The phytotoxic pathogenicity factor fusaric acid (FA) represses the production of 2,4-diacetylphloroglucinol (DAPG), a key factor in the antimicrobial activity of the biocontrol strain Pseudomonas fluorescens CHA0. FA production by 12 Fusarium oxysporum strains varied substantially. We measured the effect of FA production on expression of the phlACBDE biosynthetic operon of strain CHA0 in culture media and in the wheat rhizosphere by using a translational phlA-lacZ fusion. Only FA-producing F. oxysporum strains could suppress DAPG production in strain CHA0, and the FA concentration was strongly correlated with the degree of phlA repression. The repressing effect of FA on phlA-lacZ expression was abolished in a mutant that lacked the DAPG pathway-specific repressor PhlF. One FA-producing strain (798) and one nonproducing strain (242) of F. oxysporum were tested for their influence on phlA expression in CHA0 in the rhizosphere of wheat in a gnotobiotic system containing a sand and clay mineral-based artificial soil. F. oxysporum strain 798 (FA ؉ ) repressed phlA expression in CHA0 significantly, whereas strain 242 (FA ؊ ) did not. In the phlF mutant CHA638, phlA expression was not altered by the presence of either F. oxysporum strain 242 or 798. phlA expression levels were seven to eight times higher in strain CHA638 than in the wild-type CHA0, indicating that PhlF limits phlA expression in the wheat rhizosphere.Antibiosis is an important mechanism used by plant-beneficial microorganisms to overcome the effects of soil-borne fungal pathogens (44). The polyketide metabolite 2,4-diacetylphloroglucinol (DAPG) is one of the most effective antimicrobial metabolites produced by strains of fluorescent pseudomonads (25, 40) and is effective against bacteria, fungi, and helminths (13,18,23,30,34,39). In Pseudomonas fluorescens Q2-87 and CHA0, the four DAPG biosynthesis genes, phlACBD, are organized as an operon and are indispensable for the production of DAPG as well as monoacetylphloroglucinol (MAPG), which is either a precursor to or a degradation product of DAPG. This operon is followed by a gene coding for a putative efflux protein (phlE) and flanked by the divergently transcribed phlF gene, which encodes a repressor protein of DAPG synthesis (5,11,38).Environmental factors influence the production of antimicrobial compounds such as DAPG in fluorescent pseudomonads. Variation in the biocontrol performance of these bacteria has been attributed to changes of biotic and abiotic factors associated with field location and cropping time (14, 44). Complex biotic factors, such as plant species, plant age, host cultivar, and infection with the plant pathogen Pythium ultimum, can significantly alter phlA expression (33). DAPG production can be influenced by the carbon sources and minerals present in the bacterial environment. Fe 3ϩ and sucrose increase production of DAPG and MAPG in P. fluorescens F113 (16), but in P. fluorescens Pf-5 and CHA0, production is stimulated by glucose (15, 34). In strain S272, the highest DAPG yield ...

Tidal inlets are complex systems that provide pathways for oil to enter sheltered and typically environmentally sensitive bays, tidal flats, and wetland complexes. Because of their dynamic nature, attempts to protect these features from oil spills have not always been successful historically, often due to a lack of understanding of how the inlet system operates and where protective actions may be practical. This Field Guide has been prepared to assist oil spill planners and responders to better understand how tidal inlets function and where conditions may exist that permit control actions. Improving understanding of how tidal inlets work can help ensure that realistic expectations and appropriate tactics and equipment are available for deployment locations where they have some potential for success. During a response operation, the Field Guide can be used to ensure that available resources are put to best use and that decision makers select practical strategies based on the environmental conditions at the time. The Field Guide provides separate stepwise approaches for preplanning activities and for response decisions.

The T/V Arrow sank in 1970, spilling Bunker C fuel oil into Chedabucto Bay, Nova Scotia. In the summer and fall of 2015, residual oil leaked from the sunken vessel and re-oiled shorelines in the Bay. A K9-SCAT field study, funded by Environment and Climate Change Canada (ECCC), was conducted in June 2016 to assess the capability of detection canines to locate stranded oil following the new releases. The canine detected small amounts of weathered surface oil that were barely visible, and in some cases, not visible, to the SCAT-trained observers, as well as subsurface oil on mixed- and coarse-sediment beaches. The average speed of a survey, in terms of the length of shoreline covered, varied depending on the shore type and the width of the survey band. The most challenging site was a steep bedrock shoreline with an alongshore survey rate of 0.2 linear km/hour. Typical alongshore coverage rates for the wide, mixed sediment were in the range 0.7 to 1.2 linear km/hour, and for both straight, wide sand beaches were 1.2 km/hour. The highest alongshore rate was 2.4 linear km/hour for the narrow beach on Janvrin Island. The successful detection of 2015 T/V Arrow cargo oil (both naturally stranded and intentionally planted) on selected Chedabucto Bay shorelines indicates that there is a low risk, high confidence level that the canine did not miss subsurface oil, although that possibility may exist. Where the canine made an alert and no surface oil was visible, chemical analyses of sediment samples indicated that weathered petroleum hydrocarbons were present at those locations and, therefore, the canine had made correct alerts. The results provide further “proof of concept” for K9-SCAT teams to support surface and subsurface oil detection during traditional shoreline assessment surveys.

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ABSTRACT> The ICS 232 Resources at Risk summary form is a key tool for the communication of resources at risk from an oil or chemical spill. Completion of the form requires consideration of environmental, archeocultural, and socio-economic resources that may be affected by a spill. This process of research, identification, prioritization, documentation, and communication of potential resources in the pathway of a spill is typically conducted within the Environmental Unit (EU) by the Resources at Risk (RAR) Technical Specialist or Environmental Unit Leader (EUL), with input from relevant stakeholders and trustees. The purpose of the form is twofold: to provide environmental information to aid assessment and decision making, for example: identifying where to conduct wildlife reconnaissance surveys, identifying resources of concern for Spill Impact Mitigation Assessment (SIMA)/ Net Environmental Benefit Analysis (NEBA), and recommending cleanup techniques and endpoints; andTo provide direct priorities for protection for response operations, such as from pre-established Geographic Response Plans (GRPs) or Geographic Response Strategies (GRSs), and other static or Geographic Informational Systems (GIS) data sources. In recent years, GRP/GRSs have become more commonplace in contingency plans, and have become more practical for response operations, to a degree that some plans include executing the GRP/GRSs as ready-made ICS 204 (work order) forms to provide direct instruction to response operations on site location, access, operational strategies, and equipment required to protect specific resources. This pre-spill information can be valuable to ensure that priority resources are protected within the short window of opportunity that is typically available at the beginning of a response; and allows quick decision-making without the need for in-depth consideration of sensitivity and resource maps. A potential downside to this convenient data, which will be explored in this paper, is that we risk relying entirely on using the GRP data to provide operational protection priorities and losing the specific data on the resources we are aiming to protect. This reduces the purpose of the form to a purely operational instruction, without the documentation of environmental data that is essential for assessment and decision making within the Environmental Unit. This paper considers the use of the ICS 232 (Resources at Risk) form, how its use has developed over the years, and how the availability of GRPs has, in some areas, shifted the use of the form to a more directly operational purpose. Recommendations are provided for ensuring that the environmental information component is not forgotten.