**8. Intention for formation HABs**

There is no conclusive report available for the causes of HABs, unfortunately, the causes of HABs are uncertain to date. Though, some of the factor which are thought

accountable for causing HABs are briefly described here. An attempt made in **Figure 2** to show interface between some environmental events and microorganism with HABs.

Coastal contamination from a variety of source including household and industrialized effluents is most imperative factors in the growth of HABs. The majority times eutrophication by nutrient enrichment outcomes as blooms of algal growth, from which several are toxic to humans and as well as marine organisms. Contemporary research suggests that eutrophication and climate change are two most important processes that help for proliferation and expansion of Cyanobacterial blooms [51]. It is also important to know that nutrient enrichment can modify the species framework of ecological system [52]. Also inhabitant biota gets displace as the surroundings becomes enriched with nitrates and phosphates [53]. As the coastal eutrophication and improved offshore nutrient concentration taking place offshore due to vertical integration have been linked with the expansion of large biomass, eventually foremost to harmful impacts on ecosystems, human health and fisheries resources. At the same time if eutrophication increases nitrogen and phosphorus inputs, the ratio of these nutrients to silicates becomes very high. This favors non-diatom species including several harmful species. Additionally, it is believed that high concentration of phosphorus, and a low total nitrogen to total phosphorus (TN:TP) TN: TP ratio, are favorable for the production of Cyanobacteria blooms. Recent studies, represents that Cyanobacteria usually dominates in lakes with low TN/TP ratio and are rare in lakes with high TN:TP ratios [54, 55]. Cyanobacteria dominate in lakes where TN:TP mass ratio is below 29:1.

Nutrients consequent from anthropogenic activities have resulted in the increase in HAB account also at some places, unusual heavy rains have resulted in blooms of *L. polyedrum* owing to nutrient rich runoff into the coastal waters. Blooms of Dinoflagellate *Pfiesteria* are found in estuaries of middle and southern Atlantic coasts. The main factors controlling cycles of Dinoflagellates, includes water salinity, pH, nutrients and temperature to one side from these, studies in North California have illustrated that they thrive well near sources of organic phosphates released from sewage treatment plants [56, 57], talk about some Coastal and Continental Shelf Zone (CCSZ) and also Open Oceanic Zone (OOZ) of the Indian segment, were algal blooms can develop only when the calculated rate of biomass increase exceeds the rate of loss generally the grazing and sedimentation rates. As once a bloom develops, it persist for a long epoch under low growth if the rate of loss is small. Still the interactive effects of future eutrophication and changed climate on harmful algal blooms are versatile, and according to current knowledge such processes are likely to enhance the magnitude and frequency of these events. Temperature rise and precipitation associated with climate change falls into broad ranges, also qualms exist in their upshot stratification as North Sea flushing species like *Dinoflagellates* and *Raphidophytes* increase considerably. Some species of *D. acuminata, P. minimum, F. japonica and C. antique* are observed in this region frequently, representing an increase in HAB [58]. Discrepancy in temperature affects circulation patterns, and causes variation in the physical structure of water column that supports occurrence of HABs [59].

#### **9. HAB and impacts**

It is very important to consider harmful Cyanobacterial blooms (cHABs) as they are have noteworthy socioeconomic and environmental outlay, by having impact on water quality, drinking water, agriculture, fisheries, tourism, food web pliability, habitats, along with anoxia and fish kills [60]. Also high biomass accumulation

**43**

*Considering Harmful Algal Blooms*

frequent coughing.

**10. Oceans upwelling**

the southwest coast of India.

**11. Unhealthy coral reefs**

*DOI: http://dx.doi.org/10.5772/intechopen.94771*

and degradation of algal blooms possibly leads to depletion of dissolved oxygen, light attenuation and clogging of fish gills, resulting in fish kills and thousands of other marine life, as direct degradation of the ecosystem [61]. The most critical impacts of algal blooms are on human being health, toxins, produce HABs cause acute and chronic health effects in mammals including humans. For example toxins produced during harmful algal blooms are some of the natural toxic substances directly killing fish/shellfish and other marine life also accumulating in fish and sea food leading to human poisoning after ingestion of contaminated sea food [62]. Sometimes toxins produced during algal blooms may not found toxic to fish and other marine existence. On the other hand, they accumulate in fish and mollusks and move up the food chain and showing shocking impact on humans. Therefore aquatic toxin diseases are categorized into two types as. Shellfish carry toxins that facilitate to paralytic, neurotoxic, diarrheic and amnesic shellfish poisoning. Next type of poisoning is through mollusks tend that occurs during algal blooms. Fish takes toxin that escort to ciguatera and tetrodotoxin poisoning. Poisoning of fish is found more localized and also associated with parts of specific reefs and fishes. Sometimes bloom occurrence of species of Dinoflagellate *Pfiesteria* in estuaries of some middle and Southern Atlantic coast hint that anthropogenic stress on marine environment has caused fish kills and related health hazards in humans also [56]. Species of *Pfiesteria* are also known to cause lesions in fishes. Additionally, we humans can be exposed to toxins that are directly released into water and air. This occur as expected, cell disruption caused through human activities including water treatment. As known such phenomenon frequently occurs in the Gulf of Mexico where residents and beach goers are exposed to toxins through seas spray. Toxins can then be inhaled and lodged in the nose and throat and can down into the lungs. General symptoms associated with this are irritation in respiratory system and

Ascending motions caused due to oceanic circulation is well-known as 'Upwelling', which bring into being some affects to the environmental conditions, beside increases the nutrient content in euphotic zone thus increasing the productivity of the province. Noteworthy findings [63] suggested various factors inducing upwelling off the south west coast of India [64], also have worked to come across the occurrence of the upwelling route along the Dakshina Kannada Coast of India and description shows that upwelling was found to occur from month of March to October along the coast this could be one of the factor for occurrence HABs along

Unhealthy coral reefs play a very imperative role in the formation of blooms, as healthy coral reefs are free of external algal growth [65]. Unhealthy conditions/ death of corals is generally for the reason that pollution of oil or depositions of sediments leading to encrustations of corals by calcareous materials and algae, plus may in turn lead to the death of zooplanktons and some higher fishes in the food web. Also endolithic algal bloom can cause disease named White Syndrome (WS), entailing of distinct lines between healthy and strong corals and dead ones. Such endolithic algae, including *Ostreobium* Spp. penetrate the coral tissues of tabular *Acropora* Spp., in turn affecting the corals with micro-lessions, which

#### *Considering Harmful Algal Blooms DOI: http://dx.doi.org/10.5772/intechopen.94771*

*Environmental Issues and Sustainable Development*

accountable for causing HABs are briefly described here. An attempt made in **Figure 2** to show interface between some environmental events and microorganism with HABs. Coastal contamination from a variety of source including household and industrialized effluents is most imperative factors in the growth of HABs. The majority times eutrophication by nutrient enrichment outcomes as blooms of algal growth, from which several are toxic to humans and as well as marine organisms. Contemporary research suggests that eutrophication and climate change are two most important processes that help for proliferation and expansion of Cyanobacterial blooms [51]. It is also important to know that nutrient enrichment can modify the species framework of ecological system [52]. Also inhabitant biota gets displace as the surroundings becomes enriched with nitrates and phosphates [53]. As the coastal eutrophication and improved offshore nutrient concentration taking place offshore due to vertical integration have been linked with the expansion of large biomass, eventually foremost to harmful impacts on ecosystems, human health and fisheries resources. At the same time if eutrophication increases nitrogen and phosphorus inputs, the ratio of these nutrients to silicates becomes very high. This favors non-diatom species including several harmful species. Additionally, it is believed that high concentration of phosphorus, and a low total nitrogen to total phosphorus (TN:TP) TN: TP ratio, are favorable for the production of Cyanobacteria blooms. Recent studies, represents that Cyanobacteria usually dominates in lakes with low TN/TP ratio and are rare in lakes with high TN:TP ratios [54, 55]. Cyanobacteria dominate in lakes where TN:TP mass ratio is

Nutrients consequent from anthropogenic activities have resulted in the increase in HAB account also at some places, unusual heavy rains have resulted in blooms of *L. polyedrum* owing to nutrient rich runoff into the coastal waters. Blooms of Dinoflagellate *Pfiesteria* are found in estuaries of middle and southern Atlantic coasts. The main factors controlling cycles of Dinoflagellates, includes water salinity, pH, nutrients and temperature to one side from these, studies in North California have illustrated that they thrive well near sources of organic phosphates released from sewage treatment plants [56, 57], talk about some Coastal and Continental Shelf Zone (CCSZ) and also Open Oceanic Zone (OOZ) of the Indian segment, were algal blooms can develop only when the calculated rate of biomass increase exceeds the rate of loss generally the grazing and sedimentation rates. As once a bloom develops, it persist for a long epoch under low growth if the rate of loss is small. Still the interactive effects of future eutrophication and changed climate on harmful algal blooms are versatile, and according to current knowledge such processes are likely to enhance the magnitude and frequency of these events. Temperature rise and precipitation associated with climate change falls into broad ranges, also qualms exist in their upshot stratification as North Sea flushing species like *Dinoflagellates* and *Raphidophytes* increase considerably. Some species of *D. acuminata, P. minimum, F. japonica and C. antique* are observed in this region frequently, representing an increase in HAB [58]. Discrepancy in temperature affects circulation patterns, and causes variation in the physical structure of water

It is very important to consider harmful Cyanobacterial blooms (cHABs) as they are have noteworthy socioeconomic and environmental outlay, by having impact on water quality, drinking water, agriculture, fisheries, tourism, food web pliability, habitats, along with anoxia and fish kills [60]. Also high biomass accumulation

**42**

column that supports occurrence of HABs [59].

**9. HAB and impacts**

below 29:1.

and degradation of algal blooms possibly leads to depletion of dissolved oxygen, light attenuation and clogging of fish gills, resulting in fish kills and thousands of other marine life, as direct degradation of the ecosystem [61]. The most critical impacts of algal blooms are on human being health, toxins, produce HABs cause acute and chronic health effects in mammals including humans. For example toxins produced during harmful algal blooms are some of the natural toxic substances directly killing fish/shellfish and other marine life also accumulating in fish and sea food leading to human poisoning after ingestion of contaminated sea food [62]. Sometimes toxins produced during algal blooms may not found toxic to fish and other marine existence. On the other hand, they accumulate in fish and mollusks and move up the food chain and showing shocking impact on humans. Therefore aquatic toxin diseases are categorized into two types as. Shellfish carry toxins that facilitate to paralytic, neurotoxic, diarrheic and amnesic shellfish poisoning. Next type of poisoning is through mollusks tend that occurs during algal blooms. Fish takes toxin that escort to ciguatera and tetrodotoxin poisoning. Poisoning of fish is found more localized and also associated with parts of specific reefs and fishes. Sometimes bloom occurrence of species of Dinoflagellate *Pfiesteria* in estuaries of some middle and Southern Atlantic coast hint that anthropogenic stress on marine environment has caused fish kills and related health hazards in humans also [56]. Species of *Pfiesteria* are also known to cause lesions in fishes. Additionally, we humans can be exposed to toxins that are directly released into water and air. This occur as expected, cell disruption caused through human activities including water treatment. As known such phenomenon frequently occurs in the Gulf of Mexico where residents and beach goers are exposed to toxins through seas spray. Toxins can then be inhaled and lodged in the nose and throat and can down into the lungs. General symptoms associated with this are irritation in respiratory system and frequent coughing.
