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At least 181 records · Page 10Linked to original sources
USGS2026

Beach nourishment morphodynamics in a high-energy U.S. West Coast environment

Dredged sediment from engineered inlets can be used to nourish coastlines adjacent to these inlets, serving as a beneficial alternative to offshore disposal. Effective strategies for beneficial use of dredged sediment, however, rely on understanding of local sediment transport. A beach nourishment project utilizing dredged sand was carried out at a highly energetic beach north of the Columbia River mouth (Washington, USA). Within two weeks of placement, during a moderately energetic period, a large part of the beach nourishment had eroded. To predict local hydro- and morphodynamics there, a XBeach model was used, validated with field observations of nearshore hydrodynamics and morphology. It showed that while the subaerial nourishment eroded rapidly, it is likely that the sediment is deposited around the inner bar and is still available to the morphological system of Benson Beach. Additionally, model simulations suggest the nourishment provided a buffer against erosion of the local dune system during its presence.

Washington↗
USGS2018

Conservation threats and priorities for raptors across Asia

With long coastlines and some of the world’s most important rivers, mountain ranges, high-altitude plateaus, and islands, Asia is the largest and most populous continent in the world (Lyde 1904; Spencer 1954; Population Reference Bureau 2016). Asia supports all major terrestrial ecosystems and all major climatic types (Galloway et al. 1998; Braimoh and Huang 2015). These include barren ice fields and taigas in North Asia; boreal forests and cold deserts in West, Central, and East Asia; temperate and tropical forests (wet and dry) in East and Southeast Asia; and grasslands in Central and South Asia (Udvardy 1975; Braimoh and Huang 2015). Together, the ecoregions of Asia foster some of the greatest biodiversity on Earth, including six (24%) of 25 global biodiversity hotspots (Myers et al. 2000).

Book chapter↗
USGS2013

Improving tsunami resiliency: California's Tsunami Policy Working Group

California has established a Tsunami Policy Working Group to facilitate development of policy recommendations for tsunami hazard mitigation. The Tsunami Policy Working Group brings together government and industry specialists from diverse fields including tsunami, seismic, and flood hazards, local and regional planning, structural engineering, natural hazard policy, and coastal engineering. The group is acting on findings from two parallel efforts: The USGS SAFRR Tsunami Scenario project, a comprehensive impact analysis of a large credible tsunami originating from an M 9.1 earthquake in the Aleutian Islands Subduction Zone striking California’s coastline, and the State’s Tsunami Preparedness and Hazard Mitigation Program. The unique dual-track approach provides a comprehensive assessment of vulnerability and risk within which the policy group can identify gaps and issues in current tsunami hazard mitigation and risk reduction, make recommendations that will help eliminate these impediments, and provide advice that will assist development and implementation of effective tsunami hazard risk communication products to improve community resiliency.

California↗
USGS1992

Subsidence of Surtsey volcano, 1967-1991

The Surtsey marine volcano was built on the southern insular shelf of Iceland, along the seaward extension of the east volcanic zone, during episodic explosive and effusive activity from 1963 to 1967. A 1600-m-long, east-west line of 42 bench marks was established across the island shortly after volcanic activity stopped. From 1967 to 1991 a series of leveling surveys measured the relative elevation of the original bench marks, as well as additional bench marks installed in 1979, 1982 and 1985. Concurrent measurements were made of water levels in a pit dug on the north coast, in a drill hole, and along the coastline exposed to the open ocean. These surveys indicate that the dominant vertical movement of Surtsey is a general subsidence of about 1.1??0.3 m during the 24-year period of observations. The rate of subsidence decreased from 15-20 cm/year for 1967-1968 to 1-2 cm/year in 1991. Greatest subsidence is centered about the eastern vent area. Through 1970, subsidence was locally greatest where the lava plain is thinnest, adjacent to the flanks of the eastern tephra cone. From 1982 onward, the region closest to the hydrothermal zone, which is best developed in the vicinity of the eastern vent, began showing less subsidence relative to the rest of the surveyed bench marks. The general subsidence of the island probably results from compaction of the volcanic material comprising Surtsey, compaction of the sea-floor sediments underlying the island, and possibly downwarping of the lithosphere due to the laod of Surtsey. The more localized early downwarping near the eastern tephra cone is apparently due to greater compaction of tephra relative to lava. The later diminished local subsidence near the hydrothermal zone is probably due to a minor volume increase caused by hydrous alteration of glassy tephra. However, this volume increase is concentrated at depth beneath the bottom of the 176-m-deep cased drillhole. ?? 1992 Springer-Verlag.

Bulletin of Volcanology↗
USGS1987

Coastal lava flows from Mauna Loa and Hualalai volcanoes, Kona, Hawaii

A major carbonate reef which drowned 13 ka is now submerged 150 m below sea level on the west coast of the island of Hawaii. A 25-km span of this reef was investigated using the submersible Makali'i. The reef occurs on the flanks of two active volcanoes, Mauna Loa and Hualalai, and the lavas from both volcanoes both underlie and overlie the submerged reef. Most of the basaltic lava flows that crossed the reef did so when the water was much shallower, and when they had to flow a shorter distance from shoreline to reef face. Lava flows on top of the reef have protected it from erosion and solution and now occur at seaward-projecting salients on the reef face. These relations suggest that the reef has retreated shoreward as much as 50 m since it formed. A 7-km-wide "shadow zone" occurs where no Hualalai lava flows cross the reef south of Kailua. These lava flows were probably diverted around a large summit cone complex. A similar "shadow zone" on the flank of Mauna Loa volcano in the Kealakekua Bay region is downslope from the present Mauna Loa caldera, which ponds Mauna Loa lava and prevents it from reaching the coastline. South of the Mauna Loa "shadow zone" the - 150 m reef has been totally covered and obscured by Mauna Loa lava. The boundary between Hualalai and Mauna Loa lava on land occurs over a 6-km-wide zone, whereas flows crossing the - 150 m reef show a sharper boundary offshore from the north side of the subaerial transition zone. This indicates that since the formation of the reef, Hualalai lava has migrated south, mantling Mauna Loa lava. More recently, Mauna Loa lava is again encroaching north on Hualalai lava.

Hawaii↗
USGS1995

Surface electromagnetic geophysical exploration of the ground-water resources of Isla de Mona, Puerto Rico, a caribbean carbonate island

Two electromagnetic surface geophysical techniques were used to explore the ground-water resources of Isla de Mona, Puerto Rico—a 55-square-kilometer island located between Puerto Rico and Hispañiola, Isla de Mona is a tectonically uplifted carbonate plateau of Neogene age that has an average elevation of about 50 meters above mean sea level. This plateau is bounded by vertical cliffs except on the southwest where there is a narrow, 3-square-kilometer coastal plain. The coastal plain is composed of Quaternary carbonate deposits, and has a maximum elevation of less than 10 meters above mean sea level. No large-scale surface-water features are found on the plateau or on the coastal plain. To better understand the aquifer characteristics of the island, terrain conductivity and transient electromagnetic data were collected on the coastal plain and on the plateau. Computer programs were used to analyze quantitatively the electromagnetic data. Geoelectric models were produced to approximate the depth below land surface of the saline-freshwater interface underlying both the coastal plain and the plateau. Because the geophysical methods could not discern the water-table, it was assumed that it was near sea level. The thickness of the freshwater lens was estimated by subtracting the elevation of the land surface above mean sea level from the depth to the saline-freshwater interface as determined from the geophysical data. Results from the geophysical methods and water-level observations indicate that a freshwater lens with a maximum thickness of about 10 meters exists under the coastal plain. This lens thins towards the ocean, and it also thins away from the ocean toward the plateau. The model produced from the transient electromagnetic data indicates that the freshwater lens under the plateau has a maximum thickness of about 14 meters, which is a much thinner lens than previously estimated. A freshwater lens thickness of 14 meters is similar to direct measurements by divers in Cueva de Agua at Punta los Ingleses (located on the southeast coast), and observations by divers of freshwater seeps into the ocean at depths of 8 to 10 meters along the north coast cliffs after a major rainstorm. Ground-water flow in the coastal plain appears to be radial from the center of the freshwater mound. At the intersection between the coastal plain and the plateau, the flow is parallel to the coastline. The direction of flow on the rest of the plateau could not be determined accurately with the available data.

Carbonates and Evaporites↗
USGS2008

Tsunami probability in the Caribbean Region

We calculated tsunami runup probability (in excess of 0.5 m) at coastal sites throughout the Caribbean region. We applied a Poissonian probability model because of the variety of uncorrelated tsunami sources in the region. Coastlines were discretized into 20 km by 20 km cells, and the mean tsunami runup rate was determined for each cell. The remarkable ???500-year empirical record compiled by O'Loughlin and Lander (2003) was used to calculate an empirical tsunami probability map, the first of three constructed for this study. However, it is unclear whether the 500-year record is complete, so we conducted a seismic moment-balance exercise using a finite-element model of the Caribbean-North American plate boundaries and the earthquake catalog, and found that moment could be balanced if the seismic coupling coefficient is c = 0.32. Modeled moment release was therefore used to generate synthetic earthquake sequences to calculate 50 tsunami runup scenarios for 500-year periods. We made a second probability map from numerically-calculated runup rates in each cell. Differences between the first two probability maps based on empirical and numerical-modeled rates suggest that each captured different aspects of tsunami generation; the empirical model may be deficient in primary plate-boundary events, whereas numerical model rates lack backarc fault and landslide sources. We thus prepared a third probability map using Bayesian likelihood functions derived from the empirical and numerical rate models and their attendant uncertainty to weight a range of rates at each 20 km by 20 km coastal cell. Our best-estimate map gives a range of 30-year runup probability from 0 - 30% regionally. ?? irkhaueser 2008.

Conference Paper↗
USGS2010

Combined effects of tectonic and landslide-generated Tsunami Runup at Seward, Alaska during the Mw 9.2 1964 earthquake

We apply a recently developed and validated numerical model of tsunami propagation and runup to study the inundation of Resurrection Bay and the town of Seward by the 1964 Alaska tsunami. Seward was hit by both tectonic and landslide-generated tsunami waves during the M W "> M W MW 9.2 1964 megathrust earthquake. The earthquake triggered a series of submarine mass failures around the fjord, which resulted in landsliding of part of the coastline into the water, along with the loss of the port facilities. These submarine mass failures generated local waves in the bay within 5 min of the beginning of strong ground motion. Recent studies estimate the total volume of underwater slide material that moved in Resurrection Bay to be about 211 million m 3 (Haeussler et al. in Submarine mass movements and their consequences, pp 269–278, 2007 ). The first tectonic tsunami wave arrived in Resurrection Bay about 30 min after the main shock and was about the same height as the local landslide-generated waves. Our previous numerical study, which focused only on the local landslide-generated waves in Resurrection Bay, demonstrated that they were produced by a number of different slope failures, and estimated relative contributions of different submarine slide complexes into tsunami amplitudes (Suleimani et al. in Pure Appl Geophys 166:131–152, 2009 ). This work extends the previous study by calculating tsunami inundation in Resurrection Bay caused by the combined impact of landslide-generated waves and the tectonic tsunami, and comparing the composite inundation area with observations. To simulate landslide tsunami runup in Seward, we use a viscous slide model of Jiang and LeBlond (J Phys Oceanogr 24(3):559–572, 1994 ) coupled with nonlinear shallow water equations. The input data set includes a high resolution multibeam bathymetry and LIDAR topography grid of Resurrection Bay, and an initial thickness of slide material based on pre- and post-earthquake bathymetry difference maps. For simulation of tectonic tsunami runup, we derive the 1964 coseismic deformations from detailed slip distribution in the rupture area, and use them as an initial condition for propagation of the tectonic tsunami. The numerical model employs nonlinear shallow water equations formulated for depth-averaged water fluxes, and calculates a temporal position of the shoreline using a free-surface moving boundary algorithm. We find that the calculated tsunami runup in Seward caused first by local submarine landslide-generated waves, and later by a tectonic tsunami, is in good agreement with observations of the inundation zone. The analysis of inundation caused by two different tsunami sources improves our understanding of their relative contributions, and supports tsunami risk mitigation in south-central Alaska. The record of the 1964 earthquake, tsunami, and submarine landslides, combined with the high-resolution topography and bathymetry of Resurrection Bay make it an ideal location for studying tectonic tsunamis in coastal regions susceptible to underwater landslides.

Alaska↗
USGS2016

A study of the 2015 Mw 8.3 Illapel earthquake and tsunami: Numerical and analytical approaches

The September 16, 2015 Illapel, Chile earthquake triggered a large tsunami, causing both economic losses and fatalities. To study the coastal effects of this earthquake, and to understand how such hazards might be accurately modeled in the future, different finite fault models of the Illapel rupture are used to define the initial condition for tsunami simulation. The numerical code Non-hydrostatic Evolution of Ocean WAVEs (NEOWAVE) is employed to model the tsunami evolution through the Pacific Ocean. Because only a short time is available for emergency response, and since the earthquake and tsunami sources are close to the coast, gaining a rapid understanding of the near-field run-up behavior is highly relevant to Chile. Therefore, an analytical solution of the 2 ? 1 D shallow water wave equations is considered. With this solution, we show that we can quickly estimate the run-up distribution along the coastline, to first order. After the earthquake and tsunami, field observations were measured in the surrounded coastal region, where the tsunami resulted in significant run-up. First, we compare the analytical and numerical solutions to test the accuracy of the analytical approach and the field observations, implying the analytic approach can accurately model tsunami run-up after an earthquake, without sacrificing the time necessary for a full numerical inversion. Then, we compare both with field run-up measurements. We observe the consistency between the two approaches. To complete the analysis, a tsunami source inversion is performed using run-up field measurements only. These inversion results are compared with seismic models, and are shown to capture the broad-scale details of those models, without the necessity of the detailed data sets they invert.

Illapel↗
USGS2007

Changes in abundance and spatial distribution of geese molting near Teshekpuk Lake, Alaska: Interspecific competition or ecological change?

Goose populations molting in the Teshekpuk Lake Special Area of the National Petroleum Reserve-Alaska have changed in size and distribution over the past 30 years. Black brant (Branta bernicla nigricans) are relatively stable in numbers but are shifting from large, inland lakes to salt marshes. Concurrently, populations of greater white-fronted geese (Anser albifrons frontalis) have increased seven fold. Populations of Canada geese (Branta canadensis and/or B. hutchinsii) are stable with little indication of distributional shifts. The lesser snow goose (Anser caerulescens caerulescens) population is proportionally small, but increasing rapidly. Coastline erosion of the Beaufort Sea has altered tundra habitats by allowing saltwater intrusion, which has resulted in shifts in composition of forage plant species. We propose two alternative hypotheses for the observed shift in black brant distribution. Ecological change may have altered optimal foraging habitats for molting birds, or alternatively, interspecific competition between black brant and greater white-fronted geese may be excluding black brant from preferred habitats. Regardless of the causative mechanism, the observed shifts in species distributions are an important consideration for future resource planning. ?? 2007 Springer-Verlag.

Polar Biology↗
USGS2015

Estimating the abundance of the Southern Hudson Bay polar bear subpopulation with aerial surveys

The Southern Hudson Bay (SH) polar bear subpopulation occurs at the southern extent of the species’ range. Although capture–recapture studies indicate abundance was likely unchanged between 1986 and 2005, declines in body condition and survival occurred during the period, possibly foreshadowing a future decrease in abundance. To obtain a current estimate of abundance, we conducted a comprehensive line transect aerial survey of SH during 2011–2012. We stratified the study site by anticipated densities and flew coastal contour transects and systematically spaced inland transects in Ontario and on Akimiski Island and large offshore islands in 2011. Data were collected with double-observer and distance sampling protocols. We surveyed small islands in James Bay and eastern Hudson Bay and flew a comprehensive transect along the Québec coastline in 2012. We observed 667 bears in Ontario and on Akimiski Island and nearby islands in 2011, and we sighted 80 bears on offshore islands during 2012. Mark–recapture distance sampling and sight–resight models yielded an estimate of 860 (SE = 174) for the 2011 study area. Our estimate of abundance for the entire SH subpopulation (943; SE = 174) suggests that abundance is unlikely to have changed significantly since 1986. However, this result should be interpreted cautiously because of the methodological differences between historical studies (physical capture–recapture) and this survey. A conservative management approach is warranted given previous increases in duration of the ice-free season, which are predicted to continue in the future, and previously documented declines in body condition and vital rates.

Polar Biology↗
USGS2024

Hurricane wave energy dissipation and wave-driven currents over a fringing reef

In 2018, two successive tropical cyclones, Hurricane Hector and Hurricane Lane, generated waves that impacted the Hawaiian Islands. This study investigates wave breaking over a broad fringing reef and aims to quantify the magnitudes and length scales of the corresponding wave-driven circulation using detailed field observations and numerical models corresponding to these wave events. Detailed wave and current measurements were collected across a 1200-m wide cross-reef transect off the coral reef-lined south coast of Moloka’i, Hawai’i. High-resolution numerical model grids were developed to resolve reef features and the coupled Delft3D-SWAN modeling system was applied to simulate spectral wave transformation and wave-driven currents for these two energetic ocean wave events generated by distant passing hurricanes. The results indicate that the wave-driven circulation is generally weak, with current speeds typically less than 0.15 m/s for the wave conditions generated by Hurricane Lane, with significant wave heights up to 1.9 m. Higher energy dissipation rates from larger waves up to 2.5 m breaking during Hurricane Hector resulted in stronger observed currents up to approximately 0.3 m/s. However, the model results show that these currents are confined to the wave-breaking region over the upper fore reef in a narrow (100–300 m) region near the reef crest, and weaker flows of less than 0.1 m/s are generated over the shallow and wide reef flat. Wave heights across the reef flat are less than 0.5 m and are controlled by the tidal water levels. The coral reef structures therefore provide significant protection for the coastline even during large wave and variable sea level conditions. Climate change is likely to increase sea level and storm intensity, the combination of which will influence wave transmission over fringing reefs that may degrade habitat, fueling the need for further research on changing conditions on coral reef-lined coasts.

Hawaii↗
USGS2015

The cost of reproduction: differential resource specialization in female and male California sea otters

Intraspecific variation in behavior and diet can have important consequences for population and ecosystem dynamics. Here, we examine how differences in reproductive investment and spatial ecology influence individual diet specialization in male and female southern sea otters ( Enhydra lutris nereis ). We hypothesize that greater reproductive constraints and smaller home ranges of females lead to more pronounced intraspecific competition and increased specialization. We integrate stable carbon (δ 13 C) and nitrogen (δ 15 N) isotope analysis of sea otter vibrissae with long-term observational studies of five subpopulations in California. We define individual diet specialization as low ratios of within-individual variation (WIC) to total population niche width (TNW). We compare isotopic and observational based metrics of WIC/TNW for males and females to data on population densities, and movement patterns using both general linear and linear mixed-effects models. Consistent with our hypothesis, increasing population density is associated with increased individual diet specialization by females but not by males. Additionally, we find the amount of coastline in a sea otter’s home range positively related with individual dietary variability, with increased range span resulting in weaker specialization for both males and females. We attribute our results to sex-based differences in movement, with females needing to specialize in their small ranges to maximize energy gain, and posit that the paradigm of individual prey specialization in sea otters with increased intraspecific competition may be a pattern driven largely by females. Our work highlights a potentially broader role of sex in the mechanistic pressures promoting and maintaining diet specialization.

California↗
USGS2021

Submarine lava deltas of the 2018 eruption of Kilauea volcano

Hawaiian and other ocean island lava flows that reach the coastline can deposit significant volumes of lava in submarine deltas. The catastrophic collapse of these deltas represents one of the most significant, but least predictable, volcanic hazards at ocean islands. The volume of lava deposited below sea level in delta-forming eruptions and the mechanisms of delta construction and destruction are rarely documented. Here, we report on bathymetric surveys and ROV observations following the Kīlauea 2018 eruption that, along with a comparison to the deltas formed at Pu‘u ‘Ō‘ō over the past decade, provide new insight into delta formation. Bathymetric differencing reveals that the 2018 deltas contain more than half of the total volume of lava erupted. In addition, we find that the 2018 deltas are comprised largely of coarse-grained volcanic breccias and intact lava flows, which contrast with those at Pu‘u ‘Ō‘ō that contain a large fraction of fine-grained hyaloclastite. We attribute this difference to less efficient fragmentation of the 2018 ‘a‘ā flows leading to fragmentation by collapse rather than hydrovolcanic explosion. We suggest a mechanistic model where the characteristic grain size influences the form and stability of the delta with fine grain size deltas (Pu‘u ‘Ō‘ō) experiencing larger landslides with greater run-out supported by increased pore pressure and with coarse grain size deltas (Kīlauea 2018) experiencing smaller landslides that quickly stop as the pore pressure rapidly dissipates. This difference, if validated for other lava deltas, would provide a means to assess potential delta stability in future eruptions.

Hawaii↗
USGS1998

Tsunami generation by pyroclastic flow during the 3500-year B.P. caldera-forming eruption of Aniakchak Volcano, Alaska

A discontinuous pumiceous sand, a few centimeters to tens of centimeters thick, is located up to 15 m above mean high tide within Holocene peat along the northern Bristol Bay coastline of Alaska. The bed consists of fine-to-coarse, poorly to moderately well-sorted, pumice-bearing sand near the top of a 2-m-thick peat sequence. The sand bed contains rip-up clasts of peat and tephra and is unique in the peat sequence. Major element compositions of juvenile glass from the deposit and radiocarbon dating of enclosing peat support correlation of the pumiceous sand with the caldera-forming eruption of Aniakchak Volcano. The distribution of the sand and its sedimentary characteristics are consistent with emplacement by tsunami. The pumiceous sand most likely represents redeposition by tsunami of climactic fallout tephra and beach sand during the approximately 3.5 ka Aniakchak caldera-forming eruption on the Alaska Peninsula. We propose that a tsunami was generated by the sudden entrance of a rapidly moving, voluminous pyroclastic flow from Aniakchak into Bristol Bay. A seismic trigger for the tsunami is unlikely, because tectonic structures suitable for tsunami generation are present only south of the Alaska Peninsula. The pumiceous sand in coastal peat of northern Bristol Bay is the first documented geologic evidence of a tsunami initiated by a volcanic eruption in Alaska.

Alaska↗
USGS2008

Temporal response of hydraulic head, temperature, and chloride concentrations to sea-level changes, Floridan aquifer system, USA

Three-dimensional density-dependent flow and transport modeling of the Floridan aquifer system, USA shows that current chloride concentrations are not in equilibrium with current sea level and, second, that the geometric configuration of the aquifer has a significant effect on system responses. The modeling shows that hydraulic head equilibrates first, followed by temperatures, and then by chloride concentrations. The model was constructed using a modified version of SUTRA capable of simulating multi-species heat and solute transport, and was compared to pre-development conditions using hydraulic heads, chloride concentrations, and temperatures from 315 observation wells. Three hypothetical, sinusoidal sea-level changes occurring over 100,000 years were used to evaluate how the simulated aquifer responds to sea-level changes. Model results show that hydraulic head responses lag behind sea-level changes only where the Miocene Hawthorn confining unit is thick and represents a significant restriction to flow. Temperatures equilibrate quickly except where the Hawthorn confining unit is thick and the duration of the sea-level event is long (exceeding 30,000 years). Response times for chloride concentrations to equilibrate are shortest near the coastline and where the aquifer is unconfined; in contrast, chloride concentrations do not change significantly over the 100,000-year simulation period where the Hawthorn confining unit is thick.

Hydrogeology Journal↗
USGS2014

Inner-shelf circulation and sediment dynamics on a series of shoreface connected ridges offshore of Fire Island, NY

Locations along the inner-continental shelf offshore of Fire Island, NY, are characterized by a series of shoreface-connected ridges (SFCRs). These sand ridges have approximate dimensions of 10 km in length, 3 km spacing, and up to ∼8 m ridge to trough relief and are oriented obliquely at approximately 30° clockwise from the coastline. Stability analysis from previous studies explains how sand ridges such as these could be formed and maintained by storm-driven flows directed alongshore with a key maintenance mechanism of offshore deflected flows over ridge crests and onshore in the troughs. We examine these processes both with a limited set of idealized numerical simulations and analysis of observational data. Model results confirm that alongshore flows over the SFCRs exhibit offshore veering of currents over the ridge crests and onshore-directed flows in the troughs, and demonstrate the opposite circulation pattern for a reverse wind. To further investigate these maintenance processes, oceanographic instruments were deployed at seven sites on the SFCRs offshore of Fire Island to measure water levels, ocean currents, waves, suspended sediment concentrations, and bottom stresses from January to April 2012. Data analysis reveals that during storms with winds from the northeast, the processes of offshore deflection of currents over ridge crests and onshore in the troughs were observed, and during storm events with winds from the southwest, a reverse flow pattern over the ridges occurred. Computations of suspended sediment fluxes identify periods that are consistent with SFCR maintenance mechanisms. Alongshore winds from the northeast drove fluxes offshore on the ridge crest and onshore in the trough that would tend to promote ridge maintenance. However, alongshore winds from the southwest drove opposite circulations. The wind fields are related to different storm types that occur in the region (low-pressure systems, cold fronts, and warm fronts). From the limited data set, we identify that low-pressure systems drive sediment fluxes that tend to promote stability and maintain the SFCRs while cold front type storms appear to drive circulations that are in the opposite sense and may not be a supporting mechanism for ridge maintenance.

New York↗
USGS2014

Predicting spatial and temporal distribution of Indo-Pacific lionfish ( Pterois volitans ) in Biscayne Bay through habitat suitability modeling

Invasive species may exhibit higher levels of growth and reproduction when environmental conditions are most suitable, and thus their effects on native fauna may be intensified. Understanding potential impacts of these species, especially in the nascent stages of a biological invasion, requires critical information concerning spatial and temporal distributions of habitat suitability. Using empirically supported environmental variables (e.g., temperature, salinity, dissolved oxygen, rugosity, and benthic substrate), our models predicted habitat suitability for the invasive lionfish ( Pterois volitans ) in Biscayne Bay, Florida. The use of Geographic Information Systems (GIS) as a platform for the modeling process allowed us to quantify correlations between temporal (seasonal) fluctuations in the above variables and the spatial distribution of five discrete habitat quality classes, whose ranges are supported by statistical deviations from the apparent best conditions described in prior studies. Analysis of the resulting models revealed little fluctuation in spatial extent of the five habitat classes on a monthly basis. Class 5, which represented the area with environmental variables closest to the best conditions for lionfish, occupied approximately one-third of Biscayne Bay, with subsequent habitats declining in area. A key finding from this study was that habitat suitability increased eastward from the coastline, where higher quality habitats were adjacent to the Atlantic Ocean and displayed marine levels of ambient water quality. Corroboration of the models with sightings from the USGS-NAS database appeared to support our findings by nesting 79 % of values within habitat class 5; however, field testing (i.e., lionfish surveys) is necessary to confirm the relationship between habitat classes and lionfish distribution.

Florida↗