Harmful Algal Blooms (HABs)- An Overview

Introduction:

Some algae are harmful to animals and people that produce toxins that can cause serious illness. When there is a rapid growth of algae accumulates in the water environment, it is called a harmful algal bloom. They occur in marine and freshwater environments and are often associated with symptoms such as sneezing, coughing, watery eyes, or itchy throat.

What Is Algal Bloom?

Algal bloom or water bloom, or marine bloom is the sudden increase in the population of algae in water bodies. They usually occur in marine as well as freshwater environments. Blooms that can harm ecology or animals are called harmful algal blooms (HABs).

What Does a Harmful Algal Bloom Look Like?

Algal blooms contain toxins whose amount changes over time. Harmful algal blooms have various colors, such as green, blue, blue-green, white, brown, purple, or red. They look like scum in the water that may contain foams, tiny flecks or globs, and mat floating on it.

What Are Harmful Algal Blooms or HABs?

Harmful algal blooms or HABs are formed when colonies of algae, like simple plants that live in freshwater and sea, grow out of control and produce destructive effects or toxic effects on fish, shellfish, people, marine, birds, and mammals. Examples of harmful algal blooms are Cyanobacteria, red tide, and blue-green algae.

How Are Algal Blooms Harmful?

People get sick when they come in contact with harmful algal bloom by :

• Drinking water is affected by harmful algal blooms.

• Fishing, kayaking, swimming, or wading through water.

• Eating seafood (fish or shellfish) is affected by harmful algal blooms.

• Breathing in mist or tiny water droplets that contain algal bloom.

What Types of Algae Causes Bloom?

The various types of the harmful algal bloom are:

• Euglena.

• Diatoms.

• Golden algae.

• Green algae.

• Cyanobacteria.

What Are the Effects of Harmful Algal Blooms?

Harmful algal blooms can :

• Produce dangerous toxins that can kill or sicken people and animals.

• They tend to create dead zones in the water.

• It increases treatment costs for drinking water.

• It hurts industries that depend on clean water.

What Are the Symptoms Caused by Harmful Algal Blooms?

Symptoms of harmful algal blooms:

• Eye irritation.

• Skin irritation.

• Throat irritation.

• Nose irritation.

• Irritation of the respiratory tract.

• Vomiting.

• Fatigue.

• Excessive salivation.

• Difficulty breathing.

• Staggered walking.

• Convulsion (medical condition when the body relaxes and contracts rapidly and results in uncontrolled shaking).

• Liver failure.

• Death.

How Is Harmful Algal Bloom Formed?

A harmful algal bloom is formed by slow-moving water, sunlight, and nutrients such as nitrogen and phosphorus derived from human activities.

What Are the Health Effects of Harmful Algal Bloom?

A harmful algal bloom has the potential to cause serious health problems and even death. For example, seafood contaminated by algal toxins called Alexandrium can lead to paralytic shellfish poisoning. Paralytic shellfish poisoning can cause paralysis and even death. Pseudo-nitzschia produces a toxin called domoic acid that can cause diarrhea, vomiting, seizure, confusion, permanent short-term memory loss, or death when consumed at a higher level. Harmful algal bloom can also occur in freshwater caused by Cyanobacteria microcystis, which produces liver toxins causing liver damage and gastrointestinal illness.

How to Detect the Presence of Harmful Algal Bloom?

Detection of harmful algal blooms helps to protect public health. An environmental sample processor is a robotic system designed by the Woods hole center for ocean and human health (WHCOHH) in Massachusetts. It can be submerged in water to test the presence of harmful algal bloom.

What Are the Toxins Made by Human Algal Bloom?

• Anatoxin.

• Microcystin.

• Cylindrospermopsin.

• Saxitoxin.

• Nodularin.

• Lyngbyatoxin.

• Brevetoxin.

• Azaspiracid.

• Ciguatoxins.

• Okadaic acid.

• Dinophysistoxin.

• Domoic acid.

What Causes Algae Blooms?

Many environmental factors influence the occurrence of algal blooms, including:

• Nutrients: They help in growth of algae. The main nutrients that help in the growth of algae blooms are nitrogen and phosphorus.

• Climate and Weather: Harmful algal bloom usually develops when the water temperature is higher or during warmer months of the year.

• Water Clarity: It allows more light to penetrate the water, which creates optimal growth conditions for harmful algal growth.

• Hydrology: Large quantities of water are required for the growth of harmful algal bloom.

• Biological Community Interactions: Involves the dead organic matter with nutrients that helps in propagating the growth of algae in water leading to the blooming of the harmful algae.

What Are the Possible Health Effects of Harmful Algal Bloom?

The harmful algal bloom, if swallowed, comes in skin contact or airborne water droplets while boating, swimming, tubing, waterskiing, bathing, or showering in water that contains harmful algae. The side effects of harmful algal bloom are cough, eye irritation, sore throat, rash, diarrhea, and headache.

When Do Harmful Algal Blooms Occur?

Algal blooms can occur any time of the year:

• Green algae and diatom blooms are commonly seen in spring.

• Cyanobacterial blooms occur during summer and early fall.

• Golden algae blooms are common during winter.

What Are the Effects of Climatic Change on Harmful Algal Bloom?

Climatic change can increase the rate of growth of harmful algal in brackish, salt, and freshwater.

How to Control Harmful Algal Bloom?

Controlling the harmful algal bloom by containment or reduction of an existing bloom. Control can be done by :

• Mechanical: It involves the removal of algal bloom by physical methods such as aeration to increase oxygen level in the water, which ultimately reduces the growth of algal bloom.

• Biological: Management includes the introduction of an organism that controls viruses, bacteria, predators, or parasites. For example, Cyanobacteria is used to retard the growth of harmful algal blooms.

• Chemical: Control involves chemical release into the environment to kill the algae.

How to Prevent Harmful Algal Bloom?

The methods to prevent the formation of harmful algal blooms are :

• The disposal of pet waste is a common source of excess bacteria and nutrients.

• Introduction of pond aeration and water movement through fountains or aeration.

• Installation of rain barrels in the community to reduce polluted runoff.

• Use of phosphorus-free detergents and fertilizers to limit nutrient-rich runoff.

• Implement landscape strategies like xeriscaping that increase groundwater filtration before the water enters the lake or pond.

• Monitoring the water quality regularly.

• Application of phosphorus binding products by professionals to prevent nutrients from supporting algal growth in lakes and ponds.

• Planting shrubs, grass, and flowers minimizes the need for high-nutrient chemicals in water bodies.

Conclusion:

Harmful algal blooms are dangerous to animals and humans. Some of the harmful algal blooms deplete the oxygen in the water, which can harm species important to the ecosystem. Reducing lawn fertilizer and detergent may prevent the formation of harmful algal blooms. In addition, a harmful algal bloom is associated with large-scale marine mortality events.