Journal of Coastal Research

Sweeney, E.M.; Costa, B.; Jung, J., and Parrish, C.E., 2026. Predicting the location of threatened marine taxa using machine learning and bathymetric LIDAR waveforms. Journal of Coastal Research, 42(4), 748–762. Charlotte (North Carolina), ISSN 0749-0208. Branching corals are vital coastal resources, yet they are increasingly stressed because of human-induced environmental changes. Mapping these important coral species can be challenging, particularly when covering large spatial areas, because of limited time and accessibility. Airborne bathymetric LIDAR has been widely explored for benthic habitat mapping and has proven effective in distinguishing broad habitat classes such as coral, seagrass, macroalgae, and sand. However, the ability to classify specific coral morphologies, such as branching corals, in airborne bathymetric LIDAR remains an open research question. This study leverages LIDAR waveform metrics (LWMs) and machine learning to investigate the ability to classify branching corals west of Saipan, Commonwealth of the Northern Mariana Islands (CNMI). Results showed increased predictive performance for branching coral taxa using LWMs, as illustrated by higher values in validation percent deviance explained (PDE) and area under the receiver operating characteristic curve. LWMs consistently ranked among the top 10 most influential predictors, with at least one LWM among the two most important predictors for each modeled coral taxon. In contrast, prediction models for sandy seafloor showed minimal influence from LWM predictors, and topographic features played a more prominent role in these models. Overall, this study found that the inclusion of normalized LWMs significantly improved the ability to predict the location for branching corals in Saipan, CNMI. These improved predictions and maps are important baseline information for coral reef protection and management in the region.

Joesting, H.M.; Hinson, J., and Palacios, M., 2026. Optimal storage and germination conditions for the nursery production of Spartina alterniflora in coastal Georgia. Journal of Coastal Research, 42(4), 789–795. Charlotte (North Carolina), ISSN 0749-0208. Recently, salt-marsh restoration efforts using living shorelines (LSs) have increased along the East and Gulf coasts of the United States to mitigate erosion and restore marsh ecological processes. To support these initiatives, a continuous supply of locally sourced, genetically diverse (i.e. propagated from seed) Spartina alterniflora is needed. The observed morphological, physiological, and phenological variation among populations along the East and Gulf coasts, which are driven by genetic differences, suggests that seed germination requirements also vary along the geographic distribution of S. alterniflora. The goal of this study was to contribute to LS efforts by optimizing winter stratification and germination conditions for S. alterniflora in the coastal Georgia region. Specifically, seed viability was assessed among different storage vessels and water salinities, and germination was monitored among different temperature regimes and water salinities. Results suggested winter storage in sealed plastic bags in fresh water and germination in fresh water at alternating temperatures. These results differed from previously published methods for storage and germination from other regions. Results of this research will facilitate the nursery production of locally sourced S. alterniflora from seed to support LS projects in the coastal Georgia region, as well as provide a starting point for optimizing seed-propagation techniques for other regions within the native distribution of S. alterniflora that prioritize the use of LS methods in salt-marsh restoration.

McCullough, R.M.; Parrish, C.E.; and Imahori, G., 2026. Investigation of SuperDove for satellite-derived bathymetry and comparison with Sentinel-2. Journal of Coastal Research, 42(4), 720–734. Charlotte (North Carolina), ISSN 0749-0208. Satellite-derived bathymetry (SDB) uses multiple spectral bands of satellite imagery to retrieve depth and is increasingly used for purposes ranging from hydrographic survey planning to benthic habitat mapping and poststorm change detection. Turbidity and clouds are major hindrances to successful SDB. The recent launch of constellations of commercial small satellites (SmallSats) may help overcome these challenges, offering much higher revisit rates than conventional Earth observation satellites. In theory, the greater number of overpasses should increase the probability of acquiring at least one scene with suitable water clarity and lack of clouds needed for successful SDB retrievals. However, to determine whether and to what extent SmallSats do, in fact, facilitate SDB, comparing SDB from SmallSats with SDB from conventional Earth observation satellites should be considered in terms of rates of acquisition of usable imagery, achievable accuracies, and maximum retrieval depths. This study evaluated SDB from Planet Labs's SuperDove imagery, as compared with Sentinel-2 imagery, and considered each of these three criteria for 14 test sites encompassing thousands of images. Results showed that the SmallSat constellation increased usable imagery by a factor of 3.5 while providing similar accuracy (no statistically significant difference in the means of the squared errors) and higher resolution across the 14 study sites. Maximum depth analysis was less conclusive but suggested that Sentinel-2 may provide greater maximum depths depending on the bands used. Qualitative assessment indicated that SuperDove imagery more frequently exhibits sensor quality issues, such as band misregistration and blurriness, and that the smaller footprint sometimes necessitates a greater number of scenes to cover a site. Results of this study are currently being used by the National Oceanic and Atmospheric Administration to inform incorporation of SuperDove imagery in operational SDB software.

Affonso, J.; Kastrisios, C.; Parrish, C.E., and Calder, B., 2026. Investigating scene segmentation for improving satellite-derived bathymetry accuracy and coverage. Journal of Coastal Research, 42(4), 706–719. Charlotte (North Carolina), ISSN 0749-0208. Seafloor bathymetry is essential for assisting safe maritime navigation through up-to-date navigational charts. Satellite-derived bathymetry (SDB) can serve as a low-cost, rapid alternative or supplement to shipborne and airborne surveys, particularly for mapping remote and shallow areas. However, the accuracy of SDB is relatively low compared to other methods, and the spatial coverage is often limited. One contributing factor is that conventional SDB approaches assume that bottom type and water clarity remain constant throughout the entire area of interest, such that a single linear model can be used to retrieve bathymetric information. To enhance the accuracy and coverage of depth estimation, this work explores the segmentation of the scene into smaller spatial units and the incorporation of the water-column contribution in the SDB equation. The segmentation methods consisted of six approaches: three horizontal, one vertical (by depth), and two combinations of horizontal and vertical methods. Utilizing Sentinel-2 images over the Dry Tortugas and the St. Thomas East End Reserve, it was found that, with one exception, the geographic segmentation methods improved the accuracy of depth estimation. Accuracy improvements of up to 60% were observed, although the vertical segmentation results showed some indications of potential overfitting to the reference data, particularly at the smaller vertical bin sizes. Overall, the results provide strong indication that scene segmentation can improve both the accuracy and coverage of depth estimates compared to traditional SDB methods that employ only a single model.

Brown, N.; Briggs, T.R.; Smith, M., and Kajiura, S., 2026. Effect of beach nourishment–driven turbidity on water quality and blacktip shark aggregations. Journal of Coastal Research, 42(4), 634–643. Charlotte (North Carolina), ISSN 0749-0208. This study originally aimed to examine blacktip shark aggregations relative to the physical characteristics of the nearshore environment and explore potential effects of beach nourishment projects in Palm Beach County, Florida, U.S.A. Instead, reduced water quality from spatiotemporally extensive turbidity plumes were documented during a 2-year study period. Twenty-four turbidity plumes were documented, ranging in size from 0.60 to 14.91 km alongshore and 50 to >250 m cross shore. The poor water clarity prevented surveying the blacktip shark aggregations and observing changes in behavior within the project area, where bathymetry and geotechnical information were collected. However, blacktip sharks just south of the study area were observed with peak populations (in the hundreds) only 50 m from the shoreline during February 2020 and March 2021. Their preference of shallow water in close proximity to the shoreline suggests that the persistent turbidity plumes could interfere with prey capture and result in accidental human encounters. Further study is recommended within turbidity-producing project areas using alternative methods, such as tagging, to investigate the effects of changing water clarity on the blacktip shark locations, prey acquisition, and migration patterns.

Dabu, R. and Cruz, E., 2026. Comparative analysis of hybrid and traditional sediment transport models on a low-energy data-limited tropical coastline. Journal of Coastal Research, 42(4), 673–682. Charlotte (North Carolina), ISSN 0749-0208. This study conducts a comparative evaluation of hybrid and traditional sediment transport modeling approaches applied to the low-energy, data-limited tropical coastline of Sariaya, Quezon Province, Philippines. A hybrid model incorporating MIKE21's hydrodynamic, spectral wave, sediment transport, and shoreline morphology modules was benchmarked against conventional empirical methods—namely, the Sverdrup–Munk–Bretschneider wave hindcasting technique and the energy flux method. Results indicate that the hybrid model captured cross-shore sediment dynamics and spatial shoreline variations with higher physical fidelity, aligning more closely with observed shoreline behavior from satellite imagery. In contrast, traditional methods overestimated wave heights and sediment transport volumes but often captured directional patterns despite simplified assumptions and limited input resolution. The study highlights that although traditional approaches offer practicality in resource-constrained settings, they can introduce significant uncertainties in complex coastal environments. Consequently, the adoption of process-based hybrid models is recommended for robust coastal management in morphodynamically sensitive and data-limited regions.

Joesting, H.M.; Gregory, A.; Hinson, J., and Palacios, M., 2026. Spatial and temporal patterns in phenology, fecundity, and fertility for Spartina alterniflora in coastal Georgia. Journal of Coastal Research, 42(4), 769–779. Charlotte (North Carolina), ISSN 0749-0208. The salt-marsh grass Spartina alterniflora plays a critical role in salt-marsh growth and maintenance, and healthy populations are required for salt marshes to persist under future sea-level rise scenarios. However, to determine future population dynamics for S. alterniflora, a fundamental understanding of reproductive ecology is needed. This study contributes to this knowledge by investigating spatial and temporal patterns in S. alterniflora phenology, fecundity, and fertility by assessing proportion of reproductive stems, seed set, seed viability, germination rate, and seedling production for multiple salt marshes in coastal Georgia over several years. Results revealed the timing of peak flowering and seed set for populations during the reproductive season, as well as significant annual and spatial patterns in fecundity and fertility, potentially driven by variation in environmental variables and degree of anthropogenic disturbance. Variation in reproductive output was found within S. alterniflora populations, suggesting that only a few individuals contribute significantly to seedling production each year. These results provide valuable information on phenology and reproductive ecology for this species and contribute to predicting the response of S. alterniflora and salt marshes to future climate change.

Joesting, H.M. and Palacios, M., 2026. Is local best? Growth and survival of Spartina alterniflora from different sources in a simulated Georgia salt marsh. Journal of Coastal Research, 42(4), 780–788. Charlotte (North Carolina), ISSN 0749-0208. As salt marsh restoration efforts using nature-based solutions, such as living shorelines, increase in coastal Georgia, the best source of Spartina alterniflora needs to be identified to maximize restoration success. Several studies suggest using locally sourced plants propagated from seed to maintain population structure while promoting transplant survival, which can be termed the “Local Is Best” hypothesis. The goal of this research was to test this hypothesis by monitoring growth and survival of S. alterniflora plants from different sources and propagation methods in a simulated salt marsh over a growing season. Results showed significantly greater total biomass (aboveground and belowground) for locally sourced plants, and rhizomes were found to have greater growth rates compared to seedlings, likely due to their ability to reallocate energy stored in belowground structures to aboveground growth. The results did provide support for the “Local Is Best” hypothesis, and based on this and other studies, it is recommended that locally sourced seedlings be used in restoration to maximize transplant survival and promote ecological processes influenced by S. alterniflora.

Seymour, A.; Ciarletta, D.; Parker, K.; Doran, K.; and Palmsten, M.L., 2026. Decadal-scale characteristics of natural and anthropogenic dune morphology along North Carolina barrier islands (SE Atlantic coast). Journal of Coastal Research, 42(4), 611–633. Charlotte (North Carolina), ISSN 0749-0208. Dunes offer protection to coastal communities from storms, yet quantitative research characterizing human influences on dune systems across decades and 10–100 km spatial scales constitutes a known data gap. This study analyzed a multidecadal archive of dune crest elevations and positions to map mesoscale spatiotemporal trends in foredune morphology across the barrier island coastline of North Carolina, SE Atlantic coast. Results are summarized within four categories of coastline representing a range of coastal management intensities, integrating beach width and dune lateral accommodation space to assess the comparative influence of differing intensities of anthropogenic intervention on dune morphology. These categories account for the presence of structures, roads, and alongshore connectivity to anthropogenic sediment sources (beach nourishment). These categories show distinct dune and beach system characteristics. Dunes are largest in the areas with the longest legacy of coastal management. As categories decrease in development intensity, dune and beach system characteristics generally depart from the large, static dunes and narrow beaches consistent with hold-the-line management. Where small or transgressive dunes exist on heavily developed coasts, they coincide with relatively strong hydrodynamic forcing or sediment-limiting geology. There is evidence of indirect coastal management influence on undeveloped barrier islands with alongshore connectivity to developed barriers. While this analysis was conducted at the mesoscale, the results provide researchers with the framework to make insights at smaller scales than those demonstrated in this study.

Gama, P.L.S.S.; Silva, E.S.C.S.; Rosa, G.P., and Monteiro, S.M., 2026. Accumulation of abandoned, lost, or discarded fishing gear on beaches of the Amazon coastal zone. Journal of Coastal Research, 42(4), 683–690. Charlotte (North Carolina), ISSN 0749-0208. Abandoned, lost, or discarded fishing gear (ALDFG) represents a threat to the lives of marine organisms. The monitoring and identification of ALDFG in northern Brazil are still scarce, despite the region practicing artisanal fishing as an important economic activity. Thus, this study presents the distribution of ALDFG during different seasonal periods along the beaches of Algodoal Island (northern Brazil), located in an environmental protection area (EPA). The ALDFG records were made during the wet and dry seasons (2022), during the spring tide, along the beaches of Caixa d'água, Farol, Princesa, and Cação (totaling 5.8 km in length), which are dominated by semidiurnal macrotides. The photographic record of ALDFG was made between the high and the low tide lines (averaging 224 m in width), conducted through a walking survey. All observed ALDFG items were recorded and georeferenced. In total, 66 ALDFG items were found: 50 items during the dry season and 16 items during the wet season. Fishing nets (30 items) and nylon ropes (29 items) were the most abundant, along with polystyrene buoys (4 items), corral screens (2 items), and electrical cable (1 item). Most ALDFG items were transparent (45%) and blue (44%). Caixa d'água was the beach with the most ALDFG records (34 items). The presence of ALDFG as solid waste on beaches located in an EPA along the Amazon coast reinforces the vulnerability of these ecosystems, as well as the inadequate management of ALDFG on the island.