Harmful algal blooms (HABs) are becoming more prevalent throughout the world’s aquatic systems. These blooms have been the subjects of numerous studies because they can cause human health issues and economic impact through fish kills, contaminated shellfish and decreased tourism. Much research has focused on the “bottom-up” aspect of these blooms; namely, the potential role of increased nutrient input into coastal waters from anthropogenic sources causing increased growth in harmful algal species. However, there are also potential “top-down” controls affecting the rate at which harmful algal species are consumed by grazers. The aim of this project was to determine protozoan grazer population fluctuations and their grazing impact on HAB species through field monitoring and laboratory grazing experiments. Protozoan grazers were chosen because their growth rates could potentially keep up with those of HAB species. Declines in grazer populations before the onset of a bloom could be indicative of a release of the HAB from a “top-down” grazing control. Field samples taken during bloom and non-bloom events helped elucidate any microplankton community changes. After establishing that there appear to be changes to the grazer population before and after a bloom, ingestion experiments including direct epifluorescence microscopy and DNA analyses were conducted to determine if it is possible that a chosen protozoan grazer can ingest a HAB species. Finally, experiments were conducted to determine whether the HAB species was a favorable food source for the grazer. Population growth experiments in which grazers are fed a HAB species, 50:50 mixture, or normal culture food source were used to determine the survival and growth rate of the grazer. Although certain ciliates and heterotrophic dinoflagellates were found to feed on HAB species in the lab and in natural bloom samples, the HAB species as a food source produces lower grazer growth rates than on control food. Protozoan grazers may be a more effective control during bloom initiation than after the bloom has been established. / text

MESHWR / Department of Ecology and Resources Management / The presence of harmful algal blooms (HABs) and cyanobacteria toxins in drinking water sources are known to pose a great threat to humans. The main aim of this study was to use molecular technique to determine the origins of the cyanobacteria species at Musina raw water abstraction point by identifying and comparing the non-toxic and toxic cyanobacteria species in the Limpopo River and some of its tributaries based on the phylogenetic analyses of 16S rRNA gene. The Musina water treatment plant is located downstream of a weir and the Beit bridge on the Limpopo River and the raw water supply is abstracted from 22 boreholes of which 14 are along the Limpopo River and 8 boreholes are inside the Limpopo River channel. The bottom sediments samples were collected from these rivers: Limpopo, Crocodile, Mokolo, Mogalakwena, Nzhelele, Lephalale, Sand rivers (South Africa); Notwane (Botswana), Shashe River and Mzingwane River (Zimbabwe). The physical-chemical analysis of the bottom sediments showed the availability of nutrients, nitrates and phosphates, in excess of 0.5 mg/l for most the of rivers, alkaline pH and salinity in excess of 500 mg/l. Total genomic DNA were extracted from cyanobacteria species on the bottom sediments and Polymerase Chain Reaction (PCR) method was used to detect the genetic profile of the cyanobacteria species. Molecular identification of cyanobacteria was based on PCR amplification and sequencing of the 16S rRNA gene. The 16S rRNA gene was absent from sediments of the Mogalakwena and Lephalale rivers but present in all other selected rivers. The cyanotoxins detection was also based on PCR by amplification of microcystin/nodularin and cylindrospermopsin polyketide synthetase genes. Most of the samples showed no amplification of the toxin genes. While two samples showed the amplification of cylindrospermopsin polyketide synthetase gene (Sand River and Nzhelele River Next to Tshipise) and two samples showed amplification for microcystin/nodularin synthetase gene, Crocodile River and Mzingwane River. The first was the confirmation of similarity of samples from Crocodile River downstream of hartbeespoort Dam and Shashe River to Leptolyngbya boryana with 99% bootstrap confidence. The similarity of sample from Musina borehole to Sand River upstream to Alkalinema pantanalense with 98% bootstrap. Thus, the presence of toxic genes may imply the presence of toxic cyanobacteria species in the river sediments and may be hazardous to humans because rural communities and commercial farmers abstract water from Limpopo River catchment for human consumption, livestock and irrigation. The waters of the Limpopo River basin also provide drinking water to wildlife and a habitant for aquatic organisms/animals.

MENVSC / Department of Ecology and Resource Management / Satellite remote sensing techniques have been proved to be the best methods for quantifying chlorophyll-a levels by estimating algal concentrations in water bodies. Harmful algal blooms (HABs) are posing a significant threat to the many water bodies in South Africa. This study aims at developing remote sensing solution to estimate chlorophyll concentrations in water bodies of Vhembe district municipality using recently launched Landsat 8 OLI. It is the first study to provide quantitative water quality information for the Vhembe region’s water bodies from a time series of satellite remotely sensed data and in-situ laboratory data. The objectives of this study was to evaluate spatial and temporal distributions of algae in water bodies and fish-ponds, to assess water quality parameters, namely: chlorophyll-a and turbidity and to compare data obtained from satellite remote sensors with in situ data. The 30 meters spatial resolution multispectral Landsat 8 OLI for 2016, 2017 and 2018 were used to derive chlorophyll-a estimate from an existing model at three water bodies. The chlorophyll-a concentrations measured during in-situ were employed to validate the Landsat derived chlorophyll-a estimates. The results from this study shows that Landsat derived chlorophyll-a estimates are correlating with field measurements. In all the reservoir, it was detected that there is low content of harmful algal blooms and thus the water bodies are in good condition since the chlorophyll-a concentrations were very low (ranging from 0 to 0.6 mg.m-3). In conclusion, it can be stated that Landsat 8 OLI sensor has the potential to map inland water bodies dominated with algal blooms at certain extent. It can further be stated that Landsat 8 OLI is suitable for monitoring the growth of HABs in aquatic ecosystem and is cost effective. This study also evaluated the potential of Banana peels powder and K2SO4 to inhibits the growth of algae (batch experiment). The water samples were collected at Tshifulanani and Lwamondo fish ponds where there are floating algae. The samples were collected seasonally and analysed for pH, water temperature, Total Dissolved Solids, Electrical conductivity, Dissolved Oxygen, turbidity, chlorophyll-a and absorbance. From the laboratory experiments, there was a variation in the values of absorbance (0.936A-1.234A), PH (7.1-8.3), EC (63.1- 87.9 μs/cm), TDS (52.6-69.7mg/L), water temperature (25.5-29.3°C) and Dissolved oxygen (5.3-7.1mg/L). The concentration of chlorophyll-a for Tshifulanani and Lwamondo fish ponds ranges were (2.14-15.96 mg/m-3) and (0.65-15.66 mg/m-3) respectively. A batch experiment was conducted to determine the potential of banana peels powder on inhibition of algal blooms in water samples by measuring absorbance at 750nm. It can be concluded in this study that banana peels have a potential to inhibits the growth of algae in fish ponds. The Absorbance has shown a rapid v decrease from 0.936A to Zero from day 1 to day 7 respectively. The inhibition of cyanobacteria by banana peels is followed using Potassium sulphate in treating the algal blooms in water samples. Both banana peels and potassium Sulphate has shown a positive response in treatment of algae on the batch experiment. The results of this study revealed that high concentration of physico-chemical parameters promote the growth of cyanobacteria in fish ponds but does not have negative effects on the fish except the oxygen competition with algal blooms. The statistical analysis in correlating the chl-a field measurements and remotely sensed data showed a positive outcome where K values were very high from 70% to 89%. These results show high level of agreement of correlation values of field chlorophyll-a concentration and satellite remotely sensed variables. / NRF

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Globally, water bodies are increasingly affected by undesirable harmful algal blooms. This dissertation contributes to research methodology pertaining to quantification of the algal blooms in multiple water bodies of Mississippi using in situ, analytical, and remote sensing techniques. The main objectives of this study were to evaluate the potential of several techniques for phytoplankton enumeration and to develop remote sensing algorithms for several sensors and evaluate the performance of the sensors for quantifying phytoplankton in several water bodies. Analytical techniques such as “FlowCam”, an imaging flow cytometer; “HPLC”, high performance liquid chromatography with the chemical taxonomy program “ChemTax”; spectrofluorometric analyses; and “ELISA” assay were used to quantify a suite of parameters on algal blooms. Additionally, in-situ algal pigment biomass was measured using fluorescence probes. It was found that that each technique has unique potential. While some of the rapid and simpler techniques can be used instead of more involved techniques, sometimes use of several techniques together is beneficial for managing aquatic ecosystems and protecting human health. Algorithms were developed to quantify chlorophyll a using five remote sensing sensors including three currently operational satellite sensors and two popular sensors onboard the Unmanned Aerial Systems (UASs). Empirical band ratio algorithms were developed for each sensor and the best algorithms were chosen. Cluster analysis helped in differentiating the water types and linear regression was used to develop algorithms for each of the water types. The UAS sensor- Micasense was found to be most useful among the UAS sensors and the best overall with highest R2 value 0.75 with p<0.05 and minimum %RMSE of 28.22% and satellite sensor OLCI was found to be most efficient among the three satellite sensors used in the study for chlorophyll a estimation with R2 of 0.75 with p<0.05 and %RMSE 13.19%. The algorithms developed for these sensors in this study represent the best algorithms for chlorophyll a estimation in these water bodies based on R2 and %RMSE. The applicability of the algorithms can be extended to other water bodies directly or the approach developed in this study can be adopted for estimating Chl a in other water bodies.

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Atmospheric nutrient loading and transport though precipitation and dry deposition is one of the least understood yet one of the most important pathways of nutrient transport into many lakes. These nutrients, phosphorus and nitrogen, are essential for aquatic life and often play major roles in algae blooms that occur in lakes and reservoirs. Often heavy algal growth intensifies a variety of water quality problems. Utah Lake may be even more susceptible to atmospheric deposition due to its large surface area to volume ratio and proximity to Great Basin dust sources. In this study, eight months of atmospheric deposition data were collected and analyzed from five locations near Utah Lake. Geospatial maps were created to show the temporal distribution of phosphorus and nitrogen. Evaluation of the atmospheric deposition results indicate that between 8 to 350 tons of total phosphorus and 46 to 460 tons of dissolved inorganic nitrogen were deposited onto the surface of Utah Lake over an eight-month period. Both estimates were based on assuming that the deposition decreased exponentially from the sampling station to the middle of the lake. The large difference results from using only samples with no visible particles or insects present to give the low estimate and all samples to give the high estimate. These nutrient loading values are very significant in that it has been estimated that only about 17 tons year-1 of phosphorus and about 200 tons year-1 of nitrogen are needed to support a eutrophic level of algal growth in Utah Lake. Atmospheric deposition was found to be a major contributor in providing a eutrophic nutrient load to Utah Lake. Further, it is likely that the actual deposition loading is much higher than 8 tons per 8 months thus indicating that deposition alone adds a eutrophic phosphorus loading to the lake. Since conditions are similar in much of the Great Basin and other areas of Western United States, this seems to be a very significant finding relative to nutrient evaluation and feasible management scenarios. The results also indicate that one might expect to see more cyanobacteria blooms (Harmful Algal Blooms) in shallow ponds in this area if atmospheric deposition is the main source of nutrients, since N to P ratios are low and thus more situations arise where a shortage of ionic nitrogen favors these nitrogen-fixing cyanobacteria.

Harmful algal blooms (HABs, or "red tides") of the brevetoxin-producing dinoflagellate Karenia brevis occur periodically along Florida's Gulf coast. Mass mortalities of marine birds have long been associated with these blooms, yet there are few data documenting the accumulation of brevetoxins (PbTx) in the tissues of birds. Post-mortem evaluations were performed on 185 birds representing 22 species collected from October 2001 through May 2006 during red tide and non-red tide events to quantify their body burdens of brevetoxins. A variety of tissues and organs were selected for brevetoxin analysis including blood, brain, heart, fat, stomach or gut contents, intestinal contents or digestive tract, muscle, lung, liver or viscera, kidney, gonads, gallbladder and spleen. Brevetoxin levels in avian tissues ranged from K. brevis which may amass in various tissues of the body. As a consequence, the birds may exhibit acute brevetoxicosis during red tide events or show chronic accumulation effects during non-red tide events.