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1. The role of inputs of marine wrack and carrion in sandy‐beach ecosystems: a global review

   https://doi.org/10.1111/brv.12886  

   Hyndes, Glenn A.; Berdan, Emma L.; Duarte, Cristian; Dugan, Jenifer E.; Emery, Kyle A.; Hambäck, Peter A.; Henderson, Christopher J.; Hubbard, David M.; Lastra, Mariano; Mateo, Miguel A.; et al (August 2022, Biological Reviews)

   ABSTRACT Sandy beaches are iconic interfaces that functionally link the ocean with the landviathe flow of organic matter from the sea. These cross‐ecosystem fluxes often comprise uprooted seagrass and dislodged macroalgae that can form substantial accumulations of detritus, termed ‘wrack’, on sandy beaches. In addition, the tissue of the carcasses of marine animals that regularly wash up on beaches form a rich food source (‘carrion’) for a diversity of scavenging animals. Here, we provide a global review of how wrack and carrion provide spatial subsidies that shape the structure and functioning of sandy‐beach ecosystems (sandy beaches and adjacent surf zones), which typically have littlein situprimary production. We also examine the spatial scaling of the influence of these processes across the broader land‐ and seascape, and identify key gaps in our knowledge to guide future research directions and priorities. Large quantities of detrital kelp and seagrass can flow into sandy‐beach ecosystems, where microbial decomposers and animals process it. The rates of wrack supply and its retention are influenced by the oceanographic processes that transport it, the geomorphology and landscape context of the recipient beaches, and the condition, life history and morphological characteristics of the macrophyte taxa that are the ultimate source of wrack. When retained in beach ecosystems, wrack often creates hotspots of microbial metabolism, secondary productivity, biodiversity, and nutrient remineralization. Nutrients are produced during wrack breakdown, and these can return to coastal waters in surface flows (swash) and aquifers discharging into the subtidal surf. Beach‐cast kelp often plays a key trophic role, being an abundant and preferred food source for mobile, semi‐aquatic invertebrates that channel imported algal matter to predatory invertebrates, fish, and birds. The role of beach‐cast marine carrion is likely to be underestimated, as it can be consumed rapidly by highly mobile scavengers (e.g. foxes, coyotes, raptors, vultures). These consumers become important vectors in transferring marine productivity inland, thereby linking marine and terrestrial ecosystems. Whilst deposits of organic matter on sandy‐beach ecosystems underpin a range of ecosystem functions and services, they can be at variance with aesthetic perceptions resulting in widespread activities, such as ‘beach cleaning and grooming’. This practice diminishes the energetic base of food webs, intertidal fauna, and biodiversity. Global declines in seagrass beds and kelp forests (linked to global warming) are predicted to cause substantial reductions in the amounts of marine organic matter reaching many beach ecosystems, likely causing flow‐on effects for food webs and biodiversity. Similarly, future sea‐level rise and increased storm frequency are likely to alter profoundly the physical attributes of beaches, which in turn can change the rates at which beaches retain and process the influxes of wrack and animal carcasses. Conservation of the multi‐faceted ecosystem services that sandy beaches provide will increasingly need to encompass a greater societal appreciation and the safeguarding of ecological functions reliant on beach‐cast organic matter on innumerable ocean shores worldwide. 

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2. Impact of Hurricane Maria on Beach Erosion in Puerto Rico: Remote Sensing and Causal Inference

   https://doi.org/10.1029/2020GL087306  

   Pérez Valentín, Jaynise M.; Müller, Marc F. (March 2020, Geophysical Research Letters)

   Abstract Beach erosion due to large storms critically affects coastal vulnerability, but is challenging to monitor and quantify. Attributing erosion to a specific storm requires a reliable counterfactual scenario: hypothetical beach conditions, absent the storm. Calibrating models to construct counterfactuals requires numerous observations that are rarely available. Storm paths are unpredictable, making long‐term instrumentation of specific beaches costly. Optical remote sensing is hampered by persistent cloud cover. We use Sentinel‐1 satellite radar imagery to monitor shoreline changes through clouds and propose regression discontinuity as a strategy to estimate the causal effect of large storms on beach erosion. Applied to 75 beaches across Puerto Rico, the approach detects shoreline changes with a root‐mean‐square error comparable to the resolution of the imagery. Hurricane Maria caused an erosion of 3 to 5 m along its path, up to 40 m at particular beaches. Results reveal strong local disparities that are consistent with simulated nearshore hydrodynamic conditions. 

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3. MICROPLASTIC POLLUTION IN THE TIJUANA ESTUARY BEACHESOF SOUTHERN CALIFORNIA

   Sheppard, Q.; Gray, S.C. (February 2022, Ocean Sciences Meeting)

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   The Tijuana River Watershed encompasses 1750 square miles of territory in both Mexico and the United States, culminating at the National EstuarineResearch Reserve. While this area comprises one of the largest undisturbed wetlands in the state, it is one of the most polluted rivers in SouthernCalifornia, draining raw sewage and nonpoint source pollution. Despite extensive research, microplastic pollution along the beaches has not been explored. The objective of this study is to determine how the abundance and morphology of microplastic pollution in beach sediments vary with distance along the littoral cell from the Tijuana River outfall. Twenty samples were collected at 10 sites that span from the Tijuana River outfall to Mission Beach, San Diego. They are characterized as outfall sites, low-visitation beaches near the outfall, and high-visitation beaches further from the outfall. Solutions of 100ml sediment and 400ml hyper-saline solution were mixed and settled for 16 hours before being processed using a vacuum filtration system in a laminar fl ow hood. The microplastics (MP)were counted and classified using light microscopy. Laboratory practices to reduce laboratory contamination were employed and analytical blanks were run for every 3 samples. MPs ranged from 1 to 199/100ml sediment, of which approximately 91% were fibers. The greatest MP abundance occurred at the river outfall sites, but recovery rates were highly variable, and the analytical blanks ranged from 3-63/100ml sediment. The results oft his study suggest that microplastic distribution in sandy beach sediments is patchy but higher near the Tijuana River Outfall, and that future studies should report analytical blanks and employ methods to reduce contamination. Understanding the relationship between watersheds and microplastic distributions may inspire policy change on water quality protections in watersheds. 

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4. Growth of beach-adapted plants in recycled glass sand compared to natural beach sand

   https://doi.org/10.1007/s11104-025-07479-3  

   Richardson, Paul; Goings, Peyton; Markel, Bek; Dixon, Jacob; Ahmad, Shehbaz; Albert, Julie; Michaeloff, Leah; Clay, Keith (May 2025, Plant and Soil)

   Abstract AimsThe goal of this study was to explore the suitability of recycled glass sand for the growth of beach-adapted plant species given the potential environmental benefits of utilizing glass sand for beach and dune restoration in the face of dwindling natural sand resources. MethodsWe grew three species native to US Gulf of Mexico beaches (Ipomoea imperati(Vahl) Griseb.,I. pes-caprae(L.) R.Br., andUniola paniculata(L.)) in three greenhouse experiments in glass sand, beach sand, or mixtures. First, we investigated nutrient and microbial effects by growing each species in pure glass sand, beach sand, and 80%/20% mixtures of glass sand/beach sand. Second, we comparedU. paniculatagrowth in glass sand mixed with 100%, 75%, 50%, 25%, or 0% beach sand. These experiments included fertilizer and microbial sterilization treatments. Third, we investigated soil permeability effects by comparing growth of all species using different grain sizes of glass sand. ResultsOverall, plants produced significantly more biomass in beach sand than in glass sand, and the effect was more pronounced with the fertilizer treatment. There were significant effects of substrate mixtures and interactions with fertilizer treatments onUniolabiomass. Further, when glass sand grain sizes were manipulated, plant biomass was equal or higher in the coarsest glass sand compared to beach sand. ConclusionsOur results demonstrate that beach-adapted plants can grow in glass sand and suggest that recycled glass sand is a potential resource for ecological restoration with incorporation of soil amendments such as fertilizer and utilization of selected grain sizes. 

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5. Using Multiple Biased Data Sets to Recover Missing Trips with a Behaviorally Informed Model

   https://doi.org/10.1287/trsc.2024.0550  

   Guan, Xiangyang; Huang, Shuai; Chen, Cynthia (May 2025, Transportation Science)

   Trip generation, a critical first step in travel demand forecasting, requires not only estimating trips from the observed sample data, but also calculating the total number of trips in the population, including both the observed trips and the trips missed from the sample (we call them missing trips in this paper). The latter, how to recover missing trips, is scarcely studied in the academic literature, and the state-of-the-art practice is through the application of sample weights to extrapolate from observed trips to the population total. In recent years, big location-based service (LBS) has become a promising alternative data source (in addition to household travel survey data) in trip generation. Because users self-select into using different mobile services that result in LBS data, selection bias exists in the LBS data, and the kinds of trips excluded or included differ systematically among data sources. This study addresses this issue and develops a behaviorally informed approach to quantify the selection biases and recover missing trips. The key idea is that because biases reflected in different data sources are likely different, the integration of multiple biased data sources will mitigate biases. This is achieved by formulating a capture probability that specifies the probability of capturing a trip in a data set as a function of various behavioral factors (e.g., socio-demographics and area-related factors) and estimating the associated parameters through maximum likelihood or Bayesian methods. This approach is evaluated through experimental studies that test the effects of data and model uncertainty on its ability of recovering missing trips. The model is also applied to two real-world case studies: one using the 2017 National Household Travel Survey data and the other using two LBS data sets. Our results demonstrate the robustness of the model in recovering missing trips, even when the analyst completely mis-specifies the underlying trip generation process and the capture probability functions (for quantifying selection biases). The developed methodology can be scalable to any number of data sets and is applicable to both big and small data sets. History: This paper has been accepted for the Transportation Science Special Issue on Machine Learning Methods for Urban Mobility. Funding: This work was supported by the Division of Civil, Mechanical and Manufacturing Innovation [Grant 2114260], the National Institute of General Medical Sciences [Grant 1R01GM108731-01A1], and the U.S. Department of Transportation [Grant 69A3551747116]. Supplemental Material: The online appendix is available at https://doi.org/10.1287/trsc.2024.0550 . 

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