The effects of water pollution on aquatic life can not be counted knowing that every day the oceans and various other water bodies around us are being polluted.
The matter of the effects of water pollution on aquatic life seems not to be a popular topic now because the affected population are located underwater.
But, if we as humans don’t take this topic into deep consideration, we would eventually lose the most populated companion we have. This would surely cause a unbalance in our ecosystem.
Water is one of the main resources that guarantee life on Earth. However, its scarcity and pollution have caused millions of people to have poor access to this much-needed asset.
When foreign substances or contaminants are being introduced into water bodies that cause adverse effects or change the status of the water then, we can say the water is polluted.
According to NRDC,
“Water pollution occurs when harmful and toxic waste chemicals or other particles enter water bodies such as rivers, ponds, seas, oceans etc, gets dissolved in them or lie suspended in the water or gets deposited on the bed resulting in the degradation in the quality of water.”
Water pollution can occur through various forms of any substance which can be solid, liquid, gas, or energy (such as radioactivity, heat, sound, or light).
- Causes of water pollution
Though Humans are the main causes of water pollution which is triggered in many ways, water pollution has many sources but, they can be grouped into two:
- Natural Causes
Sometimes, water pollution can occur due to natural activities such as volcanic eruptions, animal waste, algae blooms, and residue from storms and floods.
Natural disasters also cause considerable water pollution. For example, floods and storms hurricanes often result in water being contaminated by the mixing of floodwaters with sewage.
In 2011, the Fukushima 1 nuclear power plant was hit by a 9.0 magnitude earthquake-triggered tsunami that resulted in the meltdown of three of its nuclear reactors.
One of the consequences of this disaster has been the leaking of highly radioactive water into the Pacific ocean.
- Anthropogenic Causes,
An increase in temperature results in the alteration of water by reducing the oxygen in its composition.
Deforestation causes sediments and bacteria to appear in the soil, therefore, contaminating groundwater.
Every day sewage and sometimes even garbage from cities are dumped into the oceans resulting in the tremendous pollution of the water.
In some places, rivers and the sea are internationally used for the discharge of untreated sewage and industrial waste.
In the same way, pesticides used in agricultural fields filter through underground channels and reach the consumption networks
Surface runoff and storm-water drain in urban areas carry chemical contaminants into rivers. In rural areas, runoff containing chemical fertilisers, pesticides, and farm animal faeces makes its way into rivers and streams.
Water pollution can also come from accidental oil spills. Oil spills are difficult to clean up and the costs of doing so are enormous. When people are exposed to oil spills, it can cause skin irritations and rashes.
A familiar type of pollution on both land and water bodies is litter. This is when people don’t put their unwanted man-made objects away instead of putting them in the appropriate place.
Litter is not just untidy. It can become a major threat to wildlife in both rural and marine environments.
One of the major plagues of our aquatic environment today is water pollution. Yes, many can say climate change is the major environmental problem our world faces.
But it may shock you to know that one of the underlying causes of climate change and global warming is water pollution.
When water is polluted, they are some ways that this pollution leads to climate change and global warming.
The water body can reduce its intake of carbon dioxide (CO2) when polluted especially when there exists in the water body algae caused by eutrophication (the increase in the nutrients in the water body).
The oceans, seas, and other water bodies are major sinks for carbon dioxide which is a major greenhouse gas and if these water bodies can’t take in more carbon dioxide then, the greenhouse gas would find its way into the atmosphere increasing global warming and climate change.
A report by NASA satellite imagery showed that the primary productivity of the oceans is dropping by 1% year on year.
Now if 80% of our oxygen comes from the oceans and it’s dropping at the rate of 1% per year means that at this point, 8% of the plants of the planet are dying every year.
Due to the effects of water pollution, we must ensure the availability, sustainable management and sanitation for all.
Though it’s very much known that man is the main cause of water pollution, humans are also harmed by water pollution.
This can be by contracting illnesses like cholera, dysentery and so on when drinking or using contaminated water.
This is especially in developing countries where millions of people lack access to safe drinking water due to the contamination of untreated sewage and other pollutants.
Top 11 Effects of Water Pollution on Aquatic Life.
Many research has shown that there is a greater proportion of diseased fish in polluted compared to non-polluted marine sites.
Some examples of fish diseases that can be linked to water pollution include surface lesions attributed to Serratia plymuthica, fin and tail rot caused by Aeromonas hydrophila and
Pseudomonas fluorescens, gill disease resulting from the activity of Flavobacterium spp., vibriosis is caused by Vibrio anguillarum, and enteric redmouth (causal agent, Yersinia ruckeri).
Research has shown that some of the diseases caused by Aeromonas, Flavobacterium and Pseudomonas are caused by a decrease in water quality, i.e. higher than usual quantities of organic material, oxygen depletion, changes in pH values and enhanced microbial populations.
Some infections with Serratia and Yersina may well have reflected contamination of waterways with domestic sewage, e.g. leaking septic tanks. At least one outbreak of vibriosis was linked to high concentrations of copper, which may have debilitated the fish making them more susceptible to disease.
Below are the top 11 effects of water pollution on aquatic life:
- The Rise in Mortality Rate and The Disappearance of Biodiversity and Aquatic Ecosystems
- Damage to Coral Reefs
- Massive Migration of Aquatic Life
- Adverse Impacts on the Birth Rates of Aquatic Life
- Disruption of the Food Chain of Aquatic Life
- Loss of Biodiversity
- Reduction in the Life Span of Aquatic Life
- Mutation of Aquatic Animals
- Effect of Water Pollution by Marine Debris on Aquatic Life
- The Effect of Ocean Acidification on Aquatic Life
1. The Rise in Mortality Rate and The Disappearance of Biodiversity and Aquatic Ecosystems:
The rise in mortality rate and the disappearance of biodiversity and aquatic ecosystems is one of the top 11 effects of water pollution on aquatic life.
As runoff containing chemical fertilisers, pesticides and farm animal faeces makes its way into rivers and streams,
it can result in eutrophication which is the process by which a high concentration of nutrients, particularly phosphates and nitrates, makes their way into the water bodies.
This results in algae blooms and such algal bloom may totally cover the water surface and often releases toxins and also causes deficiency of oxygen.
And also when these algae die, they consume the oxygen in the body of the water, thereby creating a state of hypoxia which in turn causes the death of other organisms such as fish.
Aquatic animals like planktons, molluscs, fish will die due to toxicity and lack of oxygen.
Some species like Tubifex and Chironomus larva can tolerate highly polluted and low DO water so, are considered as indicators of water pollution.
Also, a higher amount of organic waste increases the rate of activity of decomposers which is collectively called sewage fungus and this property of becoming decomposed through microbial activity is called putrescibility.
The higher O2 consumption, thereby (an indicator of pollution) causes a drop in dissolved oxygen (DO) content of water.
The demand for O2 is directly related to the increasing input of organic waste and is expressed as Biochemical Oxygen Demand (BOD).
The lower O2 content kills many sensitive aquatic organisms like plankton, molluscs, fish etc.
When large quantities of pollutants are released there may be an immediate impact as measured by large-scale sudden mortalities of aquatic organisms, e.g. fish kills resulting from contamination of waterways with agricultural pesticides.
Oil spills such as the Rena oil spill of the east coast of New Zealand’s North Island in 2011 have huge environmental impacts consequently causing the deaths of a large number of aquatic life and seabirds.
For example, the impacts of discarded plastic bags which killed tens of thousands of whales, birds, seals and turtles every year as they often mistake plastic bags for food such as jellyfish.
It becomes impossible for marine animals to find the right habitat for their continued existence causing the disappearance of biodiversity.
2. Damage to Coral Reefs:
Damage to coral reefs is one of the top 11 effects of water pollution on aquatic life.
Oil spills damage marine biodiversity and also damage coral reefs. Plastic waste can encourage the growth of pathogens in the ocean.
According to a recent study, scientists concluded that corals that come into contact with plastic have an 89 per cent chance of contracting disease, compared with a 4 per cent likelihood for corals that do not.
3. Massive Migration of Aquatic Life:
The massive migration of aquatic life (fishes) is one of the top 11 effects of water pollution on aquatic life.
Like humans, aquatic life also looks for greener pastures. And so if their natural habitat becomes polluted, they migrate in search of another habitat. This also creates competition with the aquatic life located in the area.
In the process of migration, some of them might die off especially their younger ones as a result of lesser adaptability capability to the new environment and because of competition with other aquatic life.
Bio-accumulation is one of the top 11 effects of water pollution on aquatic life.
Several non-biodegradable pollutants (DDT radionuclide etc) get accumulated in fat-containing tissues in increasing concentrations along the food chain and prove hazardous to the organisms.
It is called Biological Magnification/Bio-concentration/Bio-accumulation e.g, the use of DDT to check the growth of mosquitoes.
In the Island of the USA, DDT sprayed for a few years resulted in a sharp decline in fish-eating birds because a higher amount of pesticide causes cerebral haemorrhage, cirrhosis of the liver, thinning of the eggshell, malfunctioning of sex hormones, hypertension etc.
The decline in the population of the bald eagle is attributed to this cause.
Lower levels of discharge may result in an accumulation of pollutants in aquatic organisms. The results, which may occur long after the pollutants have passed through the environment, include diseases like immunosuppression, reduced metabolism, and damage to gills and epithelia.
5. Adverse Impacts on the Birth Rates of Aquatic Life:
Adverse impacts on the birth rates of aquatic life are one of the top 11 effects of water pollution on aquatic life.
A high temperature of water lowers the rate of dissolved O2 in water. It has a lower rate of putrescibility resulting in increased organic loading. Many animals such as Salmon, Trout fail to reproduce under such conditions.
Also, when water is polluted by chemicals and heavy metals, the ability of some of these aquatic lives to reproduce is adversely impacted hence, reducing their birth rate.
On many beaches, plastic pollution is so pervasive that it’s affecting turtles’ reproduction rates by altering the temperatures of the sand where incubation occurs.
6. Disruption of the Food Chain of Aquatic Life:
Disruption of the food chain of aquatic life is one of the top 11 effects of water pollution on aquatic life.
When water is polluted by chemicals and heavy metals, these toxic elements can find their way up the food chain as predator eats prey.
7. Loss of Biodiversity:
Loss of biodiversity is one of the top 11 effects of water pollution on aquatic life.
Biocide residue, PolyChlorinated Biphenyls (PCBs) and heavy metals etc can directly eliminate different species of the aquatic ecosystem.
8. Reduction in the Life Span of Aquatic Life:
Reduction in the life span of aquatic life (fishes) is one of the top 11 effects of water pollution on aquatic life.
The contamination of water ecosystems by chemicals and heavy metals has very harmful effects on aquatic life.
These contaminants are known to be implicated in the reduction of an organism’s life span.
9. Mutation of Aquatic Animals:
The mutation of aquatic animals is one of the top 11 effects of water pollution on aquatic life.
Heavy metals from industrial processes can accumulate in nearby lakes and rivers. These are toxic to marine life such as fish and shellfish, and subsequently to the humans who eat them. Heavy metals can slow development; result in birth defects and some are carcinogenic.
Contamination of the aquatic environment can make it difficult for light to pass through. When this is the case, photosynthesis can’t take place, thereby disrupting the growth of micro-organisms and plant that contributes to the growth of freshwater fish thereby causing mutation.
10. Effect of Water Pollution by Marine Debris on Aquatic Life.
Aquatic life is also threatened by solid waste such as plastic, metals, cigarette buts and others. However, the principal solid pollutant of our water resources is plastic.
40,000 tons of plastic are currently floating on the oceans’ surface and that represents 80% of all trash floating in the oceans (46,000 pieces per square mile).
These solid wastes present a real danger for aquatic life because they can be ingested by animals and cause their suffocation starvation and death.
According to the United Nations, marine debris is responsible for harming more than 800 different species of marine life.
It is estimated that up to 13 million metric tons of plastic end up in the ocean each year—the equivalent of a rubbish or garbage truck load’s worth every minute. Lower levels of discharge may result in an accumulation of pollutants in aquatic organisms.
The results, which may occur long after the pollutants have passed through the environment, include diseases like immunosuppression, reduced metabolism, and damage to gills and epithelia.
This might be an extra but it’s worthy to be one of the top 11 effects of water pollution on aquatic life.
11. The Effect of Ocean Acidification on Aquatic Life
Ocean acidification is the decrease of pH of water surfaces due to the absorption of carbon emissions. Seas absorb as much as a quarter of all man-made carbon emissions and the problem is rapidly worsening.
It is estimated that by the end of this century if we keep pace with our current emissions practices, the surface waters of the ocean could be nearly 150% more acidic than they are now.
Aquatic life is deeply affected by these chemical alterations of water surfaces. Ocean acidification is one of the top 11 effects of water pollution on aquatic life.