Algal Blooms
Algal blooms are rapid increases in the population of algae in aquatic ecosystems. These blooms can be caused by factors such as nutrient pollution, warm temperatures, and calm water conditions. While some algal blooms are harmless, others can produce toxins that are harmful to humans and wildlife, leading to water quality issues and ecological imbalances.
6 Key excerpts on "Algal Blooms"
eBook - ePubPlankton
A Guide to Their Ecology and Monitoring for Water Quality
- Iain M. Suthers, David Rissik, Anthony J. Richardson(Authors)
- 2019(Publication Date)
- CSIRO PUBLISHING(Publisher)
...Such blooms may be simply harmless transient pulses in response to episodic nutrient enrichment. Sometimes (generally through human activities), excessive nutrients entering a waterway can lead to excessive growth of phytoplankton, in turn shading important plants such as seagrass, or leading to excessive oxygen uptake in the waterway at night and causing fish kills – this is known as eutrophication (see Box 3.3). Eutrophication can affect human health, ecosystem function and fish resources, as well as the recreational amenity of beaches and embayments. Whatever factors affect their formation, the incidence of Algal Blooms may be increasing, as evident in the increased global distribution of paralytic shellfish poisoning (Hallegraeff et al. 2003). Increased connectivity of waterways across the globe as a result of ship-based transport has contributed to the spread of harmful algae and is a focus of management action (Box 3.2). Phytoplankton blooms have different effects depending on the species and their toxicity. Some may cause harmless water discolouration. Some may be non-toxic, but may be harmful to marine ecosystems (by either rotting and decreasing oxygen concentrations or by shading seagrass). Others may contain toxins that are transferred to filter-feeding bivalves (shellfish) such as mussels, oysters, scallops and clams, and thereby to fish, marine mammals, birds and humans. Phytoplankton blooms that have the potential to cause harm are commonly referred to as harmful Algal Blooms (HABs). Most blooms are simply harmless water discolourations. If Algal Blooms are sufficiently extensive, especially in enclosed or partially enclosed areas (such as coastal lagoons and estuaries), they can cause fish kills. This may be due to changes in dissolved oxygen availability (hypoxia) or by mechanical damage to fish gills...
eBook - ePubHandbook of Marine Microalgae
Biotechnology Advances
- Se-Kwon Kim(Author)
- 2015(Publication Date)
- Academic Press(Publisher)
...Algae belong to a wide range of habitats, such as fresh water and marine water, in deep oceans and in rocky shores. The planktonic and benthic algae can become important constituents of soil flora and can exist even in extreme conditions, such as in snow, sands/desert, or hot springs (temperatures above 80 °C). 3. Harmful Algal Blooms HABs are often linked to significant economic losses through massive fish killings, shellfish harvest closures, and the potential threat to humans from shellfish poisonings. To manage and mitigate the adverse impact of HABs, various strategies have been applied to control their outbreak and persistence, involving treatment with chemical agents such as copper sulfate (Anderson, 1997), flocculation of microalgae with clay (Sengco and Anderson, 2003), and other physical techniques. Although effective in controlling blooms, chemical and physical approaches are considered to be potentially dangerous because chemical agents could cause serious secondary pollution, and they could indiscriminately kill multiple organisms in the aquatic ecosystem, which may alter marine food webs and eventually impact natural fish communities (Jeong et al., 2008). Biological agents, including bacteria (Mayali and Azam, 2004), viruses (Nagasaki et al., 2004), protozoa (Jeong et al., 2008), and macrophytes (Nakai et al., 1999 ; Jin and Dong, 2003), are considered to be potential suppressors in controlling the outbreak and maintenance of Algal Blooms. Bacteria play an important role in nutrient regeneration and energy transformation in aquatic ecosystems (Azam et al., 1983). Therefore, algal–bacterial interactions are of particular interest; they have been considered to be potentially important regulators of algal growth and toxin production (Doucette et al., 1998)...
eBook - ePubGlobal Climate Change and Human Health
From Science to Practice
- Jay Lemery, Kim Knowlton, Cecilia Sorensen, Jay Lemery, Kim Knowlton, Cecilia Sorensen(Authors)
- 2021(Publication Date)
- Jossey-Bass(Publisher)
...CHAPTER 6 POTENTIAL RISKS FROM CYANOBACTERIAL AND Algal Blooms J. S. Metcalf and N. R. Souza KEY CONCEPTS Cyanobacteria and microalgae are essential ecosystem components providing the basis of food chains and food webs. They are capable of producing a range of toxic compounds of risk to human and animal health. Intoxications may increase with blooms that are geographically larger and more extensive and that can persist for longer periods of time. Climate change is considered to increase the likelihood of blooms forming. Introduction Cyanobacteria and algae are photosynthetic organisms that occur in a wide variety of environments, including marine and freshwaters. These essential primary producers are the basis for freshwater and marine food chains and webs. Within the microalgae, diatoms, dinoflagellates, euglenoids, haptophytes and cyanobacteria all have the potential to adversely affect water quality (Hallegraeff 2003). This is largely through the production of toxins, comprising both high and low molecular weight compounds. Some algal groups have the ability to cause fish kills through the blockage of gills, as spines on the physical structure of the algae become lodged in the gills, rendering fish unable to breathe (Bell 1961 ; Kent, White, and LaTrace 1995). Other adverse aspects of algae and cyanobacteria are a result of heterotrophic bacterial oxygenic respiration to decay dead or senescing mass populations of algae, microalgae, or cyanobacteria (i.e., scum) resulting in decreased oxygen concentrations in water, causing fish deaths due to suffocation (Barica 1978). Large concentrations of microalgae also have the ability to cause shading in waters (Barros et al. 2003), potentially affecting other aquatic organisms...
eBook - ePub- Daniel H. Chen, Daniel H. Chen(Authors)
- 2016(Publication Date)
- CRC Press(Publisher)
...First, in recent years, scientists are readily obtaining satellite images of large water bodies such as the Great Lakes, enhancing understanding of where near-surface blooms occur and enabling measurement of areal extent. Second, there is potential for development of in-lake continuous sensors for rapid analysis of chemical and biological aspects of blooms. Also, there is emerging availability of technologies to capture or divert suspended soil particles within rivers, offering promise of in-river installations to curb soil-associated nutrients from reaching vulnerable lake waters. Likewise, environmentally gentle technologies, such as pumps that circulate oxygen-rich water (Hudnell 2010; Nakano et al. 2001), can be targeted at shallow, stagnant, turbid, oxygen-poor waters such as Maumee Bay where Microcystis populations thrive. 3.4 IMPORTANCE OF SUSTAINABLE MONITORING OF Algal Blooms The global water supply crisis is pandemic, requiring a definite commitment toward sustainable water management and quality monitoring from all stakeholders (Nfodzo et al. 2013). Identifying environmental factors to develop pertinent water management strategies, including early warning systems, treatment of source waters, and best land management practices, is paramount to protect and sustain freshwater and brackish water resources. Cyanobacteria and their toxins are currently in the Drinking Water Contaminant Candidate List of the US Environmental Protection Agency (EPA 2012a). Methodologies for early detection or in situ and remote sensing of HAB outbreaks would provide a major mechanism for reducing or preventing exposures to the toxins released by HABs. Scientists are now challenged to monitor, assess, and even forecast the presence, severity, and toxicity of HAB events in an effort to minimize their impacts (Seltenrich 2014)...
eBook - ePubFreshwater Ecology
Concepts and Environmental Applications
- Walter K. Dodds(Author)
- 2002(Publication Date)
- Academic Press(Publisher)
...Aquifers that are eutrophic because of high organic carbon input could lack a complex invertebrate community due to anoxic conditions, so trophic state may correlate to biological characteristics. WHY IS NUTRIENT POLLUTION RESULTING IN Algal Blooms IN LAKES IMPORTANT? The stimulation of Algal Blooms and creation of anoxic hypolimnia in lakes leads to many problems. As mentioned in Chapter 1, the monetary value of property on a lake can decrease with eutrophication. Algal Blooms are not aesthetically pleasing; they look bad and smell worse. The probability of objectionable Algal Blooms increases with greater cultural eu-trophication (Hart et al., 1999). Taste and odor problems become more acute as lakes become more eutrophic (Fig. 17.4). Both planktonic and attached cyanobacteria contribute to taste and odor problems (Sugiura et al., 1998). These problems related to eutrophication are difficult to solve with standard water purification methods, leading to greatly increased costs for supplying potable water (Wnorowski, 1992). To make matters worse, Algal Blooms may be toxic; cyanobacteria and dinoflagellates produce neu-rotoxins and hepatotoxins (see Sidebar 8.2). Toxin production may be stimulated by phosphorus pollution (Jacoby et al., 2000) FIGURE 17.4 Relationship of trophic state index (determined by the method of Carlson, 1977 ; Fig. 17.2B) and water odor of surface (A) and hypolimnetic (B) samples from six Kansas reservoirs. Water odor was ranked by human testers, with a higher rank indicating lower drinking water quality (reproduced with permission from Arruda and Fromm, 1989). Fish kills related to anoxic events are common symptoms of eutroph-ication (see Sidebar 11.2). With a series of cloudy days or under an ice cover in a eutrophic lake, fish may die. Cold-water fisheries can be established in deep lakes with cool hypolimnia. If the hypolimnion is anoxic, heat-intolerant fish have no refuge from high temperatures in the epi-limnion...
eBook - ePubMonitoring Bathing Waters
A Practical Guide to the Design and Implementation of Assessments and Monitoring Programmes
- Jamie Bartram, Gareth Rees, Jamie Bartram, Gareth Rees(Authors)
- 1999(Publication Date)
- CRC Press(Publisher)
...Chapter 10 * CYANOBACTERIA AND ALGAE In freshwaters, scum formation by cyanobacterial phytoplankton is of concern to human health. Freshwater algae proliferate quite intensively in eutrophic waters and may contain irritative or toxic substances. Nevertheless, incidents of impairments of human or animal health caused by algae are rarely reported. One example was the closure of a number of bathing sites in Sweden because of mass occurrences of the flagellate Gonyostomum semen which causes skin irritations and allergies (Cronberg et al., 1988). Incidents attributed to cyanobacteria are far more numerous and, in most cases, have been caused by species of cyanobacteria that may accumulate to surface scums of extremely high cell density. As a result, the toxins they may contain (“cyanotoxins”) reach concentrations likely to cause health effects. Surface aggregations of planktonic cyanobacteria occur because of their capability to regulate their buoyancy, enabling them to seek water depths with conditions optimal for their growth. Regulation of buoyancy is a slow process, and cells adapted to ambient turbulence may take several days to adapt their buoyancy when conditions change (e.g. turbulence is reduced). Thus, cells or colonies may show excessive buoyancy and accumulate at the water surface. Light winds drive such accumulations to leeward shores and bays, where the resulting scums become thick. In extreme cases, such agglomerations may become very dense, with cells frequently concentrated by a factor of 1,000 or more, eventually reaching in some cases, one million-fold concentrations with a gelatinous consistency. More frequently, surface accumulations are seen as streaks or slimy scums that may look like blue-green paint or jelly. Such situations can change rapidly within hours with changes in the wind direction...
