Elemental signature of terrigenous sediment runoff as recorded in coastal salt ponds: US Virgin Islands

Larson, Rebekka A.; Brooks, Gregg R.; Devine, Barry; Schwing, Patrick; Holmes, Charles W.; Jilbert, Tom; Reichart, Gert‐Jan

doi:10.1016/j.apgeochem.2015.01.008

Cited by 20 publications

(13 citation statements)

References 22 publications

(20 reference statements)

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“…A model relying on P int also confirmed the significance of API in defining runoff generation thresholds. These two approaches represent improvements from previous local attempts that had exclusively relied on total rainfall as a controlling factor (Cosner, ; Jordan & Cosner, ; Larson et al, ; Ramos‐Scharrón & LaFevor, ).…”

Section: Discussionmentioning

confidence: 99%

“…With only few exceptions (e.g., Hodgson, ; Messina, ), marine‐based research attempting to understand terrestrial runoff inputs to coral reef ecosystems has lacked an explicit runoff monitoring component. Previous work on St. John has compensated for this limitation by relying on existing rainfall data (e.g., Edmunds & Gray, ; Gray et al, ; Larson et al, ). Therefore, the rainfall‐driven methods described here can serve as a framework for better distinguishing, which specific portions of the contributing watersheds are actively delivering runoff and sediment to marine monitoring sites.…”

Section: Discussionmentioning

confidence: 99%

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Effects of Forest Roads on Runoff Initiation in Low‐Order Ephemeral Streams

Ramos‐Scharrón

LaFevor

2018

Water Resources Research

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Understanding hydrologic connectivity is essential for managing ephemeral headwater streams where upstream land use influences downstream aquatic habitats. This study relies on a field‐based approach to evaluate how precipitation and roads affect runoff generation in low‐order ephemeral streams of the U.S. Virgin Islands. Logistic regression analyses show that runoff delivery from unroaded catchments agrees with a water storage conceptual model typical for subsurface storm and saturation overland flow‐dominated settings. Without roads, runoff occurs only about 4 times per year in response to 10 and 78 mm of storm rainfall, depending on antecedent precipitation. In contrast, maximum 15‐min rainfall intensities are a better predictor of runoff generation on unpaved roads than are total rainfall and antecedent conditions. Intensities surpassing ~10 mm/hr lead to road runoff, and this occurs about 40 times per year. Road‐influenced streams represent an intermediate setting for which runoff generation depends on storm and antecedent rainfall, as well as the road surface area captured by drains and flow path distance. In our focus area, roads can provoke streams to deliver runoff to coral bearing waters 10 to 13 times every year as a response to 9.3‐ to 50‐mm storms, depending on antecedent rainfall and road drain characteristics. These results highlight the sensitivity of road connectivity to specific road drain characteristics and display the potential for connectivity as a guiding watershed restoration principle.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Effects of Forest Roads on Runoff Initiation in Low‐Order Ephemeral Streams

Ramos‐Scharrón

LaFevor

2018

Water Resources Research

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“…Sampling periods with major sediment and terrigenous accumulation pulses were associated with meteorological events that produced total rainfall higher than 30 mm (Figure 3), and individual rainfall intensity higher than 15 mm/h (Figure 11). Studies conducted on St. John, US Virgin Islands, coastal sedimentary records suggest that runoff and terrigenous sediment input to marine coastal environments runoff were associated to rainfall events that exceed threshold of ∼12 mm/day Larson et al, 2015). Nevertheless, field studies have also shown that rainfall of just 3-5 mm can produce significant runoff and sediment transport from unpaved roads to coastal waters (Ramos-Scharrón and MacDonald, 2007).…”

Section: Discussionmentioning

confidence: 99%

Effects of Changing Weather, Oceanographic Conditions, and Land Uses on Spatio-Temporal Variation of Sedimentation Dynamics along Near-Shore Coral Reefs

et al. 2017

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Sedimentation is a critical threat to coral reefs worldwide. Major land use alteration at steep, highly erodible semi-arid islands accelerates the potential of soil erosion, runoff, and sedimentation stress to nearshore coral reefs during extreme rainfall events. The goal of this study was to assess spatio-temporal variation of sedimentation dynamics across nearshore coral reefs as a function of land use patterns, weather and oceanographic dynamics, to identify marine ecosystem conservation strategies. Sediment was collected at a distance gradient from shore at Bahia Tamarindo (BTA) and Punta Soldado (PSO) coral reefs at Culebra Island, Puerto Rico. Sediment texture and composition were analyzed by dry sieving and loss-on-ignition techniques, and were contrasted with environmental variables for the research period (February 2014 to April 2015. Rainfall and oceanographic data were analyzed to address their potential role on affecting sediment distribution with BEST BIO-ENV, RELATE correlation, and linear regression analysis. A significant difference in sedimentation rate was observed by time and distance from shore (PERMANOVA, p < 0.0100), mostly attributed to higher sediment exposure at reef zones closer to shore due to strong relationships with coastal runoff. Sedimentation rate positively correlated with strong rainfall events (Rho = 0.301, p = 0.0400) associated with storms and rainfall intensity exceeding 15 mm/h. At BTA, sediment deposited were mostly composed of sand, suggesting a potential influence of resuspension produced by waves and swells. In contrast, PSO sediments were mostly composed of silt-clay and terrigenous material, mainly attributed to a deforestation event that occurred at adjacent steep sub-watershed during the study period. Spatial and temporal variation of sedimentation pulses and terrigenous sediment input implies that coral reefs exposure to sediment stress is determined by local land use patterns, weather, and oceanographic dynamics. Comprehensive understanding of sediment dynamics and coastal ecosystem interconnectivity is fundamental to implement integrated and adaptive management strategies aimed to promote sustainable development at watershed and Otaño-Cruz et al.Sedimentation Dynamics Along Near-Shore Reefs island wide-scale to fully mitigate terrigenous sediment impact to marine ecosystems. Furthermore, decision-making processes and policy needs to address sedimentation stress in the context of future climate to reduce land-based threats and strengthen coral reef resilience.

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“…1). There are no perennial rivers on St. John, only a series of ephemeral gullies activated by extreme rainfall events 48–51 . This allows a situation in which the land-based sediment transport system is either turned ‘on’ (during rainfall events) or ‘off’ (Fig.…”

Section: Introductionmentioning

confidence: 99%

“…Understanding modern hurricane deposition is important for assessing impacts to coastal ecosystems and to accurately interpret the geologic record of past events. Furthermore, characterizing previous storm events is challenged by the difficulty in distinguishing a storm bed from a tsunami bed and vice versa 57,58 , despite excellent modern stratigraphic records 48,59 . In this study, we use a rare dataset to map and characterize the deposition that occurred following three major 2017 hurricanes (Irma, Jose, and Maria).…”

Section: Introductionmentioning

confidence: 99%

Widespread Deposition in a Coastal Bay Following Three Major 2017 Hurricanes (Irma, Jose, and Maria)

Browning

Sawyer

Brooks

et al. 2019

Sci Rep

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In 2017, three major hurricanes (Irma, Jose, and Maria) impacted the Northeastern Caribbean within a 2-week span. Hurricane waves can cause physical damage to coastal ecosystems, re-suspend and transport antecedent seafloor sediment, while the associated intense rainfall can yield large influxes of land-derived sediment to the coast (e.g. burial of ecosystems). To understand sedimentation provenance (terrestrial or marine) and changes induced by the hurricanes, we collected bathymetry surveys and sediment samples of Coral Bay, St. John, US Virgin Islands in August 2017, (pre-storms) and repeated it in November 2017 (post-storms). Comparison reveals morphologic seafloor changes and widespread aggradation with an average of ~25 cm of sediment deposited over a 1.28 km 2 benthic zone. Despite an annual amount of precipitation between surveys, sediment yield modeling suggests watersheds contributed <0.2% of the total depositional volume. Considering locally established accumulation rates, this multi-hurricane event equates to ~1–3 centuries of deposition. Critical benthic communities (corals, seagrasses) can be partially or fully buried by deposits of this thickness and previous studies demonstrate that prolonged burial of similar organisms often leads to mortality. This study illuminates how storm events can result in major sediment deposition, which can significantly impact seafloor morphology and composition and benthic ecosystems.

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Elemental signature of terrigenous sediment runoff as recorded in coastal salt ponds: US Virgin Islands

Cited by 20 publications

References 22 publications

Effects of Forest Roads on Runoff Initiation in Low‐Order Ephemeral Streams

Effects of Forest Roads on Runoff Initiation in Low‐Order Ephemeral Streams

Effects of Changing Weather, Oceanographic Conditions, and Land Uses on Spatio-Temporal Variation of Sedimentation Dynamics along Near-Shore Coral Reefs

Widespread Deposition in a Coastal Bay Following Three Major 2017 Hurricanes (Irma, Jose, and Maria)

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