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At least 343 records · Page 19Linked to original sources
USGS2020

Sensitivity of storm response to antecedent topography in the XBeach model

Antecedent topography is an important aspect of coastal morphology when studying and forecasting coastal change hazards. The uncertainty in morphologic response of storm-impact models and their use in short-term hazard forecasting and decadal forecasting is important to account for when considering a coupled model framework. This study provided a methodology to investigate uncertainty of profile response within the storm impact model XBeach related to varying antecedent topographies. A parameterized island Gaussian fit (PIGF) model generated an idealized baseline profile and a suite of idealized profiles that vary specific characteristics based on collated observed LiDAR data from Dauphin Island, AL, USA. Six synthetic storm scenarios were simulated on each of the idealized profiles with XBeach in both 1- and 2-dimensional setups and analyzed to determine the morphological response and uncertainty related to the varied antecedent topographies. Profile morphologic response tends to scale with storm magnitude but among the varied profiles there is greater uncertainty in profile response to the medium range storm scenarios than to the low and high magnitude storm scenarios. XBeach can be highly sensitive to morphologic thresholds, both antecedent and time-varying, especially with regards to beach slope.

Alabama↗
USGS2020

Development and application of an empirical dune growth model for evaluating barrier island recovery from storms

Coastal zone managers require models that predict barrier island change on decadal time scales to estimate coastal vulnerability, and plan habitat restoration and coastal protection projects. To meet these needs, methods must be available for predicting dune recovery as well as dune erosion. In the present study, an empirical dune growth model (EDGR) was developed to predict the evolution of the primary foredune of a barrier island. Within EDGR, an island is represented as a sum of Gaussian shape functions representing dunes, berms, and the underlying island form. The model evolves the foredune based on estimated terminal dune height and location inputs. EDGR was assessed against observed dune evolution along the western end of Dauphin Island, Alabama over the 10 years following Hurricane Katrina (2005). The root mean square error with EDGR (ranging from 0.18 to 0.74 m over the model domain) was reduced compared to an alternate no-change model (0.69–0.96 m). Hindcasting with EDGR also supports the study of dune evolution processes. At Dauphin Island, results suggest that a low-lying portion of the site was dominated by overwash for ~5 years after Katrina, before approaching their terminal height and becoming growth-limited after 2010. EDGR’s computational efficiency allows dune evolution to be rapidly predicted and enables ensemble predictions to constrain the uncertainty that may result if terminal dune characteristics are unknown. In addition, EDGR can be coupled with an external model for estimating dune erosion and/or the long-term evolution of other subaerial features to allow decadal-scale prediction of barrier island evolution.

Alabama↗
USGS2021

Reinterpreting the Bruun Rule in the context of equilibrium shoreline models

Long-term (>decades) coastal recession due to sea-level rise (SLR) has been estimated using the Bruun Rule for nearly six decades. Equilibrium-based shoreline models have been shown to skillfully predict short-term wave-driven shoreline change on time scales of hours to decades. Both the Bruun Rule and equilibrium shoreline models rely on the equilibrium beach theory, which states that the beach profile shape equilibrates with its local wave and sea-level conditions. Integrating these two models into a unified framework can improve our understanding and predictive skill of future shoreline behavior. However, given that both models account for wave action, but over different time scales, a critical re-examination of the SLR-driven recession process is needed. We present a novel physical interpretation of the beach response to sea-level rise, identifying two main contributing processes: passive flooding and increased wave-driven erosion efficiency. Using this new concept, we analyze the integration of SLR-driven recession into equilibrium shoreline models and, with an idealized test case, show that the physical mechanisms underpinning the Bruun Rule are explicitly described within our integrated model. Finally, we discuss the possible advantages of integrating SLR-driven recession models within equilibrium-based models with dynamic feedbacks and the broader implications for coupling with hybrid shoreline models.

Journal of Marine Science and Engineering↗
USGS2016

Mercury accumulation and the mercury-PCB-sex interaction in summer flounder

Patterns in the relative differences in contaminant concentrations between the sexes of mature fish may reveal important behavioral and physiological differences between the sexes. We determined whole-fish total mercury (Hg) concentrations in 23 female summer flounder (Paralichthys dentatus) and 27 male summer flounder from New Jersey coastal waters. To estimate the change in Hg concentration due to release of eggs at spawning, Hg concentration in the somatic tissue and ovaries of 5 of the 23 female summer flounder were also determined. To ascertain whether most of the Hg in the summer flounder was methylmercury (MeHg), whole-fish MeHg concentrations were determined in all 50 summer flounder. Whole-fish Hg concentrations averaged 113 ng/g for females and 111 ng/g for males. Thus, females were 2% higher in Hg concentration than males, on average, but the difference was not statistically significant. Based on Hg determinations in the somatic tissue and ovaries, we predicted that Hg concentration of females would increase by 3.6%, on average, immediately after spawning due to release of eggs. On average, 92% of the Hg in the summer flounder was MeHg. To determine whether the effect of sex on Hg concentration was significantly different from the effect of sex on polychlorinated biphenyl (PCB) concentration, we paired our Hg determinations with PCB determinations from a previous study, and applied regression analysis. Sex significantly interacted with contaminant type (Hg or PCBs), as males were 43% higher in PCB concentration than females, whereas females were 2% higher in Hg concentration than males. Males eliminating Hg from their bodies at a faster rate than females was a likely explanation for this discrepancy between the two contaminant types. Overall, the Hg and PCB concentrations in the summer flounder were relatively low, and therefore our findings also had implications for continued operation of the summer flounder fishery.

Journal of Marine Science: Research & Development↗
USGS2006

Eutrophication of freshwater and marine ecosystems

Initial understanding of the links between nutrients and aquatic productivity originated in Europe in the early 1900s, and our knowledge base has expanded greatly during the past 40 yr. This explosion of eutrophication-related research has made it unequivocally clear that a comprehensive strategy to prevent excessive amounts of nitrogen and phosphorus from entering our waterways is needed to protect our lakes, rivers, and coasts from water quality deterioration. However, despite these very significant advances, cultural eutrophication remains one of the foremost problems for protecting our valuable surface water resources. The papers in this special issue provide a valuable cross section and synthesis of our current understanding of both freshwater and marine eutrophication science. They also serve to identify gaps in our knowledge and will help to guide future research.

Limnology and Oceanography↗
USGS2012

Rapid invasion of the Indo-Pacific lionfishes (Pterois volitans and Pterois miles) in the Florida Keys, USA: evidence from multiple pre-and post-invasion data sets

Over the past decade, Indo-Pacific lionfishes, Pterois volitans (Linnaeus, 1758) and Pterois miles (Bennett, 1828), venomous members of the scorpionfish family (Scorpaenidae), have invaded and spread throughout much of the tropical and subtropical northwestern Atlantic Ocean and Caribbean Sea. These species are generalist predators of fishes and invertebrates with the potential to disrupt the ecology of the invaded range. Lionfishes have been present in low numbers along the east coast of Florida since the 1980s, but were not reported in the Florida Keys until 2009. We document the appearance and rapid spread of lionfishes in the Florida Keys using multiple long-term data sets that include both pre- and post-invasion sampling. Our results are the first to quantify the invasion of lionfishes in a new area using multiple independent, ongoing monitoring data sets, two of which have explicit estimates of sampling effort. Between 2009 and 2011, lionfish frequency of occurrence, abundance, and biomass increased rapidly, increasing three- to six-fold between 2010 and 2011 alone. In addition, individuals were detected on a variety of reef and non-reef habitats throughout the Florida Keys. Because lionfish occurrence, abundance, and impacts are expected to continue to increase throughout the region, monitoring programs like those used in this study will be essential to document ecosystem changes that may result from this invasion.

Floria Keys↗
USGS2013

Parasites in marine food webs

Most species interactions probably involve parasites. This review considers the extent to which marine ecologists should consider parasites to fully understand marine communities. Parasites are influential parts of food webs in estuaries, temperate reefs, and coral reefs, but their ecological importance is seldom recognized. Though difficult to observe, parasites can have substantial biomass, and they can be just as common as free-living consumers after controlling for body mass and trophic level. Parasites have direct impacts on the energetics of their hosts and some affect host behaviors, with ecosystem-level consequences. Although they cause disease, parasites are sensitive components of ecosystems. In particular, they suffer secondary extinctions due to biodiversity loss. Some parasites can also return to a system after habitat restoration. For these reasons, parasites can make good indicators of ecosystem integrity. Fishing can indirectly increase or decrease parasite populations and the effects of climate change on parasites are likely to be equally as complex.

Bulletin of Marine Science↗
USGS2013

How old is the Isthmus of Panama?

The Standard Model of the formation of the Isthmus of Panama proposes that final closure occurred at 4–3 Ma. The model is based on evidence from studies of marine stratigraphy, fossil sequences, divergent molecular phylogenies, the timing of the Great American Biological Interchange (GABI), and proxies for marine paleosalinity, paleobathymetry, productivity, and paleotemperatures. The new model uses cooling of magmas in the Cretaceous to Early Miocene Central American Volcanic arc to propose Eocene emergence of the discrete structural blocks of the arc and then U/Pb dating, paleomagnetic pole rotations, and atlantic sea-floor anomalies to reconfigure the blocks for different time slices back to 25 Ma. Closure is proposed at 15 Ma, because by this time the alignment of the blocks leaves no space for trans-isthmian marine passages. We propose that the Indonesian Australian Archipelago (IAA) provides a model for the Central American arc between 15 and 3 Ma because it accounts for the extensive marine interchange between the Pacific and Indian oceans through few and narrow passages while maintaining a complete separation of the terrestrial faunas (Wallace and Lydekker lines) of the two continental platforms of Sunda and Sahul. Using the Indonesian Volcanic arc as a model, we can now accommodate the general tectonic configuration and much of the emergence of the new model, while accounting for the marine fossil record, the molecular evidence of rapid recent speciation, and the delayed Great American Biotic Interchange that the New Model fails to explain.

Bulletin of Marine Science↗
USGS2013

Whole-body concentrations of elements in three fish species from offshore oil platforms and natural areas in the Southern California Bight, USA

There is concern that offshore oil platforms off Southern California may be contributing to environmental contaminants accumulated by marine fishes. To examine this possibility, 18 kelp bass (Paralabrax clathratus Girard, 1854), 80 kelp rockfish (Sebastes atrovirens Jordan and Gilbert, 1880), and 98 Pacific sanddab (Citharichthys sordidus Girard, 1854) were collected from five offshore oil platforms and 10 natural areas during 2005–2006 for whole-body analysis of 63 elements. Forty-two elements were excluded from statistical comparisons as they (1) consisted of major cations that were unlikely to accumulate to potentially toxic concentrations; (2) were not detected by the analytical procedures; or (3) were detected at concentrations too low to yield reliable quantitative measurements. The remaining 21 elements consisted of aluminum, arsenic, barium, cadmium, chromium, cobalt, copper, gallium, iron, lead, lithium, manganese, mercury, nickel, rubidium, selenium, strontium, tin, titanium, vanadium, and zinc. Statistical comparisons of these elements indicated that none consistently exhibited higher concentrations at oil platforms than at natural areas. However, the concentrations of copper, selenium, titanium, and vanadium in Pacific sanddab were unusual because small individuals exhibited either no differences between oil platforms and natural areas or significantly lower concentrations at oil platforms than at natural areas, whereas large individuals exhibited significantly higher concentrations at oil platforms than at natural areas.

California↗
USGS2017

Identification of Chelonid herpesvirus 5 (ChHV5) in endangered green turtles (Chelonia mydas) with fibropapillomatosis in Asia

Fibropapillomatosis (FP), a debilitating tumor disease of sea turtles, was first identified in green turtles [ Chelonia mydas (Linnaeus, 1758)] in Florida in 1938. In recent decades, FP has been observed globally and is an emerging panzootic disease in sea turtles. However, few reports of FP in Asia exist. Here, we provide the first evidence of Chelonid herpesvirus 5 (ChHV5) DNA associated with FP in endangered green turtles from Taiwan, through molecular characterization, phylogenetic analysis, and histopathological examination. In our study, ChHV5 was successfully detected by PCR in the FP tumor lesions of green turtles. The sequences were found to be consistent with those of tumor-inducing viruses shown to affect sea turtles in the other parts of the world. ChHV5 RNA from the FP tissues was further detected by RT-PCR, indicating active replication of the viruses inside FP tumors. In addition to the molecular evidence of ChHV5 in FP, epidermal intranuclear inclusions were identified in tumor lesions upon histopathological examination. This further suggests that ChHV5 should be in a transcriptionally active (i.e., non-latent) state in FP tumors of affected green turtles. The phylogenetic tree revealed that ChHV5 from the green turtles in Taiwan were closest to the ChHV5 from Hawaii, Puerto Rico, and Sao Tome. For conservation of endangered sea turtles, ChHV5 should be considered an emerging virus, which threatens sea turtles in marine waters in Asia.

Bulletin of Marine Science↗
USGS2019

Estimating the value of mangrove leaf litter in sesarmid crab diets: The importance of fractionation factors

Sesarmid crabs play an important role in organic matter and carbon cycling of mangrove forests. Visual observations and gut content studies have verified that sesarmid crabs are feeding on mangrove leaves, yet stable isotopes of carbon and nitrogen ( 13 C and 15 N) have indicated that leaf litter is not assimilated as a food source. Sesarmid crabs tend to be much more enriched in 13 C than leaf litter (0.9‰ – 11.6‰) and have C values that are often more like microphytobenthos (MPB). General 13 C trophic enrichment factors (TEF; 0.1‰ – 0.5‰) suggest crabs feed more heavily on MPB. Field and laboratory-based evidence reveal that general 13 C TEF for crabs feeding on mangrove leaves may be incorrect and much greater than 0.1‰ – 0.5‰. A food web study conducted annually over 2 yrs revealed a shift in the δ 13 C and δ 15 N of Parasesarma sp. crabs similar to mangrove leaves also sampled. This suggested Parasesarma sp. may be feeding more heavily on mangrove leaves than previously reported despite crabs being 4.4‰ – 11.6‰ more enriched in 13 C than mangrove leaves. A laboratory feeding study confirmed that average 13 C TEF between Parasesarma sp. and decayed Rhizophora sp. leaves was 3.3‰ (SE 0.5). The Stable Isotope Analysis in R package (SIAR) used with our TEF and the general 0.5‰ 13 C TEF revealed that published TEFs may underestimate mangrove leaf contributions to sesarmid crab diets on average by 33.3% (SE 0.1) and overestimate MPB and epiphytic algal contributions by 31.3% (SE 0.1). Food web studies in mangroves and other ecosystems will continue to inaccurately identify important food resources or food web structures unless more accurate and species-specific isotope fractionation values are determined.

Bulletin of Marine Science↗
USGS2022

Using mollusks as indicators of restoration in nearshore zones of south Florida's estuaries

Current south Florida ecosystem restoration efforts are focused on restoring more natural freshwater flow through the wetlands and into the estuaries to reestablish natural salinity gradients, particularly in the nearshore zones. Indicator taxa are used to monitor and assess restoration progress and the current suite of biota used for the estuaries in south Florida (Biscayne Bay, Florida Bay, and the southwest mangrove riverine system) does not include mollusks. Mollusks make excellent indicators because they are found in all south Florida environments, are relatively stationary in postlarval stages, and, therefore, do not leave a site when conditions change. Their hard shells increase the likelihood of preservation after death, thus, making it possible to assess death assemblages. In addition to these features, many mollusks can be quickly sampled in the field and assessed in the lab, so poor visibility and tidal cycles are not an issue for monitoring surveys. Here we examine 27 years of molluscan data from 887 samples from 640 visits to 167 sites in south Florida's estuaries and present a suite of taxa that could be used as indicators for restoration of the oligohaline to mesohaline (0.5 to 17.9 psu) nearshore zones. Cyrenoida floridana , Hydrobiidae, Polymesoda caroliniana , Crassostrea virginica , and additional taxa are included with suggested sampling strategies.

Florida↗
USGS2023

Fish community characterization of mid-shelf and shelf-edge mesophotic coral ecosystems in the expanded Flower Garden Banks National Marine Sanctuary

The mid to outer continental shelf in the northern Gulf of Mexico is composed of a patchy distribution of coral and rock reefs designated high priority for marine protection. To better understand the influence of deepwater habitat on fish community dynamics and conservation needs, we compared altiphotic-mesophotic transition (20– 40 m), upper mesophotic (40–60 m), and middle mesophotic (60–80 m) fish communities between mid-shelf (Sonnier Bank) and outer-shelf (McGrail Bank) banks from before their inclusion into the Flower Garden Banks National Marine Sanctuary. Surveys performed over two years with a remotely operated vehicle indicated that each bank and depth zone had distinct fish communities. Both banks were dominated by planktivores and piscivores, with an increase in depth specialists (e.g., deepwater anthiids and serranids) at the deeper zones surveyed, particularly in middle mesophotic depths at McGrail. An increased frequency of snappers, groupers, and amberjack was observed at Sonnier Bank, predominately in mesophotic depths, indicating the Sonnier Mesophotic Coral Ecosystem as either a hotspot or potential refuge for meso- and apex predators. This study fills a temporal gap in fish community dynamics of these two banks, serving to create a more continuous dataset available to assist in conservation assessments of the Flower Garden Banks National Marine Sanctuary.

Texas↗