Algal Blooms
Algal blooms occur when overgrowth of colonies of algae occur in a region of water. Not all algal blooms are toxic, as only a small percentage of algae produce biotoxins. Conditions needed for algal blooms are sunlight, slow-moving water, and nutrients such as nitrogen and phosphorus. The United States Environmental Protection Agency (EPA) notes that sources of nitrogen and phosphorus nutrient pollution in waterways can be attributed to agriculture water runoff, stormwater, wastewater, fossil fuel burning, fertilizers, pet waste, and certain soaps and detergents.12
Harmful Algal Blooms
Harmful algal blooms (HABs) are algae blooms that contain species of algae that produce biotoxins or harmfully affect other living organisms such as people, shellfish, fish, marine mammals, and birds. Every coastal state in the United States has reported HABs. HABs can occur in fresh and saltwater environments and are commonly referred to as “red tides,” as some HABs can turn waters red brown in color (Figure 3). However, water discoloration can appear in a variety of colors, or not at all, based on the species of phytoplankton, cyanobacteria, algae, dinoflagellates, and diatoms present in a colony. The National Oceanic and Atmospheric Administration (NOAA) works with regional agencies to monitor, track, and forecast HABs across the United States.13
Figure 3: Karenia brevis “Red Tide”, La Jolla, California.14
Climate change is implicated as a major contributor for the proliferation of a variety of harmful toxic algae blooms along the California Coast and internationally. Increased water temperatures allow toxic algae to thrive across a wider range of area. Shipping has inadvertently spread toxic algae and phytoplankton to new ecosystems on a global scale. Azaspiracid Shellfish Poisoning (AZP) originated in Europe in 1995, is now found in Asia, and is beginning to emerge in the United States.15 Overfishing of populations has thrown off the balance in some ecosystems which allowed other species to thrive. Increased aquaculture to meet the global demand for seafood has given opportunities for some parasites and toxic algae to proliferate and contaminate water sources.16
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