ects inducing an increase/decrease in the current depending on the angle between waves and current, ii) wave enhancement of the bottom friction reducing the tidal current, iii) refraction of waves by the current, generating changes in waves directions, and iv) wave breaking ascribed to tidal current. The impact of such interactions were maximal near the reverse event ( 1h30) and for a weak/medium tidal range. A non-stationary time delay, varying within a same tidal cycle, was noted at both locations, which is reduced by including the local wind e ects and by adjusting the bottom stress formulation. This study shows that wave-current interactions play a non-negligible role in Alderney Race and that they need to consider by the tidal industry.

International audience; Background: A strong behavioural plasticity is commonly evidenced in the movements of marine megafauna species, and it might be related to an adaptation to local conditions of the habitat. One way to investigate such behavioural plasticity is to satellite track a large number of individuals from contrasting foraging grounds, but despite recent advances in satellite telemetry techniques, such studies are still very limited in sea turtles. Methods: From 2010 to 2018, 49 juvenile green turtles were satellite tracked from five contrasting feeding grounds located in the SouthWest Indian Ocean in order to (1) assess the diel patterns in their movements, (2) investigate the inter-individual and inter-site variability, and (3) explore the drivers of their daily movements using both static (habitat type and bathymetry) and dynamic variables (daily and tidal cycles). Results: Despite similarities observed in four feeding grounds (a diel pattern with a decreased distance to shore and smaller home ranges at night), contrasted habitats (e.g. mangrove, reef flat, fore-reef, terrace) associated with different resources (coral, seagrass, algae) were used in each island. Conclusions: Juvenile green turtles in the SouthWest Indian Ocean show different responses to contrasting environmental conditions-both natural (habitat type and tidal cycle) and anthropogenic (urbanised vs. uninhabited island) demonstrating the ability to adapt to modification of habitat.

The generation of high-resolution data is increasingly important in understanding the complexities of coastal ocean and developing sound management strategies, especially in view of the long-term impact of severe weather systems. The impact of severe weather systems, when integrated over time, can be significant when compared with tidal oscillations. This paper presents a study of water transport out of Vermilion Bay in response to a short, intense event associated with a passing atmospheric cold front, and reports the application of an Acoustic Doppler Current Profiler (ADCP) mounted on an Automated Surface Craft (ASC), known as the auto-boat or unmanned boat, developed in our lab at the Louisiana State University, to generate high resolution data accurately at a fraction of the cost of a manned boat. In our study, we used a manned boat and an unmanned boat, each for over 24 h to cover an entire diurnal tidal cycle, to measure flow velocity profiles to calculate the total transport. A stationary ADCP was deployed in the Southwest Pass of the Vermilion Bay from May 2009 to April 2012, providing data almost continuously (with only one major gap), with a 717-day record of water transport between the northern Gulf of Mexico and Vermilion Bay, and demonstrates the importance of the pass in water transport.

Local scour around pile foundations is a major factor affecting the foundation stability in ocean engineering. A series of experiments has been conducted to study the time development of scour around pile groups under the unidirectional and tidal currents. 49 cylindrical model piles were arranged in a typical dumbbell-shaped configuration, and 20 micro-cameras as well as a 3D laser scanner were used to capture the local scour topography. In the unidirectional current test, the scour pit was spoon-shaped, and the maximum scour depth was located in the central part of upstream pile group. In the tidal tests, two similar shallow scour pits existed in the upstream and downstream pile group. During the initial stage of tide-induced local scour, the increase of scour depth was similar to that under unidirectional current. But, the repetitive scour and backfill process led to obvious fluctuations of scour depth, especially for the piles at the rear of upstream pile group and in the front of downstream pile group. It was found that the tidal cycle number had obvious effect on the scour depth development. The final scour depth after sufficient tidal cycles could reach up to 77.1% of the maximum scour depth under unidirectional current.

Atlantic sturgeon Acipenser oxyrinchus surfacing behaviour was investigated in Minas Basin (45° 20' N; 64° 00' W) and the Bay of Fundy with pop-up satellite archival tags (MiniPAT) measuring physical variables (pressure, temperature, light). Of six tags deployed during June and July, five provided pop-up locations and two were recovered after c. 4 months. Analysis of recovered archival data revealed that the frequency of surfacing events was highest (78·9%) when A. oxyrinchus were in Minas Basin at depths 40 m). The tidal cycle in Minas Basin had a significant relationship to surfacing frequency, with the most surfacing events (49·5%) occurring on the flood tide, from mid- to high-tide. Surfacing events ranged from 0-12 a day and the maximum number occurred between 2300 and 0300 hours. Maximum surfacing ascent speeds ranged from 0·50 to 4·17 m s-1 and maximum descent speeds ranged from 0·17 to 3·17 m s-1 . Buoyancy control, by gulping air to inflate the gas bladder, is proposed as the main reason for surfacing behaviour in A. oxyrinchus.

The brooding gastropod Crepipatella dilatata can feed by scraping the substrate with the radula and by suspension-feeding, which also requires use of the radula. There is a “division of labour” for the radula among three discrete tasks associated with feeding: (1) removing mucous balls from the food pouch; (2) transferring the mucous cord from the neck channel to the mouth (both components of suspension-feeding); (3) scraping the substrate. We hypothesised that the proportion of time used for each feeding activity varies according to environmental conditions. Total radular activity in females was greatest at high tide and in summer. The rate of radular extrusion for ingesting the mucous cord varied seasonally and between brooding and non-brooding females. Non-brooding females exhibited higher rates of radular extrusion for ingesting the mucous cord and for scraping the substrate than did brooders. In females, radular activity in removing the mucous ball from the food pouch was strongly influenced by the tidal cycle during winter, reaching minimum values at low tide. Differences were recorded in substrate scraping among seasons and within tidal cycles, and among males, brooding females and non-brooding females. Brooding females displayed less rasping than non-brooders, since the area available for grazing was restricted by the egg mass. Throughout the year, including low salinity periods, males allocated a greater proportion of total radular activity to rasping than to removing the mucous ball or ingesting the mucous cord. The feeding behaviour of both males and females is modulated by salinity, but the principal determinants of radular activity are the mode of reproduction (brooding in females) and, in males, motility.

Animals inhabiting the intertidal zone are exposed to abrupt changes in environmental conditions associated with the rise and fall of the tide. For convenience, the majority of laboratory studies on intertidal organisms have acclimated individuals to permanently submerged conditions, and thus we currently know little about how acclimation to cyclic emersion-immersion influences the ability of intertidal organisms to cope with fluctuations in environmental conditions. In the present study, the green shore crab Carcinus maenas was acclimated to either a simulated tidal regime of continuous emersion-immersion (tidal) or to permanently submerged conditions (non-tidal). Aquatic oxygen consumption was assessed when crabs were exposed to cooling (15 °C - 5 °C) or warming (15 °C - 25 °C) regimes. Tidal crabs had lower levels of oxygen consumption over the 15 °C - 20 °C range. During acute thermal stress, the Q10 values of non-tidal crabs increased as the temperature declined to 5 °C, whereas tidal crabs maintained relatively consistent Q10 values across the temperature range (5 °C–25 C). These changes in oxygen consumption were paralleled by changes in haematological parameters. Tidal crabs had higher levels of haemocyanin which may have augmented oxygen delivery to the tissues and buffered acid-base imbalances. Surprisingly lactate levels were higher in tidal crabs, these appeared unconnected to anaerobic metabolism, but may have been an important metabolic fuel for tidal crabs. These results suggest that acclimation to a simulated tidal cycle may result in different physiological responses to environmental stressors and as such is an important consideration when assessing the responses of intertidal animals in a laboratory setting.

Understanding erosion and accretion dynamics during an entire tidal cycle is important for assessing their impacts on the habitats of biological communities and the long-term morphological evolution of intertidal mudflats. However, previous studies often omitted erosion and accretion during very shallow-water stages (VSWS, water depths 0.2 m (i.e., probe submerged) are considered. These findings suggest that the magnitude of bed-level changes during VSWS should not be neglected when modeling morphodynamic processes. Our results are useful in understanding the mechanisms of micro-topography formation and destruction that often occur at VSWS, and also improve our understanding and modeling ability of coastal morphological changes.

This study investigates the tidal variability in methane (CH4) and nitrous oxide (N2O) emissions along a gradient of the subtropical Brisbane River estuary. Sampling was conducted at the upper, middle and lower reaches over two tidal cycles in 2013 and 2014. Methane and N2O emissions varied significantly over tidal cycles at all sites. Methane and N2O emissions measured at all locations and in both campaigns varied substantially in time, with the maximum to minimum flux ratio in a cycle varying between 2.5 - 9 and 1.7–4.7 times, respectively. Methane emissions peaked just before or at slack tides. In comparison, no clear patterns were observed between the N2O emissions and the tidal cycle despite there being large variations in N2O emissions in some cases. Methane concentrations were elevated during low tides whereas N2O concentrations showed no clear pattern over the tidal cycle. Surface water concentrations and tidal currents played important roles in CH4 and N2O emissions, but wind did not. Our findings show that measurements at a single point in time and site would result in significant errors in CH4 and N2O emission estimates. An adequate and careful sampling scheme is required to capture spatial and temporal variations of CH4 and N2O emissions and surface water concentrations which should cover at least one tidal cycle in different estuarine sections.

Characteristics and formation of the tidal shear front off the Yellow River Mouth had been previously studied based on observations and models. However, its long-term variability and thus related mechanisms have not been investigated. In this study, a three-dimensional hydrodynamic model was used to examine the long-term evolution on the location, propagation, and magnitude (length, duration, and shear strength) of the tidal shear front from 1976 to 1996. Over the 20 years, a peninsula of about 27 km long and 7 km wide (above the high water line) was formed off the new river mouth, while the coastline retreated by 5–10 km, and the water depths increased by about 2 m in the north (the abandoned river mouth). Results also show that for the period of each flood and ebb tidal cycle, the tidal shear front originated in the north of the delta, then propagated southeastwards and finally disappeared at the south of the river mouth. During the two decades, the front had an obvious shoreward movement, and its duration within a tidal cycle increased slightly. Furthermore, the length of the front decreased, while the shear strength of the front increased. The propagation of the front was determined by flood and ebb process in the delta, where both of them were from north to south due to tidal phase distribution. Long-term characteristic variations of the front were mainly caused by morphology change, which had a significant influence on the tidal current gradient and the location of maximum bottom stress gradient area. The morphology change also had a slight impact on the tidal current phase in the front area, which may have caused the slight duration variation of the front.

This research quantifies the rate and volume of oil and gas released from two natural seep sites in the Gulf of Mexico: lease blocks GC600 (1200 m depth) and MC118 (850 m depth). Our objectives were to determine variability in release rates and bubble size at five individual vents and to investigate the effects of tidal fluctuations on bubble release. Observations with autonomous video cameras captured the formation of individual bubbles as they were released through partially exposed deposits of gas hydrate. Image processing techniques determined bubble type (oily, gaseous, and mixed: oily and gaseous), size distribution, release rate, and temporal variations (observation intervals ranged from 3 h to 26 d). A semi-automatic bubble counting algorithm was developed to analyze bubble count and release rates from video data. This method is suitable for discrete vents with small bubble streams commonly seen at seeps and is adaptable to multiple in situ set-ups. Two vents at GC600 (Birthday Candles 1 and Birthday Candles 2) were analyzed. They released oily bubbles with an average diameter of 5.0 mm at a rate of 4.7 bubbles s−1, and 1.3 bubbles s−1, respectively. Approximately 1 km away, within the GC600 seep site, two more vents (Mega Plume 1 and Mega Plume 2) were analyzed. These vents released a mixture of oily and gaseous bubbles with an average diameter of 3.9 mm at a rate of 49 bubbles s−1, and 81 bubbles s−1, respectively. The fifth vent at MC118 (Rudyville) released gaseous bubbles with an average diameter of 3.0 mm at a rate of 127 bubbles s−1. Pressure records at Mega Plume and Rudyville showed a diurnal tidal cycle (24.5 h). Rudyville was the only vent that demonstrated any positive correlation (ρ = 0.60) to the 24.5 h diurnal tidal cycle. However, these observations were not conclusive regarding tidal effects on bubble release.

In recent years, the application of large-scale beach nourishments has been discussed, with the Sand Motor in the Netherlands as the first real-world example. Such protruding beach nourishments have an impact on tidal currents, potentially leading to tidal flow separation and the generation of tidal eddies of length scales larger than the nourishment itself. The present study examines the characteristics of the tidal flow field around protruding beach nourishments under varying nourishment geometry and tidal conditions, based on extensive field observations and numerical flow simulations. Observations of the flow field around the Sand Motor, obtained with a ship-mounted current profiler and a set of fixed current profilers, show that a tidal eddy develops along the northern edge of the mega-nourishment every flood period. The eddy is generated around peak tidal flow and gradually gains size and strength, growing much larger than the cross-shore dimension of the coastline perturbation. Based on a 3 week measurement period, it is shown that the intensity of the eddy modulates with the spring-neap tidal cycle. Depth-averaged tidal currents around coastline perturbations are simulated and compared to the field observations. The occurrence and behavior of tidal eddies is derived for a large set of simulations with varying nourishment size and shape. Results show that several different types of behavior exist, characterized by different combinations of the nourishment aspect ratio, the size of the nourishment relative to the tidal excursion length, and the influence of bed friction.

External corrosion on mature oil and gas field installation very challenging issues. External corrosion of pipeline riser on tidal zone is the most case for pipeline corrosion [2]. API 5L X52 is familiar pipeline for offshore oil and gas production facilities. Pipeline riser external corrosion on tidal zone have some consequences, time constrain related tidal cycle, production loss, oil spill impact to company reputation, costly maintenance. This research intended to find out effect of tidal cycle and salt water salinity to the rate and type of corrosion on API 5l X52 pipeline riser. Tidal cycle is modeling by wet and dry coupon on salt water. Corrosion rate measure by weight loss coupon. Corrosion product examine by XRD. Chloride contents and oxygen dissolve combination resulting maximum corrosion rate. Oxygen dissolve is main factor to corrosion on salt water. Maximum oxygen dissolve on salt water concentration 3.5% wt. On high salinity salt water corrosion rate depend oxygen dissolve [2]. Tidal cycle has impact to corrosion rate. General corrosion type happen on all coupon with corrosion product component Fe 2 O 3 , Fe 3 O 4 examined by XRD.

Bioirrigation, the exchange of solutes between overlying water and sediment by benthic organisms, plays an important role in sediment biogeochemistry. Bioirrigation either is quantified based on tracer data or a community (bio)irrigation potential (IPc) can be derived based on biological traits. Both these techniques were applied in a seasonal study of bioirrigation in subtidal and intertidal habitats in a temperate estuary. The combination of a tracer time series with a high temporal resolution and a mechanistic model allowed for us to simultaneously estimate the pumping rate and the sediment attenuation, a parameter that determines irrigation depth. We show that, although the total pumping rate is similar in both intertidal and subtidal areas, there is deeper bioirrigation in intertidal areas. This is explained by higher densities of bioirrigators such as Corophium sp., Heteromastus filiformis and Arenicola marina in the intertidal, as opposed to the subtidal, areas. The IPc correlated more strongly with the attenuation coefficient than the pumping rate, which highlights that the IPc index reflects more the bioirrigation depth than the rate.

International audience; Suspended particulate matter (SPM) is a key component of coastal food webs and a key variable of nutrient budgets. Understanding its variability across short time scales in estuaries may help ecologists understand seasonal and diurnal migration of estuarine organisms, and answer how their nutritional requirements are fulfilled. It may also inform biogeochemists regarding the factors that influence import and export of nutrients between terrestrial and coastal ecosystems. This study aimed to link the dynamics of fatty acids, stable isotopes (δ13C and δ15N) and C/N ratios of SPM, revealing organic matter quality, to rapidly varying factors (SPM concentration, salinity and presence of daylight) and comparing this variability to the seasonal variation induced by the alternation of dry and wet seasons in the studied region. Our results revealed that these rapidly varying factors had a strong influence on the bacterial and the phytoplanktonic compartments of SPM. They suggest that tidally resuspended particles are the site of intense heterotrophic activity and that estuarine phytoplankton store lipids during the daytime up to substantially modifying SPM quality. Our study also shows higher freshness of SPM during the wet season. We expect this study to raise the interest of both biologists and biogeochemists to introduce daily variability of SPM in food webs and nutrient budgets modelling.