**11. Unhealthy coral reefs**

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

makes them susceptible to infiltration by many pathogens. Some example includes *Gambierdiscus toxicus,* a benthic Dinoflagellate finds way on the dead corals, releasing ciguatoxin which is responsible for causing Ciguatera Fish Poisoning (CFP) [65]. Thus if contaminations affects water quality and coral reefs are affected than *G.toxicus* is likely to bloom, causing widespread release of ciguatoxin. The loads for food, water and fuel continue to increasing to support this ever increase human population. These changes in climate and nutrients are contributing to eutrophication and expanding global footprint of harmful algal blooms (HABs) worldwide. It is now clearly known that the global expansion of HABs is continuing, with increasing abundance, frequency, and geographic extent of HABs, with new species being documented in some new areas [48].

### **12. Influences of climate change**

Inconsistency in climate equally contributes to the apparent increases of HAB, therefore effects of climate change needs to be seriously understood alongside with development of the risk assessments and effective management of HABs. This chapter considers the effects of past, present and future climatic variability on HABs. The one thing we are sure regarding climate is that it is changing and for all time. With complex nature of climate, temperature is only one of many factors to be considered. Each biological life has a temperature window within which it can survive. The direct upshot of global warming with elevated water temperature may affect seasonal composition of the phytoplankton, including changes in seasonal succession, and the position of biogeographic boundaries. There is still insufficient evidence to resolve this problem.

There has been a considerable boost in phytoplankton biomass over the last decades in definite regions of the North-East Atlantic and North Sea, particularly more in the winter months. Also in the North Sea a significant increase in phytoplankton biomass has been found in both intensely anthropogenically-impacted coastal waters and the comparatively less-affected open North Sea. Considerably decreasing trends in nutrient concentrations suggest that these changes are not being driven by nutrient enrichment. The increase in biomass appears to be associated to warmer temperatures and evidence that the waters are also becoming less turbid, thus allowing the normally light-limited coastal phytoplankton to more effectively utilize lower concentrations of nutrients [66]. A study of entity phytoplankton groups has shown increased temperatures were associated with an earlier timing of the highest abundance of some Dinoflagellate species. In disparity, the diatom species examined have not shown such a shift [67]. Coastal time series of HAB phytoplankton are much shorter in extent. Most began in the 1990s various HAB species are flagellates, life forms that are favored by augmented temperatures though direct influences on cellular processes and circuitously through increased stability of the water column. An increase in sea surface temperatures may facilitate the range expansion of HAB species [48].

Eventually elevated and extreme bursts of precipitation be able to increase the amount of runoff from the land and number of floods also. This may enhancing stratification in estuaries and sea lochs favoring the growth of Dinoflagellates. Some humic material during these events may increase the absorption of available nutrients which may promote growth of phytoplankton [48]. It is well-known that changes in temperature, pH, light, nutrient supply and water movement affects algal bloom dynamics as well as their toxicity. Climate change show predictable impact on these variables to differing extents in dissimilar regions [48, 68]. Also a lower pH has the potential to influence the speciation of

**45**

*Considering Harmful Algal Blooms*

*Pedobacter* sp. *(*MaI11–5*)*

**Table 1.**

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

*Rhizobium* sp. Ambazari Lake,

*Myoviridae* Shallow lowland

*Cyclopoid copepods* Lake Ringsjon

*Trichaptum abietinum* The soil of

*Lophariaspadicea* The soil of

Nagpur India

Lake and water treatment plant

dam reservoir in Central Poland

southern Sweden

bamboo forests (Hangzhou, China)

bamboo forests (Hangzhou, China)

*Halobacillus sp.* Bioflocculation *Microcystis* 

nutrients for example nitrogen, phosphate and silica which accounts important for phytoplankton growth [69]. Increased HAB events have a direct detrimental effect on ecosystems and they can often have a direct commercial impact on aquaculture, depending on the type of HAB. Causing economic impact which will be severe as in rural areas impacts to the aquaculture industry will have a disproportionate impact on the economy of the local area. Considering all known aspects about HABs some attempts were made for removal of harmful algal

*Ankistrodesmus falcatus* Freshwater Bio-flocculation *Chlorella vulgaris* [44] *Scenedesmu sobliquus* Freshwater Bio-flocculation *Chlorella vulgaris* [44]

**Predator/Killer Habitat Mode of action Major host Reference**

Mucous-like secretion from cyanobacteria for self-defense

Species specific interaction

Lysis *Microcystis* 

Grazing *Anabaena,* 

Direct attack *Microcystis* 

Direct attack *Microcystis* 

*aeruginosa*

*aeruginosa*

*Microcystis aeruginosa*

*Microcystis*and Planktothrix species

*aerug*i*nosa, Microcystis flosaquae Oocystisborgei*

*aerug*i*nosa*

*M. aeruginosa* [7]

[30]

[33]

[5]

[41]

[43]

[43]

Climate change is negatively impacting health and leading to harmful transformation in aquatic ecosystems [70, 71]. Rising temperatures leading to acidification and oxygenation which alters basal metabolic functioning and species distributions along with the timing of essential biological activities [72, 73]. Due to acidification physiological stress found to increase among sensitive marine species along with growth inhibition of calcifying organisms. As ocean deoxygenation alters the distribution and survival of aquatic organisms [74, 75]. This further alters structure and functioning of marine and freshwater ecosystems. Temperatures rise have predictable impact on the occurrence and concentration of marine diseases, habitat loss, including ocean deoxygenation inviting various environmental contaminants [76, 77]. As increased level of carbon dioxide in atmosphere has generated decreased value of pH in surface waters, offshore, coastal and upwelling marine

blooms with help of microorganisms as shown briefly in **Table 1**.

**13. Manifestation of climate change and HABs**

*Removal of harmful algal blooms by means of some microorganisms.*

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


#### **Table 1.**

*Environmental Issues and Sustainable Development*

documented in some new areas [48].

**12. Influences of climate change**

evidence to resolve this problem.

the range expansion of HAB species [48].

makes them susceptible to infiltration by many pathogens. Some example includes *Gambierdiscus toxicus,* a benthic Dinoflagellate finds way on the dead corals, releasing ciguatoxin which is responsible for causing Ciguatera Fish Poisoning (CFP) [65]. Thus if contaminations affects water quality and coral reefs are affected than *G.toxicus* is likely to bloom, causing widespread release of ciguatoxin. The loads for food, water and fuel continue to increasing to support this ever increase human population. These changes in climate and nutrients are contributing to eutrophication and expanding global footprint of harmful algal blooms (HABs) worldwide. It is now clearly known that the global expansion of HABs is continuing, with increasing abundance, frequency, and geographic extent of HABs, with new species being

Inconsistency in climate equally contributes to the apparent increases of HAB, therefore effects of climate change needs to be seriously understood alongside with development of the risk assessments and effective management of HABs. This chapter considers the effects of past, present and future climatic variability on HABs. The one thing we are sure regarding climate is that it is changing and for all time. With complex nature of climate, temperature is only one of many factors to be considered. Each biological life has a temperature window within which it can survive. The direct upshot of global warming with elevated water temperature may affect seasonal composition of the phytoplankton, including changes in seasonal succession, and the position of biogeographic boundaries. There is still insufficient

There has been a considerable boost in phytoplankton biomass over the last decades in definite regions of the North-East Atlantic and North Sea, particularly more in the winter months. Also in the North Sea a significant increase in phytoplankton biomass has been found in both intensely anthropogenically-impacted coastal waters and the comparatively less-affected open North Sea. Considerably decreasing trends in nutrient concentrations suggest that these changes are not being driven by nutrient enrichment. The increase in biomass appears to be associated to warmer temperatures and evidence that the waters are also becoming less turbid, thus allowing the normally light-limited coastal phytoplankton to more effectively utilize lower concentrations of nutrients [66]. A study of entity phytoplankton groups has shown increased temperatures were associated with an earlier timing of the highest abundance of some Dinoflagellate species. In disparity, the diatom species examined have not shown such a shift [67]. Coastal time series of HAB phytoplankton are much shorter in extent. Most began in the 1990s various HAB species are flagellates, life forms that are favored by augmented temperatures though direct influences on cellular processes and circuitously through increased stability of the water column. An increase in sea surface temperatures may facilitate

Eventually elevated and extreme bursts of precipitation be able to increase the amount of runoff from the land and number of floods also. This may enhancing stratification in estuaries and sea lochs favoring the growth of Dinoflagellates. Some humic material during these events may increase the absorption of available nutrients which may promote growth of phytoplankton [48]. It is well-known that changes in temperature, pH, light, nutrient supply and water movement affects algal bloom dynamics as well as their toxicity. Climate change show predictable impact on these variables to differing extents in dissimilar regions [48, 68]. Also a lower pH has the potential to influence the speciation of

**44**

*Removal of harmful algal blooms by means of some microorganisms.*

nutrients for example nitrogen, phosphate and silica which accounts important for phytoplankton growth [69]. Increased HAB events have a direct detrimental effect on ecosystems and they can often have a direct commercial impact on aquaculture, depending on the type of HAB. Causing economic impact which will be severe as in rural areas impacts to the aquaculture industry will have a disproportionate impact on the economy of the local area. Considering all known aspects about HABs some attempts were made for removal of harmful algal blooms with help of microorganisms as shown briefly in **Table 1**.
