A modified stratification index method to assess reservoir water quality trends.

Harmful algal blooms (HABs) have been a harm to reservoir health for decades and it is believed that as climate changes and temperatures rise, frequency and severity of HABs are likely to increase as well. Understanding the relationships between physical factors in a reservoir and bloom trends could be key for keeping rising blooms at bay. A modified stability index based on temperature dependent water density at multiple depths was adapted into a code to process high frequency reservoir monitoring data. Metrics and visual tools were developed to use this stability index to objectively analyze how stratification - including intensity, start date, and turnover point - and water quality characteristics are changing, and how they are likely to change in the coming decades. This code was then used to analyze the relationships between physical and environmental reservoir characteristics, a generated stratification index, and algal bloom behavior for several United States Army Corps of Engineers (USACE) reservoirs, with specific focus on Shenango reservoir. Surface temperature, maximum temperature difference, and depth were found to correspond with strength of stratification. The calculated stratification index showed significant strength of correlation to algae when compared to other commonly collected reservoir parameters. Bettering our understanding of when stratification is occurring within reservoirs, as well as when blooms are occurring, will lead to more informed management decisions and better HAB control. For Shenango reservoir, it was determined that a hydrodynamic management strategy that maintains stability (horizontal flushing, epilimnetic withdrawals) during peak periods, while removing epilimnetic biomass and reducing nutrient availability, would be the most practical management strategy for bloom reduction.

A critical review of operational strategies for the management of harmful algal blooms (HABs) in inland reservoirs.

Occurrences of freshwater harmful algal blooms (HABs) are increasing on a global scale, largely in part due to increased nutrient input and changing climate patterns. While reservoir management strategies that can influence phytoplankton are known, there is no published guideline or protocol for the management of harmful algal blooms. There is a need to establish what factors are the predominant drivers of blooms, and how common reservoir management strategies specifically influence each factor. The following literature review seeks to establish the benefits and drawbacks of operational management strategies that currently exist. The main focus is altering hydrodynamic conditions (hypolimnetic withdrawals, surface flushing, pulsed inflow, artificial mixing), in order to induce environmental changes within the reservoir itself. Since excess nutrients are one of the biggest contributors to worsening bloom conditions, internal nutrient dynamics and reduction are also discussed. Additionally, we review the predominant seasonal factors (stratification, light, temperature, and wind) that affect likelihood of bloom occurrence and duration. The ultimate objective of this review is to increase understanding of the relationships between HAB drivers and reservoir operations in order to inform the development of data, modeling, and management strategies for the prevention and mitigation of blooms.

How does buoyancy behavior impact microplastic transport in an estuarine environment?

Much is still unknown about the transport behavior of microplastic pollutants within the marine environment, particularly smaller scale coastal systems such as estuaries. Through the use of a Lagrangian particle-tracking model coupled with a validated 3D hydrodynamic model, we examined the transport, pathway and ultimate fate of microplastic particles, both in an idealized estuary and Galveston Bay, Texas, USA. Emphasis was placed on differences based on settling behavior (neutrally versus negatively buoyant), use of random walk for diffusion processes, and release location. For Galveston Bay, settling behavior had a noteworthy impact on both the transport pathway of microplastic particles, as well as overall time spent within the bay. Particles with negative buoyancy were retained approximately seven times longer than those with neutral buoyancy. Negatively buoyant particles also showed a tendency to be dispersed eastward to Trinity Bay through the bottom baroclinic flow, while neutrally buoyant particles took a more direct route along the ship channel to the mouth of the bay. Idealized model simulations suggest impact of settling depends on the vertical mixing strength. For a system with stronger tidal mixing, negatively buoyant particles with small settling velocities may still behave similarly to neutrally buoyant particles, and differences only become apparent for particles that sink rather quickly (> 10 m d-1). Future sea-level rise or channel deepening tends to flush out neutrally buoyant particles more quickly, while increasing the retention time for negatively buoyant particles. Our results suggest that plastics within estuaries could show substantially different behavior depending on their buoyancy characteristics, highlighting a need to quantify specific settling velocities of plastic pollutants entering the coastal estuarine system.

Ongoing initiatives to improve the use of antibiotics in Botswana: University of Botswana symposium meeting report.

BACKGROUND AND OBJECTIVE: There are ongoing initiatives in Botswana to enhance appropriate antibiotic use. The objective of this meeting was to discuss ongoing initiatives in Botswana since February 2016 to improve antibiotic use. Subsequently, use the findings to refine national and local action plans. METHOD: Presentation and review of ongoing initiatives. RESULTS: There was a high rate of antibiotic prescribing among ambulatory care patients in the public sector (42.7%) as well as for patients with upper respiratory tract infections in the private sector (72.9%). Prophylactic antibiotics were given to 73.3% of surgical patients to reduce surgical site infections (SSIs) in a leading tertiary hospital in Botswana; however, SSIs at 9% of patients can be reduced further with better timing of antibiotic prophylaxis. To date, 711 patients have been enrolled into the national point prevalence study. Highlighted concerns included limited ordering and use of sensitivity tests despite functional laboratories, as well as concerns with missed doses of antibiotics across most hospitals. CONCLUSION: A number of issues and concerns regarding antibiotic use were highlighted. Activities are ongoing across sectors to address identified concerns.