9/22/2023 0 Comments Algal bloom red tide algae![]() In a mini bloom, this fast growth benefits the whole ecosystem by providing food and nutrients for other organisms. Once the nutrient is present in the water, the algae begin to grow at a much faster rate than usual. These blooms are recognizable by large blades of algae that may wash up onto the shoreline. Blooms may also consist of macroalgal (non- phytoplanktonic) species. Bright green blooms in freshwater systems are frequently a result of cyanobacteria (colloquially known as "blue-green algae") such as Microcystis. Depending on the organism, its pigments, and the depth in the water column, algal blooms can be green, red, brown, golden, and purple. The photosynthetic pigments in the algal cells, like chlorophyll and photoprotective pigments, determine the color of the algal bloom. Īlgal blooms, especially large algal bloom events, can reduce the transparency of the water and can discolor the water. Along coastal regions and in freshwater systems, agricultural, city, and sewage runoff can cause algal blooms. In the open ocean and along coastlines, upwelling from both winds and topographical ocean floor features can draw nutrients to the photic, or sunlit zone of the ocean. There are several mechanisms for the addition of these nutrients in water. This growth-limiting nutrient is typically nitrogen or phosphorus, but can also be iron, vitamins, or amino acids. īlooms are the result of a nutrient needed by the particular algae being introduced to the local aquatic system. For example, definitions of blooms have included when the concentration of chlorophyll exceeds 100 ug/L, when the concentration of chlorophyll exceeds 5 ug/L, when the species considered to be blooming exceeds concentrations of 1000 cells/mL, and when the algae species concentration simply deviates from its normal growth. ![]() ![]() Because there is no scientific consensus, blooms can be characterized and quantified in several ways: measurements of new algal biomass, the concentration of photosynthetic pigment, quantification of the bloom's negative effect, or relative concentration of the algae compared to the rest of the microbial community. Since algae is a broad term including organisms of widely varying sizes, growth rates, and nutrient requirements, there is no officially recognized threshold level as to what is defined as a bloom. The term algal bloom is defined inconsistently depending on the scientific field and can range from a "minibloom" of harmless algae to a large, harmful bloom event. The process of the oversupply of nutrients leading to algae growth and oxygen depletion is called eutrophication.Īlgal and bacterial blooms have persistently contributed to mass extinctions driven by global warming in the geologic past, such as during the end-Permian extinction driven by Siberian Traps volcanism and the biotic recovery following the mass extinction. Blooms that can injure animals or the ecology, especially those blooms where toxins are secreted by the algae, are usually called " harmful algal blooms" (HAB), and can lead to fish die-offs, cities cutting off water to residents, or states having to close fisheries. An algal bloom affects the whole ecosystem.Ĭonsequences range from the benign feeding of higher trophic levels to more harmful effects like blocking sunlight from reaching other organisms, causing a depletion of oxygen levels in the water, and, depending on the organism, secreting toxins into the water. Īlgal blooms are the result of a nutrient, like nitrogen or phosphorus from various sources (for example fertilizer runoff or other forms of nutrient pollution), entering the aquatic system and causing excessive growth of algae. An example of a macroscopic algal bloom is a kelp forest. Algal bloom commonly refers to the rapid growth of microscopic unicellular algae, not macroscopic algae. The term algae encompasses many types of aquatic photosynthetic organisms, both macroscopic multicellular organisms like seaweed and microscopic unicellular organisms like cyanobacteria. It is often recognized by the discoloration in the water from the algae's pigments. A very large algae bloom in Lake Erie, North America, which can be seen from space.Īn algal bloom or algae bloom is a rapid increase or accumulation in the population of algae in freshwater or marine water systems.
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