Our EWC seminar on this Friday, Nov 11, will feature Dr. Ibrahim Alameddine, who will discuss a case study of modeling and management of cyanobacterial algal blooms in Lebanon. A title and abstract are attached to this message. Please join us in Mann 304 from 11:45am-12:35pm.

The schedule for future seminars is available here:
http://go.ncsu.edu/ewc-seminar-schedule

Title: Monitoring, modeling, and controlling cyanobacterial algal blooms in a hyper-eutrophic reservoir: A case study of the Qaraoun reservoir-Lebanon

Abstract: Cyanobacterial blooms are an emerging worldwide problem, affecting many important freshwater systems. The proliferation of these blooms has been linked to public health concerns and to the impairment of the designated uses of many fresh water systems. Qaraoun Lake, a semi-arid poorly monitored eutrophic reservoir in Lebanon, has been experiencing consistent cyanobacterial blooms throughout the growing season. Blooms have been responsible for clogging sprinkles and irrigation pumps and negatively affecting the touristic sector in the area. In an effort to better understand eutrophication and bloom dynamics in the reservoir, an in situ monitoring program was initiated and coupled with the development of remote sensing based algorithms to track chlorophyll, total suspended solids, and secchi disk depth spatio-temporal variability. Lake data were then used to develop a Structural Equation Model that explains observed cyanobacteria biovolume dynamics in Qaraoun Reservoir, as a function of direct and indirect physio-chemical drivers. The model explained 46% of the variation in cyanobacteria biovolume, 82% of the variation in surface total phosphorus, and 14% of the variation in lake stratification. While basin-level management measures that aim to control nutrient loading are the most effective on the long-term to control cyanobacteria blooms, they are hard to implement in Lebanon given the socio-economical constrains. As such, the use of chemical algaecides was explored as a short-term mitigation measure. The efficacy of three algaecides, namely Copper Sulfate, Potassium Permanganate, and Diquat, was examined with regards to controlling two toxin-releasing cyanobateria, Aphanizomenon flos-aquae and Microcystis aeruginosa. The efficacy of each algaecide was quantified under laboratory conditions over a range of selected dosages. Results show that the reduction rates for both cyanobacteria varied temporally, with the largest drop in concentration recorded between 48 and 72 hours following treatment. Regrowth was observed for Microcystis aeruginosa subsequent to treatment but not for Aphanizomenon flos-aquae.