Tidal Height Research Articles

Frequency of Temperature Fluctuations Subtly Impacts the Life Histories of a Tropical Snail.

AbstractMost organisms are faced with daily cyclic changes in a suite of environmental conditions, including temperature. In shallow marine waters, populations of the same species may experience either intertidal or subtidal conditions, such that some individuals experience extreme daily fluctuations as the tide ebbs and flows, while others only a few meters away experience less pronounced or less frequent fluctuations or almost constant thermal conditions. This study used a fully factorial combination of three thermal treatments and two diet treatments to test the hypotheses that (1) individuals experiencing fluctuating temperatures perform more poorly than those experiencing the same mean temperature under constant conditions and that (2) the negative impact of fluctuating temperatures is greater under food-limiting conditions. Five life-history components of the slipper snail Crepidula cf. marginalis were used as response variables. We found that temperature fluctuations impacted size at hatching and time to hatching, as well as growth rate, to some extent. Diet treatments impacted growth rates, clutch sizes, time to first brood, and time to hatching. There were no statistically significant interactions between the two factors. These results show that fluctuations between two temperatures that are typically experienced by these animals in the field can significantly affect fitness-related characters and, therefore, suggest the tidal height at which larvae settle can significantly impact individual fitness. This is one of the first studies to demonstrate that differences in the frequency of fluctuations, in the absence of differences in the magnitude or the mean, can have significant impacts on invertebrate life histories.

The Development of A Rigorous Model for Bathymetric Mapping from Multispectral Satellite-Images

Models for bathymetry retrieval from multispectral images have not considered the errors caused by tidal fluctuation. A rigorous bathymetric model that considers the variation in tide height time series, including the tide height calculation and instantaneous tide height correction at the epoch of satellite flight into the bathymetric retrieval model, is proposed in this paper. The model was applied on Weizhou Island, located in Guangxi Province, China, and its accuracy verificated with four check lines and seven checkpoints. A scene from the Landsat 8 satellite image was used as experimental data. The reference (“true”) water depth data collected by a RESON SeaBat 7125 multibeam instrument was used for comparison analysis. When satellite-derived bathymetry is compared, it is found that maximum absolute error, mean absolute error, and RMSE have decreased 54, 45, and 30% relative to that of the traditional model in the entire test field. The accuracy of the water depths retrieved by our model increased 30 and 56% when validated using four check lines and seven checkpoints, respectively. Therefore, it can be concluded that the model proposed in this paper can effectively improve the accuracy of bathymetry retrieved from Landsat 8 images.

Assessment of Coastal Locations Safety Using a Fuzzy Analytical Hierarchy Process-Based Model

Worldwide tourist beaches have been an ideal destination for people searching for a recreational place to visit; however, several conditions could generate risks for these visitors. At present, the main efforts to assess these risks and prevent people from danger are essentially focused on monitoring tidal height in the zone, ignoring other risk sources. Therefore, this work generates an overall evaluation that considers the tidal height, bathymetry, temperature, solar radiation, and wind speed, establishing a relationship between parameters and safe beach conditions using a fuzzy logic approach. In addition, this paper presents the design and implementation of a computational model, based on a fuzzy analytical hierarchy process (FAHP), to evaluate coastal and climatological parameters involved in tourist safety, which can be continuously monitored. Tourist beaches in South Baja California, México, with diverse environmental and coastal conditions, were assessed with the proposed model, providing several safety scenarios that contrast the results between sites and demonstrate the capacity of the model to evaluate them. The evaluation, obtained as a result of the computational model, presents information about the safety conditions in the assessed zone, considering the possible risks for all the parameters analyzed, which could be presented to beach visitors to prevent dangerous situations and avoid accidents.

Microbially induced sedimentary structures (MISS) generated by episodic storm surges in a temperate coast

This study recognizes the creation of primary sedimentary structures in a modern environment that reports valuable insights into the role of microbiota in sculpting sedimentary structures, and it may explain many previously confusing sedimentary structures in the rock record. The research considered the frequent flooding events on a coastal sedimentary flat colonized by microbial mats and the effect produced by severe storm surge events. Large-scale microbially induced sedimentary structures (MISS) were created; thus, the interaction between meteorologic, oceanographic, and geomorphologic conditions necessary to form them was analysed. The study was developed in Paso Seco, Argentina (40°38′31” S - 62°12′54” W), a sedimentary flat behind a sand spit, coated by thick microbial mats recurrently affected by storm events. Water level measurements were recorded continuously for five years (measurement interval 10 min). The seawater inundations were related to synoptic weather maps and oceanographic parameters (wave height, period, and tides) to analyse the cause of storm surges. Two situations of severe storms were studied in 2018 and 2019. The inundation of the study area occurs when a cold front in association with a low-pressure centre in the Atlantic Ocean, moving in an SW-NE direction, produces strong SW winds higher than 45 km h−1 and wave height higher than 2 m. Strong winds and storm duration (two or three days) in co-occurrence with spring tides create an extreme erosional event that affects the sedimentary microbial flat. In sum, the interaction between storm surge, high tide, wave setups and wave heights in Paso Seco produces coastal hinterland flooding that creates meter-sized MISS such as roll-ups, erosional pockets, and remnants mats structures. The impact of storm surges on the coast is common and catastrophic in modern times but is challenging to identify in the sedimentary record. Therefore, the microbial structures presented here could help interpret high-energy events occurrence, favourable to assessing past environmental conditions.

Muography for a dense tide monitoring network

Sub-hourly to seasonal and interannual oceanographic phenomena can be better understood with high special resolution and high frequency tidal observations. However, while current tidal measurements can provide sufficiently high observational density in terms of time, the observational density in terms of space is low mainly due to the high expense of constructing tide gauge stations. In this work, we designed a novel tide monitoring technique with muography that could be operated in near-shore basements (or similar structures on land below sea level) and found that more practical, stable, robust and cost-effective high-spatiotemporal-density tide measurements are possible. Although the time resolution, sensitivity, and the distance between the detectors and the shorelines are tradeoffs, hourly and annual sensitivity (ability to detect the tide height variations) of less than 10 cm and 1 mm can be statistically attained, respectively. It is anticipated that the current muographic technique could be applied as an alternative, cost-effective and convenient dense tidal monitor network strategy in coastal areas worldwide.

Habitat use of the common bottlenose dolphin (Tursiops truncatus) in the Gulf of Guayaquil, Ecuador: Management needs for a threatened population

The habitat use by two neighboring coastal bottlenose dolphin communities (Posorja and El Morro) was evaluated in the western inner estuary of the Gulf of Guayaquil, Ecuador (3°S, 80°55′W). The study aimed to determine to what extent some environmental variables influence dolphins' distribution and behavior. The analysis included 344 dolphin groups recorded between 2014 and 2019. For both dolphin communities, 95% of home ranges were estimated (23.5 km2 Posorja and 44.8 km2, El Morro). Home ranges overlapped in an area of 11.2 km2. No clear preference for areas to carry out specific activities was found, as dolphins used the same areas for multiple purposes. Multinomial logistic regression with four environmental parameters (distance to shore, depth, hour of day and tide) were used as predictor variables of behavior. A significant relationship between the tidal cycle and behavioral states was found with feeding occurring more frequently during the low tide, socializing and transit during high tide, and resting during mid-tide. Count models were used with environmental and behavioral variables to explore their relationship with dolphins' group size. Differences with respect to dolphin counts were associated with tide height and socialization. Depth is relevant for predicting dolphin counts mainly during high tide. We recommend that environmental authorities consider the dolphins' preference to carry out their activities within small home ranges, identify overlapping human activities and take steps to reduce potential conflicts, such as prohibiting all types of gillnets in areas of high concentration of dolphins. Likewise, regular assessments are required to detect future changes in both dolphins' habitat and human uses over time.

Tidally driven submarine groundwater discharge to a marine aquaculture embayment: Insights from radium and dissolved silicon

For understanding the significance of tidal pumping for driving submarine groundwater discharge (SGD), two time series observations were conducted over tidal cycles in typical mariculture areas of Sanmen Bay, China. Based on 224Ra and dissolved silicon (DSi), the tide-driven SGD fluxes showed significant negative correlations with tidal height, and were 16.4 ± 5.6 cm d−1 and 21.7 ± 13.9 cm d−1 at two coastal sites of the Sanmen Bay, highlighting the potential of DSi in SGD calculation when coastal waters are on short time scales. Furthermore, nutrient fluxes through tidally influenced SGD were estimated to be 11.5–26.5 mmol m−2 d−1 for dissolved inorganic nitrogen, 0.06–0.34 mmol m−2 d−1 for dissolved inorganic phosphorus and 11.5–32.1 mmol m−2 d−1 for DSi, which were higher than those from surface loadings, revealing that tide-driven SGD with large amounts of nutrient and high N:P ratios may significantly contribute to the development of marine aquaculture.

Eutrophication Amplifies the Diel Variability of Carbonate Chemistry in an Equatorial, Semi-Arid, and Negative Estuary

This study presents high-resolution data on diel variations of carbonate chemistry in a semi-arid estuary (Jaguaribe River) in NE Brazil, which has witnessed decreasing annual rainfall and freshwater inputs due to climate change and river damming. In addition, the estuary has been suffering with increasing discharges from shrimp farm and urban effluents. We monitored surface water and atmospheric CO2 partial pressure (pCO2), temperature, salinity, and wind speed with continuous real-time measurements during two eulerian surveys in October 2017 (33 h) and September 2018 (44 h), during spring tides in the dry season. Additionally, pH, total alkalinity (TA), dissolved inorganic carbon (DIC), carbonate (CO32–), and saturation state of calcite (Ωcal) and aragonite (Ωara) were monitored hourly. Higher salinity (>38) during ebb tides confirmed the hypersalinity and negative estuarine circulation. TA and DIC concentrations in the estuary were higher than in the adjacent coastal ocean due to evaporation, showing positive correlation with salinity and negative correlation with tidal height. Measured TA and DIC concentrations were slightly higher than those calculated by the conservative evaporation model, suggesting their production in the estuary by aerobic and anaerobic processes. CO32–, Ωcal, and Ωara showed a clear semi-diurnal (tidal-driven) and diel (24 h; biological-driven) patterns: lowest values occurred at flood tide during night-time (respectively, 185 μmol kg–1, 4.3 and 2.8), whereas highest occurred during ebb tide and daytime (respectively, 251 μmol kg–1, 5.7 and 3.8). DIC/TA ratios were higher at night-time supporting a diel control (linked to solar irradiance) of the carbonate buffering capacity. pCO2 was oversaturated comparing to the atmosphere (512–860 μatm) and the estuary was a source of CO2, with fluxes ranging from 2.2 to 200.0 mmol C m–2 d–1 (51.9 ± 26.7 mmol C m–2 d–1), which are higher than emissions normally found in low-inflow, marine-dominated estuaries. The diel variability of DIC indicated a net heterotrophic metabolism averaging −5.17 ± 7.39 mmol C m–2 h–1. Eutrophication amplifies the diel variability of the CO2 system generating large differences between daytime and night-time. The results highlight the importance of considering diel variability when estimating CO2 fluxes and carbonate chemistry in eutrophic, semi-arid, and tidally dominated estuaries under rapid environmental changes, and may represent future conditions in estuaries worldwide experiencing warming, increasing aridity and eutrophication.

Effect of tide to storm surge in Do Son coastal zone, Hai Phong

The magnitude of storm surge depends on many factors: The intensity, direction, and speed of the storm, coastal topography, tidal height, etc. This paper presents the study results of the influence of tide on storm surge in Do Son coatal zone, Hai Phong City, based on the calculating results of storm surge in cases tidal and non-tidal storms landed into this coastal area from 1951 to 2020. The numerical model is used to calculate storm surge in this study is the TSIM11 model. This model can calculate wave, tide and storm surge and it was constructed by the Institute of Mechanics, Vietnam Academy of Science and Technology. The numerical model has been calibrated and validated using measurement data from stations in the study area.

Movement and habitat use of non‐breeding Semipalmated Sandpiper (Calidris pusilla) at the Banco dos Cajuais in Northeast Brazil

AbstractSemipalmated sandpipers are Arctic breeding shorebirds that migrate to South America during the non‐breeding season. Little work has been done to understand the daily movements, foraging habits and metabolic state of this species on stationary nonbreeding grounds. Our work was conducted at the Banco dos Cajuais Western Hemisphere Shorebird Reserve Network (WHSRN) site in Northeast Brazil. We captured semipalmated sandpipers in February and March 2019 and 2020 and attached nanotags to monitor their daily movements. Blood samples were taken to measure plasma triglycerides (an index of fattening rate). We also conducted behavioral observations on foraging birds. Using tracking data we determined that most semipalmated sandpipers appeared to use sunrise/sunset as an indicator for movement between salina and tidal flat habitats, and a smaller portion used tidal height. We found birds spent similar amounts of time foraging on tidal flats and in salinas, though different foraging modes were used. Plasma triglyceride measures suggest semipalmated sandpipers had not started preparing to migrate when sampled. We successfully tracked semipalmated sandpipers to North America during northward migration in 2020, detecting eight within the United States. Tracking results suggest many stopped elsewhere in South America to fuel for migration, though some may have fueled at the Banco dos Cajuais. By demonstrating substantial use of both natural and altered habitats in the region by migrant semipalmated sandpipers, these data highlight the need for broader conservation measures throughout coastal regions of South America.

Coastal observation of sea surface tide and wave height using opportunity signal from Beidou GEO satellites: analysis and evaluation

Coastal observation of sea surface tide and wave height using opportunity signal from Beidou GEO satellites: analysis and evaluation

Fungal endophytes vary by species, tissue type, and life cycle stage in intertidal macroalgae.

Fungal symbionts of terrestrial plants are among the most widespread and well-studied symbioses, relatively little is known about fungi that are associated with macroalgae. To fill the gap in marine fungal taxonomy, we combined simple culture methods with amplicon sequencing to characterize the fungal communities associated with three brown (Sargassum muticum, Pelvetia canaliculata, and Himanthalia elongata) and two red (Mastocarpus stellatus and Chondrus crispus) macroalgae from one intertidal zone. In addition to characterizing novel fungal diversity, we tested three hypotheses: fungal diversity and community composition vary (i) among species distributed at different tidal heights, (ii) among tissue types (apices, mid-thallus, and stipe), and (iii) among "isomorphic" C. crispus life cycle stages. Almost 70% of our reads were classified as Ascomycota, 29% as Basidiomycota, and 1% that could not be classified to a phylum. Thirty fungal isolates were obtained, 18 of which were also detected with amplicon sequencing. Fungal communities differed by host and tissue type. Interestingly, P. canaliculata, a fucoid at the extreme high intertidal, did not show differences in fungal diversity across the thallus. As found in filamentous algal endophytes, fungal diversity varied among the three life cycle stages in C. crispus. Female gametophytes were alsocompositionally more dispersed as compared tothe fewer variable tetrasporophytes and male gametophytes. We demonstrate the utility of combining relatively simple cultivation and sequencing approaches to characterize and study macroalgal-fungal associations and highlight the need to understand the role of fungi in near-shore marine ecosystems.

Comparing Sentinel-2 and WorldView-3 Imagery for Coastal Bottom Habitat Mapping in Atlantic Canada

Satellite remote sensing is a valuable tool to map and monitor the distribution of marine macrophytes such as seagrass and seaweeds that perform many ecological functions and services in coastal habitats. Various satellites have been used to map the distribution of these coastal bottom habitat-forming species, with each sensor providing unique benefits. In this study, we first explored optimal methods to create bottom habitat maps using WorldView-3 satellite imagery. We secondly compared the WorldView-3 bottom habitat maps to previously produced Sentinel-2 maps in a temperate, optically complex environment in Nova Scotia, Canada to identify the top performing classification and the advantages and disadvantages of each sensor. Sentinel-2 provides a global, freely accessible dataset where four bands are available at a 10-m spatial resolution in the visible and near infrared spectrum. Conversely, WorldView-3 is a commercial satellite where eight bands are available at a 2-m spatial resolution in the visible and near infrared spectrum, but data catalogs are costly and limited in scope. Our optimal WorldView-3 workflow processed images from digital numbers to habitat classification maps, and included a semiautomatic stripe correction. Our comparison of bottom habitat maps explored the impact of improved WorldView-3 spatial resolution in isolation, and the combined advantage of both WorldView’s increased spatial and spectral resolution relative to Sentinel-2. We further explored the effect of tidal height on classification success, and relative changes in water clarity between images collected at different dates. As expected, both sensors are suitable for bottom habitat mapping. The value of WorldView-3 came from both its increased spatial and spectral resolution, particularly for fragmented vegetation, and the value of Sentinel-2 imagery comes from its global dataset that readily allows for large scale habitat mapping. Given the variation in scale, cost and resolution of the two sensors, we provide recommendations on their use for mapping and monitoring marine macrophyte habitat in Atlantic Canada, with potential applications to other coastal areas of the world.

Using machine learning and beach cleanup data to explain litter quantities along the Dutch North Sea coast

Abstract. Coastlines potentially harbor a large part of litter entering the oceans, such as plastic waste. The relative importance of the physical processes that influence the beaching of litter is still relatively unknown. Here, we investigate the beaching of litter by analyzing a data set of litter gathered along the Dutch North Sea coast during extensive beach cleanup efforts between the years 2014 and 2019. This data set is unique in the sense that data are gathered consistently over various years by many volunteers (a total of 14 000) on beaches that are quite similar in substrate (sandy). This makes the data set valuable to identify which environmental variables play an important role in the beaching process and to explore the variability of beach litter concentrations. We investigate this by fitting a random forest machine learning regression model to the observed litter concentrations. We find that tides play an especially important role, where an increasing tidal variability and tidal height leads to less litter found on beaches. Relatively straight and exposed coastlines appear to accumulate more litter. The regression model indicates that transport of litter through the marine environment is also important in explaining beach litter variability. By understanding which processes cause the accumulation of litter on the coast, recommendations can be given for more effective removal of litter from the marine environment, such as organizing beach cleanups during low tides at exposed coastlines. We estimate that 16 500–31 200 kg (95 % confidence interval) of litter is located along the 365 km of Dutch North Sea coastline.

A formula for the value of the gravitational constant

A concise and precise formula for ‘Big G’ has been derived from an electron positron model of vacuum space (the epola model) that regards gravitation as a push force resulting from magnetic spin moments. Extended tests have revealed the significance of the peculiar velocity of the Solar System as a factor within the Fine Structure Constant, by experimentally monitored periodicity of nuclear decay rates. Correlations to gravitational field intensity, indicated by tide heights, also deny a purely random function for nuclear decay. The epola model’s definition of EM waves and their spectral characteristics had indicated possible substructure of the electron as a charged hadronic pion. This study resolves anomalies of the electron by identifying Twist in addition to Spin moments that has exposed an epola mechanism for Quantum Entanglement. When free guest particles interact with the bound particles of the lattice, binding energy density reduction induces gravitational forces and reveals the factors comprising the value of Big G, that further indicate pion sub-structure of leptons with a different fine structure.

Assessing tropical cyclone compound flood risk using hydrodynamic modelling: a case study in Haikou City, China

Abstract. The co-occurrence of storm tide and rainstorm during tropical cyclones (TCs) can lead to compound flooding in low-lying coastal regions. The assessment of TC compound flood risk can provide vital insight for research on coastal flooding prevention. This study investigates TC compound flooding by constructing a storm surge model and overland flooding model using Delft3D Flexible Mesh (DFM), illustrating the serious consequences from the perspective of storm tide. Based on the probability distribution of storm tide, this study regards TC1415 as the 100-year event, TC6311 as the 50-year event, TC8616 as the 25-year event, TC8007 as the 10-year event, and TC7109 as the 5-year event. The results indicate that the coastal area is a major floodplain, primarily due to storm tide, with the inundation severity positively correlated with the height of the storm tide. For 100-year TC event, the inundation area with a depth above 1.0 m increases by approximately 2.5 times when compared with 5-year TC event. Comparing single-driven flood (storm tide flooding and rainstorm inundation) and compound flood hazards shows that simply accumulating every single-driven flood hazard to define the compound flood hazard may cause underestimation.

Simple and complex burrow morphology in two Macrophthalmus species on the intertidal mudflats of Barr Al Hikman, Sultanate of Oman

ABSTRACT Burrowing Ocypodoidea crabs are an abundant component of many tropical and temperate coastal areas and central to the ecosystem functioning, for instance because they recycle nutrients, are important food for many shorebirds and alter the sediment through their burrowing behaviour. The burrow morphology of these crabs may differ between and within species, often correlated with differences in habitat preferences, crab morphology and life-history traits. Here we studied the burrow morphology and complexity of Macrophthalmus sulcatus and Macrophthalmus depressus, by means of casts (n = 7 and 10, respectively) and burrow excavations (n = 17 and 16, respectively) at the pristine intertidal mudflats of Barr Al Hikman in the Sultanate of Oman. We found that M. sulcatus construct simple burrows that were in all but one case inhabited by a single crab. By contrast, all burrows of M. depressus were complex, with multiple entrances and many (deep-reaching) branches. There was a strong relationship between M. sulcatus carapace width and burrow entrance size, indicating that the simple burrows are adapted to and made by the occupant. There was no relation between M. depressus carapace width and burrow entrance size, and in six burrows more than one crab was encountered, suggesting that the complex burrows are not made by and adapted to a single occupant. The complex burrows were found close to the shore whereas the simple burrows were found at the intermediate tidal zone. We speculate that the striking differences in burrow morphology may be explained by difference in habitat selection of the studied crabs, which most importantly relates to differences in sediment structure and tidal height. Crab morphology and life-history traits of the studied crabs could also account for the observed difference in burrow morphology.

Extending a canopy reflectance model for mangroves: A case study in south east queensland, Australia

Mangroves are essential coastal wetland vegetation and their extent and leaf area index (LAI) have been mapped using remotely sensed Earth Observation images. However, the physics-based relationship between biophysical properties of mangroves, tidal height, and their spectral values remains underexplored. In order to quantitatively evaluate the impact of woody material on mangrove spectra from optical imagery, a canopy reflectance model (CRM) was extended to simulate and analyse the reflectance of mangroves. The fractional cover, leaf-to-total area ratio and water depth were included as model parameters, increasing the fidelity of the canopy architecture in the CRM. A mangrove study area in South East Queensland, Australia, was chosen for model parameterisation and verification using field and satellite data. Simulated Sentinel-2 reflectance spectra of the mangrove plots closely matched the observed pixel reflectance spectra, with their coefficient of determination (R2) values higher than 0.98 and root mean square error values lower than 0.01, which was better than the performance of the original CRM omitting the fractional cover and woody material. The inverted plant area index and fractional cover values from the satellite imagery closely matched the field-derived reference values (R2 = 0.78 and 0.97, respectively). Simulation results revealed that a higher proportion of woody material in crowns reduced the canopy reflectance of mangroves in the near infrared region and increased the reflectance in the shortwave infrared region. Moreover, the simulated reflectance of the Sentinel-2 red edge 1 (695–714 nm) was not sensitive to the wood proportion for the examined cases. The modelling framework may be used to evaluate the impact of woody material for estimating mangrove LAI from optical imagery. The model may also be used to quantitatively analyse the mangrove reflectance spectra when including other important factors such as tidal height.

The bioprotective properties of the blue mussel (Mytilus edulis) on intertidal rocky shore platforms

Biogeomorphological processes are an important component in the geomorphic evolution of rocky coasts. Sessile organisms, including those which form dense biological covers, enhance and/or retard weathering and erosion. The common blue mussel (Mytilus edulis) is found on rocky shores in many parts of the world, typically forming extensive beds several centimetres thick. Yet, unlike other canopy forming marine organisms (e.g., seaweeds), the influences of mussels on processes of rock breakdown lack quantitative analysis. This study assesses the potential of M. edulis to act as a biogeomorphic agent through weathering experiments and field trials on a mudstone shore platform in Wales, UK.Monitoring on the shore platform showed that daily near-surface temperature maxima, range and short-term variability were lower on surfaces colonised by M. edulis compared to those that were bare. This was supported by laboratory simulations which showed that (artificial) mussel beds consistently reduced the internal (subsurface) temperature of rock samples during ‘low-tide’ periods. As mechanical rock weathering processes are influenced by surface and subsurface temperature regimes, it is inferred that these stabilising effects may translate to a reduction in the efficiency of particular rock breakdown processes. Rock hardness (Equotip Piccolo) measurements collected from the shore platform support this assertion as mussel-colonised surfaces were found to be significantly harder than bare surfaces, indicating they had experienced less breakdown during exposure to intertidal weathering and erosion. A supplementary field experiment based on the disintegration of gypsum ‘domes’ as an indirect measure of water/wave motion both within and outside of mussel beds further indicates that mussels may act as bioprotective agents by reducing turbulence at the rock surface.Overall, this study presents the first empirical evidence of mechanisms by which mussels may protect intertidal rocks from weathering and erosional processes through the moderation of near-surface microclimate regimes and water motion in temperate environments. Importantly, compared to other canopy forming species, such as seaweeds, the observed dampening effects of M. edulis are likely only small in magnitude. However, as mussels can dominate the surfaces of rocky shores at certain tidal heights, they may act as locally important geomorphic agents that warrant further consideration as one component of the collective effect of bioprotective and bioerosive species in these environments. Further work is now needed to examine the geomorphic roles of mussel beds on a variety of other rock types, and the extent to which their impacts vary in time and space in relation to other biological, chemical and physical agents of change.

Validation of significant wave height from Jason-3 and Sentinel-3A/B and relation to tidal currents in coastal regions of the Korean Peninsula

ABSTRACT As climate change and oceanic warming have an increasing impact on coastal waves, accurate observation of satellite significant wave height (SWH) in coastal regions is becoming more important. In addition to the validation of satellite SWHs in the global ocean, the SWHs should also be validated in coastal regions for their diverse applications. In this study, the accuracy and error characteristics of altimeter SWH data, Jason-3 Geophysical Data Records Version D and Sentinel-3A/B Level-2 marine scientific products, were investigated using SWH measurements from 18 buoy stations in the coastal region of the Korean Peninsula from 2017 to 2019. Results showed that the Jason-3 and Sentinel-3A/B SWHs exhibited root mean square errors (RMSE) and bias errors of 0.59–1.60 m and 0.03–0.42 m, respectively. Cross-validation between Jason-3 and Sentinel-3A/B exhibited a consistency comparable to that of the global ocean. The spatial distribution of comparison between altimeter SWH and wave model data was similar to that obtained using altimeter SWH and in situ measurements. Validation of altimeter SWH from the buoy stations yielded the highest error in the southwestern coastal region of the Korean Peninsula, with high tidal currents in the Yellow Sea. The stronger the tidal current speed, the more amplified the satellite SWH errors. The SWH differences exhibited a high dependence on the tidal index, including the elements of tidal current speed, water depth, and tide height. A relationship was found between the tidal index and the altimeter SWH differences from the in situ measurements. Based on this relation, formulas were proposed to reduce satellite SWH errors due to tidal currents in the coastal regions of the Korean Peninsula. For the matchups with tidal index less than 2, RMSE and bias errors of each satellite sensor were improved by up to 14.25% (0.28 m) and 94.40% (0.84 m), respectively.