Question- Karenia brevis was sometimes seen in the news. It is related to-
(a) It is a light pollution identified throughout the globe recently
(b) It is a new plant species discovered in Amazon emitting CO2 on large scale
(c) It is an algae that cause red tide in Florida coast
(d) It is a new frog specis discovered in eastern ghats
Ans. (c)
Related Facts-
- In Florida, red tide is caused by the accumulation of Karenia brevis, a type of single celled organism called a dinoflagellate.
- Red tides occur around the world and are not all caused by the same species, nor are they always red.
- In fact, most dinoflagellates are harmless.
- Though some, including K. brevis, produce neurotoxins that can cause respiratory problems in humans and attack the central nervous systems of fish and other wildlife.
- Many scientists refer to blooms of K. brevis as harmful algal blooms (HABs) due to the impacts they can have on the environment, humans, and our coastal economies.
- Red tides are not always red.
- When K. brevis blooms in high enough concentrations, the water can appear red, brown, rusty orange or green. Sometimes, the hue of the water will remain normal, even during a bloom.
- Red tide blooms in Florida begin 10-40 miles offshore in the bottom waters of the Gulf of Mexico, where K. brevis is almost always present at low and harmless concentrations.
- K. brevis cells that hang out at the bottom are brought to the surface by a phenomenon known as upwelling, a process in which deep, cold and nutrient-rich water rises to the surface.
- K. brevis, like all algae, requires three things to grow and survive:
-Optimal light
-Temperature
-Nutrients, specifically nitrogen and phosphorus.
- The sources of these nutrients vary among the offshore, nearshore, and estuarine environment.
- Various algae species cause red tides all around the globe.
- But, K. brevis is found almost almost exclusively in the Gulf of Mexico.
- Because red tides are transported by currents, some, including last year’s bloom, have even been carried by the Gulf Stream current into the Atlantic Ocean.
- K. brevis is considered harmful because it produces a variety of natural toxins, the most important of which are the neurotoxic brevetoxins.
- Through inhalation, direct contact or ingestion, these toxins, in high enough concentration, can harm and kill fish, birds, and marine mammals.
- The last red tide resulted in serious impacts to fish, marine mammals, marine birds, residents and coastal businesses.
- These types of impacts are typical during severe red tide events. However, more fish have died during the most recent red tide in Lee and Charlotte counties compared to past severe red tide events.
- “Brevetoxin is very deadly to fish of all life stages. Invertebrates are generally less affected during red tides, but studies have shown that bivalve larvae have a dramatically reduced survival rate when exposed to K. brevis, and this could be the case for other species of invertebrates as well.’
By- Yogesh Pratap Singh
Reference- https://www.floridamuseum.ufl.edu/earth-systems/blog/red-tide-karenia-brevis/.