Toxic algal blooms in our waterbodies which causes, Slides of Marine Science and Biology

Download Toxic algal blooms in our waterbodies which causes and more Slides Marine Science and Biology in PDF only on Docsity! Effects of Toxic Algal Blooms Presentation taken by 1. Muzammil Siddiqui – BFS-2020-01-50 Introduction • An algal blooms is the rapid increase in the population of algae in various aquatic ecosystems. Blooms which produce toxins are called ‘Toxic Algal Blooms’. There are many species which are capable of producing biologically active secondary metabolites, which are highly harmful. • They are recognised by the discoloration in water due to the algae’s pigments. Blooms can last from a few days to a month. • Natural causes, such as river flood or upwelling in the seas, are responsible. But man-made activities are also causing it due to terrestrial run-off, eutrophication, sewage wastes, etc. • The toxins belong to various chemical classes; cyclic peptides, alkaloides, lipopolysaccharides, among others. • Various genera of dinoflagellates, cyanobacteria and diatoms form such blooms. 2. Hepatotoxin • Nodularin and microcystin are common hepatotoxins from algae. • They damage hepatic cells. They injure key subcellular structures, such as mitochondria and plasma membrane. • Together with ROS, they act as oxidising species within hepatocyte to cause oxidative stress by creating imbalance between pro oxidants and anti oxidants. • They are taken up to the liver cells through active transport via bile acids by the multi-specific anion transporters. Thus, it causes bloodpools in liver and causes 100% weight gain for liver and causes massive liver haemorrhage. • They also bind irreversibly to macromolecules such as lipids and proteins. Thus they inactivate key enzymes. 3. Lipopolysaccharides • Lipid + Polysaccharide • It activates innate immune system which synthesises pro-inflammatory factors. They, then give rise to inflammation in tissues. • They are potent activator of macrophages and can result in the production of cytokine and growth factors. So, they have immuno-endocrinological effect. • They are known as irritant toxins and are found in the outer membrane of cell walls of Gram-negative bacteria. • It is generally the fatty acid component of the molecule which elicits an irritant allergic response in animals and humans. 4. Saxitoxins • Saxitoxins are heterocyclic guanidine neurotoxins. Shellfish poisoning is due to them mainly. • Blooms releasing them have often resulted in mass deaths of fish and livestock, and has polluted water resources. • It blocks the passage of nerve impulse by blocking sodium ion entry into nerves. • The Paralytic Shellfish Poisoning(PSP) symptoms begin within 30 min of ingestion with tingling sensation of lips, tongue and throat which becomes total numbness soon. Vomiting and diarrhoea occurs. • In case of acute poisoning, numbness spreads to neck and extremities. So, muscular weakness and loss of motor coordination happens. 7. Anatoxins • Anatoxins are neurotoxic alkaloids made exclusively made by Anabena, Aphanizomenon and Planktothrix. • It is bi-cyclic secondary amine which mimics acetylcholine and binds to acetylcholine receptor at the axon terminal. Its binding is irreversible, so the sodium channel is locked open. It becomes over-stimulate, fatigued and eventually paralysed. • It results in lack of oxygen to the brain, subsequent convulsions and thereafter, death. • It also is cholinestrase inhibitor. Cholinestrase degrades acetylcholine so that overstimulation is prevented, but anatoxin presence facilitates overstimulation. 8. Contactdermatitins • In some cases, a skin reaction may develop by touching fish or fish residue. Allergic reactions of varying severity have been reported from number of cases. • Cyanobacterial pigment, cyanophycin has been found responsible. • Skin irritation were frequent. Ocular and nasal irritation happened to swimmers exposed to Oscollatoriaceae. • Sensitive individuals may react severely. Tongue swelling, rapid heart rate can also happen.