Aquatic Settings Research Articles

Kinetics of the nucleophilic dissolution of hydrophobic and hydrophilic elemental sulfur sols by sulfide

The reaction most directly responsible for polysulfide formation in aquatic settings, as a key part of overall biotic and abiotic sulfur cycling, is the nucleophilic reaction between elemental sulfur and sulfide. The reactivity of elemental sulfur, and therefore the production of polysulfide, is fundamentally tied to a suite of poorly understood surface properties of elemental sulfur, that in natural environments is thought to primarily exist in the most stable state (α-S8), or as biologically produced elemental sulfur (S8bio). Sulfur sols, a group of particles from nanoparticle to colloidal size, can be used as model systems to isolate key characteristics responsible for poorly understood reactivity associated with sulfur cycling. Specifically, Weimarn sols (S8weimarn), as hydrophobic particles, and Raffo sols (S8Raffo) as hydrophilic particles, represent ideal end members for biologically produced elemental sulfur.The reaction most directly responsible for polysulfide formation in aquatic settings, as a key part of overall biotic and abiotic sulfur cycling, is the nucleophilic reaction between elemental sulfur and sulfide. A series of pseudo-first order kinetic batch reactions were performed after development of a technique to measure sulfur sol concentrations with sufficient quality at second time scales on a 96-well microplate UV–Vis spectrophotometer. The experiments facilitated determination of the kinetics of the reaction between elemental sulfur sols and sulfide as a function of specific surface area, sulfide concentration, pH, ionic strength, and temperature for both Raffo and Weimarn sols, and determination of the effect of organic surfactants (using sodium dodecylsulfate, SDS, as an analogue). A broad governing rate law for either sol proved statistically undefinable, likely a result of key back reactions, surface reaction details, and undefined side reactions. However, a series of rate laws for specific conditional variables and defined rates for an array of conditions set a kinetic framework to define these rates. Activation energy for sols are relatively close to that determined for S8bio and significantly lower than those measured for α-S8. Reaction rates as a function of surface character (hydrophilic v hydrophobic) are significantly different, and rates as a function of surfactant concentration suggest enhancement of reaction rates as a surface process, not linked to dissolution of the elemental sulfur by surfactants. An accurate description of kinetic pathways governing intermediate sulfur species thus requires specific definition of the form of elemental sulfur.

Egestion Versus Excretion: A Meta-Analysis Examining Nutrient Release Rates and Ratios across Freshwater Fauna

In aquatic settings, animals directly affect ecosystem functions through excretion of dissolved nutrients. However, the comparative role of egestion as an animal-mediated nutrient flux remains understudied. We conducted a literature survey and meta-analysis to directly compare nitrogen (N), phosphorus (P), and N:P of egestion compared to excretion rates and ratios across freshwater animals. Synthesizing 215 datasets across 47 animal species (all primary consumers or omnivores), we show that the total N and P egestion rates exceed inorganic N and P excretion rates but not total N and P excretion rates, and that proportions of P egested compared to excreted depend on body size and animal phylum. We further show that variance of egestion rates is often greater than excretion rates, reflecting greater inter-individual and temporal variation of egestion as a nutrient flux in comparison to excretion. At phylogenetic levels, our analysis suggests that Mollusca exhibit the greatest rates and variance of P egestion relative to excretion, especially compared to Arthropoda. Given quantitative evidence of egestion as a dominant and dynamic animal-mediated nutrient flux, our synthesis demonstrates the need for additional studies of rates, stoichiometry, and roles of animal egestion in aquatic settings.

Simultaneous determination of dissolved inorganic carbon (DIC) concentration and stable isotope (δ13C-DIC) by Cavity Ring-Down Spectroscopy: Application to study carbonate dynamics in the Chesapeake Bay

Dissolved inorganic carbon (DIC) and its stable isotope (δ13C-DIC) are powerful tools for exploring aquatic biogeochemistry and the carbon cycle. Traditionally, they are determined separately with a DIC analyzer and an isotope ratio mass spectrometer. We present an approach that uses a whole-water CO2 extraction device coupled to a Cavity Ring-Down Spectroscopy (CRDS) CO2 and isotopic analyzer to measure DIC and δ13C-DIC simultaneously in a 3–4 mL sample over an ~11 min interval, with an average precision of 1.5 ± 0.6 μmol kg−1 for DIC and 0.09 ± 0.05‰ for δ13C-DIC. The system was tested on samples collected from a Chesapeake Bay cruise in May 2016, achieving a precision of 0.7 ± 0.5 μmol kg−1 for DIC and 0.05 ± 0.02‰ for δ13C-DIC. Using the simultaneously measured DIC and δ13C-DIC data, the biogeochemical controls on DIC and its isotope composition in the bay during spring are discussed. In the northern upper bay, the main controlling processes were CO2 outgassing and carbonate precipitation, whereas primary production (surface) and degradation of organic carbon (subsurface) dominated in the southern upper bay and middle bay. By improving the mode of sample introduction, the system could be automated to measure multiple samples. This would give the system the potential to provide continuous shipboard measurements during field surveys, making this method more powerful for exploring the complicated carbonate system across a wide range of aquatic settings.

Noisy waters.

In this Issue, Popper & Hawkins (2019) provide “An overview of fish bioacoustics and the impacts of anthropogenic (human-made) sounds on fishes.” For fishes, hearing provides extremely important information about their environment, including information about events at distances well beyond those detectable by other senses. Moreover, acoustic cues in the underwater soundscape play an essential role in communication, predator–prey interactions, orientation and migration. The authors point out that the term ‘noise’ refers to unwanted sounds that are judged unpleasant, loud or disruptive to hearing and/or behaviour. Since the industrial revolution, human-generated noise has increased substantially in aquatic habitats. Activities such as shipping, sonar, pile driving, dredging, etc. may all have important negative impacts on fish populations and communities. The review begins with an overview of basic elements of underwater sound and the major sources of underwater noise. It proceeds to consider the biology of hearing and acoustics for fishes. It then reviews how anthropogenic sound could potentially affect fishes, noting that sound rarely causes mortality, but that biologically important effects can include temporary hearing impairment, masking the detection of biologically important sounds, physiological changes including stress, and changes in behaviour. The authors point out that there are numerous gaps in our knowledge of potential effects of anthropogenic sound on fishes and that much research is needed in order to fill the gaps and allow much better understanding of potential anthropogenic effects. The authors take the view that experiments performed in enclosed spaces such as tanks do not provide very useful information about how fishes will respond to anthropogenic noise in the wild. They suggest this because the sound fields presented in tanks and confined spaces are quite unlike what fishes would experience in natural aquatic settings and because animals may behave differently when not confined. The reader should be aware that these viewpoints are not shared by all researchers working on effects of noise on fishes. The review also considers existing criteria and guidelines regarding regulation of exposure of fishes to sound, with a particular emphasis on Europe and the United States. Given the absence of information on sound sensitivity for a vast majority of species, the authors suggest that classification of fishes based upon their auditory apparatus is a useful means of generalising across species. The review concludes with research directions and recommendations, specifically on the need to select representative species and to focus upon behavioural responses, the fact that fish hearing is mostly sensitive to particle motion rather than sound pressure, and how to scale up effects to understand implications for populations. The authors mention that “Further research is required on the responses of a range of fish species to different sound sources, under different conditions. There is a need both to examine the immediate effects of sound exposure and the longer-term effects, in terms of fitness and likely impacts upon populations.”

Ultrasensitive Detection of Hepatotoxic Microcystin Production from Cyanobacteria Using Surface-Enhanced Raman Scattering Immunosensor.

Microcystin-LR (MC-LR) is considered the most common hazardous toxin produced during harmful algal blooms. In addition to potential risk of long-term exposure to low concentrations in drinking water, acute toxicity due to MC-LR resulting from algal blooms could result in fatalities in rare cases. Although several methods are currently available to detect MC-LR, development of a low-cost, ultrasensitive measurement method would help limit exposure by enabling early detection and continuous monitoring of MC-LR. Here, we develop a surface-enhanced Raman scattering (SERS) spectroscopic immunosensor for detection and quantification of the hepatotoxic MC-LR toxin in aquatic settings with excellent robustness, selectivity, and sensitivity. We demonstrate that the developed SERS sensor can reach a limit of detection (0.014 μg/L) at least 1 order of magnitude lower and display a linear dynamic detection range (0.01 μg/L to 100 μg/L) 2 orders of magnitude wider in comparison to the commercial enzyme-linked immunosorbent assay test. The superior analytical performance of this SERS immunosensor enables monitoring of the dynamic production of MC-LR from a Microcystis aeruginosa culture. We believe that the present method could serve as a useful tool for detection of hepatotoxic microcystin toxins in various aquatic settings such as drinking water, lakes, and reservoirs. Further development of this technique could result in single-cell microcystin resolution or real-time monitoring to mitigate the associated toxicity and economic loss.

Algal-Mediated Priming Effects on the Ecological Stoichiometry of Leaf Litter Decomposition: A Meta-Analysis

In aquatic settings, periphytic algae exude labile carbon (C) that can significantly suppress or stimulate heterotrophic decomposition of recalcitrant C via priming effects. The magnitude and direction of priming effects may depend on the availability and stoichiometry of nutrients like nitrogen (N) and phosphorus (P), which can constrain algal and heterotrophic activity; in turn, priming may affect heterotrophic acquisition not only of recalcitrant C, but also N and P. In this study, we conducted a meta-analysis of algal-mediated priming across leaf litter decomposition experiments to investigate (1) bottom-up controls on priming intensity by dissolved N and P concentrations, and (2) effects of algal-mediated priming on the fate of litter-periphyton N and P during decomposition. Across a total of 9 datasets, we quantified priming intensity and tested algal effects on litter-periphyton C:N, C:P, and N- and P-specific mass loss rates. Algal effect sizes did not significantly differ from zero, indicating weak or inconsistent algal effects on litter-periphyton stoichiometry and nutrient loss. These findings were likely due to wide variation in algal priming intensity across a limited number of experiments, ranging from strongly negative (410% reduced decomposition) to strongly positive (104% increased decomposition). Correlation and response surface analyses showed that priming intensity switched from negative to positive with increasing dissolved inorganic N:P across datasets. Algal effects on litter-periphyton stoichiometry and nutrient loss further co-varied with dissolved N:P across datasets, suggesting algae most strongly influence the stoichiometry of decomposition under imbalanced N:P, when priming is most intense. Our findings from this limited meta-analysis support the need for additional tests of aquatic priming effects, especially across gradients of N and P availability, with consideration of coupled C and nutrient dynamics during priming of organic matter decomposition.

Palaeofacies and biomarker characteristics of Paleogene to Neogene rocks in the Makassar Straits, Indonesia

Abstract Borehole K-1 is an exploratory well that was drilled in the North Makassar Basin (West Sulawesi) in 2011. Gas chromatography (GC) and gas chromatography-mass chromatography (GC-MS) analyses have been conducted on extracts from well cuttings from the Paleogene to Neogene interval in order to investigate the characteristics of biomarkers present. Although the well was drilled with oil-based mud and gas chromatographic analysis reveals that the alkane fractions are heavily contaminated, detailed investigation of biomarkers in these rock extracts and comparison with biomarkers in the oil-based mud has revealed that, while there are hopane and sterane biomarkers in the mud, there are also a discrete set of biomarkers that are indigenous to the rocks. These include oleanane, bicadinanes, taraxastane and other higher-plant-derived triterpanes. The presence of these compounds in environments that range from bathyal to marginal marine and even to lacustrine, shows the extent of reworking of terrestrial material into aquatic settings in this region during the Paleogene and Neogene and provides further evidence of a predominance of terrestrial material, even in deep-marine settings, with little ‘in-situ’ material noted. These findings have important implications for the use of biomarkers as indicators of palaeoenvironment in both source rocks and oils.

Waterproof, electronics-enabled, epidermal microfluidic devices for sweat collection, biomarker analysis, and thermography in aquatic settings.

Noninvasive, in situ biochemical monitoring of physiological status, via the use of sweat, could enable new forms of health care diagnostics and personalized hydration strategies. Recent advances in sweat collection and sensing technologies offer powerful capabilities, but they are not effective for use in extreme situations such as aquatic or arid environments, because of unique challenges in eliminating interference/contamination from surrounding water, maintaining robust adhesion in the presence of viscous drag forces and/or vigorous motion, and preventing evaporation of collected sweat. This paper introduces materials and designs for waterproof, epidermal, microfluidic and electronic systems that adhere to the skin to enable capture, storage, and analysis of sweat, even while fully underwater. Field trials demonstrate the ability of these devices to collect quantitative in situ measurements of local sweat chloride concentration, local sweat loss (and sweat rate), and skin temperature during vigorous physical activity in controlled, indoor conditions and in open-ocean swimming.

Eastern Oyster (<i>Crassostrea virginica</i>) Filtration Efficiency of Chlorophyll-<i>a</i> under Dynamic Conditions in the Hudson-Raritan Estuary at Pier 40, New York City

Eastern oyster (Crassostrea virginica) abundance has declined severely over the past century along the Atlantic and Gulf coasts of the United States. For varied reasons, overfishing among the foremost, bivalves no longer make up considerable reefs as was common. While discourse continues on oyster restoration and augmentation, gaps in knowledge of C. virginica and regional environmental interactions remain. Our primary aim was to examine the C. virginica filter feeding of phytoplankton in the Hudson River Estuary, New York City. Secondarily, this study examined the filtration of these oysters in relation to environmental attributes. Chlorophyll-a, the predominant photosynthesizing pigment in red and green algae, is an indicator of phytoplankton productivity in aquatic settings. Crassostrea virginica consumes first-tier plankton from the water column’s seston; thus analysis of chlorophyll-a content allows estimating phytoplankton concentrations, from which oyster filtration efficiency (FE) was quantified. Water conditions (temperature, dissolved oxygen, pH, salinity, turbidity, tide and flow rate) also were recorded. Spectrophotometric determination of chlorophyll-a concentration methodology was derived from the Standard Methods text favored by the US EPA. This project compared real-time Hudson River Estuary (HRE) water samples prior to passing through a contained oyster reef and samples of water post-filtration. This sampling scenario was unique as the contained reef used was fed by HRE water. Most studies on oyster filtration have been laboratory-based, and few assessed oysters in the field. This study took place at Pier 40, the River Project Wetlab, lower Hudson River along Manhattan. The FE of this reef was calculated for two months during various environmental states which can be the basis of future investigations. Statistically significant differences were found between pre- and post-filtration water samples (Z = 4.620, p < 0.001). This study provides a glimpse at how the oysters fare in the HRE environment and expands upon known oyster ecological services and environmental interactions.

Antibiotic Sensitivity Patterns of Urine and Biofilms in Patients with Indwelling Urinary Catheter in Denden Hospital, Asmara, Eritrea

The intricate infections leading to long-term morbidity of catheterized patients are due to the presence of a covering and blocking the lumen of urinary catheters by biofilms which have increased ability of resistance to host immune system and antibiotic treatment. The biofilm mode of growth is a basic survival strategy implemented by bacteria in a wide range of settings such as environmental, industrial and clinical aquatic settings. Bacterial growth on the inner surface of the catheter with biofilm formation is frequent and may occur within days of catheter placement. This study investigated the formation of biofilm inside catheter lumen of patients from Denden hospital, Asmara, Eritrea. And also, it assessed the antimicrobial sensitivity pattern of biofilm isolates and compared it with urine isolates. Resistance to antibiotics was observed in biofilm isolates more than urine isolates. E. coli was the most frequently isolated organism in both biofilm and urine samples.

A Novel Approach To Quantify Air-Water Gas Exchange in Shallow Surface Waters Using High-Resolution Time Series of Dissolved Atmospheric Gases.

Gas exchange across the air-water interface is a key process determining the release of greenhouse gases from surface waters and a fundamental component of gas dynamics in aquatic systems. To experimentally quantify the gas transfer velocity in a wide range of aquatic settings, a novel method based on recently developed techniques for the in situ, near-continuous measurement of dissolved (noble) gases with a field portable mass spectrometer is presented. Variations in observed dissolved gas concentrations are damped and lagged with respect to equilibrium concentrations, being the result of (a) temperature (and thus solubility) variations, (b) water depth, and (c) the specific gas transfer velocity ( ki). The method fits a model to the measured gas concentrations to derive the gas transfer velocity from the amplitude and the phase lag between observed and equilibrium concentrations. With the current experimental setup, the method is sensitive to gas transfer velocities of 0.05-9 m/day (for N2), at a water depth of 1 m, and a given daily water temperature variation of 10 °C. Experiments were performed (a) in a controlled experiment to prove the concept and to confirm the capability to determine low transfer velocities and (b) in a field study in a shallow coastal lagoon covering a range of transfer velocities, demonstrating the field applicability of the method.

Periphytic algae decouple fungal activity from leaf litter decomposition via negative priming.

1. Well-documented in terrestrial settings, priming effects describe stimulated heterotrophic microbial activity and decomposition of recalcitrant carbon by additions of labile carbon. In aquatic settings, algae produce labile exudates which may elicit priming during organic matter decomposition, yet the directions and mechanisms of aquatic priming effects remain poorly tested. 2. We tested algal-induced priming during decomposition of two leaf species of contrasting recalcitrance, Liriodendron tulipifera and Quercus nigra, in experimental streams under light or dark conditions. We measured litter-associated algal, bacterial, and fungal biomass and activity, stoichiometry, and litter decomposition rates over 43 days. 3. Light increased algal biomass and production rates and increased bacterial abundance 141-733% and fungal production rates 20-157%. Incubations with a photosynthesis inhibitor established that algal activity directly stimulated fungal production rates in the short-term. 4. Algal-stimulated fungal production rates on both leaf species were not coupled to long-term increases in fungal biomass accrual or litter decomposition rates, which were 154-157% and 164-455% greater in the dark, respectively. The similar patterns on fast- vs. slow-decomposing L. tulipifera and Q. nigra, respectively, indicated that substrate recalcitrance may not mediate priming strength or direction. 5. In this example of negative priming, periphytic algae decoupled fungal activity from decomposition, likely by providing labile carbon invested toward greater fungal growth and reproduction instead of recalcitrant carbon degradation. If common, algal-induced negative priming could stimulate heterotrophy reliant on labile carbon yet suppress decomposition of recalcitrant carbon, modifying energy and nutrients available to upper trophic levels and enhancing organic carbon storage or export in well-lit aquatic habitats.

Synthesis reveals ladderane secrets

Since their unlikely discovery in wastewater sludge at the tail end of the past century, anaerobic ammonium (anammox) bacteria have been spotted in all manner of aquatic settings. These bacteria consume ammonium and nitrite, churning out gaseous nitrogen and water. Researchers have sought to harness the microbes to remove ammonium, which is released into the environment by agricultural fertilizers, from wastewater. But studying these microbes, much less manipulating them, hasn’t been easy. The bacteria grow slowly, doubling every one to two weeks, and are sensitive to oxygen, which means that scientists must use glove boxes to extract certain enzymes. Now, in a step toward understanding these enigmatic bacteria, researchers at Stanford University have investigated two key molecules found in the membrane of the bacteria’s anammoxosome, the organelle where the ammonia-oxidizing process is thought to occur (Proc. Natl. Acad. Sci. USA 2018, DOI: 10.1073/pnas.1810706115). Known as ladderane phospholipids, these compounds possess

Potential application of SMART II for Vibrio cholerae O1 and O139 detection in ship's ballast water

Ballast water is used to safely stabilize and operate shipping vessels worldwide, in a multitude of aquatic settings, including inland, coastal and open oceans. However, ballast water may pose ecological, public health, and/or economic problems as it may serve as vehicles of transmission of microorganisms. Current ballast water regulations include limits of Escherichia coli, Enterococcus spp. and toxigenic Vibrio cholerae. Several United States Environmental Protection Agency approved standard operating protocols (SOPs) exist for detection of E. coli and Enterococci, yet none exists for V. cholerae. Current V. cholerae detection methods include colony blot hybridization, direct fluorescent antibody test (DFA), and/or polymerase chain reaction (PCR), which can be time consuming and difficult to perform. This study utilizes Cholera SMART II to determine its potential use in detection of V. cholerae. Validation of this method would help provide quick and accurate analysis for V. cholerae in ballast discharge waters in the field.

Surface complexation modeling of interactions between freshwater and marine diatom species and trace elements (Mo, W, Cr, Ge, Ga, Al)

Towards a better understanding of photosynthetic algae interaction with less common trace elements, we performed adsorption experiments of Al, Ga, Ge, Cr (VI), Mo, and W onto four diatom species typical for marine, estuarine, and freshwater aquatic systems. Using a surface complexation approach, we tentatively identified the nature of functional groups involved in the complexation of trace elements with diatom surface moieties and we quantified the stability of surface complexes formed at the diatom – solution interface. The differences in binding properties between freshwater and marine species are linked to variable proportion of three main binding groups at the diatom surfaces, namely amine, carboxylate and silanol. Under acidic conditions, the oxyanion (MoO42−, WO42−, CrO42−) sorption occurred electrostatically with a 1:1 ratio to the protonated amino groups. Trivalent cations (Ga3+ and Al3+) were complexed by deprotonated carboxyl groups, while the anionic hydroxylated forms of these metals (Ga(OH)4− and Al(OH)4−) formed mononuclear monodentate complex with positively charged amino groups at higher pH. Finally, Ge(IV) sorption was controlled by interaction with neutral carboxylic, silanol and amino groups. Taken together, the surface complexation model developed in this study allows rigorous description of anions and trivalent hydrolysates adsorption onto diatom surfaces and demonstrates potential importance of diatoms for the control of trace element transfer in aquatic settings.

Drowning Prevention: Assessment of a Classroom-Based Water Safety Education Program in Vietnam.

Youth drowning continues to be a primary public health issue globally with Eurasian countries experiencing some of the highest recorded rates of injury and death in aquatic settings. The country of Vietnam is currently working toward reducing the number of youth drowning fatalities. Part of these efforts is the introduction of an in-school water safety educational program. For this study, pilot pre/post data were acquired and used to assess overall knowledge acquisition and changes in knowledge of youth in grades 1 to 5 in central Vietnam. A total of 229 schools participated, resulting in 40 198 usable surveys. The results indicated that overall there was a significant change in scores with an acceptable effect size between measures. Mean scores for each of the water safety messages were rated as acceptable (above 90%), satisfactory (between 70% and 90%), and areas of concern (under 70%). Recommendations were made to program leaders about identified areas of concern.

A consistent global approach for the morphometric characterization of subaqueous landslides

Abstract Landslides are common in aquatic settings worldwide, from lakes and coastal environments to the deep sea. Fast-moving, large-volume landslides can potentially trigger destructive tsunamis. Landslides damage and disrupt global communication links and other critical marine infrastructure. Landslide deposits act as foci for localized, but important, deep-seafloor biological communities. Under burial, landslide deposits play an important role in a successful petroleum system. While the broad importance of understanding subaqueous landslide processes is evident, a number of important scientific questions have yet to receive the needed attention. Collecting quantitative data is a critical step to addressing questions surrounding subaqueous landslides. Quantitative metrics of subaqueous landslides are routinely recorded, but which ones, and how they are defined, depends on the end-user focus. Differences in focus can inhibit communication of knowledge between communities, and complicate comparative analysis. This study outlines an approach specifically for consistent measurement of subaqueous landslide morphometrics to be used in the design of a broader, global open-source, peer-curated database. Examples from different settings illustrate how the approach can be applied, as well as the difficulties encountered when analysing different landslides and data types. Standardizing data collection for subaqueous landslides should result in more accurate geohazard predictions and resource estimation.

QStatin, a Selective Inhibitor of Quorum Sensing in Vibrio Species.

ABSTRACTPathogenic Vibrio species cause diseases in diverse marine animals reared in aquaculture. Since their pathogenesis, persistence, and survival in marine environments are regulated by quorum sensing (QS), QS interference has attracted attention as a means to control these bacteria in aquatic settings. A few QS inhibitors of Vibrio species have been reported, but detailed molecular mechanisms are lacking. Here, we identified a novel, potent, and selective Vibrio QS inhibitor, named QStatin [1-(5-bromothiophene-2-sulfonyl)-1H-pyrazole], which affects Vibrio harveyi LuxR homologues, the well-conserved master transcriptional regulators for QS in Vibrio species. Crystallographic and biochemical analyses showed that QStatin binds tightly to a putative ligand-binding pocket in SmcR, the LuxR homologue in V. vulnificus, and changes the flexibility of the protein, thereby altering its transcription regulatory activity. Transcriptome analysis revealed that QStatin results in SmcR dysfunction, affecting the expression of SmcR regulon required for virulence, motility/chemotaxis, and biofilm dynamics. Notably, QStatin attenuated representative QS-regulated phenotypes in various Vibrio species, including virulence against the brine shrimp (Artemia franciscana). Together, these results provide molecular insights into the mechanism of action of an effective, sustainable QS inhibitor that is less susceptible to resistance than other antimicrobial agents and useful in controlling the virulence of Vibrio species in aquacultures.

Closing the regulatory gap: revisions to the conventional practice of ex-post plans for EIAs to protect the valued components of Aboriginal peoples in Canada

Aboriginal peoples have distinct perspectives and relationships with the terrestrial and aquatic settings and components that sustain cultural modes of life. Valued components derived from these cultural understandings are to be incorporated into environmental impact assessments (EIA) that occur in their respective territories. Despite this technical and legal basis, Aboriginal cultures are often inadequately accounted for in many ex-post plans of development activities and projects. This paper examines changes made to the regulatory requirements of an ex-post plan that involved Aboriginal peoples and a pipeline project located in north-east British Columbia, Canada. The research context and the revisions made to the conventional practice are presented, followed by a discussion of the possible broader implications for future EIAs. The study provides useful insights into the deficiencies of conventional practices and contributes to technical understandings in terms of integrating and protecting Aboriginal cultures through ex-post plans.

Positioning Theory: Kinesiology Students’ Experiences Teaching in an Adapted Aquatics Practicum

Abstract The purpose of this study was to describe and explain undergraduate students’ positions of teaching and assisting students with disabilities during adapted aquatics practicum experiences. The participants were eight kinesiology students who enrolled in an introductory adapted physical education (APE) course at a public university in the Midwest region of the United States. This study used a descriptive qualitative research method and exploratory case study design (Yin, 2003). This case study was situated in the positioning theory. The term positioning means to analyze interpersonal encounters from a discursive viewpoint (Hollway, 1984). This framework allows researchers to explore the capacity of students to position themselves and, in this case, to describe how undergraduate students negotiate and implement aquatics lessons with students with disabilities. The data sources were face-to-face interviews, self-reflective journaling entries, and follow–up e-mail messages. Data were analyzed using constant comparative analysis and we uncovered the following themes: (a) ethical and unethical treatment of students with disabilities, (b) conflicts of parents’ and students’ interests, and (c) medical and gender sensitivity. This study’s results indicate that all the undergraduate students were becoming, albeit novice, reflective practitioners and ascribed their own reflective positions to their sense of advocacy. They were concerned that they had managerial challenges that exacerbated the difficulties in adjusting to the disability, medical, family and gendered backgrounds of students with disabilities. To improve preparation of undergraduate students, APE course instructors are required to use an appropriate adapted aquatic curriculum model such as the curriculum and assessment model. Using the logic of the positioning theory, researchers should study undergraduate students’ self and interactive positioning about assisting and teaching students with various levels of disabilities in adapted aquatic settings.