37 research outputs found
Macrobenthic infaunal communities associated with deepâsea hydrocarbon seeps in the northern Gulf of Mexico
There are thousands of seeps in the deep ocean worldwide; however, many questions remain about their contributions to global biodiversity and the surrounding deepâsea environment. In addition to being globally distributed, seeps provide several benefits to humans such as unique habitats, organisms with novel genes, and carbon regulation. The purpose of this study is to determine whether there are unique seep macrobenthic assemblages, by comparing seep and nonseep environments, different seep habitats, and seeps at different depths and locations. Infaunal community composition, diversity, and abundance were examined between seep and nonseep background environments and among three seep habitats (i.e., microbial mats, tubeworms, and softâbottom seeps). Abundances were higher at seep sites compared to background areas. Abundance and diversity also differed among microbial mat, tubeworm, and softâbottom seep habitats. Although seeps contained different macrobenthic assemblages than nonseep areas, infaunal communities were also generally unique for each seep. Variability was 75% greater within communities near seeps compared to communities in background areas. Thus, high variability in community structure characterized seep communities rather than specific taxa. The lack of similarity among seep sites supports the idea that there are no specific infauna that can be used as indicators of seepage throughout the northern Gulf of Mexico, at least at higher taxonomic levels
Valuing Nature Waste Removal in the Offshore Environment Following the Deepwater Horizon Oil Spill
The offshore and deep-sea marine environment provides many ecosystem services (i.e., benefits to humans), for example: climate regulation, exploitable resources, processes that enable life on Earth, and waste removal. Unfortunately, the remote nature of this environment makes it difficult to estimate the values of these services. One service in particular, waste removal, was examined in the context of the Deepwater Horizon oil spill. Nearly 5 million barrels of oil were released into the offshore Gulf of Mexico, and 14 billion dollars were spent removing about 25% of the oil spilled. Using values for oil spill cleanup efforts, which included capping the wellhead and collecting oil, surface combustion, and surface skimming, it was calculated that waste removal, i.e., natural removal of spilled oil, saved BP over $35 billion. This large amount demonstrates the costs of offshore disasters, the importance of the offshore environment to humans, as well as the large monetary values associated with ecosystem services provided
Environmental heterogeneity throughout the clarion-clipperton zone and the potential representativity of the APEI network
Environmental variables such as food supply, nodule abundance, sediment characteristics, and water chemistry may influence abyssal seafloor communities and ecosystem functions at scales from meters to thousands of kilometers. Thus, knowledge of environmental variables is necessary to understand drivers of organismal distributions and community structure, and for selection of proxies for regional variations in community structure, biodiversity, and ecosystem functions. In October 2019, the Deep CCZ Biodiversity Synthesis Workshop was conducted to (i) compile recent seafloor ecosystem data from the Clarion-Clipperton Zone (CCZ), (ii) synthesize patterns of seafloor biodiversity, ecosystem functions, and potential environmental drivers across the CCZ, and (iii) assess the representativity of no-mining areas (Areas of Particular Environmental Interest, APEIs) for subregions and areas in the CCZ targeted for polymetallic nodule mining. Here we provide a compilation and summary of water column and seafloor environmental data throughout the CCZ used in the Synthesis Workshop and in many of the papers in this special volume. Bottom-water variables were relatively homogenous throughout the region while nodule abundance, sediment characteristics, seafloor topography, and particulate organic carbon flux varied across CCZ subregions and between some individual subregions and their corresponding APEIs. This suggests that additional APEIs may be needed to protect the full range of habitats and biodiversity within the CCZ
Estimating Interspecific Economic Risk of Bird Strikes With Aircraft
The International Civil Aviation Organization promotes prioritization of wildlife management on airports, among other safety issues, by emphasizing the risk of wildlifeâaircraft collisions (strikes). In its basic form, strike risk comprises a frequency component (i.e., how often strikes occur) and a severity component reflecting the cost of the incident. However, there is no widely accepted formula for estimating strike risk. Our goal was to develop a probabilistic risk metric that is adaptable for airports to use. Our specific objectives were to 1) update species-specific, relative hazard scores (i.e., the likelihood of aircraft damage or effect on flight when strikes occur) using recent U.S. Federal Aviation Administration (FAA) wildlife strike data (2010â2015); 2) develop 4 a priori risk models, reflecting species-specific strike data and updated relative hazard scores; 3) test these models against independent data (monetary costs associated with strikes); and 4) apply our best model to strike data from 4 large, FAA-certificated airports to illustrate its application at the local level. Our best-fitting risk model included an independent variable that was an interaction of quadratic transformed relative hazard score and number of wildlife strikes (r2=0.74). Top species in terms of estimated risk nationally were red-tailed hawk (Buteo jamaicensis), Canada goose (Branta canadensis), turkey vulture (Cathartes aura), rock pigeon (Columba livia), and mourning dove (Zenaida macroura). We found substantial overlap among the top 5 riskiest species locally across 3 of 4 airports considered, illustrating the degree of site specific differences that affect risk. Strike risk is dynamic; therefore, future work on risk estimation should allow for model adjustment to reflect ongoing wildlife management actions at airports that could influence future strike risk. Published 2018. This article is a U.S. Government work and is in the public domain in the USA
Ecological risk assessment for deep-sea mining
Ecological risk assessment for deep-sea mining is challenging, given the data-poor state of knowledge of deep-sea ecosystem structure, process, and vulnerability. Polling and a scale-intensity-consequence approach (SICA) were used in an expert elicitation survey to rank risk sources and perceived vulnerabilities of habitats associated with seabed nodule, sulfide, and crust mineral resources. Experts identified benthic habitats associated with seabed minerals as most vulnerable to habitat removal with a high degree of certainty. Resource-associated benthic and pelagic habitats were also perceived to be at risk from plumes generated during mining activities, although there was not always consensus regarding vulnerabilities to specific risk sources from different types of plumes. Even for risk sources where habitat vulnerability measures were low, high uncertainties suggest that these risks may not yet be dismissed. Survey outcomes also underscore the need for risk assessment to progress from expert opinion with low certainty to data-rich and ecosystem-relevant scientific research assessments to yield much higher certainty. This would allow for design and deployment of effective precautionary and mitigation efforts in advance of commercial exploitation, and adaptive management strategies would allow for regulatory and guideline modifications in response to new knowledge and greater certainty
Capillary filling with wall corrugations] Capillary filling in microchannels with wall corrugations: A comparative study of the Concus-Finn criterion by continuum, kinetic and atomistic approaches
We study the impact of wall corrugations in microchannels on the process of
capillary filling by means of three broadly used methods - Computational Fluid
Dynamics (CFD), Lattice-Boltzmann Equations (LBE) and Molecular Dynamics (MD).
The numerical results of these approaches are compared and tested against the
Concus-Finn (CF) criterion, which predicts pinning of the contact line at
rectangular ridges perpendicular to flow for contact angles theta > 45. While
for theta = 30, theta = 40 (no flow) and theta = 60 (flow) all methods are
found to produce data consistent with the CF criterion, at theta = 50 the
numerical experiments provide different results. Whilst pinning of the liquid
front is observed both in the LB and CFD simulations, MD simulations show that
molecular fluctuations allow front propagation even above the critical value
predicted by the deterministic CF criterion, thereby introducing a sensitivity
to the obstacle heigth.Comment: 25 pages, 8 figures, Langmuir in pres
Macrobenthic infaunal communities associated with deepâsea hydrocarbon seeps in the northern Gulf of Mexico
There are thousands of seeps in the deep ocean worldwide; however, many questions remain about their contributions to global biodiversity and the surrounding deepâsea environment. In addition to being globally distributed, seeps provide several benefits to humans such as unique habitats, organisms with novel genes, and carbon regulation. The purpose of this study is to determine whether there are unique seep macrobenthic assemblages, by comparing seep and nonseep environments, different seep habitats, and seeps at different depths and locations. Infaunal community composition, diversity, and abundance were examined between seep and nonseep background environments and among three seep habitats (i.e., microbial mats, tubeworms, and softâbottom seeps). Abundances were higher at seep sites compared to background areas. Abundance and diversity also differed among microbial mat, tubeworm, and softâbottom seep habitats. Although seeps contained different macrobenthic assemblages than nonseep areas, infaunal communities were also generally unique for each seep. Variability was 75% greater within communities near seeps compared to communities in background areas. Thus, high variability in community structure characterized seep communities rather than specific taxa. The lack of similarity among seep sites supports the idea that there are no specific infauna that can be used as indicators of seepage throughout the northern Gulf of Mexico, at least at higher taxonomic levels
Do Native Warm-season Grasslands Near Airports Increase Bird Strike Hazards?
Bird aircraft collisions (bird strikes) are a recognized safety hazard and land uses that attract birds hazardous to aircraft should be avoided on and near airports. Many airfields contain large areas of anthropogenic grassland habitats, often dominated by cool season grasses. Land managed as native warm season grasses (NWSG) potentially could increase bird strike hazards on and near airports by attracting hazardous birds and harboring small mammals that are prey for hazardous raptors. We investigated bird and small mammal communities at three NWSG areas and three adjacent on airfield grassland areas in western Ohio, U.S.A. to determine whether NWSG increased bird strike hazards. Species specific differences in bird abundance and density were evident between the two landcover types, presumably the result of differences in plant community characteristics. Seven species of birds were found exclusively in NWSG or airfield grasslands. Birds of species categorized as âmoderateâ to âextremely highâ in regard to hazard (severity) level to aircraft accounted for only 6% and 2% of all birds observed in airfield grasslands and NWSG areas, respectively. Small mammal capture success was approximately three times higher in NWSG areas, although raptor abundance did not differ between the two landcover types. Our findings suggest that NWSG might be considered a viable land use adjacent to airfields; however, similar research at additional locations, including larger NWSG areas, should be conducted