Hagerthey S.E.,South Florida Water Management District |
Cole J.J.,Cary Institute of Ecosystem Studies |
Kilbane D.,South Florida Water Management District |
Kilbane D.,CSA International Inc.
Limnology and Oceanography | Year: 2010
Using high-frequency measurements of tree water dissolved oxygen (O 2), we assessed gross primary production (GPP), respiration (R), and net aquatic production (NAP) in the shallow-water Everglades peatland between 1996 and 2005. We distinguish NAP from net ecosystem production since the boundary for shallow aquatic ecosystems may include aboveground GPP of wetland biota. Metabolism was estimated for 68 sites distributed among nine habitats and yielded 1085 5-d deployments or 5425 site-days. Habitats differed in vegetation composition, trophic status, and hydrology. Systemwide O 2 averaged 3.8 ± 2.2 mg L -1 (mean ± SD), or 49% ± 30% of atmospheric saturation. GPP, R, and NAP averaged 103 ± 76, 220 ± 79, and -117 ± 65 mmol O 2 m -2 d -1 , respectively. Metabolism was greater during the summer-wet season when greater irradiance, temperature, and material flux stimulate primary production and decomposition. Paradoxically, GPP was inversely related to total phosphorus (TP), with oligotrophic (TP < 7 μg L -1) open-water habitats dominated by periphyton having the highest and eutrophic (TP > 35 μg L -1) habitats with dense emergent macrophytes the lowest rates. R was greatest for moderately enriched (TP = 15 μg L -1) open-water habitats with floating macrophytes. The prevalence of net heterotrophy, 96% of the 1085 NAP estimates, reveals the importance of aboveground biota in regulating aquatic metabolism and O2 dynamics in shallow ecosystems. R is not only regulated by the influx of aboveground autochthonous carbon but also by aquatic GPP. Carbon turnover is greater in habitats where O 2 production by aquatic vegetation enables aerobic respiration. Conversely, water-column GPP is suppressed by dense emergent macrophytes, which limits O 2 availability, favors anaerobic respiration, and reduces carbon turnover. © 2010, by the American Society of Limnology and Oceanography, Inc.
Levesque J.C.,CSA International Inc
Wildlife Biology in Practice | Year: 2010
Natural Resource management is evolving toward ensuring sustainable ecosystems rather than sustainable yields. Understanding how a species interacts with its environment is fundamental for sound ecosystem management. If we are progressing toward an ecosystem management approach, then we must first understand how a species interacts with its environment and how the environment affects a species population dynamics. Ladyfish (Elops saurus) are a valuable commercial and recreational species; however, limited information is available describing the importance of their habitat. To date, only a few studies have noted the environmental conditions during ladyfish field-collections, and only one study has investigated ladyfish nursery habitats in any detail. Given the economic importance of ladyfish in Florida (USA), the objective of this investigation was to define, for the first time, juvenile ladyfish relative abundance in association to environmental conditions and habitat use at multiple Florida estuaries. In addition, this investigation re-examined some of the scientific findings and conclusions of previous ladyfish studies; incorporated additional data sets; and evaluated available ladyfish data at a finer scale of phenomena. Overall, juvenile ladyfish were collected in waters with wide-ranging environmental conditions having a sandy bottom, but preferred specific locations with particular dissolved oxygen, pH, water temperature, and salinity levels according to their size.
Balcom B.J.,CSA International Inc. |
Graham B.D.,CSA International Inc. |
Hart A.D.,CSA International Inc. |
Bestall G.P.,Tullow Ghana Ltd.
Society of Petroleum Engineers - SPE/APPEA Int. Conference on Health, Safety and Environment in Oil and Gas Exploration and Production 2012: Protecting People and the Environment - Evolving Challenges | Year: 2012
To address the potential for modification of discharge regulations concerning residual oil on cuttings concentrations (OOCC), a scientific study was conducted in 2011 to evaluate the fate and effects of drill cuttings resulting from completion of a development well using a non-aqueous drilling fluid (NADF). The design of the study conducted in deepwater offshore Ghana was statistically defensible and OSPAR-compliant, utilizing a stratified random sampling design. The study integrated various sampling techniques and matrices to provide a comprehensive assessment of the impacts of cuttings discharges on the marine environment and to verify the results of dispersion modeling. Survey results were used to develop recommendations for regionally applicable OOCC discharge limitations. The physico-chemical and macroinfaunal sampling of sediments at varying distances from the wellsite offered insight into the benthic fate and effects of NADF-based cuttings discharges. Statistical analyses of the data, including correlation, analysis of variance, Tukey's analysis, and pattern analysis, revealed the following results. Benthic impacts were limited to within several hundred meters of the wellsite and included reduced numbers of species, reduced species diversity and evenness, increases in hydrocarbon levels (including NADF tracers), and elevated levels of drilling-related metals. Macroinfaunal and physico-chemical metrics return to ambient levels within approximately 500 m of the wellsite. On a worldwide basis, most regulations pertinent to residual OOCC have limits ranging from 1 to 9.4%. An OOCC level of approximately 5% was achieved for the NADF-based cuttings discharges during this development drilling program. Survey results indicate minimal and localized environmental impacts to the sediment chemistry and macroinfaunal community structure from NADF-based cuttings discharges, consistent with findings from other studies. Based on this survey, it would be reasonable to apply the results of this study to establishing appropriate drill cuttings discharge guidelines for deepwater operations that utilize NADFs. Copyright 2012, SPE/APPEA International Conference on Health, Safety, and Environment in Oil and Gas Exploration and Production.
Dungan C.F.,Cooperative Oxford Laboratory |
Carnegie R.B.,Virginia Institute of Marine Science |
Hill K.M.,Virginia Institute of Marine Science |
Hill K.M.,Smithsonian Institution |
And 6 more authors.
Diseases of Aquatic Organisms | Year: 2012
To assess potential benefits and liabilities from a proposed introduction of Asian Suminoe oysters, susceptibilities of exotic Crassostrea ariakensis and native C. virginica oysters were compared during exposures to pathogens endemic in temperate, mesohaline waters of Chesapeake Bay and sub-tropical, polyhaline Atlantic waters of southern Florida, USA. Cohorts of diploid, sibling oysters of both species were periodically tested for diseases while reared in mesocosms receiving ambient waters from the Choptank River, Maryland (>3 yr) or the Indian River Lagoon, Florida (10 to 11 mo). Haplosporidium sp. infections (e.g. MSX disease) were not detected in oysters from either site. Perkinsus sp. infections (dermo disease) occurred among members of both oyster species at both sites, but infections were generally of low or moderate intensities. A Bonamia sp. was detected by PCR of DNAs from tissues of both oyster species following exposure to Florida waters, with maximum PCR prevalences of 44 and 15% among C. ariakensis and C. virginica oysters respectively during June 2007. Among C. ariakensis oysters sampled during April to July 2007, a Bonamia sp. was detected in 31% of oysters by PCR (range 11 to 35%) and confirmed histologically in 10% (range 0 to 15%). Among simultaneously sampled C. virginica oysters, a Bonamia sp. was detected in 7% by PCR (range 0 to 15%), but histological lesions were absent. Although this is the first report of a Bonamia sp. from Florida waters, sequences of small subunit (SSU) rDNA and in situ hybridization (ISH) assays both identified the Florida pathogen as Bonamia exitiosa, which also infects oysters in the proximate waters of North Carolina, USA. © Inter-Research 2012.
Levesque J.C.,CSA International Inc
Reviews in Fisheries Science | Year: 2011
Understanding a species life history is fundamental for managing and conserving a population. Despite the importance of this type of information, research attention is often directed at species with the highest economic value. This funding approach is problematic for preserving diversity and rarely considers ecological systematic functions; it prevents resource agencies from allocating funds for studying lower-valued species. For example, the ladyfish (Elops saurus) is a valuable commercial and recreational species in Florida, but in comparison to tarpon (Megalops atlanticus) and bonefish (Albula vulpes), ladyfish have received less funding and research attention. To date, comparably little biological information and no recent reviews are available for ladyfish; research interest is almost non-existent. First, a new review of ladyfish information is provided, and second, statistical evidence is presented and discussed that suggests that there is more published information for tarpon and bonefish than ladyfish because their socio-ecological values are greater. This study’s findings confirm that there are significantly more published articles on tarpon than ladyfish, and the number of articles on ladyfish has declined with time. The number of articles on tarpon and bonefish were positively correlated with time, while the number of articles on ladyfish was negatively correlated with time. Natural resource management is shifting from a sustainable yield to a sustainable ecosystem perspective. Given this shift in management approach, successful ecosystem management requires substantial biological information on a variety of species within a given system, regardless of their socio-economic status. It is important to understand that although some species have been ranked higher than others, in terms of economic importance, ecosystems are functioning systems that do not discriminate or have any jurisdictional boundaries. © Taylor and Francis Group, LLC.
Viada S.T.,CSA International Inc. |
Graham B.D.,CSA International Inc. |
VanGraafeiland K.B.,CSA International Inc.
Society of Petroleum Engineers - SPE International Conference on Health, Safety and Environment in Oil and Gas Exploration and Production 2010 | Year: 2010
This paper describes a study that integrated geographic information system (GIS) habitat mapping, habitat sensitivity analysis, and direct observational data to develop an efficient means of locating shallow water seafloor features warranting environmental protection during seismic operations off northern Mozambique. Data collected during the study were then used to develop a mitigation plan to minimize potential impacts associated with proposed geophysical survey activities. This study combined proven survey techniques for rapid assessment and large-scale mapping of sensitive seafloor features. Preliminary seafloor habitat categorization and mapping of the project area was conducted using high-resolution satellite imagery and a review of relevant published scientific literature. An operation-specific environmental sensitivity index (ESI) was applied to habitat types, and selection criteria were developed for habitats warranting environmental protection (sensitive habitats) from proposed geophysical survey activities. Sensitive habitats were protected from potential impacts from the seismic sound source by mitigation buffers. A subsequent field survey, consisting of a combined side-scan sonar survey of selected geophysical survey lines and rapid assessment groundtruthing of selected seafloor features, was conducted over a 21-day period, surveying 250 km of seafloor in water depths between 2 and 15 m. The side-scan sonar data were reviewed during collection to identify seafloor features that potentially met sensitive habitat criteria. The locations of seafloor features of interest were obtained for subsequent examination by diver scientists utilizing rapid assessment methods for selection criteria verification. Seventy-nine targets were selected for examination during the field survey. The results of the field survey were used during the design of the geophysical survey, with protective areas placed around sensitive habitats. The study demonstrates an integration of survey techniques that collectively provide a time-efficient and cost-effective means to identify and map environmentally sensitive shallow-water seafloor features within a large and environmentally complex geographical area. This study additionally presents the application of an operational-specific ESI based on habitat characteristics which are sensitive to impact producing factors associated with offshore oil and gas exploration activities. This combined technical approach is a practical means to minimize environmental impact while meeting industry engineering and logistic constraints. Copyright 2010, Society of Petroleum Engineers.
Levesque J.C.,CSA International Inc.
ICES Journal of Marine Science | Year: 2011
Marine resource managers designate marine protected areas (MPAs) to conserve, protect, and enhance fragile marine resources. A form of MPAs sometimes used by resource managers in the United States is a national marine sanctuary (NMS), and for all MPAs, managers need to use updated information during sanctuary management plan reviews (MPRs). In 2006, the Flower Garden Banks NMS (FGBNMS) began its first MPR by conducting public hearings and soliciting comments. Some 66% of comments were about the potential impacts fisheries posed to the sanctuary, so a description of commercial fishery activity in the NW Gulf of Mexico can help guide resource managers make sound, informed decisions. Despite limitations on data and knowledge of fishing effort spatially for the FGBNMS, commercial landings vary by Gulf state, area, and fishing gear, with most landings from the Louisiana and Texas coasts taken with trawls and nets. The main species landed from the NW Gulf of Mexico are shrimp, yellowfin tuna, and red snapper. Some conservation measures proposed for the FGBNMS will likely impact some commercial fisheries (hook and line, bottom longline), but not others (otter trawl, pelagic longline). © 2011 International Council for the Exploration of the Sea.
Csa International Inc. | Date: 2012-08-15
An apparatus comprises at least one cutting jet configured to inject a fluid into a first layer of soil below a surface layer of underwater soil in a first region. At least one soil extractor is configured to remove at least a portion of the injected fluid and a portion of the first layer of soil in the first region. A mixing manifold is provided for mixing the removed portion of the injected fluid and the removed portion of the first layer of soil. A discharge is provided for depositing the mixed fluid and soil over the surface layer of underwater soil.