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Degradation, diagenesis, and mineralogical changes in foraminiferal tests are recognized as mechanisms that control their preservation and destruction under the subaquatic/aerial conditions, commonly influenced by processes such as dissolution, abrasion, breakage, and mineralogical replacement. In this paper, we discuss test degradation and early diagenesis on the large benthic foraminifera Archaias angulatus from the Yucatan Peninsula beach sands, a region absent in surficial rivers and terrigenous input seawards. Two main sites of Yucatan beach were selected: the high-energy environment of the Gulf of Mexico coast (GOMC) and the low-wave-energy environment of the Mexican Caribbean coast (MCC). Test degradation in the GOMC and MCC is affected by chemical dissolution, bioerosion, and physical abrasion. Among other factors, we found the effects of the bacterial microboring and dissolution by lowering pH in seawater (i.e., nearshore springs discharging seaward), as well as longshore currents and waves, depending on the prevailing conditions before transport and resuspension of the tests landwards. The observed degradation features in the tests are wall loss, chamberlet exposure, surface pits, and highly abraded edges. However, we explain the presence of pristine A. angulatus tests in the MCC beach through its association with Thalassia seagrass patches. Very low Mg/Ca ratios were found, which suggest the early diagenesis in the foraminiferal tests and the absence of recrystallized processes. Rare-earth element analyses suggest reduced authigenic precipitation of Mn–Fe coatings in the tests, and the absence of freshwater discharges or terrigenous inputs in the beach sands. [ABSTRACT FROM AUTHOR]

This paper presents a qualitative assessment of coastal processes along the northern coast of the Yucatan Peninsula based on a method used to estimate the potential longshore sediment transport. Despite the deep-water low-energy wave conditions (Hs = 1 m) in the study area, erosion is critical in many locations, including the urbanized stretches of coast. The waves were characterized using a 12 y (1997-2009) deep-water wave hindcast data (WAVEWATCH III) as forcing for a spectral wind-wave numerical model (MIKE 21 SW) used to propagate the waves to the coast. Simulated time series of significant wave height, peak period, and direction are compared against in situ measurements at 10 m water depth. Numerical results are further employed for estimation of the nearshore wave climate along the coast. Wave conditions are strongly affected by the wide continental shelf in front of the northern Yucatan Peninsula, with an increase in wave energy at the eastern part of the peninsula where the shelf narrows. The nearshore wave climate is employed for the qualitative assessment of potential longshore sediment transport (LITDRIFT model) in the study area. The sediment transport calculations are consistent with both volume impoundment estimations at a groin and dredging estimates at a harbor (-35,000 m³/y). A net westward potential longshore sediment transport is found along the entire coast, ranging between --20,000 and --80,000 m³/y, except west of Holbox, where longshore transport direction is inverted. Based on sediment transport gradients, potential erosion and deposition areas are identified. Erosion/accretion patterns at nonurbanized areas are consistent with field observations. This dominant westward longshore transport suggests an extremely sensitive shoreline to littoral barriers, as supported by observations in the most urbanized areas. These areas show no gradients on longshore sediment transport, whereas beach erosion is a common feature enhanced by littoral barriers. Shore protection should then be oriented toward sediment management strategies. [ABSTRACT FROM AUTHOR]

The breeze phenomenon is of great importance in coasts around the world owing to both its impact on local atmospheric dynamics and its influence on coastal processes. The northwest of the Yucatan Peninsula (YP) is characterized by the presence of intense sea breezes and Cold Surge (CS) events (locally known as Nortes). Field observations suggest that nearshore hydrodynamics and beach evolution in the study area are strongly controlled by waves generated during sea breeze events. In this paper, the diurnal wind component associated with the breeze phenomenon and its variability due to the presence of a CS event are investigated utilizing the Weather Research and Forecasting (WRF) model. The WRF model is implemented in three nested domains with a maximum resolution of 3.6-km. The numerical model was validated with observations at 20 stations located across the YP, adequately reproducing wind speed and direction at Sisal, Yuc. coast, with a correlation coefficient of 0.56 and a circular correlation coefficient of 0.83, respectively. Diurnal wind components were least-squares fitted to a sinusoidal signal, and the resulting parameters were used to obtain an elliptical hodograph related to the breeze phenomenon. Numerical results suggest that sea breezes, with wind intensities higher than 10 ms−1, extend more than 100 km offshore in the northern YP. Although breeze events are caused by differential heating at a small spatial scale, particularly in the Gulf of Mexico, this diurnal signal exceeds the local spatial scale. Furthermore, the interaction between the sea breeze and the mean wind associated to the trade winds generates a line of convergence that crosses the YP. Model results allow us to identify that the mechanisms responsible of such large amplitude of the diurnal signal in this area are: (i) the thermal gradient, (ii) the relatively small value of the Coriolis force, (iii) the orography, (iv) the friction, and (v) the peninsula's geometry. The numerical results revealed that during the interaction between local breezes and a CS event, the diurnal signal remains, except for the initial day of the event. However, further research is needed to generalize the current results for other CS events with different intensity and displacement characteristics. • The WRF model was implemented to reproduce the sea-land breeze local variability • The wind diurnal component and its variability due to a cold surge were analyzed • Different mechanisms are responsible for the large amplitude of the breeze in Yucatan • The Yucatan Peninsula is dominated by a land breeze of large amplitude • A convergence line crosses the Yucatan Peninsula during sea breezes [ABSTRACT FROM AUTHOR]

Beach and dune morphology are spatially and temporally variable, changing over a broad range of scales simultaneously. Strong wind, waves, and storm surge from Hurricane Harvey substantially eroded the beach and dunes along the Texas coast, causing significant scarps and berms. This paper presents information about how anthropogenic activity, such as driving on the beach, affected the response and recover of a barrier island with regard to the post-storm resiliency along the Texas-Gulf of Mexico coast by comparing two adjacent 7 km stretches of coast: a driving section and a limited-access section. A collection of field photos, aerial imagery, and a September 2016 LiDAR-derived digital elevation model (DEM) dataset provide information on pre-storm morphology, while field photos, taken only 3 days after Hurricane Harvey made landfall, and a structure-from-motion (SfM)-derived DEM and imagery provide qualitative and quantitative information about the post-storm morphology. While beach and dune erosion in the non-driving section was restricted entirely to the beach and incipient dune system, the driving section exhibited complex patterns of erosion and deposition along the beach and the entire foredune profile was altered. Despite the hurricane making landfall north of the study site and closer to the non-driving section, beach-dune erosion and scarping was greatest in the southern section which is accessible to public vehicles. Results demonstrate that human activity affects the response and recovery of the beach-dune system along the Gulf side of the island by decreasing alongshore variability in erosion-deposition and limiting vegetative and geomorphic recovery. Unlabelled Image • Driving on the beach affects beach-dune response to and recovery following a storm. • Non-driving areas show substantial evidence of recovery within 6 months post-storm. • Driving on the beach limits incipient foredune development and recovery. • Limiting low dune recovery can reinforce the effects of framework geology. [ABSTRACT FROM AUTHOR]